Abstracts
Neurotrauma 2024
San Francisco, California

Ms. Natalie Jenkins¹, Prof. Graciela Muniz-Terrera², Prof. William Stewart^1,3

¹University Of Glasgow, Glasgow, United Kingdom, ²University of Ohio, Athens, United State of America, ³NHS Greater Glasgow and Clyde, Glasgow, United Kingdom

Objectives: The link between traumatic brain injury (TBI) and neurodegenerative disease is well established. 30% of women will experience intimate partner violence (IPV), often with repetitive TBI. However, long-term effects of IPV on brain aging in later life have not been investigated. To address this, we compare cognitive performance and structural brain volumes in older adults with a history of physical, sexual, or emotional IPV to individuals with no exposure.

Methods: 18,555 participants from UK BioBank were included in these analyses. 5225 reported IPV of which, 2257 reported physical IPV, 2507 emotional IPV, and 461 sexual IPV. All participants completed neuropsychological testing and brain MRI. Participants with and without exposure to IPV were compared on eight tests of neuropsychological function, as well as structural brain volumes.

Results: The mean age of participants was 65.43 (SD=7.58) years. Physical IPV, but not emotional or sexual IPV, was associated with reduced hippocampal (p=.027) and white matter volumes (p=.033), and poorer cognitive performance in fluid intelligence (p=.009), trail making (p=.004), and digit symbol substitution (p=.010) compared to participants with no exposure. In those with a history of physical IPV, higher frequency of abuse was associated with reduced hippocampal volumes (p=.040) and poorer performance on all cognitive tests (p>.001) except reaction time.

Conclusion: Our results reveal reduced structural and functional brain changes in older adults associated specifically with physical IPV. These highlight the importance of considering the long-term effects of IPV related TBI on brain ageing and neurodegenerative disease risk.

Supported by The Drake Foundation.

Miss. Oluwagbemisola Aderibigbe¹, Dr. Levi B. Wood^1,2,3, Dr. Susan S. Margulies¹

¹Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, United States, ²George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, United States, ³Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, United States

Mild traumatic brain injury (mTBI) triggers pathophysiological cascades that induce neurodegeneration. Previous work in our lab has shown that 20mg/kg/day Cyclosporine A infused over 24h (starting 6h post-mTBI) displays neuroprotective effects by improving mitochondrial health and decreasing injured brain volume. To explore the genes and biological processes modulated by Cyclosporine A, we profiled piglet hippocampus + amygdala brain region after a rapid non-impact rotation (RNR) mTBI. 4-week-old female Yorkshire piglets were anesthetized and assigned to one of 4 groups: sham injury (N=18); RNR injury with brain perfused and collected at 24 hours (N=10) or 1 week (N=15); and RNR followed by 20mg/kg/day Cyclosporine A infusion, starting at 6 hours post-injury (N=10). Brains were formalin-fixed paraffin embedded and sectioned for RNA-sequencing.

Differential expression analysis revealed that 5 genes downregulated at 24h post-mTBI (compared to Sham) were restored to Sham levels by Cyclosporine A treatment: VAMP2, AIF1L, OLFM2, RAMP3, and LRFN1. Meanwhile, 6 genes upregulated at 24h post-mTBI were restored to Sham levels by Cyclosporine A: NXPH1, LYRM1, AHR, FHL5, KIAA0586, and MGP. These gene alterations are associated with improved synaptic signaling, protective immune signaling, mitochondria protection, and neurogenesis. Weighted gene co-expression network analysis (WGCNA) revealed upregulated Cyclosporine A responses in 4 out of 13 modules, compared to mTBI without treatment at 24 hours or 1 week, associated with neuronal and immune GO biological processes. We conclude that 20 mg/kg/day Cyclosporine A infusion, initiated 6h post-mTBI, accelerates improved neuronal and immune protective processes. Funded by Georgia Research Alliance and NIH (R01NS097549, U01NS069545, R01NS039679).

Dr. Marissa Smail¹, Rebecca Boland², Michaela Breach¹, Courtney Dye¹, Ashley Walters¹, Olga Kokiko-Cochran^2,3,4, Kathryn Lenz^1,2,3,4

¹Department of Psychology, Ohio State University, Columbus, United States, ²Department of Neuroscience, Ohio State University, Columbus, United States, ³The Institute for Behavioral Medicine and Research, Ohio State University, Columbus, United States, ⁴The Chronic Brain Injury Program, Ohio State University, Columbus, United States

Children are especially vulnerable to the adverse effects of traumatic brain injury (TBI), given that their brains are still developing at the time of injury. The immune system has been implicated in adult TBI mechanisms and plays numerous roles in brain development. Here we developed a rat model of pediatric TBI to examine the relationship between early life TBI, immune cells, and long-lasting behavioral outcomes.

At postnatal day 15, male and female rats were randomly assigned to 3 groups: Naïve, Sham, or TBI (n=12/group). Injury was delivered via lateral fluid percussion. Rats were either euthanized at 3 days post injury (DPI) for neuroanatomical analyses of microglia and mast cells or aged out to adulthood for cognitive, social, and anxiety-like behavioral testing.

At 3 DPI, microglia medial to the injury expressed significantly more CD68 (p=0.023) in TBI rats than Naïve or Sham rats. Mast cells were more abundant (p=0.020) and more degranulated (p=0.022) throughout the brain in TBI rats. Both results indicate a heightened immune response acutely following pediatric TBI. Preliminary behavioral results indicate that adult TBI animals exhibit no change in spatial memory (p=0.48) but increased spontaneous alternation (p=0.001). Analyses of other behavioral tasks are ongoing.

Early life TBI leads to enhanced immune activity in both microglia and mast cells. Given the many important roles of microglia in development, the enhanced immune activity observed acutely following pediatric TBI has the potential to contribute to long-lasting consequences of this early life insult.

Supported by NIH R01 NS1030517 to KML.

Dr. Javier Allende Labastida¹, Dr. Preeti Vyas¹, Dr. Nirnath Sah¹, Dr. James L. Sowers¹, Dr. Maria Paula Avalos¹, Jinhuan Liu¹, Dr. Raymond C. Koehler¹, Dr. Sujatha Kannan¹

¹Johns Hopkins School Of Medicine, Baltimore, United States

Traumatic brain injury (TBI) is a leading cause of morbimortality in children worldwide. Diffuse axonal injury is associated with high mortality and long-term sequelae; it accounts for ∽1/3 of hospital admissions in children <2-years-old. Postnatal formation and maturation of white matter in the rabbit closely resembles human brain development, making the rabbit an ideal model to study diffuse axonal injury. To better explore neonatal and pediatric brain injury, we developed a novel juvenile rabbit model of TBI using the CHIMERA system, aiming to replicate mechanisms of injury observed in accidental and non-accidental TBI in humans. The goal of this new model is to provide insights into diffuse axonal injury and development of therapeutic strategies.

In this study, neonatal and pediatric kits were randomly assigned into sham, single (sTBI) or repetitive injury groups (rTBI, two injuries, 24hrs apart). Kits were subjected to impacts at ∽6.1 or ∽4.5 m/sec for neonatal (PND5-7) sTBI and rTBI, respectively, and ∽9.25 or ∽10.5 m/sec for pediatric (PND17-19) sTBI and rTBI, respectively. Injured kits showed periods of apnea, as seen in patients, and decreased bodyweight in both age groups. Neonatal sTBI showed developmental delays, and signs of vestibular dysfunction. All TBI groups/ages showed significant motor and cognitive deficits two weeks post-injury.

Our findings demonstrate pathological similarities to human TBI, including developmental delays, neurocognitive deficits, and neuroinflammation (periventricular microgliosis). These exciting results show the clinical relevance of this pediatric TBI model.

Support: This work was supported partly by the Richard J Traystman professorship endowment (SK).

Dr. James Sowers¹, Dr. Javier Allende Labastida¹, Dr. Wathsala Liyanage², Dr. Zhi Zhang¹, Dr. Rangaramanujam Kannan², Dr. Sujatha Kannan

¹Department of Anesthesiology and Critical Care Medicine Johns Hopkins University School of Medicine, Baltimore, United States, ²Center for Nanomedicine, Department of Ophthalmology Wilmer Eye Institute Johns Hopkins University School of Medicine, Baltimore, United States

In this study, we report metabolic changes from a juvenile rabbit traumatic brain injury model using a controlled cortical impact model. Metabolic changes were determined through a mass spectrometry-based metabolomics approach where post-natal day five rabbit kits were injured. Ipsilateral brain regions to the impact site were collected one and three days after injury and compared to sham controls. Six biological replicated samples were analyzed per experimental condition. At one day and three days post injury, markers of oxidative stress/ antioxidant utilization were elevated. In addition, several metabolites in the kynurenine pathway were elevated, including, kynurenate, a neuroprotective metabolite. Finally, perturbations in bioenergetic metabolites including glucose, N-acetyl aspartate, creatine, urate, NAD+/NADH and coenzyme A were found one day after injury. Three days after injury, NAD+ and NADH continued to decrease. The kynurenine pathway is the only pathway that contributes to de novo NAD+/NADH biosynthesis. In the central nervous system, the kynurenine pathway is thought to occur predominantly in microglia. These results are in accordance with our previous data demonstrating an increase in indoleamine 2,3-dioxygenase (rate limiting enzyme in the kynurenine pathway) and microglial staining in the ipsilateral hemisphere that persists up to 21 days post-injury. Our results help improve our understanding of the temporal evolution of metabolic changes and the immune response during injury and repair after TBI in the hopes of identifying novel therapeutic strategies and targets. Future studies will focus on probing the kynurenine pathway and bioenergetic homeostasis within microglia under pro-inflammatory/injured conditions.

Mr. Carlos Almeida¹, Ms. Carleigh Litteral¹, Dr. David Magnuson¹

¹University Of Louisville, Louisville, United States

Following a traumatic spinal cord injury (SCI), patients experience profound inactivity and/or limb disuse (ILD) for weeks before they start rehabilitation. In contrast, Sprague-Dawley female rats with less than 15% spared white matter following a T2 contusion SCI may ambulate upwards of 100 meters per night within 2 weeks of an injury and can achieve plantar hindlimb stepping. Several factors prevent humans from experiencing functional recovery similar to rodents with comparable injuries, but the difference in activity following a SCI between humans and rats may be one factor that helps to explain some differences in recovery and, in part, the difficulty in translation treatments from bench-to-bedside. Here, we developed a model of simulated bedrest (BR) for rats to test if ILD disrupts recovery following a SCI. Within 24 hours of a T2 225 kdyn contusion SCI animals were housed in a standard rat cage or a BR cage (3.5 x 8 x 3 Inches) for 8 weeks. While BR did not affect overground ambulation, it affected gait and coordination, and increased thermal sensitivity in the tail. Unexpectedly, rats housed in standard cages had more severe injuries compared to those in simulated BR which suggests inactivity spares white matter following injury. Overall, it appears that the effect of BR on primary locomotor and sensory function after spinal cord injury in rats was modest despite the dramatic decrease in activity. It remains to be determined if simulated BR influenced other systems such as metabolism and autonomic function.

Mx. Adriana Hernandez Vasquez¹, Dr. Brian N. Johnson², Anthony Farrugia¹, Dr. Akiva S. Cohen¹

¹University Of Pennsylvania, Philadelphia, United States, ²Children’s Hospital of Philadelphia, Philadelphia, United States

The hippocampus, a brain structure highly involved in learning and memory, is susceptible to impairment from traumatic brain injury (TBI). Reduced hippocampal CA1 output due to augmented inhibition was previously demonstrated as decreased action potential firing from pyramidal neurons (PNs). The action potential firing of PNs is strongly modulated by inhibitory cholecystokinin interneurons (CCK INs). Importantly, CCK IN GABAergic signaling onto PNs is regulated by depolarization induced suppression of inhibition (DSI). This study aimed to measure DSI before and after TBI to determine if disruption in this circuit-mechanism contributes to augmented inhibition in area CA1. To investigate the changes in DSI after mild TBI, mice were injured using the well-validated lateral fluid percussion injury model of TBI. Spontaneous inhibitory postsynaptic currents (sIPSCs) were recorded from PNs in area CA1 using whole-cell voltage clamp recording. PNs were held at -70mV and DSI was induced with a 5 second depolarizing step to 0mV. PNs from both sham (n = 16, p > 0.0001) and injured (n = 11, p = 0.0021) animal brain slices showed a decrease in charge transfer after the depolarizing step, indicating a decrease in sIPSC activity after DSI induction. Interestingly, there was a greater reduction in charge transfer after DSI for the injured group compared to sham (p = 0.0148). These results indicate that the post-injury increase in inhibition from CCK INs was not due to decreased DSI and may instead reflect decreased intrinsic excitability and/or net excitatory synaptic input of CCK INs. Supported by NIH-NICHD Grant R37HD059288.

Mr. Xianghao Zhan¹, Dr. Zhou Zhou², Dr. Yuzhe Liu³, Mr. Nicholas J. Cecchi¹, Dr. Marzieh Memar⁴, Dr. Michael M. Zeineh¹, Dr. Gerald A. Grant⁵, Dr. David B. Camarillo¹

¹Stanford University, Stanford, United States, ²KTH Royal Institute of Technology, Stockholm, Sweden, ³BeiHang University, Beijing, China, ⁴University of Texas at San Antonio, San Antonio, United States, ⁵Duke University, Durham, United States

Maximum principal strain rate (MPSR) has been shown in multiple studies as an effective biomechanical parameter predictive of traumatic brain injury (TBI) across multiple species. However, there have been two schemes of MPSR calculation based on previous literature: either by directly differentiating maximal principal strain (MPS) over time (MPSR1) or using the first eigenvalue of the strain rate tensor (MPSR2). This study evaluates the differences between two MPSR calculation schemes in TBI prediction using eight head impact datasets (n=3825) across different contact sports, simulations and car crashes. Recognizing the ambiguity in MPSR calculation, we compared the implications of these schemes on TBI prediction accuracy. Our method involved analyzing brain deformations calculated using the KTH finite element head model, comparing MPSR and the product of MPS and MPSR (MPS×SR) at both the element and whole-brain levels. The main results revealed significant differences in the MPSR calculated by these two schemes (p<0.05, for most datasets) and differences in the prediction of TBI between the two schemes, with scheme 2 showing better fit in logistic regression models for TBI diagnosis data (deviance: 41.1, compared with 42.0 from scheme 1). This suggests that MPSR2 may more accurately correlate with injury outcomes. The study concludes that while both MPSR1 and MPSR2 are utilized in TBI research, scheme 2’s calculation method provides a closer association with observed TBI diagnosis, highlighting the need for specificity in MPSR calculation methods to enhance predictive accuracy in TBI studies.

Ms. Shraddha Pandey¹, Dr. Geoffrey Manley^2,3, Amy Markowitz², Dr. John K Yue^2,4, Dr. Christopher B Colwell⁵, Dr. Alan HB Wu⁶, Dr. Debbie Y Madhok⁵

¹University of California, San Francisco, School of Medicine, San Francisco, United States, ²University of California San Francisco, Neurological Surgery, San Francisco, United States, ³UCSF Weill Institute for Neurosciences, San Francisco, United States, ⁴San Francisco General Hospital, Brain and Spinal Injury Center, San Francisco, United States, ⁵Department of Emergency Medicine, University of California, San Francisco, San Francisco, United States, ⁶Department of Laboratory Medicine, University of California, San Francisco, San Francisco General Hospital, San Francisco, United States

The rapid, point-of-care iSTAT mTBI Plasma Test (iSTAT test), was cleared by the FDA to detect levels of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase-L1 (UCH-L1); elevated levels of the biomarkers were validated as a means to assist clinicians to determine whether head CT was indicated. We compared correlation of positive CT with varying levels of GFAP/UCH-L1 measured by the iSTAT for mTBI patients with a Glasgow Coma Scale (GCS) score of 13-15 presenting within 12 hours of non-penetrating head injury. We included 43 cases where an iSTAT test and head CT were ordered for an mTBI patient in the ED. iSTAT tests were documented as either “elevated” or “not elevated” in the electronic medical record (EMR) with specific concentrations of GFAP and UCH-L1 recorded. Thirty-three iSTAT results were documented as elevated, with a median GFAP of 82 pg/ml, IQR (36, 140) and median UCH-L1 of 489.5 pg/ml, IQR (235, 805). Ten tests were not elevated, with median GFAP <30 pg/ml and median UCH-L1 241 pg/ml, IQR (200, 240). Of non-elevated iSTAT cases, 100% of cases showed no findings on head CT consistent with TBI. Thus, among mTBI patients at a Level 1 Trauma Center tested within 12 hours of non-penetrating head injury, GFAP and UCHL1 levels read as “not elevated” on the iSTAT were 100% sensitive in predicting a negative head CT; these patients could likely have benefited from CT diversion, avoiding radiation exposure and potentially, shorter ED length of stay.

Mr. Jonathan Vincent^1,2,3,4, Dr. Teresa Macheda², Mrs. Kelly Roberts², Mrs. Heather Spearman², Dr. Chris Norris^1,3, Dr. Adam Bachstetter^1,2,3

¹University of Kentucky College of Medicine, Department of Neuroscience, Lexington, United States, ²Spinal Cord and Brain Injury Research Center, Lexington, United States, ³Sanders-Brown Center on Aging, Lexington, United States, ⁴University of Kentucky College of Medicine, MD/PhD Program, Lexington, United States

Objective: This study was designed to evaluate hippocampal neuronal functions, specifically targeting basal synaptic strength, presynaptic excitability, and population spike threshold at 1 week, 3 weeks, and 6 weeks after a closed-head injury (CHI) mouse model of traumatic brain injury (TBI).

Method: 4 month old wild-type (C57BL/6) male mice underwent either a sham procedure or CHI to model TBI. We assessed neuronal function within the CA1 and dentate gyrus (DG) regions of the hippocampus at 1 week, 3 weeks, and 6 weeks post-injury using extracellular field potential recordings. Our evaluations focused on measuring basal synaptic strength, presynaptic excitability, and population spike threshold via input-output curves.

Results: Preliminary findings indicate that CHI mice exhibited alterations in hippocampal neuronal functions compared to sham controls at 6 weeks post-injury. In the CA1, CHI mice demonstrated a decrease in basal synaptic strength concurrent with increased presynaptic excitability, while population spike threshold was unaffected. In the DG, basal synaptic strength remained unchanged, while both presynaptic excitability and population spike threshold were reduced.

Conclusion: The differential effects observed between the CA1 and DG highlight the nuanced vulnerability of hippocampal circuits to injury, suggesting that TBI induces a multifaceted disruption of synaptic homeostasis. These findings not only deepen our understanding of the pathophysiological consequences of TBI but also emphasize the critical need for targeted therapeutic strategies that address the specific neuronal dysfunctions associated with different hippocampal regions.

Acknowledgements: Support for this study was provided by the NIH T32AG078110, R01NS120882, and R01NS103785.

Dr. John Yue¹, Ms. Leila Etemad¹, Dr. Thomas van Essen², Dr. Mahmoud Elguindy¹, Dr. Patrick Belton³, Dr. Lindsay Nelson⁴, Dr. Michael McCrea⁴, Dr. Shawn Eagle⁵, Dr. Frederick Korley⁶, Dr. Claudia Robertson⁷, Dr. Ann-Christine Duhaime⁸, Dr. Cathra Halabi⁹, Ms. Gabriela Satris¹, Ms. Joye Tracey¹, Ms. Christine Gotthardt¹, Mr. Justin Wong¹, Dr. Phiroz Tarapore¹, Dr. Michael Huang¹, Dr. Joseph Giacino¹⁰, Dr. Amy Markowitz¹, Dr. Pratik Mukherjee¹¹, Dr. Esther Yuh¹¹, Dr. Alex Valadka¹², Dr. Ava Puccio⁵, Dr. David Okonkwo⁵, Ms. Xiaoying Sun¹³, Dr. Sonia Jain¹³, Dr. Geoffrey Manley¹, Dr. Anthony DiGiorgio¹

¹University Of California, San Francisco, San Francisco, United States, ²Leiden University Medical Center, Leiden, The Netherlands, Leiden, The Netherlands, ³Department of Neurological Surgery, University of Wisconsin-Madison, Madison, United States, ⁴Department of Neurological Surgery, Medical College of Wisconsin, Milwaukee, United States, ⁵Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, United States, ⁶Department of Emergency Medicine, University of Michigan, Ann Arbor, United States, ⁷Department of Neurological Surgery, Baylor College of Medicine, Houston, United States, ⁸Department of Neurological Surgery, Massachusetts General Hospital, Boston, United States, ⁹Department of Neurology, University of California, San Francisco, San Francisco, United States, ¹⁰Department of Physical Medicine and Rehabilitation, Harvard Medical School and Massachusetts General Hospital, Boston, United States, ¹¹Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, United States, ¹²Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, United States, ¹³Biostatistics Research Center, Herbert Wertheim School of Public Health and Longevity Science, University of California, San Diego, San Diego, United States

Objectives: An estimated 7-23% of traumatic brain injury (TBI) patients have multiple TBIs, and its risk to outcomes after another acute moderate-to-severe (msTBI) is not well-understood. Associations between prior TBI history, in-hospital mortality, and outcomes across 12-months post-injury were examined in a prospective United States msTBI cohort.

Methods: Hospitalized subjects with ED arrival Glasgow Coma Scale score (GCS)=3-12 were extracted from the TRACK-TBI Study (2014-2018). Prior TBI was determined using the Ohio State University TBI Identification Method. Competing risk regressions adjusting for age, sex, psychiatric history, GCS, and injury severity examined associations between prior TBI and in-hospital mortality, with hospital discharge=alive as the competing risk. Adjusted hazard ratios (aHR; [95% confidence interval]) were reported. Multivariable regressions evaluated associations between prior TBI, mortality, and unfavorable/favorable outcome (Glasgow Outcome Scale-Extended (GOSE)=1-3/4-8) at 3-/6-/12-months after msTBI.

Results: In 411 subjects (no prior TBI=78.6%, yes prior TBI=21.4%), prior TBI was associated with male sex (87.5%/77.1%, p=0.037) and psychiatric history (34.1%/21.1%, p=0.016). Median length of stay was 14 days (IQR=6-24) and in-hospital mortality was 10.1%. Competing risk regressions indicated prior TBI was associated with greater risk of in-hospital mortality (aHR=1.98 [1.05-3.76], p=0.036), but not with likelihood of hospital discharge=alive. Prior TBI was not significantly associated with mortality or unfavorable outcomes at 3-/6-/12-months post-injury.

Conclusions: Prior TBI is independently associated with risk of in-hospital mortality after acute msTBI. Sociodemographic and clinical factors specific to msTBI patients with prior TBI, and the burden of prior TBIs, constitute next-step investigations to improve our understanding of this elevated risk.

Mr. Bahram Jafari¹, Dr Marzieh Memar¹

¹University of Texas at San Antonio, San Antonio, United States

Sex differences in brain structure significantly influence traumatic brain injury (TBI) onset and progression, yet this area is understudied. Herein, we developed sex-specific brain anatomical (macroscale) and axonal tract (mesoscale) templates and explored the sex-variations at subject level using a set of T1-MRI (609 males, 721 females) and DTI images (506 males, 594 females). The FreeSurfer, ANTs, and DSI-Studio packages were used. We investigated overall/regional volumes, DTI metrics (including fractional anisotropy (FA), mean diffusivity, and radial diffusivity), and connectivity matrix across 23 brain regions. The brain connectome was derived by multiplying the fiber tract counts and the FA values within the connecting tracts, quantifying the connection strength within each pair of regions. Our subject-wise analysis revealed significant sex-based differences (Mann-Whitney p-values < 0.05) across most studied regions for all parameters. The largest sex differences in brain connections were observed in five regions: corpus callosum and right/left cortex and cerebral white matter, all stronger in females. Brain regions were typically larger in males, yet females had higher fractional volumes in the majority of regions except for CSF and ventricles, known for their cushioning effect during head impacts. Additionally, the sex-specific templates better represented their targeted sex compared to opposite or mixed-sex populations as evaluated by root-mean-square-errors when comparing the DTI metrics and connectivity from the DTI templates against the median of subjects and deformation field in registering the subjects to the T1-MRI templates. Our findings highlight the necessity of sex-specific templates in accurate brain modeling and TBI research. Funded by NSF-2138719.

Mr. Amirhossein Bagherian Rekavandi¹, Ms. Allison Kosub¹, Dr. Morteza Seidi¹, Dr. Marzieh Memar¹

¹University Of Texas At San Antonio, San Antonio, United States

Understanding the relationship between pathology, psychological, and behavioral changes offer crucial insights into traumatic brain injury (TBI) mechanisms. This study investigates the correlation between psychological parameters measured in open-field test and astrocyte reactivities within specific brain regions by employing a ferret TBI model (CHIMERA, Canada), chosen due to the similarity of ferret brain structure and astrocytic territory to humans. Animals were divided into repeated TBI (n=5, one ∼15m/s plus three ∼10m/s impacts, 10-minutes apart) and sham (n=3) groups. Behavioral tests were performed at pre-TBI and at 6-hours, 1-day, 3-days, and 7-days post-TBI. Brains were sectioned at 2mm and GFAP stained at 7-days post-TBI, and analyzed for overall and regional astrocytic reactivity. Results revealed significant differences (Wilcoxon Signed-Ranks Test, p-value <0.05) in anxiety-associated parameters—maximum speed, average speed, and total distance traveled—especially at 3- and 7-days post-TBI, when the effects of medication and anesthesia had disappeared, indicating a delayed development of anxiety in TBI group compared to stability or decline of anxiety in Sham group. Moreover, significantly higher astrocyte activation was observed in TBI group compared to Sham group (Mann-Whitney test, p-value<0.05), especially in white matter region, which cause disruption in neural communication and synaptic balance, contributing to heightened anxiety. Spearman correlation analysis showed a strong link between the psychological changes and astrocytic reactivity in the TBI group, suggesting heightened TBI-induced astrocyte reactivity in white matter region correlate with more changes in anxiety levels, highlighting astrocytes’ critical role in TBI response. Funded by UTSA-SwRI CONNECT program.

Mrs. Lauren Rooks¹, Dr. Nicholas Port¹

¹Indiana University, Bloomington, United States

Objective: The purpose of this study is to A) rigorously evaluate the Sport Concussion Assessment Tool (SCAT) symptom list and improve the sensitivity and sensitivity by creating a mini-SCAT (mSCAT) and B) identify an added utility of doing additional tests/exams in addition to mSCAT. Methods: Cohort study of collegiate athletics and military service academies. 59,901 athletes and cadets were enrolled in the NCAA/DOD CARE consortium; 5,075 were diagnosed with a concussion. These analyses utilize the SCAT Symptoms and other concussion assessments in concussed versus non-concussed individuals. Results: Individual symptoms demonstrate a variety of Cohen’s-d effect sizes, the smallest being Nervous/Anxious (d=0.23) and Sadness (d=0.43). The largest effects are Pressure in Head (d=2.59), Don’t Feel Right (d=2.51), and Headache (d=2.85). The largest AUCs for concussion assessments are BSI Somatization Score (0.75), SCAT Symptom Severity Score (0.88), VOMS/modified VOMS (0.92). A proposed mini-SCAT (mSCAT) including the symptoms of headache, pressure in head, don’t feel right, sensitivity to light, dizziness, and sensitivity to noise improves the AUC to 0.94 with a sensitivity of 87% and specificity of 88%. The only concussion test/exam which adds utility to mSCAT is VOMS, all other test/exams in CARE are non-additive in acute concussion identification. Conclusion: These results suggest a mSCAT symptom list should be considered, possibly to 6 questions for an AUC improvement from 0.88 to 0.94 with a 2% improvement in sensitivity and 12% improvement in specificity.

Dr. Amelia Hicks¹, Dr Fanny Elahi¹, Ms Enna Selmanovic¹, Dr Kristen Dams-O’Connor¹

¹Icahn School of Medicine at Mount Sinai, New York, United States

The term post traumatic neurodegeneration (PTND) has been employed to describe the progressive post-recovery decline in cognitive and neurobehavioral function experienced after traumatic brain injury (TBI). Neurovascular injury is an important but under-studied contributor to the poly-pathology of PTND. Our objective was to conduct a novel examination and characterization of 12 blood-based biomarkers of neurovascular injury in a chronic TBI cohort. We also examined associations of neurovascular markers with markers of neuronal and glial injury (AB40, AB42, p-tau231, brain-derived tau, NfL, GFAP). This prospective longitudinal study recruited participants with a history of complicated mild-severe TBI exposure at least 1 year prior. Participants completed a clinical assessment battery that uses NIH TBI CDEs to provide rigorous characterization of outcomes. Clinical impairment in each domain was defined as performance 1.0 SDs below the normative average. Blood samples were acquired for analysis of protein expression. Mesoscale MSD ultra-sensitive multiplex ELISA assay was used to measure the 12 proteins (PlGF, VCAM-1, ICAM-1, CRP, SAA, bFGF, PIGF, Tie2, VEGF, VEGF-A, VEGF-C, VEGF-D). Serum samples were analyzed from 147 individuals with TBI (M = 11.9 years; SD = 9.6 years since injury). Complex inter-relationships between markers of neurovascular injury, neuronal injury, and glial injury highlight the poly-pathology that characterizes chronic TBI (Kendall’s tau 0.14 - 0.55; p < .05). Multivariate logistic regressions with Bonferroni correction highlighted how neurovascular injury markers were associated with clinical impairment in cognitive and neurobehavioral domains. Markers of neurovascular injury provide important insights into the complex poly-pathology and clinical presentation of PTND.

Mr. Satvik Tripathi¹, Mr. Drew Parker¹, Dr. Alexa Walter¹, Dr. Lee Lancashire³, Dr. Pratik Mukherjee², Dr. Geoff Manley², Dr. Ramon Diaz-Arrastia¹, Dr. Ragini Verma³

¹Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States, ²University of California San Francisco, San Francisco, United States, ³Cohen Veterans Bioscience, New York City, United States

Background. Long-term outcome prediction following mild traumatic brain injury (mTBI) remains a clinical challenge. Diffusion MRI (dMRI) based features like fractional anisotropy (FA) have demonstrated sensitivity in characterizing axonal damage and other injury-induced changes, but its use in creating outcome predictors remains elusive. Deep Learning-based (DL) methods work differently from traditional prediction models, as they learn complex hierarchical representations of data.

Objective. To develop a dMRI-based model to predict outcome at 6 months post-injury from 2-week imaging measures using DL.

Methods. 422 mTBI patients (70.8% male, mean age 37.9±15.4) from TRACK-TBI and Penn-TBIRI studies were included. Post-injury 2-week dMRI scans and 6-month outcome measures of Rey Auditory Verbal Learning Test (RAVLT), Wechsler Adult Intelligence Scale (WAIS), Trails Making Test Part-A (TMTA) and Part-B (TMTB) were used. Average FA values in 100 white matter regions were used as features, harmonized using ComBat. After dimensionality reduction with principal component analysis, a DL model consisting of 4 dense layers with L2 regularization was trained using these features to predict outcomes. 10% data was held out for validation before training using 5-fold cross-validation. Model performance was evaluated using mean absolute error (MAE) and coefficient of determination (R²) between actual and predicted values.

Results. Models predicted 6-month RAVLT (MAE=7.74; R²=0.60), WAIS (MAE=8.45; R²=0.81), TMTA (MAE=5.98; R²=0.68), and TMTB (MAE=12.27; R²=0.88) scores with p-value<0.001 achieved in all correlation analyses.

Conclusions. We have designed dMRI-based long-term outcome predictors using DL-based integration of imaging information, highlighting the potential of dMRI-derived measures in the clinic, and in patient-centered care.

Ms. Glenae Nora^1,2, Ms. Gabrielle Mazet¹, Ms. Veronica Nguyen¹, Ms. Yushra Rashid¹, Mr. Rakshith Gowda¹, Dr. Michelle Hook^1,2

¹Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College of Medicine, Bryan, United States, ²Texas A&M Institute for Neuroscience, Texas A&M University, College Station, United States

Mounting evidence suggests that changes in gut microbiota are disease-modifying factors contributing to the pathophysiology of spinal cord injury (SCI). SCI-induced gut dysbiosis has been associated with reduced locomotor recovery. The present study aimed to determine whether reducing the leakiness of the blood-gut barrier (BGB), and the translocation of endotoxins, bacteria, and immune cells from the gut into the periphery, would benefit recovery. First, we tested whether SCI causes changes in the BGB integrity. Twenty-five 3-month-old male Sprague-Dawley rats served as subjects. Rats were given a moderate spinal contusion injury at T6 or T11, or served as sham and intact controls. Two days after surgery, rats were humanely euthanized, and the distal ileum and proximal colons were collected for analysis of epithelial wall length, villus:crypt ratios, and surface goblet cells numbers. We found that SCI rapidly changed the gut epithelium and muscular wall. Villus:Crypt ratios, surface goblet cell numbers and the ileum muscle wall thickness were reduced in the T11 SCI rats, relative to controls. Next, we tested whether IGF-1 could improve the BGB integrity and protect recovery. Rats were treated with IGF-1 (i.p.) or vehicle 4 and 24 hrs after a T11 contusion or sham injury, and locomotor recovery was recorded for 60 days. We found that IGF-1 treatment significantly improved locomotor recovery following SCI. Future studies will determine whether this beneficial effect of IGF-1 is due to a direct action at the spinal lesion site or the indirect action of restoring BGB integrity.

Funding: Woodnext Foundation.

Diana Chung¹, Austin Smith¹, Lisa Baker², David Sharp³, Kimberly Byrnes⁴

¹Neuroscience Program, Uniformed Services University of the Health Sciences, Bethesda, United States, ²MicroCures, Inc., Bronx, United States, ³Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, USA, Bronx, United States, ⁴Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, United States

The microtubule severing enzyme, fidgetin-like 2 (FL2), regulates microtubule dynamics, affecting cell growth and migration, including axonal sprouting and regeneration. We have previously shown that nanoparticle-based FL2 siRNA (SiFi2) can increase microglial motility and phagocytic activity in vitro. We now aim to determine the effect of FL2 downregulation on oligodendrogenesis, as well as the functional effect after SCI in vivo. Adult male and female td-tomato-FL2 reporter mice underwent a moderate contusion spinal cord injury and immediately received an intrathecal injection of SiFi2 or scrambled siRNA nanoparticles (SiCon) at the injury site. The relative quantification of RT qPCR revealed that SiFi2 treatment reduced FL2 expression at 1- and 7-days post-injury in the spinal cord. By 7 days post-injury, the expression of oligodendrocyte progenitor cell (OPC) marker, Pdgfrα, was reduced in SiFi2 treated male mice in comparison to SiCon treated male mice, potentially due to OPCs differentiating to oligodendrocytes (OLs) more robustly with SiFi2 treatment, compared to SiCon treatment; this trend was not observed in female mice. Evaluation of myelinating OL marker, Myrf gene expression is currently underway to support the speculation. Motor function using the Basso Mouse Score (BMS) showed some of the SiFi2 treated mice achieving a marked improvement, although a clear difference between responding and non-responding mice appeared. Additional motor function analysis and post-injury histology is currently ongoing. These data demonstrate that FL2 downregulation plays a role in post-injury oligodendrogensis and functional recovery, which warrants additional future evaluation.

Acknowledgements: This work was supported by R21.

Ms. Mia Pacheco^1,2, Mrs. Miranda Leal-Garcia², Dr. Dylan McCreedy^1,2

¹Texas A&M Institute of Neuroscience, College Station, United States, ²Texas A&M Dept. of Biology, College Station, United States

Following spinal cord injury (SCI), an inflammatory cascade ensues that can worsen tissue damage and impair recovery. Neutrophils, the most abundant circulating leukocytes in humans, infiltrate the injured spinal cord in large numbers and have canonically been thought to exacerbate tissue damage and functional deficits post-SCI. Previous studies that have assessed the effect of antibody-mediated neutrophil depletion in SCI have yielded conflicting results, and the role of neutrophils in spinal cord injury damage and repair remains unclear. Here, we utilize antibody-mediated neutrophil depletion via anti-Ly6G (clone 1A8) to further investigate the contribution of neutrophils to recovery after SCI. Using flow cytometry, we found that 2.5mg/kg of anti-Ly6G administered via intraperitoneal injection in naïve mice reduced the abundance of circulating neutrophils for at least 1-day post-injection. We then administered 2.5 mg/kg of either anti-Ly6G (1A8) or IgG (2A3) control antibody to wildtype mice at either 1-day before or immediately after SCI. Antibody-mediated neutrophil depletion 1-day prior to SCI had no impact on recovery, however, neutrophil depletion immediately post-injury markedly impaired long-term hindlimb locomotor recovery. Flow cytometry analysis confirmed that post-SCI neutrophil depletion substantially reduced neutrophil numbers in the injured spinal cord at 1-day post-injury. Post-injury neutrophil depletion also reduced white matter sparing at the lesion epicenter at 35-days post-SCI, suggesting neutrophils in the acutely injured spinal cord may play a role in mitigating long-term tissue damage. Collectively, our findings indicate a temporally-restricted role for neutrophils in promoting long-term recovery following SCI.

¹University of Alabama at Birmingham, Birmingham, United States

Within minutes after spinal cord injury (SCI), microglia and astrocytes become activated and produce inflammatory mediators such as TNF-α, IL-6, CXCL1 and COX-2 which promote secondary tissue injury through cytotoxicity, vascular hyperpermeability, edema, and secondary ischemia. This inflammatory cascade is further amplified by chemokines that promote recruitment of peripheral immune cells. A key level of regulation for many inflammatory mediators is post-transcriptional, mediated by adenine- and uridine-rich elements in the 3’ untranslated regions of the mRNA. HuR is an RNA regulator that binds to these regions and promotes RNA stability and enhanced translational efficiency. We have developed an inhibitor, SRI-42127, that blocks HuR function by preventing its homodimerization. This study sought to determine whether SRI-42127 could blunt secondary neuroinflammatory responses after SCI and improve outcome. After a mid-thoracic spinal cord percussion injury, mice received SRI-42127 or vehicle intraperitoneally. Inflammatory responses were measured in spinal cord tissue and blood by qPCR, ELISA, immunohistochemistry, and western blot. Recovery was assessed by a battery of motor function tests.

With SRI-42127 treatment, there was significant improvement in all motor function modalities. Pro-inflammatory mediators in the injured spinal cord, including iNOS, COX-2 and IL-6, were blunted by ∼70-90% compared to vehicle. There was a robust suppression of cytokines in the blood. Histologically, there was a decrease in glial scar size and concomitant astrocyte recruitment and activation. In summary, our findings indicate that HuR inhibition with SRI-42127 after SCI suppresses acute pro-inflammatory responses and improves functional outcome.

Ms. Esmeralda Mendoza¹, Dr. Hannah Radabaugh¹, Dr. Abel Torres-Espin², Dr. Katherine Giordano³, Kyli McQueen³, Dr. Luisa Rojas Valencia¹, Dr. Naoki Takegami¹, Dr. Rachel Rowe⁴, Dr. Amy Wagner⁵, Dr. Michelle LaPlaca⁶, Dr. Grace Griesbach⁷, Dr. Courtney Robertson⁸, Dr. Kimberly Byrnes⁹, Dr. Gene Gurkoff¹⁰, Dr. Audrey Lafrenaye¹¹, Dr. H.E. Hinson¹, Dr. Adam Ferguson¹

¹University of California San Francisco, San Francisco, United States, ²University of Waterloo, Waterloo, Canada, ³University of Arizona College of Medicine-Phoenix, Phoenix, United States, ⁴University of Colorado Boulder, Boulder, United States, ⁵University of Pittsburgh, Pittsburgh, United States, ⁶Georgia Institute of Technology, Atlanta, United States, ⁷University of California Los Angeles, Los Angeles, United States, ⁸Johns Hopkins University, Baltimore, United States, ⁹Uniformed Services University, Bethesda, United States, ¹⁰University of California Davis, Davis, United States, ¹¹Virginia Commonwealth University, Richmond, United States

Background: The first National Neurotrauma Symposium was held in 1983 followed by the founding of the society as a professional organization in 1988. More recently, the National Neurotrauma Society (NNS) leadership has developed directed efforts toward diversity, equity, and inclusion (DEI) in both the society and the annual Symposium.

Methods: We used Namsor, which is a natural language processing tool, to capture Symposium abstract author’s identity from the existing archives representing 40 years’ worth of data. We also used self-reported demographics provided by conference attendees to measure diversity trends, for gender and race/ethnicity, in the society in recent years. Finally, we measured the gender composition of the members, officers, and attendees over the past 40 years.

Results: NNS and the associated Symposium have transformed from a largely white, male-dominated demographic profile to a more diverse society with women now composing the majority (46.3%) of conference attendees relative to men (43.2%) and unspecified attendees (10.3%). In addition, there has been an increase in author submission and conference attendance diversity with respect to race and ethnicity (from 33.5% in 1983 to 49.6% in 2023).

Conclusion: Despite increasing diversification of the membership of NNS, the demographics of the society do not yet fully reflect the race and ethnicity of the US population. NNS will continue striving to become more representative with targeted initiatives and improved demographics collection.

Acknowledgement: US NIH: R13NS137717; R01NS122888; UH3NS106899, U19AR076737; U24NS122732; US VA: 1I01RX002245, I01RX002787, I01BX005871, I50BX005878; Craig H. Neilsen Foundation; Wings for Life Foundation.

¹The University Of Alabama, Tuscaloosa, United States

The purpose was to determine the prevalence of diagnosed migraines, attention disorders, and psychiatric disorders in adaptive athletes with spinal cord injury (SCI) and spina bifida (SB) by concussion history. 30 adaptive athletes (SB=20, SCI=10) from a national sample self-reported medical history on the Sport Concussion Assessment Tool 5 (SCAT5) medical background, consisting of a diagnosis of the following: spinal pathologies, history of concussion (HoC), migraines, learning disabilities (LD), attention disorders (AD), and depression, anxiety, or psychiatric disorders (PD). A series of separate chi-square tests for association were conducted between concussion history and comorbidities for both SCI and SB samples, individually. No comorbidities were reported by 30% of athletes with SCI and HoC and by 50-70% with SCI and no HoC for all four comorbidities. Only 1 and 2 athletes with SCI and no HoC reported a LD and PD, respectively. Athletes with SB and HoC saw a prevalence of 12.5% (migraines), 25% (LD), and 50% (AD and PD) for comorbidities, with only 8.3% (migraines, LD, AD) and 16.7% (PD) with no HoC. There were only significant associations between HoC and AD for athletes with SB (χ2=4.44, p=0.03). No other associations were observed for comorbidities and HoC for athletes with SB (χ2 range=0.93-2.54, p-range=0.11-0.76) and SCI (χ2 range=0.46-1.07, p-range=0.30-0.49). Collegiate adaptive athletes with SB may have a higher prevalence of attention disorders and comorbidities based on HoC than SCI. HoC and comorbidities need to be considered as modifiers for concussion assessment in adaptive athletes with SCI and SB.

Dr. Alireza Khanteymoori¹, Roza Atamny¹, Prof. Jürgen Beck¹, Prof. Jan M. Schwab^2,3, Dr. Ralf Watzlawick¹

¹Department of Neurosurgery, Neurocenter, Faculty of Medicine, University of Freiburg, Freiburg, Germany, ²Departments of Neurology and Neurosciences, The Ohio State University, Columbus, United States, ³Belford Center for Spinal Cord Injury, The Ohio State University, Columbus, United States

Recovery following spinal cord injury (SCI) holds promise through plasticity-enhancing treatments, with an emerging focus on the Nogo-A pathway known to inhibit neuroaxonal plasticity in experimental SCI models. This systematic review and meta-analysis assess therapeutic interventions targeting the Nogo-A pathway’s effects on functional locomotor recovery post-SCI.

Analyzing 51 manuscripts with 76 experiments involving 1572 animals, we observed a significant neurobehavioral improvement of 18.9% (95% CI 14.5–23.2). Subgroup analysis (40 experiments, N = 890) identified factors influencing outcome variability, revealing that the absence of reported randomization and smaller group sizes correlated with larger effect sizes. Among the main options to intervene with the Nogo pathway, the application of NgR blockers revealed the highest effect sizes followed by Nogo-A antibody interventions. Delayed treatment initiation was associated with diminished effects. We observed a relative exaggeration of efficacy for animal studies reporting the use of fewer than 8 animals in the treatment group. Assessment through Trim and Fill analysis and Egger regression indicated potential publication bias, reducing the effect size to 8.8% (95% CI 2.6–14.9) after accounting for theoretically absent studies.

Inhibiting the Nogo-A/NgR1 pathway demonstrated significant alterations in functional recovery post-SCI in animal studies. However, considerable variations exist among applied injury mechanisms and study details, proving challenges in assessing other SCI interventions.

Dr. Matthew Kercher¹, Dr. Kee D. Kim¹, Dr. Yashar Javidan², Dr. Rolando F. Roberto², Dr. Hai V. Le², Dr. Richard L. Price¹, Dr. Safdar N. Khan², Dr. Allan R. Martin¹

¹UC Davis Health Department of Neurological Surgery, Sacramento, United States, ²UC Davis Health Department of Orthopaedic Surgery, Sacramento, United States

Introduction: Traumatic spinal cord injury (SCI) is a common injury with devastating impact on patients and significant health care costs. Rapid treatment mitigates secondary injury and disability. Ambiguous clinical practice guidelines lead to wide variations in practice across surgeons and institutions. New evidence supports earlier surgical decompression to optimize recovery. Pre-injury magnetic resonance imaging (MRI) affects surgical planning. Code Stroke protocols significantly improved stroke outcomes and hospital workflow timing. There exists a need for standardization of SCI hospital workflows to ensure early operative evaluation and treatment, as well as ongoing prospective data collection.

Methods: A single institution, multi-departmental Code SCI protocol was developed involving physicians from emergency medicine, radiology, trauma surgery, orthopaedic surgery, and neurological surgery. We reviewed the relevant literature, enabled early surgical consultation and imaging acquisition, created an 8-minute SCI MRI protocol, reduced surgery timing variability, and standardized prospective data collection. Time from injury to decompression, hemodynamics and spinal perfusion pressure, MRI results, ISNCSCI exams, and EQ-5D and SCIM scales will be collected prospectively. We recommend when feasible, pre and post-operative MRI, intraoperative ultrasound, and lumbar drain placement for high-grade SCI. Other management considerations include corticosteroids, early closed reduction, intraoperative neuromonitoring, extent of decompression, and expansile duraplasty.

Conclusion: With this evidence-based protocol, we reduced hospital barriers to urgent surgical treatment of SCI. With ongoing prospective data collection, we will evaluate our aggressive management strategy and inform ongoing research. We hope to replicate the outcome improvement seen in Code Stroke datasets.

Dr. Luisa Rojas Valencia¹, Katherine R Giordano^1,2, Jhon Bryce Ortiz¹, Kyli A McQueen^1,2, Daniel R Griffiths^1,2, Jonathan Lifshitz^1,2

¹Department of Psychiatry, University of Arizona College of Medicine-Phoenix, Phoenix, USA, ²Phoenix Veterans Affairs Health Care System, Phoenix, USA

TBI pathophysiology is characterized by a central neuroinflammatory response followed by peripheral inflammation. Peripheral inflammation has been linked to impairments in gut function and structure in TBI patients. We hypothesized that probiotic treatment would regulate gut microbiome diversity and composition and reduce peripheral inflammation after TBI.

We induced TBI by midline fluid percussion or sham injury on adult male (n=14) and female (n=15) mice. Next, mice consumed normal drinking water or the probiotic Target GB-X™ (Lactobacillus and Bifidobacterium) in drinking water for 7 days post-injury (DPI). Submandibular blood draws were collected at baseline, 1, 3, and 7 DPI to quantify leukocytes, monocytes, and neutrophils by flow cytometry. Fecal samples were collected at 1, 3, and 7 DPI, and bacterial DNA was extracted for microbiome analysis.

There were no significant differences in peripheral immune cell populations between treatment groups (probiotic vs control) in either males or females. Linear-mixed-effects model analysis indicated a main effect of probiotic treatment on beta diversity (between samples) among treatment groups in females (z(0.007-0.030)=3.232,P>|z|=0.001), but not in males. In females, members of the phylum Bacteroidetes (Bacteroidales and Rikenellaceae) increased in the injury+water group. Members of the phylum Firmicutes (Allobaculum and Turicibacter) increased in sham+probiotic and injury+probiotic groups. Our results indicate that probiotics modulated the Firmicutes/Bacteroidetes ratio after TBI by increased abundance of Firmicutes. As Firmicutes are associated with microbiome beneficial functions and members of Bacteroidetes associate with pathology in the gut, probiotic treatment could be used to rebalance gut microbiome composition after TBI.

Funding: Fulbright-Colombia, AAC, VRP.

Dr. Georgene Hergenroeder¹, Anthony Moore¹, Dr. Mark Burish¹, Dr. Jovanny Cruz-Navarro², Dr. Claudia Robertson², Dr. W. Zack Ray³, Dr. Karl Schmitt¹, Dr. H. Alex Choi¹, Dr. Alice Chuang¹, Dr. Pramod Dash¹

¹McGovern Medical School at UTHealth Houston, Houston, United States, ²Baylor College of Medicine, Houston, United States, ³Washington University at St. Louis, St. Louis, United States

Neuropathic pain (NP) is a debilitating condition that occurs in 40-70% of persons with spinal cord injury (SCI). Unfortunately, NP is frequently refractory to treatment and difficult to predict. As a consequence of the trauma, the blood-spinal cord barrier can be disrupted and CNS proteins released where they can elicit an autoimmune response. Our objective was to identify autoantibodies that can be used to identify those people at risk for developing NP. A clinical grade test that can predict the development of NP may aid in selecting pain medications and preventive measures.

Capillary westerns measured plasma immunoreactivity from SCI patients to antigens identified by a 2-D western screen. To identify prognostic biomarkers, we compared the immunoreactivity levels in SCI patients who subsequently developed NP (NP=64) and those who did not (No NP=19). The pain classification of each patient was assigned a level of confidence (high or low) based on the availability of data. Autoantibodies (ab) that could differentiate the two groups were used to generate a biomarker signature.

Regression analysis determined that ab-1 was the strongest predictor of NP, OR=1.44 (95% CI=1.10, 1.89), p=.008. ab-1 was found to be “good” at differentiating between SCI patients who will develop NP and those who will not, with an AUC of 0.82. Examining only those patients whose pain status was unequivocal, the AUC for ab-1 increased to 0.88, p=.037. The addition of ab-2 and ab-3 improved the prognostic accuracy to 0.96.

Acknowledgment: The National Institutes of Health through the NIH HEAL Initiative, 1R61NS113329-01.

Dr. Ying Ma^1,2,3, Mr. Shengqi Zhang^1,2,4, Dr. Xiaolong Du^1,2,5, Dr. Aytak khabbaz^1,2, Mrs Samhita Chakraborty^1,2, Mrs Kristen Cohen^1,2, Mr. Fang Yuan^1,2, Mrs. Yihong Zhang^1,2, Dr. Lingxiao Deng^1,2, Dr. Xiang Gao^1,2

¹Indiana university Department of Neurological Surgery, indianapolis, United States, ²Indiana university Stark Neuroscience Research Institute, indianapolis, United States, ³Department of Neurology, Shengjing Hospital of China Medical University, shenyang, China, ⁴Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, China, ⁵Department of Vascular Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China

Objective: Although systemic hypothermia after spinal cord injury (SCI) has demonstrated neuroprotective potential, its effectiveness is often hindered by delayed initiation in clinical practice. This study aimed to evaluate the effect of the FDA-approved drug Dexmedetomidine (Dex) on rapidly inducing hypothermia and providing neuroprotection following SCI.

Method: Moderate contusive SCI was induced at the T9 level using the Lisa and Infinite Horizon impact (IH) mouse models. One-hour post-injury, a single dose of Dex (100 µg/kg) was administered intraperitoneally. Motor function recovery was assessed through multiple behavioral tests including BMS, Rotarod, and Grid walk. Histological analyses were conducted to evaluate pathological changes.

Results: A single dose of Dex induced moderate to modest hypothermia (30-32°C) within one hour, at an ambient room temperature of 24.5°C. This hypothermic effect was sustained for up to 16 hours post-SCI. Importantly, Dex administration did not require auxiliary heating or cooling equipment, suggesting its potential for on-site use. Furthermore, compared to conventional hypothermia therapies involving physical cooling, Dex-induced hypothermia resulted in significantly enhanced and prolonged motor function recovery, along with improved pathological changes.

Conclusion: This study presents a promising application of the FDA-approved sedative drug Dexmedetomidine in effectively treating SCI, offering potential for rapid integration into clinical practice.

Acknowledgement: This study was supported by Department of Defense (GRANT13705040), National Institute of Health (R21NS130241), Indiana Traumatic Brain and Spinal Cord Injury Award/Indiana State Department of Health (74247 and 55051) awarded to LD.

Mr. Vasanth Raja¹, Dr John Kanter², Dr Phillip Bonney², Dr Phiroz Tarapore², Dr Anthony DiGiorgio²

¹Touro University California, Vallejo, United States, ²University of California, San Francisco, Department of Neurosurgery, San Francisco, United States

Traumatic spinal cord injury (SCI) is associated with substantial acute care needs. SCI patients are at risk for acute kidney injury (AKI) through multiple mechanisms. This study aims to assess the incidence of AKI in SCI patients in a nationally representative dataset and identify associated factors. We queried the National Trauma Databank (NTDB) for patients aged 18 years or older with cervical or thoracic SCI based on International Classification of Disease (ICD) codes from 2017 to 2021. Patients with pre-existing chronic renal failure were excluded. There were 70,924 patients with cervical (77%) or thoracic SCI (23%) (mean age 50 years, 64% male). A total of 937 (1.32%) patients were diagnosed with AKI during acute hospitalization. In multi-variable logistic regression analysis, increasing age (OR 1.14 for 10-year increase, 95% CI 1.08 to 1.19), male sex (OR 1.73, 95% CI 1.34 to 2.33), thoracic-level injuries (OR 1.52, 95% CI 1.23 to 1.88), higher ISS scores (1.15 for 5-point increase, 95% CI 1.12 to 1.18), motor-vehicle collisions (OR 1.61 compared to falls, 95% CI 1.27 to 2.05), and fresh-frozen plasma administration (OR 1.05 per unit, 95% CI 1.03 to 1.07), were associated with AKI (all p<0.001). Death (29.4% vs. 6.3%, p&lt;0.001) and discharge to long-term care facility (72.8% vs. 27.7%, p<0.001) were more common in AKI patients. Given the morbidity AKI portends in SCI, additional investigation into its prevention and treatment is necessary.

Ms. Regan M. Shanahan¹, Anna L. Slingerland¹, Dr. Ali Alattar¹, Samuel Adida¹, Jhair Colan¹, Adam Monek¹, Ashtah Das², Dr. Joseph S. Hudson¹, Dr. David K. Hamilton¹, Dr. Nitin Agarwal¹, Dr. Daryl P. Fields

¹Department of Neurosurgery, University of Pittsburgh, Pittsburgh, United States, ²Jacobs School of Medicine and Biomedical Sciences, Buffalo, United States

Introduction: Traumatic spine fractures are a leading cause of chronic pain and disability in the United States. To better develop strategies to limit disparities in pain outcomes, we must delineate confounding influences amongst social determinants, healthcare access, and provider biases.

Methods: Retrospective review of opioid naïve patients presenting to a Level I trauma center with isolated, non-operative, spine fractures. Area Deprivation Index (ADI) scores from home zip code was metric of socioeconomic disadvantage. 3-month follow-up appointments and insurance were surrogates for healthcare access. Physician Drug Monitoring Program data was used to determine provider prescribing patterns. Differences were considered significant if p≤0.05.

Results: Of the 1,155 patients in this study, mean age was 59.05 years (SE:0.65), ADI was 14.55 (SE:0.54), with patients being predominantly male (53.68%), white (87.71%), and holding private insurance (57.92%). 141/1155 (12.2%) remained on a new opioid pain medication at ≥12months post-injury. Race and socioeconomic status influenced healthcare access with significantly lower 3-month follow-up rates amongst blacks (OR:0.564; CI:0.356–0.894; p=0.015) and disadvantaged individuals (high ADI; OR:0.99; CI:0.985–0.995; p<0.001). On multivariable analysis, neither healthcare access (p=0.533), race (p=0.176) or insurance status (p>0.05) influenced prescribing patterns. Conversely, socioeconomic status independently influenced pain medication prescribing patterns, with disadvantaged individuals being less likely to receive prescriptions (OR:0.982; CI:0.965-0.995; p=0.019).

Conclusions: Providers were less likely to prescribe pain medications for socioeconomically disadvantaged individuals – independent of healthcare access. Strategies targeting provider management decisions, and not healthcare system access, may improve disparities in pain management and disability amongst spine fracture patients.

Mr. Austin Lui^1,2, Dr. Philip Bonney², Dr. John Burke³, Dr. John Kanter², Dr. John Yue², Dr. Naoki Takegami², Dr. Phiroz Tarapore², Dr. Michael Huang², Dr. Praveen Mummaneni², Dr. Sanjay Dhall², Dr. Debra Hemmerle², Dr. Adam Ferguson², Dr. Abel Torres-Espin⁴, Ms. Xuan Duong-Fernandez², Ms. Nicole Lai², Dr. Rajiv Saigal², Dr. Jonathan Pan², Dr. Vineeta Singh², Dr. Nikos Kyritsis², Dr. Jason Talbott², Dr. Lisa Pascual², Dr. Russell Huie², Dr. William Whetstone², Dr. Jacqueline Bresnahan², Dr. Michael Beattie², Dr. Philip Weinstein², Dr. Geoffrey Manley², Dr. Anthony DiGiorgio²

¹Touro University California, Vallejo, United States, ²University of California, San Francisco, San Francisco, United States, ³University of Oklahoma, Oklahoma City, United States, ⁴University of Waterloo, waterloo, Canada

The International-Standards-for-Neurological-Classification-of-Spinal-Cord-Injury (ISNCSCI) assessment is the gold standard for evaluating, classifying, and documenting neurologic function after spinal cord injury (SCI) in clinical trials, but is time-intensive and may be impractical in acute settings. Inpatient clinical neurologic exams performed during standard medical care could serve as a surrogate for ISNCSCI when the latter is not performed. This study evaluates agreement between neurosurgery motor exams (NMEs) and ISNCSCIs. The prospective, multicenter Transforming Research and Clinical Knowledge in Spinal Cord Injury (TRACK-SCI) registry was queried for ISNCSCI and NME scores for SCI patients. Sixty-three patients had at least one timepoint where there was a complete ISNCSCI and NME exam within 24-hours of each other, with a total of 73 pairs of exams included in analysis. NME scores were strongly correlated with ISNCSCI scores (R=0.962, p<0.001). Both upper- and lower-extremity NMEs were strongly correlated with upper- and lower-extremity ISCNSCI scores, respectively (R=0.939, p<0.001; R=0.959, p<0.001). Using modified Bland-Altman analysis, total, upper-, and lower-extremity NME and ISNCSCI scores showed low systematic bias and high agreeability (total: bias=0.3, limit-of-agreement (LoA)=36.6; upper-extremity: bias=-0.5, LoA=17.6; lower-extremity: bias=0.8, LoA=20.0). There were 66 pairs of exams that had thorough sensory and rectal exams for AIS grade calculation. Using Kappa analysis to test inter-rater reliability of AIS grade calculation using NME versus ISNCSCI scores, we found weighted kappa=0.883 (SE=0.061, 95% CI=0.736-0.976), indicating strong agreement. When inpatient ISNCSCI cannot be performed, NME can be a useful surrogate.

Mr. Austin Lui^1,2, Dr. Naoki Takegami², Dr. Nikos Kyritsis², Dr. Russell Huie², Dr. Debra Hemmerle², Dr. Alan Nima², Dr. Timothy Chryssikos², Dr. Abel Torres-Espin³, Ms. Xuan Duong-Fernandez², Ms. Nicole Lai², Dr. Rajiv Saigal², Dr. Jacob Blitstein⁴, Dr. Jason Talbott², Dr. Jonathan Pan², Dr. Adam Ferguson², Dr. William Whetstone², Dr. Vineeta Singh², Dr. Philip Weinstein², Dr. Sanjay Dhall², Dr. Praveen Mummaneni², Dr. Lisa Pascual², Dr. Geoff Manley², Dr. Jacqueline Bresnahan², Dr. Michael Beattie², Dr. Anthony DiGiorgio²

¹Touro University California, Vallejo, United States, ²University of California, San Francisco, San Francisco, United States, ³University of Waterloo, Waterloo, Canada, ⁴Virginia Commonwealth University, Richmond, United States

Central cord syndrome (CCS) accounts for ∼25% of spinal cord injuries. Although studies suggest early surgical decompression for CCS, there is no established optimal surgery timing. We examined association between decompression timing and short-term outcomes in CCS. The Transforming-Research-and-Clinical-Knowledge-in-SCI registry was queried to identify cervical-CCS patients (ASIA C/D with lower-extremity-motor (LEM) scores > upper-extremity-motor (UEM) scores by at least 5 points). Patients were divided into ultra-early-decompression-group (<12 hours), early-decompression-group (12-24 hours), and late-decompression-group (>24 hours). Forty-one CCS patients underwent decompression surgery (26 ultra-early, 6 early, 9 late). The groups differed in age (p=0.007), with the ultra-early-group and early-group being younger than the late-group. There were no differences in sex, SCI etiology, injury severity score (ISS), UEM, LEM, and total motor scores at day-0 (+/-2 days) between the groups. A multivariate linear regression including age, ISS, decompression timing (ultra-early, early, late), day-0 UEM scores, and neurological level of injury (NLI) showed that only day-0 UEM scores (p<0.001) and NLI of C2 (p=0.038) were associated with day-7 UEM scores. A multivariate linear regression including the previous predictor variables along with in-hospital complications and Charlson-comorbidity-index (CCI) scores showed that only day-0 UEM scores (p=0.014), in-hospital complications (p=0.048), and CCI scores (p=0.043) were associated with ICU LOS. Finally, a multivariate logistic regression model including age, ISS, decompression timing, day-0 UEM scores, and CCI scores showed no association between any predictor variables with in-hospital complications. Ultra-early-decompression was not associated with longer ICU LOS or increased in-hospital complications, suggesting that ultra-early decompression is safe.

Ms. Olivia Raymond¹, Dr. John Amburgy¹, Mr. David Puccio¹, Dr. Lori Shutter¹, Dr. Joseph Darby¹, Dr. David Okonkwo¹, Dr. Ava Puccio¹

¹University Of Pittsburgh, Pittsburgh, United States

Background/Objective: Spinal Cord Injury (SCI) is a major health problem worldwide. Both primary and secondary pathological processes are thought to be associated with clinical decline in SCI patients. Hyperthermia has been associated with exacerbation of many of these processes including increased metabolism, neurotoxicity, and axonal damage. Before targeted temperature management strategies are being assessed as therapeutic strategies, clarity on the incidence of hyperthermia in SCI patients should be better assessed. This study assesses the incidence of hyperthermia amongst SCI patients at a large neurotrauma tertiary center to determine if further temperature management may be recommended.

Methods: Eighteen consecutive patients with SCI, ASIA C or greater, were followed throughout their hospital stay at a large tertiary trauma facility. Hourly vital assessments were collected that included heart rate, core temperature, respiratory rate, blood pressure, and oxygen saturation. Mean temperature, median temperature, and total percentage of time over 38.0 Celsius (C) were all calculated to evaluate the magnitude of hyperthermia in SCI patients.

Results: The median temperature was 36.8C with a range of 33.0‐43.3 C. The mean temperature was 36.83 C. Fifteen of the 18 patients had temperatures over 38.0 C and these patients had core temperatures above 38.0 C for 21% of their total hospital stay.

Conclusion: Overall, hyperthermia (T > 38.0 C) was very prevalent in this patient population. Given the pathological implications of hyperthermia, a targeted temperature management system to prevent hyperthermia may be warranted and clinically beneficial to these patients.

Dr. Naoki Takegami¹, BA Austin Lui¹, Dr. Rajiv Saigal¹, Dr. John Kanter¹, Dr. Nikos Kyritsis¹, Dr. Russell Huie¹, Dr. Debra Hemmerle¹, Dr. Alan Nima¹, Dr. Timothy Chryssikos², Dr. Abel Torres-Espin³, BA Xuan Duong-Fernandez¹, BA Nicole Lai¹, BA Jacob Blitstein¹, Dr. Jason Talbott¹, Dr. Jonathan Pan¹, Dr. William Whetstone¹, Dr. Vineeta Singh¹, Dr. Philip Weinstein¹, Dr. Sanjay Dhall¹, Dr. Praveen Mummaneni¹, Dr. Lisa Pascual¹, Dr. Geoff Manley¹, Dr. Jacqueline Bresnahan¹, Dr. Michael Beattie¹, Dr. Anthony DiGiorgio¹, Dr. Adam Ferguson¹

¹UCSF, San Francisco, United States, ²University of Maryland, College Park, United States, ³University of Wateroo, Waterloo, Canada

Achieving consistent follow-up in clinical research, especially within trauma populations such as spinal cord injury (SCI) patients, presents a set of challenges influenced by various biopsychosocial factors. This study aims to identify the main factors contributing to loss to follow-up within the context of clinical research participation in the prospective TRACK-SCI studies. Analyzing data from 154 participants, this study assessed biopsychosocial factors affecting follow-up data collection at 3, 6, and 12 months post-injury using logistic regression. A predictive model using LightGBM was developed, with model performance evaluated using the area under the receiver (AUC) operating characteristic (ROC) curves. Logistic regression analysis identified significant odds ratios for several biopsychosocial variables that were significantly associated with the likelihood of loss to follow-up. These include Injury Severity Score (ISS) on arrival, alcohol and illicit drug use, family income, household size, occupation, education length, race, and insurance type (P < 0.05). The LightGBM model showed strong predictive performance with AUCs of 0.77, 0.87, and 0.80 for 3, 6, and 12 months, respectively. Results of this study identify biopsychosocial factors that lead to loss of follow-up in clinical research involving SCI patients. By developing precise predictive models, we are better positioned to anticipate and address factors contributing to participant loss to follow-up. This enhances the quality and reliability of clinical research outcomes. Focusing on research participation, our approach offers avenues for interventions designed to boost engagement and retention in clinical studies, thereby supporting the integrity of research aimed at improving care for SCI patients.

Dr. Debra Hemmerle^1,2,3, Mr. Austin Lui¹, Dr. J. Russell Huie^1,2,9, Ms. Esmeralda Mendoza^1,2, Dr. Lisa U. Pascual^3,4, Ms. Xuan Duong-Fernandez^1,2, Ms. Nicole J. Lai^1,2, Dr. Abel Torres-Espin^1,2, Dr. Jonathon Z. Pan^1,3,5, Dr. Vineeta Singh^1,3,6, Dr. Nikos Kyritsis^1,2, Dr. Anthony M. DiGiorgio^1,2,3, Dr. John H. Kanter^1,2,3, Dr. Rajiv Saigal^2,3, Dr. Jason F. Talbott^1,3,7, Dr. William D. Whetstone^3,8, Dr. Philip R. Weinstein^1,2,6, Dr. Jacqueline C. Bresnahan^1,2, Dr. Michael S. Beattie^1,2, Dr. Adam R. Ferguson^1,2,9

¹UCSF Brain and Spinal Injury Center, San Francisco, ²UCSF Dept. of Neurological Surgery, San Francisco, ³Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, ⁴UCSF Dept. of Orthopedic Surgery, San Francisco, ⁵UCSf Dept. of Anesthesia and Perioperative Care, San Francisco, ⁶UCSF Dept. of Neurology, San Francisco, ⁷UCSF Dept. of Radiology and Biomedical Imaging, San Francisco, ⁸UCSF Dept. of Emergency Medicine, San Francisco, ⁹San Francisco Veterans Affairs Healthcare System, San Francisco

There is an increasing prevalence of traumatic spinal cord injuries (SCI) in older adults aged >65 years, yet little is known about factors relating to cause of injury in this population. Eighty-two adults aged >65 years were enrolled in the Transforming Research and Clinical Knowledge in SCI (TRACK-SCI) study between 2015 and 2023. Falls were the mechanism of injury in 84.1% (69/75) of patients in this age group; 97.1% of these were cervical injuries. The mean age of older adults with fall-related SCIs was 76.1 years (SD=7.8, range: 65-93 years) and 26 (37.7%) were female. There were 11 older adults (15.9%) with functionally complete cord injuries. Total 90-day SCI mortality was 14.5%. Injury mechanisms included falls from sitting/lying (N=7, 10.1%), standing/walking (N=32, 46.4%), single step (N=2, 2.9%), staircases (N=18, 26.1%), ladders (N=3, 4.4%), and heights >1 story (N=2, 2.9%). There were 42 (72.4%) older adults that fell in home versus 16 (27.6%) that fell in the community. Positive ethanol urine screen was noted in 20.3%. Neither completeness of injury nor mortality were associated with fall mechanism, location, or ethanol level. Falls from height (i.e. staircase, ladder, >1 story) were significantly due to accidents that occurred in the community setting (p=0.02). Further study is needed on pre-injury level of physical dependence and presence of medical comorbidities. This descriptive study provides useful insight into SCI etiology in older adults and validates prior geriatric research supporting the importance of preventing older adult falls in and out of the home setting.

Dr. Jacob Davis¹, Dr. Jason Gumbel, Cleopa Omandi, Dr. J Russell Huie, Emma Iorio, Dr. Adam Ferguson

¹University of California, San Francisco, San Francisco, United States

In addition to loss of sensorimotor and autonomic functions, spinal cord injury (SCI) also often results in maladaptive plasticity represented by spasticity, hyperreflexia, and intractable pain. Prior research has established that maladaptive synaptic plasticity after SCI results in pain that is refractory to therapeutics and inhibited locomotor recovery in part due to increased spasticity and rigidity. However, the mechanisms driving maladaptive plasticity remain poorly understood. Prior research has suggested that intermittent nociceptive stimulation after SCI increases AMPAR subunit GluA1 serine 831 phosphorylation and trafficking to synapses with accompanied reduction in synaptic GluA2. This reflects an increase in calcium-permeable AMPARs. Therefore, the goal of this study is to further assess if inhibiting AMPAR through the administration of NASPM (calcium-permeable AMPAR antagonist) after injury with the addition of spared nerve injury (SNI) reverses injury-driven maladaptive plasticity.

Dr. Lyandysha Zholudeva¹, Dr Tara Fortino², Dr Michael Lane², Dr Todd McDevitt¹, Dr Deepak Srivastava¹

¹Gladstone Institutes, San Francisco, United States, ²Drexel University, Philadelphia, United States

Advances in cell therapies offer new promise for devastating neural injuries like spinal cord injury (SCI). One particular type of neuron – the spinal V2a interneuron – has been implicated as a key component in plasticity and therapeutically driven recovery post-SCI. In this study, we engineered V2a spinal interneurons (SpINs) from human induced pluripotent stem cells and tested their ability to form functional synapses with injured motor networks. We used a clinically-relevant cervical contusion SCI in adult rats, that damages the phrenic motor network and impairs breathing, to test anatomical integration, functional connectivity and overall contribution to respiratory recovery mediated by transplanted human V2a SpINs. Neuroanatomical tracing and immunohistochemistry were performed to demonstrate transplant integration and synaptic connectivity with injured host tissue, and diaphragm electromyography was used to assess functional recovery of the injured phrenic network. Optogenetic activation of transplanted human V2a SpINs revealed functional synaptic connectivity to injured host circuits and improved diaphragm activity. Optogenetic activation of host supraspinal pathways at the transplant epicenter revealed functional innervation of transplanted cells from host brainstem neurons. These studies are the first to 1) engineer human spinal V2a interneurons as an intended therapeutic product, and 2) demonstrate functional integration of human SpINs with injured respiratory pathways post-SCI. Having rigorously established improvement in diaphragm muscle activity with objective metrics, this strategy holds great promise to establish motor recovery post-SCI.

Dr. Kun-Ze Lee¹, Ms. Tzu-Ting Liu¹, Ms. Rui-Yi Chen¹

¹National Sun Yat-sen University, Kaohsiung, Taiwan

Cervical spinal cord injury usually caused cardiorespiratory dysfunctions due to damages of the supraspinal pathways innervating the cervical phrenic motoneurons and thoracic sympathetic preganglionic neurons. The guideline recommends the maintenance of the mean arterial blood pressure at 85–90 mmHg within the first week after injury; however, there is only a few evidence from the pre-clinical animal model to support this concept. The current study was designed to examine the therapeutic effect of different adrenergic agonists on systemic and spinal hemodynamics following cervical spinal cord contusion in the rat. The blood pressure, heart rate, and spinal cord blood flow were monitored in response to cervical spinal cord contusion and intravenous infusion of adrenergic agonists (phenylephrine, dobutamine, and norepinephrine). Cervical spinal cord contusion induces an immediately reduction in the arterial blood pressure (54.6 ± 6.3 %baseline) and spinal cord blood flow (43.9 ± 27.7 %baseline). Infusion of phenylephrine (500, 1000, and 2000 μg/kg/hr) and norepinephrine (125, 250, and 500 μg/kg/hr) can significantly elevate the arterial blood pressure to the pre-injury level, but only norepinephrine can improve the spinal cord blood flow. Both arterial blood pressure and spinal cord blood flow was instead reduced by infusion of dobutamine (1000 and 2000 μg/kg/hr). These results demonstrated that infusion of norepinephrine can effectively maintain the blood pressure and improve spinal cord blood flow at the acute injured stage. We proposed that norepinephrine may be a suitable medicine for hemodynamic management during acute cervical spinal cord injury.

Ms Sarah Wheeler, Dr. Bethany Kondiles, Dr. Sohrab Manesh, Dr. Jie Liu, Mr. Min Lu, Dr. Wolfram Tetzlaff

¹ICORD/University of British Columbia, Vancouver, Canada, ²UBC/Graduate Program in Cell and Developmental Biology, Vancouver, Canada, ³UBC/Department of Zoology, Vancouver, Canada, ⁴UBC/Graduate Program in Neuroscience, Vancouver, Canada

The average age at which spinal cord injury (SCI) occurs has increased and is fairly equally spread out between 20-65 years of age. SCI often causes demyelination of spared axons around the epicentre. Surprisingly, we did not find locomotor impairments after SCI when remyelination was inhibited after SCI in young mice (Duncan et al. 2018, Nat. Comm). However, the functional impact of remyelination failure after SCI at an advanced age is unknown. Here, we assessed the importance of remyelination for locomotor recovery, cognitive function, and anxiety in young (3-5 month) and aged (15-18 month) mice of both sexes. To inhibit remyelination we crossed a PDGFRαCreERT2 driver line, which targets oligodendrocyte progenitor cells (OPCs) and vascular fibroblasts, with a line carrying lox-P sites in the myelin regulatory factor gene (myrf-exon8), coding a transcription factor expressed only in OPCs. Loss of functional Myrf inhibits oligodendrocyte maturation and new myelin production.

Mice either underwent a moderate/severe thoracic (T9/10) level contusion or a sham injury and were analyzed with a variety of behavioral tests for 3 months. The aged, remyelination-incompetent mice showed delayed locomotor recovery after SCI, as assessed by the Basso Mouse Scale, horizontal ladder, and Noldus Catwalk. They also displayed cognitive deficits measured through Y-maze, the object relocation task, and novel object replacement task. No differences were found in test of anxiety. Overall, the current results suggest that remyelination treatments may have a greater impact in older than in younger individuals with SCI, pointing to the need for personalized therapies post SCI.

Ms. Natasha Wilkins¹, Kyle Beasley¹, Betsy Perez De Corcho Vazquez¹, Dr. Charles H Hubscher^1,2

¹University Of Louisville School of Medicine, Louisville, United States, ²Kentucky Spinal Cord Injury Research Center, Louisville, United States

Approximately 95% of men with spinal cord injuries (SCI) will exhibit sexual dysfunction with symptoms in males related to erection, ejaculation, and poor sperm quality. The current interventions focus on sperm harvest for in vitro fertilization; however, these interventions pose a risk of triggering autonomic dysreflexia and do not help individuals with physical intimacy or sexual satisfaction. Spinal cord epidural stimulation (scES) and activity-based recovery training (ABRT) are two interventions that have been found to improve bladder and sexual function in clinical and pre-clinical cases of SCI. In the current study, a clinically relevant rodent model of incomplete SCI was used to determine the efficacy of scES for ejaculatory function in animals that were non-trained (CX-NT) or received ABRT two times per week (CX-2DPWT) or five times per week (CX-5DPWT). A greater number of animals from CX-2DPWT and CX-5DPWT were responsive to scES for sexual function when compared to CX-NT, with CX-2DPWT displaying the most responses to scES. Electromyography revealed that CX-2DPWT and CX-5DPWT had significantly longer burst duration in the bulbospongiosus muscle (P<0.01) and CX-NT and CX-2DPWT had significantly greater excitation in the external urethral sphincter (P<0.05) during the urethrogenital reflex when compared to spinally intact rats. CX-NT and CX-5DPWT but not CX-2DPWT displayed a decreased trend in sperm counts relative to sham. ABRT twice a week has promise to improve sensitivity to scES for ejaculatory function in individuals with SCI, supporting the use of ABRT in conjunction with neuromodulation.

Dr. Kotaro Sakashita¹, Dr. Masao Koda¹, Dr. Shun Okuwaki¹, Dr. Hiroshi Takahashi¹, Dr. Masashi Yamazaki¹

¹Department of Orthopaedic Surgery, Institute of Medicine, University of Tsukuba, Tsukuba, Japan

Multilineage-differentiating stress enduring (Muse) cells were endogenous pluripotent stem cells characterized by ease and safety of administration without pre-differentiation induction, and their clinical application is highly promising. Despite the established safety in spinal cord injury (SCI) clinical trials, the therapeutic time window of administration of Muse cells remains undetermined. This study aims to determine the ideal window for Muse cell administration.

Using severe SCI mice, cells were administered at four different times: 2, 8, 14, and 28 days post-injury (DPI). PBS (control), mesenchymal stem cells (MSC), or Muse cells were intravenously administered (n=10). Hindlimb paralysis was assessed using the Basso mouse scale. Histological evaluation and immunofluorescence imaging were conducted.

Behavioral improvement was significant exclusively in the 2-DPI Muse cell group compared with the control 6 weeks after SCI (control: 2.8±1.0, MSC 3.6±1.2, Muse cell: 5.2±1.4; two-way ANOVA followed by Bonferroni post hoc test: P<0.01). Histological evaluation revealed significantly smaller scar tissue areas and larger preserved myelinated tissue areas in the 2- and 8-DPI Muse cell groups compared with the control. Furthermore, Muse cells spontaneously differentiated into cells positive for neural, glial, and oligodendrocyte markers among all Muse cell groups. The number of synapses touching a motor neuron in the lumbar enlargement was greater in the 2- and 8-DPI Muse cell group compared with MSC group (each P<0.01).

Despite 28 days post-SCI, homing and differentiation of the Muse cells were confirmed. Early administration of Muse cells proved more effective in severe SCI.

Ms. Emily Hibbard¹, Xiaolong Du², Yihong Zhang², Xiao-Ming Xu², Lingxiao Deng², Dale Sengelaub¹

¹Indiana University, Bloomington, United States, ²Indiana University School of Medicine, Indianapolis, United States

Spinal cord injuries (SCI) induce deficits in locomotor and autonomic function. After SCI, surviving motoneurons innervating hindlimb muscles exhibit extensive dendritic atrophy, which is attenuated by exercise or treatment with gonadal hormones. Moreover, both exercise and hormone treatment improve urinary function after SCI. Here, we examine the potential protective effects of exercise or hormone treatment on the structure and function of motoneurons innervating the external urethral sphincter (EUS) after SCI.

Male rats received either a sham or thoracic contusion injury. One cohort of SCI-animals was immediately implanted with subcutaneous capsules filled with estradiol (E) and dihydrotestosterone (D); continuous hormone treatment occurred for 4 weeks. A separate cohort of SCI-animals received 12 weeks of forced wheel running exercise starting two weeks after injury. At the end of treatment, void volume was measured using metabolic cages and EUS motoneurons were labeled with cholera toxin-conjugated horseradish peroxidase, allowing for assessment of dendritic morphology.

Void volumes increased in all SCI-animals; void volume was unaffected by treatment with exercise, but was dramatically improved by treatment with E+D. Dendritic length of EUS motoneurons was significantly decreased after SCI compared to sham animals; exercise did not reverse this injury-induced atrophy, however E+D treatment significantly improved dendritic length.

These results suggest that some aspects of urinary dysfunction after SCI can be improved through treatment with gonadal hormones, potentially through their effects on EUS motoneurons; however, a more comprehensive treatment regime that addresses multiple SCI-induced sequalae, i.e., locomotor and voiding deficits, would include both hormones and exercise.

Miss. Natsuka Kobayashi¹, Calvin Phinney¹, Jacob Davis², James Grau¹

¹Texas A&M University, College Station, United States, ²University of California San Francisco, San Francisco, United States

We have previously shown that engaging pain fibers a day after a thoracic spinal cord injury (SCI) impairs long-term recovery in rats. We have related this effect to increased hemorrhage at the site of injury and shown that local application of an anesthetic (lidocaine) blocks the adverse effects of nociceptive stimulation (Turtle, 2017, J Neurotrauma, 34). The present experiment examined whether local anesthesia protects the injured spinal cord when applied soon after injury, in the absence of additional pain. Male rats received a moderate thoracic (T10-11) contusion injury and were fitted with an intrathecal catheter for drug infusion. The anesthetic bupivacaine was selected because it is widely used in the clinic and has a longer duration of action. Five min after injury, animals received 30 µl of 0.75% bupivacaine or its vehicle. Separate groups then received 0, 1, 3, or 7 additional injections at 90 min intervals. This yielded four treatment conditions: 1.5, 3, 6, or 12 hrs of local anesthesia. A day after injury, locomotor performance was assessed and a 1 cm region of the spinal cord encompassing the area of injury was taken and assayed for hemorrhage. Animals that received bupivacaine for 3-12 hrs exhibited improved locomotor performance and less hemorrhage at the site of injury. Further work is being conducted to determine whether bupivacaine has a protective effect when the time of treatment is delayed.

This work is supported by the Craig H Neilsen Foundation under Grant Number 1000927.

Dr. Usha Nekanti¹, Dr. Andrea Anzalone¹, Dr. Hui Song¹, Rebecca Nishi¹, Skylar McDonald¹, Pooja Sakthivel¹, Dr. Courtney Dumont², Dr Paul Gershon¹, Dr. Andre Obenaus¹, Dr. Lonnie Shea², Dr. Brian Cummings¹, Dr. Aileen Anderson¹

¹UNIVERSITY OF CALIFORNIA Irvine CA, Irvine, United States, ²University of Michigan, Ann Arbor, USA

Spinal cord injury (SCI) causes permanent paralysis below the damage level, resulting from complex pathological mechanisms and neural cell death. Multichannel biomaterial interventions are instrumental in promoting axonal regeneration, circuit restoration, and motor recovery in acute SCI. However, achieving similar outcomes in chronic injury models is challenging due to a combination of intrinsic and extrinsic factors. These include the reduced capacity of the neuronal cell body to sustain a growth-activated state and the formation of a physical and chemical barrier at the injury site, preventing axonal regeneration. To combat these inhibitory barriers and to achieve regeneration, we investigated the combinatorial effect of poly (lactide-co-glycolide) (PLG) bridge implantation to guide axonal growth through the injury site and the delivery of Epothilone B (EpoB), which stabilizes microtubules and strengthens the axons to regrow. Utilizing a transgenic corticospinal tract (CST) reporter mouse model, we demonstrated the regeneration of CST axons through the PLG bridge and reentry into the host tissue. At 12 weeks post-PLG bridge implantation, immunohistology and diffusion tensor imaging analysis revealed increased axonal regrowth within the combination treatment group that was confined to the bridge channels. In addition, we investigated the proteomic profile of corticospinal neurons ipsilateral and contralateral to SCI lesion and PLG bridge, further comparing the effect of EpoB treatment using mass spectrometry-based analysis to gain insight into the regeneration program of cortical neurons. The combination of PLG bridge and EpoB delivery supported robust improvement in locomotor recovery compared to mice receiving either bridge or EpoB treatment alone.

Mr. Nathan Gonsalves^1,3, Ms. Min Kyong Sun^1,2, Dr. Pradeep Chopra⁴, Dr. Charles-Francois Latchoumane^1,5, Mr. Simar Bajwa¹, Mr. Ruiping Tang^1,3, Ms. Bianca Patel¹, Dr. Geert-Jan Boons^4,6,7, Dr. Lohitash Karumbaiah^1,2,3,5

¹Regenerative Bioscience Center, University Of Georgia, Athens, United States, ²Division of Neuroscience, Biomedical Health Sciences Institute, University of Georgia, Athens, United States, ³College of Agricultural and Environmental Science, University of Georgia, Athens, United States, ⁴Complex Carbohydrate Research Center, University of Georgia, Athens, United States, ⁵Edgar L. Rhodes Center for Animal and Dairy Science, College of Agriculture and Environmental Sciences, University of Georgia, Athens, United States, ⁶Department of Chemistry, University of Georgia, Athens, United States, ⁷Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University, Utretch, Netherlands

Severe traumatic brain injury (sTBI) induced neuronal loss and tissue atrophy contribute significantly to long-term disabilities. Brain extracellular matrix (ECM) associated chondroitin sulfate (CS) glycosaminoglycans promote neural stem cell (NSC) maintenance, and CS hydrogel implants have been demonstrated to enhance neuroprotection in preclinical sTBI studies. However, the ability of CS hydrogels carrying neuritogenic chimeric peptides (CP) to promote functional recovery after controlled cortical impact (CCI) and suction ablation (SA) induced sTBI has not yet been demonstrated. We hypothesized that CS hydrogels carrying neuritogenic integrin binding peptides will promote neuritogenesis and accelerate functional recovery in sTBI rats. Results indicated that chondroitin 4,6-O-sulfate (CS-E)CP hydrogels significantly enhanced human NSC aggregation (****p<0.0001) and migration via focal adhesion kinase complexes (*p<0.05) when compared to NSCs in chondroitin 4-O sulfate (CS-A)CP hydrogels in vitro. In contrast, NSCs encapsulated in (CS-A)CP hydrogels differentiated into neurons bearing longer neurites, and showed greater spontaneous activity when compared to those in (CS-E)CP hydrogels (p = n.s.). The intracavitary implantation of (CS-A)CP hydrogels, acutely after CCI-SA-sTBI, prevented neuronal and axonal loss as determined by immunohistochemical analyses [Sham (n=6), CCI-SA (n=8) and CCI-SA-(CS-A)CP (n=8), *p<0.05, ***p<0.001, ****p<0.0001]. (CS-A)CP hydrogel implanted animals (n=7) also demonstrated significantly accelerated recovery of ‘reach-to-grasp’ function when compared to CCI-SA (n=9) controls, over a period of 5-weeks after sTBI (*p<0.05, **p<0.01, ***p<0.001 and ****p<0.0001). These findings demonstrate the neuritogenic and neuroprotective attributes of CS-CP “click” hydrogels in a challenging CCI-SA model of sTBI.

Funding: NIH grants R01NS099596 and R21NS130468 to L.K. and HLBI R01HL151617 to G.-J.B.

Mr. Vipin Jagrit¹, Ms. Ashley Smith², Mr. Logan Friedrich⁴, Ms. Gabrielle Dampf¹, Dr. Murray Blackmore⁴, Dr. Jennifer Dulin^1,3

¹Department of Biology, Texas A&M University, College Station, United States, ²Department of Biochemistry and Biophysics, Texas A&M University, College Station, United States, ³Texas A&M Institute for Neuroscience, Texas A&M University, College Station, United States, ⁴Department of Biomedical Sciences, Marquette University, Milwaukee, United States

Spinal cord injury (SCI) is a traumatic injury that often leads to lifelong disabilities. Neural progenitor cells (NPCs) are a promising potential treatment for SCI due to their ability to replace lost neurons after an SCI, integrate into injured host spinal cord circuitry, and participate in new neuronal relays. In pre-clinical models of SCI, research has shown positive results of neural progenitor cell transplantation and rehabilitation, as individual treatments, on motor functional outcomes. We utilized a combinatorial approach of NPC transplantation with task-specific rehabilitation to determine whether combinatorial treatment could further enhance functional recovery and synaptic integration of graft neurons into forelimb motor circuits. We administered a dorsal wire knife lesion to the C5 spinal cord and provided rehabilitative training using a skilled specific pellet-reaching task over a twelve-week period. Beginning at week 8 post-injury, we used a chemogenetic (hM4Di) approach to acutely silence graft activity for two weeks. In addition, we used pseudorabies virus to trace the synaptic integration of grafted cells with host neuronal circuits. In a preliminary validation study, we found that combined NPC transplantation and rehabilitation resulted in significant improvement of forelimb motor functional recovery. Ongoing work is evaluating whether combined treatment can augment functional recovery to a greater extent than either treatment alone, and how rehabilitation promotes plasticity in graft-host synaptic connectivity. These results highlight the therapeutic potential of combining NPC transplantation with activity-based rehabilitation for forelimb motor functional recovery.

Dr. Ana M. Lucas-Osma¹, Dr. Keith K. Fenrich¹, Krishnapriya Hari¹, Leo Sanelli¹, Dr. David J. Bennett¹

¹University Of Alberta, Edmonton, Canada

Sensory feedback regulation involves GABAergic neuron terminals interacting with primary afferents via axo-axonic interactions. However, the distribution of GABA A and GABA B receptors along the afferent pathway and their alterations post-spinal cord injury (SCI) remain poorly understood. We employed transgenic mice (GAD2-creERT2/flx-ChR2) to visualize GAD2 neurons contacting afferents labeled with AAV9-tdTom viral vector. Immunolabeling of synaptic Gamma2 and extrasynaptic Alpha5 subunits of GABAA receptors, and GABAB receptors (B1 subunit) was conducted, along with identifying myelinated proprioceptive sensory axons’ nodes or paranodes using antibodies against sodium channels or Caspr, respectively. The SCI model involved a chronic complete transection at the sacral S2 level. Our findings demonstrate that GABAA receptors predominantly cluster at nodes and the proximal part of paranodes along the axon, while GABA B receptors concentrate in a diffuse layer over axon terminals. After a SCI, there is a significant increase in the percentage of nodes with GABA A receptors: synaptic GABAA receptors increase from 38% ± 5 to 58% ± 9.6 (P < 0.001), and extrasynaptic GABA A receptors increase from 33% ± 10 to 54% ± 13 (P = 0.0027). Conversely, the density of metabotropic GABA B receptors in terminals reduces from 51 ± 8% to 26 ± 5% of the density in motoneurons (P < 0.001) after SCI. Considering that GABAA receptors have recently been shown to increase sensory transmission and GABAB decrease sensory transmission, these findings suggest that after SCI exaggerated reflexes and spasms in part result from increased GABAA and decreased GABAB receptor expression.

Dr. Zhonghui Guan¹, Dr. Wei Sun¹, Dr. Peipei Pan¹, Dr. Wei Li¹, Amity Lin¹, Jacob Greene¹, Virginia Yao¹, Jessica Yu¹, Dr. Lingyi Zhang¹, Dr. Nikolaos Kyritsis¹, Xuan Duong Fernandez¹, Esmeralda Mendoza¹, Dr. Russell Huie¹, Dr. Adam Ferguson¹, Dr. Jason Talbott¹, Dr. Phil Weinstein¹, Dr. Lisa Pascual¹, Dr. Vineeta Singh¹, Dr. Anthony DiGiorgio¹, Dr. Rajiv Saigal¹, Dr. William Whetstone¹, Dr. Geoffrey Manley¹, Dr. Sanjay Dhall², Dr. Jacqueline Bresnahan¹, Dr. Mervyn Maze¹, Dr. Michael Beattie¹, Dr. Jonathan Pan¹, TRACK-SCI Investigators¹

¹University of California San Francisco, San Francisco, United States, ²University of California, Los Angeles, Torrance, United States

Introduction: In spinal cord injury (SCI), extensive work has identified many potential biomarkers for clinical patients. However, none of these biomarkers are specifically induced in injured neurons early after SCI. As neuronal injury is one of the major pathologies in SCI and strongly correlates with the neurological outcomes, biomarkers that have low baseline expression and are induced specifically in the neurons after injury are likely to correlate better with injury severity and recovery. In the current study, we investigate ATF3, an early response gene and transcriptional factor, on its biological function and potential as a biomarker for SCI.

Methods: In animal studies, global ATF3 knock out and wildtype mice had unilateral cervical 5 (C5) SCI (30 Kdyne). The expression of ATF3 was measured by RNA-sequencing and qRT-PCR and its protein was detected in injured spinal tissue by immunostaining. Serum ATF3 levels in animal SCI model and clinical human samples were measured by ELISA assays.

Results: ATF3 gene expression is significantly upregulated early after SCI. ATF3 protein is induced specifically in neurons of spinal cord within 1 day after SCI. Further, we demonstrate that serum ATF3 protein levels in human samples are elevated 24 hours after SCI and correlate with injury severity. In Atf3 KO mice, we observe worse neurological outcomes and larger damage regions after SCI.

Conclusion: ATF3 is an easily measurable, neuron-specific biomarker for clinical SCI, with neuroprotective function.

Acknowledgment: this work is supported by DoD W81XWH2210930 (SC210077) to J.Z.P.

Dr. Bradford Berk¹, Ms Amanda Pereira¹, Ms Velia Vizcarra¹, Dr. Christoph Pröschel¹, Dr. Chia Hsu²

¹University of Rochester Medical Center, Rochester, United States, ²The University of Texas at San Antonio, San Antonio, United States

The severity of spinal cord injury (SCI) is closely tied to pulmonary function, especially in cases of higher injury levels. Despite this connection, the underlying pathological mechanisms in the lungs post-SCI are not well comprehended. Previous research has established a connection between disrupted sympathetic regulation and splenocyte apoptosis in high thoracic SCI, leading to pulmonary dysfunction. The aim of this study is to investigate whether mice with low-level SCI exhibit increased susceptibility to acute lung injury by eliciting systemic inflammatory responses that operate independently of the sympathetic nervous system. Here, we employed lower lever T9 contusion SCI using the OSU SCI device and exposed mice to aerosolized lipopolysaccharide (LPS) to simulate lung inflammation associated with acute respiratory distress syndrome (ARDS). Twenty-four hours post-LPS exposure, lung tissues and bronchoalveolar lavage (BAL) fluid were analyzed. LPS markedly induced proinflammatory gene expression (SAA3, IRG1, NLRP3, IL-1beta, MCP-1) and cytokine release (IL-1beta, IL-6, MCP-1) in SCI mice compared to controls, indicating an exaggerated inflammatory response. Infiltration of Ly6G/C positive neutrophils and macrophages was significantly higher in SCI mice lungs post-LPS exposure. Interestingly, spleen size and weight did not differ between control and SCI mice, suggesting that T9 SCI alone does not alter spleen morphology. Notably, Bone-marrow-derived macrophages (BMDMs) from SCI mice exhibited hyper-responsiveness to LPS. This study unveils the potentiation of lung inflammation and immune responses in low SCI, shedding light on potential therapeutic targets for respiratory complications post-SCI.

Dr. Michael Donovan¹, William Cleveland¹, Dr. Alpa Trivedi², Lauren Smith¹, Dr. ByungGee Im³, Dr. Aaron Baker³, Dr. Linda Noble-Haeusslein^1,4

¹University of Texas at Austin Dell Medical School, Department of Neurology, Austin, United States, ²University of California at San Francisco, Department of Laboratory Medicine, San Francisco, United States, ³University of Texas at Austin, Department of Bioengineering, Austin, United States, ⁴University of Texas at Austin, Department of Psychology, Austin, United States

Reduced bladder compliance after spinal cord injury (SCI) results from abnormal remodeling of the bladder wall and results in reduced storage capacity, with increased risk of urinary tract infections and kidney damage. We show that matrix metalloproteinases (MMPs), upregulated in the bladder wall, contribute to loss of bladder compliance after SCI in male mice. Gelatin zymography confirmed upregulation of MMP-2 and MMP-9 (p<0.001) within the first week post-SCI (p<0.001). Mechanical testing revealed increased bladder wall stiffness at 3d (p<0.01), followed by a decrease at 7d (p< 0.001), with similar temporal variability in viscoelastic properties. Mice treated systemically with a general MMP inhibitor for the first 3 days(d) post-injury showed suppressed bladder wall MMP activity (p<0.001) and long-term improvement in voiding efficiency (p<0.001), coincident with reduction in detrusor area (p<0.05). Such findings implicate MMPs in local action within the bladder wall. Lastly, MMP inhibition over 3 days post-SCI improved hind-limb function in male mice by 6 weeks (p<0.05). Preliminary studies were conducted in female mice that were treated with the inhibitor either acutely (1-3d) or subacutely (7-10d) post injury. There was no improvement in locomotor function in the acute group and impaired recovery in the subacute group compared to controls (p<0.01). These collective findings suggest distinct and dynamic functional roles of MMPs following SCI in recovery processes including restoration of bladder compliance. Supported by the Department of Defense, SCIRP (W81XWH-22-1-0645) and the Craig H Neilsen Foundation (642910).

Dr. Alireza Khanteymoori¹, Roza Atamny¹, Prof. Jürgen Beck¹, Prof. Jan M. Schwab^2,3, Dr. Ralf Watzlawick¹

¹Department of Neurosurgery, Neurocenter, Faculty of Medicine, University of Freiburg, Freiburg, Germany, ²Departments of Neurology and Neurosciences, The Ohio State University, Columbus, United States, ³Belford Center for Spinal Cord Injury, The Ohio State University, Columbus, United States

Spinal cord injury (SCI) is a severe trauma that often causes life-long tremendous disability and has not yet been able to be treated sufficiently increasing a patient´s quality of life. To enhance treatment efficacy validation, we analyzed the recovery of untreated animals after experimental SCI. A critical evaluation of the endogenous recovery potential of untreated animals would help to: 1. Characterise the relationship between the severity of human and animal injuries, 2. Identify the onset of the chronic phase after a SCI and 3. Define the impact of different models of injury (hemisection, contusion, transection, compression) concerning functional outcome.

Our meta-analysis, encompassing 432 publications, investigates diverse factors: animal type, strain, sex, sample size, injury models, and injury level.

Lower lumbar lesions showed superior compensation through the spinal cord’s neuronal network, resulting in enhanced recovery compared to cervical and thoracic SCI. Gender differences influenced recovery, revealing distinct patterns in the time course of recovery. Plateaus show the maximum achievable recovery at a certain time-point determining the maximum recovery that the animal could achieve. Recovery plateaus suggest a finite period for experimental observation. There was no obvious difference in recovery patterns for different strains. However, the stratified analysis for the used injury model indicated better recovery for hemisection compared to contusion and transection.

A better characterization of the endogenous recovery of spinal cord injured animals is crucial for the development and evaluation of ‘promising’ therapeutic agents.

Mr. Danny John¹, Mr. Corey Fehlberg¹, Mr. James Choi¹, Dr. Jae Lee¹

¹University of Miami, Miller School of Medicine, Miami, United States

Age-related differences in clinical response to spinal cord injury (SCI) have long remained poorly addressed in the aggregate of relevant literature, justifying investigation by animal model. Most such studies have focused on age-extremes in the murine model, with young faring better than old, but neglected the pursuit of analysis in a ‘middle’ age population despite its correspondence to the human age-group in which the median incidence of SCI is clinically observed. While extant literature argues for an age-mediated decline in favorability of murine response to SCI, its failure to represent this intermediate group leaves the decline largely uncharacterized. A proper understanding of such variations in SCI pathology is indispensable to clinical precision. To compare the murine response to controlled SCI at young (2-4-month-old) and middle-aged (10-12-month-old) lifetime-points with respect to histopathology, behavioral recovery, and single-cell analysis. We relied upon the Jackson Laboratory for our human-to-murine age-matching paradigm, hypothesizing that middle-aged mice would fare worse than young mice following SCI; we tested this hypothesis at various post-injury timepoints using behavioral assessment, histological analysis, and single-cell analysis. Contrary to our hypothesis, we observed no significant differences between young and middle-aged mice as measured by the aforementioned criteria. Our findings suggest that young and middle-aged mice respond similarly to SCI, implying that the transition from middle-age to elderly may host a more precipitous decline in recovery-capacity than previously acknowledged. These findings hold implications for clinical trial design and treatment efficacy in age-matched human patients with spinal cord injury.

¹University of Miami, Miami, United States

Following spinal cord injury (SCI), infiltrating immune cells, especially monocyte-derived macrophages, contribute to the inflammatory environment that promotes fibrosis through the activation of fibroblasts. However, the molecular interaction between macrophages and fibroblasts that leads to fibrotic scar formation is not well understood. We recently showed that IL1a is one of the most highly upregulated cytokine in foamy macrophages in vitro. Interestingly, the receptor for IL1a, IL1R1, is expressed highly in fibroblasts at the injury site. Thus, the goal of this study was to determine the role of IL1a-IL1R1 signaling in formation of the fibrotic scar after SCI in mice. Our overall hypothesis was that reducing IL1a-IL1R1 signaling will attenuate fibrotic scar formation. We performed mid-thoracic contusive spinal cord injury in IL1a, IL1b, and IL1R1 knockout mice and assessed behavioral recovery over a 4 week recovery period and performed end-point histological analysis of the injury site. Our data show that IL1R1 knockout mice showed signs of improved open field locomotion as well as reduced fibrotic scarring at 4 weeks after SCI compared to wildtype controls. IL1a and IL1b knockout mice did not show improved behavior or histopathology. Taken together, our data suggests that IL1a and IL1b signal via the IL1R1 to have an additive effect on fibrosis after SCI.

Dr. Zhuofan Lei¹, Dr. Balaji Krishnamachary¹, Dr. Rodney Ritzel¹, Dr. Niaz Khan¹, Dr. Yuanyuan Ji², Dr. Yun Li¹, Mr. Hui Li¹, Ms. Kavitha Brunner¹, Dr. Alan Faden¹, Dr. Jace Jones², Dr. Junfang Wu¹

¹Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, United States, ²Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, United States

Approximately 20% of all spinal cord injuries (SCI) occur in persons aged 65 years or older. However, little research has examined the impact of aging on SCI pathobiology and mechanisms linking SCI and brain dysfunction. The present study examined neurobehavioral and molecular changes in the brain and the underlying mechanisms associated with brain dysfunction in aged C57BL/6 male mice using a contusion SCI model. At 2 months post-injury, aged mice displayed worse performance in locomotor, cognitive and depressive-like behavioral tests compared to young adult animals. Histopathology in injured spinal cord tissue was exacerbated in aged SCI mice. In the brain, transcriptomic analysis identified activated microglia and dysregulated autophagy as the most significantly altered pathways by both age and injury. Flow cytometry demonstrated increased myeloid and lymphocyte infiltration, altered microglial function, and dysregulated autophagy function in both microglia and brain neurons. Furthermore, altered plasma extracellular vesicles (EVs) responses were found in aged mice after acute SCI. Circulating EVs cargoes analysis identified distinct profiles of microRNA, protein, and lipid components in old and injury animals. In cultured microglia, astrocytes, and neurons, plasma EVs from aged SCI mice, at a lower concentration comparable to those of young adult SCI mice, induced the secretion of pro-inflammatory cytokines and neuronal apoptosis. Moreover, systemic administration of plasma EVs derived from SCI animals altered general physical function and caused brain transcriptomic changes in intact aged mice. Collectively, these findings highlight the importance of circulating plasma EVs altered by old age and its role in SCI-mediated brain dysfunction.

Ms. Ashley Scheinfeld^1,2, Ms. Sydney Lee^1,2, Dr. Andrew Gaudet^1,2

¹University Of Texas At Austin, Austin, United States, ²Department of Neurology, Dell Medical School University of Texas at Austin, Austin, United states

Abstract: Spinal cord injury (SCI) causes neuroinflammation that persists indefinitely, worsening neurologic recovery and promoting chronic neuropathic pain. SCI-elicited immune responses lead to cascading inflammation and expansion of the lesion. Therefore, promoting inflammatory resolution may support neuroprotection and recovery after SCI. Phagocytosis aids inflammatory resolution through engulfment of extracellular debris following injury to promote wound healing. Engulfment of apoptotic cells and cellular debris is facilitated by the phagocytic receptor MerTK. Here, we hypothesize that deletion of MerTK in male and female mice will exacerbate secondary damage and locomotor deficits after T9 contusion SCI. Compared to wildtype mice, MerTK knockout mice show impaired locomotor recovery after SCI. In accordance, MerTK knockout spinal cord epicenters had a larger lesion volume and cross-sectional area. qPCR analysis shows that MerTK knockout spinal cord epicenters have increased expression of potentially damaging pro-inflammatory mediators. Our results suggest that MerTK is required for typical healing and locomotor recovery after SCI. Ongoing studies involve MerTK modulation as a novel neuroimmune therapy to enhance recovery after SCI.

Support: Supported by Mission Connect, a program of the TIRR Foundation (ADG). Partial support was provided by start-up funds from the University of Texas at Austin, and by the National Institute Of Neurological Disorders And Stroke of the National Institutes of Health under Award Number R01NS131806 (ADG).

Mr. Jaechang Kim¹, Ms. Ruby Maharjan¹, Mr. Daniel Kolpek¹, Mr. Jonghyuck Park^1,2

¹Department of Pharmaceutical Sciences, University of Kentucky, Lexington, United States, ²Spinal Cord and Brain Injury Research Center, College of Medicine, University Of Kentucky, Lexington, United States

Secondary injury after primary traumatic spinal cord injury (SCI) is accompanied by inflammatory response, caused by the invasion and activation of immune cells. Particularly, males and females have different inflammatory profiles after SCI. In this study, we investigate the immunomodulatory effects of nanoparticles (NPs) on both sexes after SCI by using the intravenous (IV)-administered poly (lactic-co-glycolic acid) (PLGA)-based NPs to reprogram circulating innate immune cells and promote a more permissive environment. Initially, we fabricated 500nm PLGA-based NPs with Poly (ethyl methacrylate) (PEMA) as a surfactant for a negative surface charge and injected the NPs daily for 7 days via the tail vein. Spinal cord samples were collected 7 days after injury from both sexes and the proportion of immune cells including monocytes, monocyte-derived macrophages (MDMs), and microglia was analyzed using flow cytometry and immunofluorescence imaging. We also confirmed the alteration of Inflammatory-related gene expression through qRT-PCR and NanoString. Our data indicates that the administration of NPs decreased the proportion of infiltrated MDMs and microglia and induced immune polarization in both sexes after SCI, but the extent of their effects was sex dependent. Our qRT-PCR and NanoString data demonstrated that the change in gene expression was also sex-dependent. These findings indicated that the effect of NP treatment is sex-dependent and NP-mediated immunomodulation has the potential to yield sex-specific therapy for inflammation-derived disorders.

Ms. Devika Shukla¹, Ms. Simone Mohite¹, Dr. Jae K. Lee¹

¹University of Miami Miller School, Miami, United States

Spinal cord injury (SCI) results in a persistently lipid debris-ridden and scarred lesion site. This environment is non-permissive to proper wound repair and axon regeneration, which limits functional recovery. Astrocytes are a main component of the injury site border. Reactive astrocytes begin to rapidly proliferate 3 days after injury and slow by 7 days. By 14 days post-injury, a prominent gliotic region is present where reactive astrocytes densely surround the lesion. It has been previously shown that macrophages become oversaturated by uptaking excessive lipid debris and become inflammatory foamy cells that fill the injury site – possibly blocking regeneration across the injury. In this study, we sought to determine whether reactive astrocytes also accumulate lipid droplets and become foamy glia. We performed mid-thoracic contusive spinal cord injury in transgenic mice in which astrocytes are genetically labeled with eYFP, and determined the time course of lipid accumulation in astrocytes by measuring lipid droplet density (visualized by Oil Red O) at 3-, 7-, and 21-days post injury(dpi). By 21 dpi, reactive astrocytes that surround the injury site show dense accumulation of lipid droplets, indicating that excessive lipid accumulation is a pathology that is common to different cell types after SCI.

Mr. Neal Wrobel¹, Mr. Dustin Kim¹, Dr. Richard G. Fessler¹, Dr. Brian T. David¹

¹Rush University Medical Center, Department of Neurosurgery, Chicago, United States

The neuroimmune response which takes place within the spinal cord following a traumatic spinal cord injury (SCI) is widely recognized as a major influencer of the progression and severity of the secondary tissue damage which occurs after injury onset. Immunomodulatory therapies aimed at reducing secondary injury are, therefore, a notable point of focus in SCI research. To inform future studies aimed at development of such therapies, we present a detailed characterization establishing the dynamics of the SCI neuroimmune response in wild-type mice, until 6 months post-injury. Experimental mice received moderate, mid-thoracic spinal cord contusions; naïve mice were used as controls. Flow cytometry was used to quantify levels of immune cells within the spinal cord, including T Cells, helper T cells, cytotoxic T cells, regulatory T Cells, macrophages, and microglia. The spinal cord neuroimmune response exhibits a biphasic pattern, with one peak of peripheral immune cell infiltration between 1 and 2 weeks post-injury, followed by a second peak at 2 months post-injury. Both T cells and macrophages remain elevated at 6 months post-injury. At 6 months, but not at earlier timepoints, higher immune cell infiltration correlates with more normalized sensory function but may also be associated with spleen hypertrophy. Our results highlight the persistent and highly dynamic nature of the SCI neuroimmune response and indicate that certain effects of the spinal cord immune environment on behavioral function and on the peripheral immune system are still developing even in the chronic phase of injury.

This work is funded by the Rice Foundation.

Ms Krithika Iyer¹, Karianne Zamiar¹, Alyson Galvan-Lara², Sydney Rippy², Arianna Romano¹, Kaya Amin¹, Dr. Hiroshi Saito², Dr. Timothy Butterfield³, Dr. Samir P. Patel¹

¹Spinal Cord & Brain Injury Research Center and Department of Physiology, University of Kentucky, Lexington, United States, ²Departments of Surgery and Physiology, University of Kentucky, Lexington, United States, ³Athletic Training and Clinical Nutrition, University of Kentucky, Lexington, United States

Systemic infection (sepsis) following spinal cord injury (SCI) is a predominant secondary complication that induces a hyperinflammatory immune response causing multiple-organ damage, consecutively, poor functional recovery, or even death. To date, no experimental model is available to study post-SCI sepsis complications. Current study is designed to develop a novel, clinically relevant rodent model that mimics the long-term dysfunction of sepsis survivors post-SCI.

Adult female Sprague Dawley rats were divided in 4 groups: Sham, SCI, Sepsis and SCI+Sepsis. Rats in SCI and SCI+Sepsis received T10-contusion SCI (200 kDyn) using Infinite Horizon Impactor. Designated Rats were injected with 3 ml cecal slurry (i.p.) to induce sepsis. All the rats received antibiotics and fluid-resuscitation starting at 8h post-SCI and/or sepsis induction, which was repeated twice a day for 5-days.

Decreased survival was observed in SCI+Sepsis (∼39.3%) and Sepsis (∼55%) compared to SCI and Sham (100%). SCI followed by sepsis resulted in significantly impaired hindlimb locomotor recovery. Rats in SCI+Sepsis group were able to stand or walk without support (BBB∼9) whereas rats in SCI group walked with occasional coordination (BBB∼12) at 12-weeks post-SCI. In vivo muscle-strength test also showed significant muscle weakness in SCI+Sepsis versus SCI. Ongoing studies are assessing blood cytokines and histological changes to corelate with BBB and skeletal muscle-strength.

In summary, this study is the first step towards understanding underlying mechanisms of sepsis post-injury and paving the way to elucidate therapeutic strategies for SCI.

Dr. Luisa Rojas Valencia^1,2, Lex M Davis^1,2, Esmeralda Mendoza^1,2, Hannah Radabaugh^1,2,3, Abel Torres-Espin⁴, Russell Huie^1,2,3, Jonathan Lifshitz^5,6, Adam R Ferguson^1,2,3

¹Department of Neurological Surgery, University of California San Francisco (UCSF), San Francisco, USA, ²Brain and Spinal Injury Center (BASIC), Weill Institute of Neurosciences, UCSF, San Francisco, USA, ³San Francisco Veterans Affairs Healthcare System, San Francisco, USA, ⁴School of Public Health Science, University of Waterloo, Waterloo, Canada, ⁵Department of Psychiatry, University of Arizona College of Medicine-Phoenix, Phoenix, USA, ⁶Phoenix Veterans Affairs Health Care System, Phoenix, USA

Scientific data are rarely revisited after initial publication. After publication, raw data values themselves remain in formats that are not easily findable, accessible, interoperable, or reusable (FAIR), such as paper records or poorly curated digital files. This does not allow easy comparison of the raw data between datasets across years. In the 1990s, raw data in a single center was curated by a young graduate student who placed them in the cutting edge database technology at the time, a Microsoft Access structured query language (SQL) store. At the time investigators were skeptical of the value of databases since distillation of multidimensional data would require an unthinkable level of computation. After 30 years, we are now able to revisit these data, combine them with data from additional sites, and perform multidimensional analysis to gain insights into the context of the data and evaluate the integrity and sources of variance across 31 studies (N∼2250 animals). In addition, the data have been curated into tidy data format and uploaded to the Open Data Commons for Traumatic Brain Injury (odc-tbi.org), an NIH-supported FAIR data repository for TBI that provides persistent identifiers to support data citation and reuse (e.g., https://doi.org/10.34945/F51P49; https://doi.org/10.34945/F5PC77). Together the results demonstrate the value of old TBI data for supporting reproducibility and modern data-driven discovery.

Funding: odc-tbi.

Dr. Prakruthi Amar Kumar¹, Dr. Russell J Huie^1,2, Dr. Abel Torres-Espin^1,7, Dr. Hannah L Radabaugh¹, Dr. Anastasia Keller^1,2, Dr. Ubbo Visser⁶, Mr. Kenneth Fond¹, Dr. Vance Lemmon⁶, Dr. John L Bixby⁶, Dr. Romana Vavrek³, Dr. John Gensel⁵, Dr. Michael Beattie^1,2, Dr. Jacqueline Breshnahan^1,2, Dr. Jeffrey Grethe⁴, Dr. Maryann Martone⁴, Dr. Karim Fouad³, Dr. Adam Ferguson^1,2

¹Brain and Spinal Injury Center, University Of California, San Francisco, San Francisco, United States, ²San Francisco Veterans Affairs Healthcare System, San Francisco, United States, ³University of Alberta, Edmonton, Canada, ⁴University of California, San Diego, San Diego, United States, ⁵University of Kentucky College of Medicine, Lexington, United States, ⁶University of Miami, Coral Gables, United States, ⁷School of Public Health Sciences, University of Waterloo, Waterloo, Canada

Traumatic spinal cord injury (SCI) has impacted the lives of over 300,000 individuals in the United States. Despite decades of research efforts, finding an effective cure has been challenging. Major hurdles to identifying successful treatment strategies feasible for clinical translation are-complexity, inaccessibility and heterogeneity of research data. To overcome these barriers, the NIH has outlined data sharing mandates aimed at promoting transparency, reproducibility, and collaboration in scientific research. In this regard, ODC-SCI, a dedicated data sharing repository for the field of SCI was launched in 2017 as a community-led initiative. The ODC-SCI complies with FAIR (Findable, Accessible, Interoperable and Reusable) data sharing principles and is an NIH-supported repository for SCI, enabling data-driven discovery to ultimately expedite translation (www.nlm.nih.gov/NIHbmic/domain_specific_repositories.html).

Although initially ODC-SCI was designed to house preclinical SCI data, several deidentified clinical SCI datasets have been uploaded/published through the platform. Clinical data harmonization becomes extremely important to understand results of clinical trials, and to guide future preclinical experiment designs through a reverse translation approach crucial to eliminate wasteful animal experiments. To date, the platform contains 64,929,065 unique fields comprising variables and data from over 400 deidentified individuals (includes SCI & related CNS trauma patients,and healthy controls). Here, we present a descriptive analysis of the deidentified clinical SCI data publicly available within the ODC-SCI portal and highlight criteria for data deposition to obtain a public DOI (digital object identifier), with the objective of informing and encouraging clinical SCI researchers to contribute to data sharing initiatives.

Funding: NIH:U24NS122732,R01NS122888,UH3NS106899; US VA: I01RX002245; I01RX002787;CHN Foundation;WfL Foundation.

Dr. Maryan Zirkle¹, Dr. Ragini Verma¹, Eugene Rakhmatulin¹, Dr. Lee Lancashire¹

¹Cohen Veterans Bioscience, Philadelphia, United States

In the new era of brain research, multimodal data acquisition technologies necessitate an interoperability framework to connect and integrate disparate data across studies, diseases, and platforms. Addressing this need, Cohen Veterans Bioscience (CVB) spearheaded the BRAINCommons™ (BC), a cloud-based platform for data management, analysis and sharing. BC is designed to lower barriers to accessing brain health data and maximize its utility, supporting accelerated research workflows and enabling sharing of public, controlled and restricted data across the globe.

BC’s back-end architecture, powered by Amazon Web Services (AWS) and managed by a certified AWS managed service provider, for constant monitoring and maintenance, ensures scalability, security and compliance with global data privacy regulations, all while supporting a flexible sharing approach. The Common Data Model (CDM) at BC’s core is tailored for the complexities of brain research, promoting harmonization and integration, allowing unprecedented cross-cohort and cross-disease analysis, as well as federated discovery and analysis with participating platforms.

The BC’s user interface showcases the value of data with enhanced data exploration tools, fostering analysis both within BC and across platforms. BC workspaces offer access to a comprehensive suite of tools, from data exploration and visualization portals to advanced analytics pipelines. As a result, BC stands as the first integrative technology platform that democratizes data, enables guided and advanced analysis, allowing researchers of any level of expertise to contribute to and accelerate brain research discoveries on a global scale. The BRAINCommons is committed to technical innovation, collaborative ingenuity, and the acceleration of brain health advancements.

Dr. Harshit Arora¹, Dr. Harshit Arora¹, Dr. Hassan Darabi¹

¹University Of Kentucky, Lexington, United States

Introduction: Traumatic cervical spinal cord injury (tSCI) is associated with a prolonged increased risk of morbidity and mortality. Various demographic and clinical factors are known to influence clinical outcomes in the chronic recovery phase. The aim of the study is to generate prediction models that can help predict the likelihood of improvement in American Spine Injury Association impairment scale (AIS) scores over one year after acute tSCI.

Methodology: Consecutive patients admitted within 72 hours of acute tSCI and who underwent standard-of-care interventions, including surgery, were included in the analysis. Various baseline parameters including age, sex, BMI, mechanism of injury, and quantitative MRI-based assessments such as maximal spinal cord compression, maximal canal compromise, extent of cord compression, maximal cord swelling, intramedullary lesion (IML) length, and BASIC scores were recorded. Various machine learning prediction models (XGBoost, Random Forest and KNN) evaluating AIS conversion at one year were generated. Model performance was compared using area under the receiver operating curve (AUC) analysis.

Results: Of 103 patients, 27 patients died and 50 showed AIS conversion at one year. AUC values for the Random Forest, XGBoost and KNN models were 0.928, 0.881 and 0.706, respectively. Across the various models, BASIC scores and IML length were the strongest predictors of AIS conversion at one year.

Conclusion: Amongst the various prediction models, the Random Forest model performed the most robustly in predicting neurological improvement after acute tSCI.

¹National Institutes Of Health, Rockville, United States

Access to biospecimens is an oft cited challenge to the progress in research on neurological disorders. The National Institute of Neurological Disorders and Stroke (NINDS) is committed to providing high quality biospecimens for NINDS-mission relevant disorders, including TBI. The NINDS human biospecimen repository, BioSpecimen Exchange for Neurological Disorders (BioSEND), acquires, maintains, and distributes biospecimen collections for biomarker research in neurological disorders. The NINDS Human Cell and Data Repository (NHCDR) acquires, maintains, and distributes fibroblast, induced pluripotent stem cell (iPSC), and edited iPSC lines from neurological disorders. Samples from BioSEND and NHCDR can be distributed to academic and commercial entities globally to further research from basic to translational stages. At BioSEND, biospecimens are available from Parkinson’s Disease, Lewy Body Dementia, Huntington’s Disease, Myalgic Encephalomyelitits/Chronic Fatigue Syndrome, Frontotemporal Dementia, Spinocerebellar Ataxia, and Traumatic Brain Injury. Biospecimen types include DNA, RNA, plasma serum, cerebrospinal fluid (CSF), whole blood, urine, and saliva. At NHCDR, iPSC and fibroblast lines are available from control subjects and patients with various genetic mutations in disorders such as Alzheimer’s Disease, Amytrophic Lateral Sclerosis, Frontotemporal Dementia, Huntington’s Disease, Lewy Body Dementia, Mild Cognitive Impairment, Parkinson’s Disease, Spinocerebellar Ataxia and others. Access to biospecimens is a critical need across all stages of research. BioSEND and NHCDR provide biofluid and patient-derived cell lines from various neurological disorders, including TBI. Both repositories continue to expand available cohorts which are distributed worldwide. More information about BioSEND can be found at https://biosend.org/index.html. More information about NHCDR, including ordering, can be found at https://stemcells.nindsgenetics.org/.

Mr. Drew Parker¹, Dr. Alexa Walter¹, Dr. Pratik Mukherjee², Dr. Lee Lancashire³, Dr. Geoff Manley², Dr. Andrew Chen⁴, Dr. Ramon Diaz-Arrastia¹, Dr. Ragini Verma^1,3

¹University of Pennsylvania, Philadelphia, United States, ²University Of California San Francisco, San Francisco, United States, ³Cohen Veterans Bioscience, New York, United States, ⁴Medical University of South Carolina, Charleston, United States

Introduction: Developing MRI-based TBI biomarkers requires integration of patient data from multiple sites and harmonization to remove acquisition and processing differences without removing biology and injury-related differences. Traditional harmonization requires data pooling, making their clinical translation challenging due to patient privacy laws. Federated harmonization provides a framework to integrate knowledge without pooling data.

Objective: To create a federated framework for harmonizing MRI data with the ability to preserve injury related differences without controls.

Methods: Diffusion MRI data were combined from TRACK-TBI (11 sites) and Penn-TBIRI (1 site), totaling 545 patients (69% male, mean age: 38.1±15.4 years) at 2 weeks post-injury and 142 controls (64% male, mean age: 36.9±14.0 years). Average fractional anisotropy in 176 regions of the JHU-MNI-SS atlas were harmonized in a federated manner with Distributed-ComBat. ANCOVA with terms for site, group, age and sex were evaluated before and after harmonization. We simulated real life scenarios of patients without controls, by repeating harmonization after site-wise removing controls from TRACK-TBI, resulting in pairs of harmonized data from patients with and without their respective controls. We evaluated the effect of missing controls by average percentage error.

Results: F-tests revealed significant regional site-effects (p<0.001) before harmonization, that were removed (p>0.99) upon applying Distributed-ComBat harmonization. After removing controls from each site, regional average percentage error was less than 3% in any region, and biological effects of sex, age and injury were preserved.

Conclusion: We have a federated harmonization for building large TBI samples for biomarker development without pooling data.

Ms. Rachel Fox^1,2, Dr. Afshin Paydar^1,2, Mr. Azad Azargushasb^1,2, Mr. Samuel Vander-Dussen^1,2, Dr. Neil G Harris^1,2

¹UCLA Department of Neurosurgery, Los Angeles, United States, ²UCLA Brain Injury Research Center, Los Angeles, United States

Dynamic functional connectivity (dFC) analysis can capture transitions between recurrent brain states. We employed dFC analysis of functional-MRI resting-state and forelimb-stimulation task data acquired at 1-7wks after rat contusion injury and in shams (n=38-39/group). Phase locking states were computed using the leading eigenvector dynamic analysis model, which computes the leading eigenvector for each region, followed by k-means clustering to capture dominant connectivity patterns. We have previously shown group and time-dependent differences using static-FC in these data, and we hypothesized that dynamic analysis would demonstrate increased differences in injured groups vs-sham across time, revealing time-dependent global alterations.

Stratified cross-validation of brain states in task-based data revealed a higher number of optimal network states in shams compared to injured (k=5 and 2, respectively), demonstrating network-level differences potentially hindering accurate group comparison. dFC from the highest cross-validated-scored clustering of k=3 in combined data revealed a group_x_time difference in state transition probabilities (Kruskal-Wallis p<0.05) and an increase in state 2 (bilateral midbrain/hippocampal regions) occupancy in injured versus shams at 1wk (p<0.05). During forelimb stimulation, there was increased occupancy in state 1 (Left-Posterior Thalamus, Right-M2, Right-S1,Hindlimb) in injured versus shams at 7wks(k=3,p<0.05), but no differences in state-to-state transitions across group or time.

Although dynamic-FC can be used to capture time-dependent network changes, pointing to altered neural topology after injury, further investigation using additional analytic models and sedation-free data is necessary to determine if dFC provides added utility over static-FC.

Dr. William Haskins^1,8, Devin Jackson¹, James Meabon², Elizabeth Colasurdo², Kristy Radeker¹, Anthony DeLizza¹, Katie Tehas¹, Ava Puccio³, Raquel Gardner⁴, John Williamson⁵, Lisa Merck^6,7, Owen Leary⁷, Tyler Harder⁷, Amber Salter⁸, Jeffrey Illiff², Elaine Peskind², Kevin Wang^1,8

¹Gryphon Bio, Inc., South San Francisco, United States, ²Northwest Mental Illness Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle, United States, ³University of Pittsburgh, Pittsburgh, United States, ⁴Sheba Medical Center, Tel Aviv, Israel, ⁵Brain Rehabilitation Research Center, Gainesville, United States, ⁶Virginia Commonwealth University, Richmond, United States, ⁷Brown University, Providence, United States, ⁸Owl Therapeutics, LLC, San Antonio, United States

Introduction. Gryphon is developing a novel, highly scalable and cost-effective sampling and testing solution for brain injury and health in pre-hospital, hospital, and post-hospital environments. The “solution” combines (i) point-of-care, minimally invasive sampling methods that use saliva or capillary blood with (ii) laboratory-based, high sensitivity immunoassays for determining the levels of acute, subacute, and chronic biomarkers from susceptible brain cell types. Purpose. To demonstrate the feasibility of the solution for early detection and monitoring of brain injury and health in different contexts of use. Methods. Biomarker data was collected for saliva, capillary blood, plasma, serum, and CSF specimens prospectively collected from cross- and longitudinal-cohorts, from three observational clinical studies underway at five sites, as an interim readout. Additional biomarker data was collected from archived specimens from historical cohorts. Results. Preliminary results show striking evidence for the utility of the solution - including high frequency longitudinal studies and diurnal sampling studies of glymphatic impairment and clearance. Capillary blood recoveries of 25-50%, compared to venous plasma levels, were observed at pg/mL ranges for numerous well-known biomarkers including p-tau181, tau, Aβ1-42, NFL, GFAP, and IL6. We also report the discovery of several promising biomarkers in biofluid specimens. Conclusion. These results demonstrate that the Gryphon solution, combined with other modules and factors, such as cognitive assessments and age, can help address the unmet medical needs of traumatic brain injury (TBI), mild cognitive impairment (MCI), and Alzheimer’s disease (AD) patients in military and civilian populations. We acknowledge support from the DoD (W81XWH2110469, W81XWH22C0059, and HT94252310392).

Dr. Numaira Obaid^1,2, Dr. Brian Kwon^2,3, Dr. Carolyn Sparrey^1,2

¹Mechatronic Systems Engineering, Simon Fraser University, Coquitlam, Canada, ²International Collaboration on Repair Discoveries (ICORD), Vancouver, Canada, ³Vancouver Spine Surgery Institute, Department of Orthopaedics, University of British Columbia, Vancouver, Canada

Geriatric cervical spinal cord injuries (SCI) are becoming increasingly prevalent, with fall-induced neck hyperextension being the leading cause of this injury. Age-related spinal degeneration results in stenosis and makes this population more susceptible to experiencing an SCI. This study examined how ligamentum flavum (LF) thickening, a common degenerative condition in the spine, alters the biomechanics of the spinal cord when the neck is extended. A finite-element model of the cervical spine was developed, consisting of the C4-C6 vertebral bodies, the spinal cord, dura mater, cerebrospinal fluid (CSF), intervertebral discs partitioned into the annulus fibrosis and nucleus pulposus, and key ligaments. The geometry was modified to parametrically examine the effect of a LF thickness (1-mm vs. 2-mm) by compensating with reduced CSF thickness. An extension moment of 3 Nm was applied to the C4 level with the C6 constrained, and the impact on the biomechanics of the spinal cord was examined. Increasing the thickness of the ligamentum flavum increased the stress experienced by the spinal cord with increased levels in the anterior-posterior segments of the cord compared to the center. This study highlights how age-related degeneration alters the spinal cord biomechanics over the range of motion and places some individuals at a higher risk of experiencing an SCI.

We acknowledge the support of the Craig H. Neilsen Foundation, Michael Smith Health Research BC, NSERC, and SFU Community Trust Endowment Fund, and the DRAC. BKK is the Canada Research Chair in Spinal Cord Injury and the Dvorak Chair in Spine Trauma.

Ms. Natalie Smith¹, Mr. Anthony Baker², Dr. Michaelann Tartis², Dr. Zane R. Lybrand¹

¹Texas Woman’s University, Denton, ²New Mexico Tech, Socorro

Linking the mechanical response of brain tissue to traumatic brain injury (TBI) is critical to understand the neurophysiological changes to injury. Current animal models do not fully recapitulate both the biological and mechanical properties of the human brain. To provide a potential in vitro model, we have a designed biofidelic chip system to embed cerebral organoids that integrate into a polyacrylamide (PAA) brain phantom. Human cerebral organoids are 3D tissue cultures that mimic the cell composition and neurophysiological function of the brain. Key design factors for a living brain phantom model require long-term culturing of embedded organoids that successfully attach to the PAA gel and maintain optimal cell viability. To measure the viability of organoids embedded into our biofidelic chip, organoids (n=5) were infected with AAV-hSyn-GFP to visualize neurons, embedded in PAA chips for 7 or 14 days, dissociated using a papain treatment, then analyzed with a trypan blue assay for cell viability. After 14 days in PAA, organoids did not have a significant difference in percentage of live cells compared to non-embedded control organoids. This demonstrates the feasibility of culturing cerebral organoids in a biofidelic PAA chip for extended durations. The goal of this project is to incorporate the cerebral organoids into our engineered brain phantom to study the effects of mechanical forces from different brain traumas on the physiological functions of the brain.

Bryce West¹, Jack Monday¹, Dr. Patrick Devlin¹, Trang Do¹, Dr. Chunfeng Tan¹, Romeesa Khan¹, Swati Mohapatra¹, Dr. Michael Maniskas¹, Dr. Rodney Ritzel¹

¹University Of Texas Health Science Center At Houston, Houston, United States

Recent studies indicate the skull bone marrow reservoir may play a key role in the hematopoietic response to brain injury. Our study proposes an ex-vivo co-culture approach to deepen our understanding the dynamic interactions between the skull and brain in a murine model of traumatic brain injury (TBI). This method utilizes a naïve donor calvarium, that harbors fluorescently tagged bone marrow cells, which is then placed on top of an injured brain for short-term culture. We hypothesized that TBI triggers the mobilization and directed migration of myeloid cells from the calvarial bone marrow reservoir into the lesion site. Using a controlled cortical impact (CCI) model of unilateral, severe TBI in mice, with cellular tracing, immunohistochemistry (IHC), qPCR, and flow cytometry techniques, we aim to describe the mode and mechanisms underlying calvarial bone marrow cell egress and migration into the TBI brain. We utilized CCR2/5 and CXCR2 antagonists to modulate monocyte and neutrophil cell egress, respectively, from the calvarium into the contused area and investigated the role of aging skull on TBI-induced myelopoiesis. Flow cytometry analyses demonstrated that CCI causes robust myeloid cell infiltration directly from the skull into the ipsilesional brain hemisphere relative to the contralateral side, which was confirmed by IHC. Significant effects of age were seen in leukocyte composition and number. In summary, we establish that the Bonehead coculture system is effective for investigating skull-brain communication during the acute phase of injury, with the potential for experimental manipulation of calvarial myelopoiesis, bone marrow leukocyte egress/migration, and brain pathology.

Nicholas J. Cecchi¹, Dr. Yuzhe Liu^1,2, Ramanand V. Vegesna³, Xianghao Zhan¹, Weiguang Yang^1,4, Leslie Campomanes¹, Miss. Jessica Towns¹, Dr. Gerald A. Grant⁵, Dr. David B. Camarillo¹

¹Department of Bioengineering, Stanford University, Stanford, United States, ²School of Biological Science and Medical Engineering, Beihang University, Beijing, China, ³Department of Biomedical Engineering, University of Southern California, Los Angeles, USA, ⁴Department of Pediatrics, Stanford University, Stanford, USA, ⁵Department of Neurosurgery, Duke University, Durham, USA

Advances in shock absorber technology can often be translated from various industries to protective helmet products that protect humans from traumatic brain injury. In this study, we leveraged the energy dissipation of fluid flow using soft structures to prototype a novel, wearable hydraulic shock absorber — the Soft Hydraulic Shock. The Soft Hydraulic Shock achieved a fully efficient energy absorption ratio of 100% across a range of impact masses and speeds due to its fluid-based mechanism of energy absorption. In comparison, five shock absorbers taken from existing American football helmets were found to have average energy absorption ratios ranging from 74.0% to 90.0%. Furthermore, the Soft Hydraulic Shock maintained a stable energy dissipation across a wide range of temperatures common to helmeted applications (-18ºC, 19.5ºC, 50ºC), while the energy dissipation of other shock absorbing technologies varied up to 20% across these temperatures. Analyses of the behavior of the Soft Hydraulic Shock with different design parameters and impact loadings were further explored with a validated finite element model of the device. Finally, the Soft Hydraulic Shock demonstrated the ability to significantly mitigate brain injury risk (23.9% reduction in Head Acceleration Response Metric, a metric associated with concussion risk) when implemented into a full helmet system. The results of this study demonstrate the promise of wearable hydraulic shock absorbers and provide a platform for further optimizing their performance.

Ms. Tawny Stinson¹, Mr. Benjamin Baskin¹, Ms. Inori Kawauchiya¹, Mr. Michael Mikaelian¹, Ms. Krystal Qiao¹, Mr. Aarush Patnala¹, Ms. Mariana Gonzalez Rodriguez¹, Mr. Venkat Ayalavarapu¹, Ms. Linda Kwakman¹, Dr. Josephine Lok^3,4, Dr. Beth Costine-Bartell^1,2

¹Department of Neurosurgery, Massachusetts General Hospital, Charlestown, United States, ²Department of Neurosurgery, Harvard Medical School, Boston, United States, ³Department of Pediatrics, Pediatric Critical Care Medicine, Massachusetts General Hospital, Boston, United States, ⁴Department of Pediatrics, Harvard Medical School, Boston, United States

Our severe model of TBI includes cortical impact, mass effect, seizure, subarachnoid hemorrhage, apnea, and hypoventilation and results in evolving hypoxic-ischemic tissue damage. Injuries are induced after piglets are transitioned to a non-GABA acting, seizure-permissive anesthesia. Severe TBI reduces neurologic function and requires mechanical ventilation necessitating 2 staff present for the 30-hour experiment. Staffing nurses for prolonged ICU experiments might be cost-prohibitive and limit the utilization of severe TBI models and ICU research.

Over the past decade, we have optimized a training pipeline that allows us to conduct up to 3, 30-hour experiments per month, training college and medical student interns in ICU nursing. Lean management resulted in comprehensive protocols implemented by 7+ students/experiment trained to perform intensive care in 5-8h shifts. Training included an anesthetic complications chapter, flipped classroom sessions (3h), hands-on training by shadowing team leads (30-64h), inventorying acquired skills, knowing when to contact the on-call/onsite veterinary technician trained in resuscitation protocols (OCVT), and post-ICU communications reviewing areas for improvement.

In this severe TBI model, the annual rate of piglets receiving chest compressions was 18.7% (± 16.2%). Observations of pediatric ICU nursing staff that improved outcomes were script guided shift transitions, partial body repositioning, and regular servicing of endotracheal tubes. The training pipeline reduced exclusions, accidental extubations (< 12%), direct contact time by the OCVT, and increased surgical volume for other projects. By sharing our protocols, we hope to increase the accessibility of severe, gyrencephalic models of TBI.

This work was funded by NIH NICHD K01HD083759 and R01HD099397.

Dr. Manoj Govindarajulu¹, Mr. Aymen Al-Lami¹, Dr. Jishnu Krishnan¹, Mr. Gaurav Phuyal¹, Dr. Rex Jeya Rajkumar Samdavid Thanapaul¹, Dr. Joseph B. Long¹, Dr. Peethambaran Arun¹

¹Walter Reed Army Institute of Research, Silver Spring, United States

Blast-induced traumatic brain injury (bTBI) causes acute and chronic neurobehavioral abnormalities and clinical observations of several military blast casualties have revealed tauopathy and development of chronic neurodegenerative disorders post-blast. However, the mechanisms by which bTBI initiates the neurodegenerative processes are not completely understood. We investigated the differential expression of axonal injury markers namely phosphorylated Tau (pTau) and phosphorylated neurofilament heavy chain (pNFH) levels in various brain regions following blast exposure. Ferrets were exposed to two tightly coupled blasts (19psi) using an advanced blast simulator. Different brain regions, plasma, and cerebrospinal fluid (CSF) were collected at 24h and 1-month post-blast. Protein levels of pTau and pNFH were quantified by Western blotting. pNFH levels in plasma and CSF were quantified by commercially available ELISA kit. Our results reveal increased phosphorylation of Tau at serine (Ser396 and Ser404) and threonine (Thr205 and Thr231) at 24h and 1-month post-blast with associated activation of the protein kinases (GSK3β, CDK5 and MAPK) involved in the phosphorylation of Tau in prefrontal cortex, cortex, cerebellum and brainstem. Increased protein expression of pNFH was also evident at both time points in those brain regions. Furthermore, increased CSF pNFH levels were noted at both time points. However, statistically significant increase in plasma pNFH levels were noted only at 24h. Our results indicate that blast exposure causes acute and persistent tauopathy and axonal degeneration in different brain regions. Further extensive investigation in the field is needed to develop therapies to protect bTBI patients from increased risk of developing neurodegenerative diseases.

Ms. Tawny Stinson¹, Mr. Benjamin Baskin¹, Mr. Aarush Patnala¹, Dr. Beth Costine-Bartell^1,2

¹Department of Neurosurgery, Massachusetts General Hospital, Charlestown, United States, ²Department of Neurosurgery, Harvard Medical School, Boston, United States

Severe TBI has been associated with both acute and chronic cardiac dysfunction. Similarly, we observe cardiac dysfunction in a subset of subjects after severe TBI. We hypothesized that severe TBI model injuries would increase concentrations of serum cardiac biomarkers.

Yorkshire piglets aged 7 or 30 days received severe TBI model injuries with (n=11) or without anti-seizure medications (ASMs) 1-hour after seizure initiation (n=8) or received sham surgery (n=4). Injuries and insults included cortical impact, apnea, hypoventilation, mass effect, subdural hematoma/subarachnoid hemorrhage, and seizures. Cardiac troponin I (cTnI), creatine-kinase MB (CKMB), and epinephrine were measured in duplicate in serum from blood samples collected pre-injury, at 3, 6, 8, and 16h post-seizure timepoints, and at brain collection.

In this interim analysis, piglets receiving severe TBI model injuries with or without ASMs required vasopressors, chest compressions, and had an early death due to cardiac dysfunction at a higher rate than sham piglets (P<0.0001). Cardiac dysfunction was 3-fold greater with severe TBI + ASM than without ASM but was not statistically different. Concentrations of cTnI increased in severe TBI piglets (P<0.0001) at 3-hours post-seizure initiation compared to pre-injury increasing earlier (P=0.015) than sham piglets at an average of 3-hours prior to early death. To date, no increase in CKMB nor epinephrine has been observed.

Acute myocardial injury occurs post-severe TBI. We will continue to examine the role of severe TBI and ASMs on cardiac dysfunction. Managing and protecting the heart might improve outcomes after severe TBI.

This work was supported by R01 HD099397.

Dr. Molly Goodfellow¹, Mr. Boris Piskoun¹, Ms. Amanda Hrdlick¹, Ms. Julie Proctor¹, Dr. Ulrich Leiste², Dr. William Fourney², Dr. Gary Fiskum¹

¹University of Maryland School of Medicine Department of Anesthesiology and the Center for Shock, Trauma, and Anesthesiology Research (STAR), Baltimore, United States, ²University of Maryland-College Park Department of Aerospace Engineering, College Park, United States

Improvised explosive device detonation under vehicles can cause traumatic brain injuries (TBI) in warfighters with or without an accompanying impact injury. In rodents, aeromedical evacuation-relevant hypobaria exposure (HB; ∼8000 ft) exacerbates TBI, though translating findings in lissencephalic rodents to humans is challenging. Thus, a blast + impact model was developed in ferrets to study single and multiple HB exposure effects on the injured gyrencephalic brain.

The protocol was approved by the UMB IACUC and US Air Force General’s Office of Research Oversight and Compliance.;Sedated male ferrets were secured to a metal plate “vehicle” and exposed to under-vehicle blast followed by a controlled cortical impact (BCCI) under anesthesia. Animals underwent one or five 6-hour HB or normobaria (NB; sea level) exposure(s) over the 6 months post-injury. Mood (Play, Open Field), motor function (Ladder Walk), and memory (Novel Object Recognition & Location) were assessed.

HB exposure after BCCI induces lasting neurobehavioral deficits relative to naive animals. Multiple HB exposures after BCCI induced anxiety-like behavior on Open Field. HB also caused motor impairment on Ladder Walk. BCCI led to Novel Object Recognition impairments and increased Play latency, further suggestive of anxiety. No differences were noted in Object Location or activity level.

Results from this study will inform guidelines for the safe transport of TBI patients.

The views expressed are those of the authors and do not reflect the official guidance or position of the United States Government, the DOD or of the USAF. Supported by USAF FA8650-20-2-6H20. Cleared for public release AFRL-2023-1184.

Prof. Sharon Juliano¹, Dr. Nicholas Breehl¹, Dr. David Priemer¹, Dr. Daniel Perl¹

¹USUHS, Bethesda, United States

Blast traumatic brain injury (bTBI) results in chronic pathology, especially after repetition. To evaluate cellular changes induced by bTBI, we studied post-mortem prefrontal cortex of military personnel exposed to multiple blasts. Our focus included the astrocyte proteins GFAP, aquaporin-4 (AQP-4), and connexin-43 (Conn43) at interface regions of neocortex. Astrocyte morphology in injured samples altered significantly, revealing a disintegrated, beaded shape. We also observed a shift in astrocyte immunoreactivity, where control brains showed two dominant populations, either GFAP+ or AQP-4+, with few co-labeled cells. Injured brains revealed the emergence of a third dominant population with abnormal morphology co-labeled with GFAP and AQP-4; significant increases in astrocytes with abnormal morphology also occurred, including those both GFAP+ and AQP-4+. Conn43, a protein that helps maintain neural homeostasis, significantly co-labeled with AQP-4, and not GFAP, in both control and injured brains, suggesting the AQP-4+ subtype to be homeostatic. Interlaminar astrocytes consistently showed abnormal morphology in injured brains, featuring extensive GFAP+ beaded, interrupted processes. These injured processes were encased by AQP-4 immunoreactivity and co-labeled with phosphorylated Conn43, indicating an inflammatory phenotype. To investigate maladaptive secondary pathology that might relate to immune dysfunction, immunoreactivity with IgG revealed autoantibody in injury samples, which labeled neurons in layer 2-3 also co-immunoreacted with complement C3. The interlaminar astrocytes in half of the injured brains also immunoreacted with C3. We conclude that military related TBIs inflict chronic alterations in expression of astrocytic proteins that coincide with induction of autoantibodies directed towards neurons and recruit complement. Supported by USU- PAT-74-3439.

Dr. Morteza Seidi¹, Dr. Marzieh Memar¹

¹University of Texas at San Antonio, San Antonio, United States

Traumatic Brain Injury (TBI) stands as a major global health concern, affecting millions of people worldwide. TBI research aims to improve our understanding of brain injuries and diagnostic tools, with a key focus on exploring blood biomarkers. This study investigated post-TBI elevation and temporal profiles of serum biomarkers including glial-fibrillary-acidic-protein (GFAP), associated with glial damage, and Neurofilament-Light-Chain (NFL), linked to axonal damage, in single (sTBI) and repeated (rTBI) closed rapid head rotation ferret TBI model. Ferrets were divided into sTBI (n=5, ∼15m/s), rTBI (n=5, one∼15m/s plus three∼10m/s impacts, 10-minutes apart), and sham (n=3) groups and blood samples were collected pre-injury, at 1- and 6-hours, and 1-, 3- and 7-days post-TBI and analyzed by a Single Molecule Array system. For all groups, NFL concentrations were significantly elevated from 1-day and were peaked at 3-days with 16-, 6-, and 2-folds increase for rTBI, sTBI, and sham groups. The elevation of NFL in sham group may be attributed to the anesthesia and medication used but the elevation is much lower than injury groups. GFAP concentrations significantly elevated (2-3 folds) at 1-hour/6-hours post-TBI for both rTBI and sTBI groups, but not sham, and return to baseline afterward. The substantially higher elevation of NFL in rTBI compared to sTBI suggest that even low severity impacts following a more severe impact can worsen axonal damage. Additionally, the biomarker elevations are much higher in ferrets compared to other animals like pigs, suggesting that ferrets are a good model for studying TBI biomarkers. Funded by UTSA-SwRI CONNECT program.

Ms. Sarah Schantz^1,2, Mrs. Sydney Sneed^1,3, Dr. Holly Kinder^1,3, Dr. Kylee Duberstein^1,3, Dr. Erin Kaiser^1,2,3, Dr. Franklin West^1,2,3

¹Regenerative Bioscience Center, Athens, United States, ²Biomedical and Health Sciences Institute Neuroscience Program, Athens, United States, ³Department of Animal and Dairy Science, Athens, United States

Pediatric traumatic brain injury (TBI) causes significant tissue damage and loss, abnormal brain development;and results in long-term functional deficits. Induced pluripotent stem cell-derived neural stem cells (iNSCs) may serve as a potential treatment for TBI through cellular replacement, regeneration, and neural protection. In the present study, we evaluated the effect of cerebrally transplanted iNSCs in a translational piglet TBI model. TBI was induced by controlled cortical impact over the left motor cortex and stereotaxic transplantation of iNSCs (n=6) or PBS (n=5) was delivered into the perilesional region 5 days later. Sham control piglets (n=6) received only a craniectomy. Modified Rankin Scores (mRS) were collected pre-TBI to 12 weeks post-transplantation (PT). At 12 weeks PT, magnetic resonance imaging (MRI) was performed and brain tissue was collected for immunohistochemistry. PBS pigs demonstrated greater mRS scores compared to sham pigs whereas no differences were found between iNSC treated and sham animals, indicating iNSCs decreased neurological injury severity (p<0.05). MRI revealed iNSCs decreased lesion volume, hemispheric atrophy, and midline shift as well as preserved cerebral blood flow (p<0.05). Immunohistochemical analysis indicated iNSC treatment led to increased NeuN+ neuron survival and neurogenesis confirmed by DCX+ neuroblasts and reduced neuroinflammation of Iba1+ immune cells (p<0.05). These results in a predictive large animal model suggest iNSC treatment decreased tissue damage following TBI leading to increased functional recovery. Moreover, these findings support the use of iNSCs as a potential therapeutic treatment option for human pediatric patients following severe TBI.

Dr. Colin Huber¹, Akshara Thakore¹, Dr. Anna Oeur¹, Dr. Susan Margulies¹

¹Georgia Institute Of Technology And Emory University, Atlanta, United States

Effective treatment of traumatic brain injury (TBI) remains elusive. Previously, we found that cyclosporin A (CsA) treatment decreased axonal injury and preserved mitochondrial function in focal and diffuse TBI. Here, we hypothesize that 24h CsA treatment decreased acute glial fibrillary acidic protein (GFAP) and neurofilament light (Nf-L) serum biomarker responses (Simoa Human Neurology 4-Plex A assay) in focal and diffuse TBI. Baseline and 1-day post serum samples were collected from 4-week-old female swine: sham (n=10), controlled cortical impact (CCI, n=35), and sagittal rapid non-impact head rotation (RNR, n=67). Injured animals received continuous intravenous saline (untreated, RNR n=39, CCI n=13) or CsA (10-60 mg/kg) for 24 hours beginning 1h or 6h after injury (RNR n=28, CCI n=22). Injury type contributed significantly (ANOVA, p<0.05) to biomarker profiles at 1d. For GFAP, RNR was similar to pre (32 to 34 pg/mL, p>0.999), while CCI increased significantly (21 to 1669 pg/mL, p<0.001) above sham and an established healthy reference range (RR, p<0.001). For Nf-L, CCI (23 to 89 pg/mL, p<0.001) and RNR (33 to 65 pg/mL, p<0.001) increased relative to baseline and RR. There was no CsA effect at 1d post-RNR. For CCI, treatment concentration groups were compared to saline by Mann Whitney U tests, 60 mg/kg CsA treatment (n=4) lowered GFAP (609 pg/mL, p=0.036) and Nf-L (54 pg/mL, p=0.036) below the saline group. Serum biomarkers are sensitive to injury type and CsA treatment after TBI. This study was supported by the Georgia Research Alliance and the National Institutes of Health (R01NS097549, U01NS069545, R01NS039679).

Dr. Michael Grovola^1,2, Dr. D. Kacy Cullen^1,2

¹University Of Pennsylvania, Philadelphia, United States, ²Philadelphia VAMC, Philadelphia, United States

Traumatic brain injury (TBI) is a public health concern with an estimated 42 million cases globally every year. The majority of TBIs are mild TBI, also known as concussion, and can result from any type of mechanical force on the head. Most patients make a complete recovery and mortality is rare, therefore studying mild TBI in a purely clinical setting is limited. To address this constraint, our research group conducts preclinical research using a pig model of closed-head rotational acceleration-induced TBI. This model recreates the biomechanical loading parameters of TBI on a large gyrencephalic brain similar to humans. While our previous research has focused on immunohistochemical characterization of neuropathology, the current study utilizes transcriptomic assays to evaluate an array of TBI-induced neurodegenerative analytes. Pigs subjected to TBI were survived for 3 days post-injury (DPI) (n = 3), 30 DPI (n = 3), or 1 year post-injury (YPI) (n = 3) and compared to sham (n = 8). RNA was isolated from fixed tissue and multiplexed on a Nanostring neuropathology panel. Differential expression analysis revealed 11 differentially expressed genes at 3 DPI, including downregulation of the synaptotagmin calcium sensor gene, SYT1, upregulation of the neurofibromin gene, NF1, and the Alzheimer’s disease associated receptor gene, SORL1. There were no differentially expressed genes at 30 DPI or 1 YPI. This study adds to a growing body of literature on transcriptomic changes in a clinically-relevant large animal model of closed-head TBI, which highlights potential therapeutic targets and may ultimately provide treatment to TBI survivors.

Holly Carrington¹, Ariel Pruyser¹, Dr. Emily Dennis², Enna Selmanovic¹, Lisa Bura¹, Holly Freeman³, Alexander Atalay³, Dr. Brian Edlow^3,4, Dr. Jeanne Hoffman⁵, Dr. Christine Mac Donald⁶, Dr. Alan Seifert⁷, Dr. Elisabeth Wilde^2,8, Dr. Kristen Dams-O’Connor^1,9

¹Department of Rehabilitation and Human Performance, Icahn School of Medicine at Mount Sinai, New York, United States, ²Department of Neurology, University of Utah School of Medicine, Salt Lake City, United States, ³Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States, ⁴Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, United States, ⁵Department of Rehabilitation Medicine, University of Washington School of Medicine, Seattle, United States, ⁶Department of Neurological Surgery, University of Washington, Seattle, United States, ⁷Department of Diagnostic, Molecular and Interventional Radiology, Biomedical Engineering and Imaging Institute, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, United States, ⁸George E. Wahlen VA, Salt Lake City Health Healthcare System, Salt Lake City, United States, ⁹Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, United States

Brain age prediction models reveal atrophy in the first several years after traumatic brain injury (TBI), which may contribute to observed associations with dementia risk/clinical decline. Less is known about stability/progression of atrophy many years post-injury. The objective of this study was to use data from the longitudinal Late Effects of TBI (LETBI) study to investigate whether predicted brain age difference (PBAD) is greater among those with complicated mild, moderate, or severe TBI (cmsTBI), and whether those with higher PBAD show greater progression of PBAD over time. The LETBI sample includes 301 individuals with cmsTBI, of whom 247 completed MRI and 93 completed at least one follow-up MRI and passed quality checks. Replicating methods developed by the ENIGMA Adult Moderate and Severe TBI working group, T1-weighted MR images were processed with brainageRv2.1 workflow trained on brain MRIs from public datasets (3,377 individuals aged 18-92). Spatially normalized images were vectorized and underwent principal components analysis to yield 435 components/participant; the training dataset rotation matrix was applied to yield 435 components for each LETBI participant and used to predict brain age. PBAD was calculated by subtracting chronological age from predicated age. The analytic sample was 66% male, 86% white, 12% Hispanic, and aged 58(SD=16) years. PBAD was greater in cmsTBI relative to controls, after covarying for age and sex. Accelerated aging at study entry (1-31 years post-TBI (mean=9y)) increases risk for PBAD progression over time. PBAD reflects an efficient index of post-traumatic neurodegeneration that may inform trial selection and chronic TBI phenotyping.

Dr. Katherine Hunzinger¹, Dr. Andrea Schneider², Dr. Emma Russell³, Dr. Donald Lyall⁴, Dr. Willie Stewart^3,5

¹Department of Exercise Science, Thomas Jefferson University, Philadelphia, United States, ²Depertments of Neurology and Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, United States, ³School of Psychology and Neuroscience, University of Glasgow, Glasgow, United Kingdom, ⁴School of Health and Wellbeing, University of Glasgow, Glasgow, United Kingdom, ⁵Department of Neuropathology, Queen Elizabeth University Hospital, Glasgow, United Kingdom

Objectives: To investigate the relationship between repetitive head impacts (RHI) and traumatic brain injury (TBI) with subsequent risk of stroke among two populations with varying exposure profiles.

Methods: Former contact sports athletes were identified as 11,954 Scottish former professional soccer players while community level TBI comprised 284,195 individuals identified with documented, hospitalized TBI from electronic health records. Each cohort was then matched to general population comparator groups by year of birth, sex, and area socioeconomic status, with 35,758 controls identified for the former contact sport athlete group and 938,239 controls for the community TBI group. Incident stroke was defined using hospitalization ICD 9/10 codes. Participants were followed from age 30 years to stroke, death, or administrative censoring at either age 90 years or 12/31/2020. Cox proportional hazard models were used to estimate associations with incident stroke risk.

Results: No difference in stroke risk was detected between former soccer players and their matched population comparator group (HR=0.98, 95%CI=0.83-1.15). In contrast, risk of incident stroke among individuals with community level TBI history was higher than among their matched controls with no history of TBI (HR 2.18, 95%CI=2.13-2.22).

Conclusions: These data demonstrate that while risk of stroke is approximately doubled following community level, hospitalized TBI, there is no such observed increase in risk among individuals with histories of contact sports participation and RHI exposure. Future work to identify factors underlying the differences observed between these different populations is warranted.

Support: NNS TEAM VISA.

Dr. Shawn Eagle¹, Dr Maxwell Wang¹, Regan Shanahan¹, Anna Slingerland¹, Shovan Bhatia¹, Michael Kann¹, Tyler Augi¹, Ava Puccio¹, David Okonkwo¹

¹University Of Pittsburgh, Pittsburgh, United States

Background: The International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) is the most studied prognostic model for severe TBI and uses data from hospital admission to predict 6-month neurological outcome. We evaluated dynamic trends of clinical labs within the first two weeks of hospitalization to improve upon this model.

Methods: Severe TBI patients (GCS=3-8) presenting to a level 1 trauma center were enrolled under an IRB-approved protocol to collect injury and acute care data as well as neurological outcome(n=240). IMPACT was the base model with daily rates of sodium, hemoglobin, platelets and glucose. Random forest predictor models were developed to identify the variance accounted for (R2) between predicted and 6-month neurological outcome measured by Glasgow Outcome Scale Extended (GOSE). Spearman correlations were conducted for clinical labs to six-month GOSE. Cortisol labs were collected in a subset (n=100) within 48 hours and correlated to glucose, sodium and platelet levels.

Results: The IMPACT model had an R2 of 22%, while addition of serial clinical labs increased R2 to 31%. Glucose and sodium trends over the first two weeks significantly correlated with 6-month outcome (r=-0.41 to -0.14). Higher platelet count on Days 4-9 correlated with better outcomes (r=0.15-0.29; p=0.006). Cortisol correlated with glucose on days 1-6 (r=0.27-0.34; p=0.016) and platelets on days 6-11 (r=-0.40 to -0.23; p=0.01).

Conclusions: The magnitude of sodium and glucose increase was negatively linked to patient outcomes. The magnitude of platelet increase was linked to positive recovery. Acute cortisol was associated with these glucose and platelet responses.

Prof. Wilco Peul¹, Dr. Thomas van Essen, MSc Rick Vreeburg, MSc Ranjit Singh, MSc Inge van Erp, Dr. Angelos Kolias, Prof Ewout Steyerberg, Prof Peter Hutchinson, Dr. John Yue, Prof Geoffrey Manley, Prof Andrew Maas

¹Leiden University Neurosurgical Center Holland, Leiden, Netherlands

Objective: Compare outcomes of early cranioplasty (≤90 days) to delayed cranioplasty (>90 days) following decompressive craniectomy (DC) in patients with traumatic brain injury (TBI).

Methods: We analyzed participants enrolled in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) and the Neurotraumatology Quality Registry (Net-QuRe) diagnosed with TBI, receiving DC and subsequent cranioplasty. These multicenter, observational cohort studies included 5091 patients from 2014 to 2020. The effect of cranioplasty timing on functional outcome was evaluated with multivariable ordinal regression, and propensity score matching (PSM) for functional outcome (Glasgow Outcome Scale-Extended score [GOSE]), and quality of life (Quality of Life after Brain Injury scale, QoLIBRI) at 12 months following DC.

Results: Among 173 eligible participants, 73 (42%) received early cranioplasty and 100 (58%) received delayed cranioplasty. In ordinal logistic regression and PSM, similar outcomes were found for 12-month GOSE (adjusted odds ratio (aOR) 0.87 [95% CI 0.61-1.21] and 0.88 [95% CI 0.48-1.65], respectively). In ordinal logistic regression, early cranioplasty was associated with higher risk for hydrocephalus compared with delayed cranioplasty (aOR 4.0 [95% CI 1.2-16]). Post-discharge seizure rates (early cranioplasty: aOR 1.73 [95% CI 0.7-4.7]) and QoLIBRI scores (β -1.9 [95% CI -9.1-9.6]) were similar.

Conclusions: Functional outcome and quality of life are similar comparing early cranioplasty versus delayed cranioplasty in patients who receive DC for TBI. Neurosurgeons may consider performing cranioplasty during the index admission (early) to simplify the patient’s chain of care and prevent readmission for cranioplasty but should be vigilant for possible increased risk of hydrocephalus.

Dr. Ava Puccio¹, Dr Sarah Svirsky¹, Dr Hansen Deng¹, Dr Andrea Jaquins-Gerstl¹, Dr David Okonkwo¹, Dr Adrian Michaels¹

¹University of Pittsburgh, Pittsburgh, United States

Minimizing secondary injury is key for treating patients with severe traumatic brain injury (sTBI). Expanding the toolkit of multi-modal neuromonitoring provides additional real-time data to the neurocritical care team. Microdialysis using electrochemical biosensors has the potential to identify secondary injury, namely spreading depolarizations (SD), in real-time. This pilot study aims to characterize detected SD, defined as potassium (K+) transients, alongside cerebral glucose levels as a metric of metabolic demand, in patients with sTBI. Participants were enrolled between 2019-2023 under an IRB-approved protocol (inclusion criteria: >18yo, initial Glasgow Coma Scale (GCS) score of 3 − 10, received intracranial pressure and brain tissue oxygen catheters as a standard of care). Continuous online microdialysis (coMD) monitored K+ and glucose in the dialysate stream in real-time. 17 participants were enrolled and analyzed (mean age 50±19yrs, 59% male; median GCS 6). Average monitoring time was 77.35hrs (range 34.5-137.42hrs) and median SDs detected was 3 (range 0-8). Three predominant SD phenotypes emerged: high K+/glucose decline, high K+/glucose increase, and high K+/no change. SD phenotypes reveal K+ spikes occur independent of glucose levels and ongoing efforts aim to quantify K+ transients to further understand phenotypic differences, in conjunction with existing oxygen and glucose monitoring. Future directions include incrementally collecting cerebral dialysate, cerebrospinal fluid and blood to measure metabolic biomarkers, providing a comprehensive assessment of SD secondary injury pathology. This pilot study paves the way for integration of this novel, innovative and safe neuro-monitoring method into standard of care for sTBI and other severe neurological injuries. (Funding-NIH-R01-NS102725 AM/AMP).

Mr. Jakob Liker^1,2, Ms. Tasha Bierling², Dr. Mark Liker^2,3

¹SUNY Downstate Medical School, Brooklyn, United States, ²Brainstim Centers, Santa Clarita, United States, ³University of Southern California, Keck School of Medicine; Department of Neurosurgery, Los Angeles, United States

According to the CDC, there were approximately 214,110 TBI related hospitalizations in 2020, many continue to be burdened by post-concussive symptoms affecting many aspects of their lives. Current treatments involve symptomatic interventions only, thus a need to provide adequate treatment for long lasting concussion symptoms. Transcranial magnetic stimulation has been shown to be effective in treating PTSD and depression in a Veterans Administration population. The objective of the study was to determine the effect that transcranial magnetic stimulation has on relieving post concussive syndrome (PCS) symptoms in a population of mild traumatic brain injury patients. 16 patients who were diagnosed with ongoing symptoms of PCS at least 3 months after injury underwent repetitive bifrontal transcranial magnetic stimulation for a total of 50 sessions. Rivermead Post Concussive Questionnaire (RPQ) was obtained before and after treatment. The average RPQ score for the pretreatment group was 32 while the post treatment group’s average RPQ score was 22. A paired T-test was used to analyze the difference in RPQ scores before and after treatment for each patient. The T-Test was significant (p<.05), indicating that there is a difference between the pre and post treatment concussion symptoms. In conclusion, TMS significantly decreased late RPQ score and thus improves delayed post concussive syndrome symptoms.

Aaron Thomas¹, Dr. Michael Lopez¹, Kirti Patel¹, Dr. Areg Grigorian², Dr. Andy Lee³, Dr. Bernadette Boden-Albala⁴, Dr. Patrick Chen¹

¹Neurology Traumatic Brain Injury & Concussion (NTBIC) Program, Department of Neurology, University Of California, Irvine, Orange, United States, ²Department of Surgery, University of California, Irvine, Orange, United States, ³Division of Cardiology, Department of Medicine, University of California, Irvine, Orange, United States, ⁴Program in Public Health, University of California, Irvine, Irvine, United States

Objectives: TBI is emerging as a chronic disease linked to an increased risk of chronic cardiometabolic disease (CM). Baseline CM health and screening accessibility in TBI patients are poorly understood. This study examines the prevalence of elevated body mass index (BMI) and blood pressure in TBI patients, their relation to outcomes, and the role of social determinants of health (SDOH)/healthcare access.

Methods: Using a retrospective analysis of the NTBIC TBI clinic-database we investigated the association between obesity (BMI ≥ 30), elevated systolic blood pressure (SBP ≥ 130), SDOH, patient-reported CV disease (HTN/HLD/CAD/Obesity) and outcomes including disability (Glasgow-Outcome-Scale-Extended > 6) and healthcare access. Statistical analysis: T-test/Fischer-Exact-Test/Multivariable-regression, significance p<.05.

Results: 91 total TBI patients (Age mean: 46 years (54% > 50 yr, 79% mTBI, 43% women, 47% nonwhite), 14% were obese (median BMI 13 [IQR 22-27]), 38% had elevated-SBP (median BP 126 [IQR 117-134]), 8% had both, and 24% had pre-existing CM disease. 9% reported a new diagnosis of CV-disease post-TBI. No significant differences in SDOH/disability were found between CM and non-CM groups. 22% did not have a primary-care-provider, 35% did not have insurance, 7% had neither. TBI patients with limited- healthcare-access were unmarried [52% vs 38 %, p=.05] and from lower Census-Area-median-income locations [$93968 vs. $107970, p=.007], compared to those with access. BMI/SBP did not predict disability on regression.

Conclusion: Early CM signs are prevalent in TBI patients and there are gaps in healthcare-access among those with poor support-networks, underscoring the need for targeted research on at-risk groups and prevention strategies.

Ms. Ellyn Pier¹, Dr. Yelena Bodein^1,2,3, Dr. Michael A. McCrea⁴, Mr. Jason Barber⁵, Dr. Nancy R. Temkin⁵, Dr. Lindsay D. Nelson⁴, Dr. John Corrigan⁶, Amy J. Markowitz⁷, Dr. Geoffrey T. Manley⁷, Dr. Joseph Giacino^1,2,3

¹Spaulding Rehabilitation Hospital, Charlestown, United States, ²Harvard Medical School, Boston, United States, ³Massachusetts General Hospital, Boston, United States, ⁴Medical College of Wisconsin, Milwaukee, United States, ⁵University of Washington, Seattle, United States, ⁶Ohio State University, Columbus, United States, ⁷University of California, San Francisco, San Francisco, United States

Objective: To investigate changes in functional outcome among patients with severe TBI (sTBI) who completed a baseline assessment at 6 or 12 months and were followed between 2-9 years post-injury.

Methods: In this prospective observational study involving TRACK-TBI participants with sTBI, we calculated cumulative mortality rates using the Kaplan-Meier estimator and reported the proportion of participants alive at 12 months who improved, declined, remained stable or fluctuated on the Glasgow Outcome Scale- Extended (GOSE) between baseline and 2-9 year follow-up.

Results: Among 302 sTBI participants (77.8% male; mean [SD] age 40.4 [17.3] years; 79.1% white, 11.9% black, 8.9% other/unknown; mean [SD] total admission GCS score 4.3 [1.8]) who underwent baseline assessment, 48.3% completed at least one follow-up and 28.1% completed three follow-ups. Most deaths occurred during the first 12 months (27.6%), leveling off at 24 months (year 2: 30.0%; year 9: 35.2%). Comparing the baseline GOSE score to each available follow-up, the most common trajectory was “no change” (33%-56%, depending on time from injury to first follow-up) followed by “improved” (+1 point: 17%-25%; ≥2 points: 9%-23%) and “declined” (-1 point: 6%-17%; ≤-2 points: 3%-8%).

Conclusions: This study builds on prior TRACK-TBI and TBI Model System findings showing that the trajectory of recovery after sTBI remains dynamic across the first decade. In the majority of persons with sTBI who survive across the first year, functional outcome remains stable or improves between 2 and 9 years post-injury. These findings should be considered when establishing early goals of care.

Assoc. Prof. Haruo Nakayama¹, Dr. Yu Hiramoto¹, Prof Satoshi Iwabuchi¹

¹Toho University Ohasi Medical Center, Tokyo, Japan

Objective: To clarify the effect of the visual system on “dizziness” after SRC, which could not be clarified previously, using virtual reality (VR).

Subjects and Methods: The study design was a non-interventional, backward- looking, case-control study, and the centers were sports-related head injury clinics in Japan. The observation period was from April 2018 to March 2020.

Selection criteria: 1) sports injury, 2) SRC cases, 3) cases evaluated by the same neurosurgeon, 4) cases that could be followed continuously for 28 days, 5) cases with dizziness.

The following items: 1) age/sex, 2) athletic events, 3) Reproducibility of symptoms by VR System.

Main Outcomes and Measures: Days to symptom recovery.

Statistical Methods: A t-test was used.

Results: A total of 54 participants were included(VR with Rehabilitation: n=18; mean age 17.6 y/o [13-23], 4 female [22%]; VR without Rehabilitation, n=18; mean age 21.8 y/o [12-30], 4 female [22%]; No-VR: n=18; mean age 21.7 y/o [16-31], 4 female [22%]). There were no differences in age, sex and Collision sport rate. All 36 cases that underwent evaluation using VR confirmed the reproduction of symptoms in VR.

Main Outcomes are follows; VR with Rehabilitation participants recovered in a mean of 31 days (14-48), whereas VR without Rehabilitation participants recovered in a mean of 157 days (28-315), and whereas No-VR participants recovered in a mean of 229 days (15-741). There was a significant difference (P value 0.0001).

Conclusion: Several post-SRC “dizziness” symptoms include a visual component, potentially prolonging symptoms if appropriate therapeutic intervention is not provided.

Mr. Zachary Bellini^1,2, Ms. Grace Recht¹, Mrs. Taylor Zuidema^1,3, Dr. Kyle Kercher¹, Ms. Sage Sweeney¹, Dr. Jesse Steinfeldt⁴, Dr. Keisuke Kawata^1,3,5

¹Department of Kinesiology - Indiana University School of Public Health, Bloomington, United States, ²Department of Neuroscience - Pomona College, Claremont, United States, ³Program in Neuroscience - The College of Arts and Sciences - Indiana University, Bloomington, United States, ⁴Department of Counseling and Educational Psychology - School of Education - Indiana University, Bloomington, United States, ⁵Department of Pediatrics - Indiana University School of Medicine, Indianapolis, United States

Subconcussive head impacts influence brain development and aging, and neuro-ophthalmologic function may reflect subtle brain damage. The goal of this study was to examine whether neuro-ophthalmologic function, as assessed by the King-Devick test (KDT), alters during a high school football season and to explore the role of auditory interference on the sensitivity of KDT. This multisite prospective cohort study was conducted during the 2021 and 2022 high school football seasons, where football players’ neuro-ophthalamogic function was assessed at 5 timepoints (preseason, 3 in-season, postseason) whereas control athletes were assessed at pre- and postseason. The study consisted of 210 football players and 80 control athletes. The year 1 cohort (n=94 football, n=10 control) was tested with conventional KDT while the year 2 cohort (n=116 football, n=70 control) was tested with KDT while listening to loud traffic sounds to induce auditory interference. Head impact exposure for football players was tracked via instrumented mouthguards. There were significant improvements on performance for both conventional (β=-1.7, SE=0.12, p<0.01) and auditory interference KDT (β=-1.7, SE= 0.11, p<0.001). For further analysis, football players were clustered into high-, medium-, or low-impact frequency groups. Similarly, all groups improved on KDT performance throughout the season in both conventional (β=-0.12, SE=0.15, p=0.41) and auditory-interference (β=-0.15, SE=0.14, p=0.26). Control athletes followed the same pattern of improved KDT perfomance from preseason to postseason (conventional KDT: β=-1.6, SE=1.9, p<0.001; KDT with auditory interference: β=-0.7, SE=0.2, p=0.001). Our data suggests that KDT performance improves throughout a season, regardless of auditory interference or head impact exposure.

Dr. Lanya Tianhao Cai¹, Jaclyn Xiao¹, Dr. Esther Yuh¹, Dr. Xiaoying Sun², Amir Sadikov¹, Dr. Christine Mac Donald³, Dr. Ramon Diaz-Arrastia⁴, Dr. Joseph Giacino⁵, Dr. Sonia Jain², Dr. Michael McCrea⁶, Dr. David Okonkwo⁷, Dr. Claudia Robertson⁸, Dr. Murray Stein², Dr. Nancy Temkin³, Dr. Geoffrey Manley¹, Dr. Pratik Mukherjee¹, TRACK-TBI Investigators

¹University Of California San Francisco, San Francisco, United States, ²University of California San Diego, San Diego, United States, ³University of Washington, Seattle, United States, ⁴University of Pennsylvania, Philadelphia, United States, ⁵Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, United States, ⁶Medical College of Wisconsin, Milwaukee, United States, ⁷University of Pittsburgh Medical Center, Pittsburgh, United States, ⁸Baylor College of Medicine, Houston, United States

Objective: To identify cortical regions influencing persistent post-concussive symptoms.

Methods: Freesurfer/SynthSeg volumetrics was performed on 3T T1-weighted MRI at 2-weeks and 6-months after TBI in patients age 17-90 years from 13 Level 1 trauma centers. Cortical volumes (normalized by intracranial volume) in reward, salience, and resilience networks were compared to 6-month Rivermead Post-Concussion Questionnaire (RPQ16) scores using zero-inflated negative binomial models, adjusting for age, sex, years of education, and psychiatric history.

Results: In 835 patients, volume increases were observed in right cuneus (+0.5%, p=0.005) and right lingual cortex (+0.4%, p=0.01). In 780 patients with RPQ16 (63% male; 96% GCS 13-15), larger right cuneus at 2-weeks predicted better odds of no symptoms at 6-months (OR=1.21, p=0.03). Volume increases of right lateral orbitofrontal cortex (OR=1.29, p=0.005) and right nucleus accumbens (OR=1.19, p=0.049) were linked to symptom-free recovery, but not with severity in persistently symptomatic patients. Right insula volume change correlated with 6-month RPQ16 (r=0.1, p=0.003) but not after covariate adjustment (OR=0.87, p=0.2).

Conclusions: Increasing volumes of right hemispheric hubs for processing negative stimuli and motivating behavior to avoid negative outcomes improve the likelihood of symptom-free recovery after TBI. An observed trend in right insula supports future investigations targeting its anterior segment, which is more specific for negative emotional valence. Among resilience centers, larger right cuneus predicted symptom-free recovery and both right cuneus and adjacent lingual gyrus show increases in volume during subacute/chronic TBI.

This study was funded by NIH U01 NS086090 and DoD W81XWH-14-2-0176.

Mr. David Castro¹, Dr. Julio Rojas¹, Dr. Ketura Berry¹, Ms. Joy Youn¹, Dr. Lawren Vandevrede¹, Dr. Thelma Garcia², Dr. Nida Degesys¹, Dr. John Boscardin¹, Dr. Kenneth Covinsky¹, Dr. Stephanie Rogers¹, Dr. Adam Boxer¹, Dr. John Newman^1,2, Dr. Bruce Miller¹, Dr. Vanja Douglas¹, Dr. Sara LaHue^1,2

¹University Of California, San Francisco, San Francisco, United States, ²Buck Institute for Research on Aging, Novato, United States

Objectives: To prospectively investigate the association between acute traumatic brain injury (TBI), plasma neuronal injury markers, and preoperative delirium following hip fracture (HF).

Methods: Adults age 55+ hospitalized <48hr after traumatic HF underwent preoperative delirium screening (Confusion Assessment Method) and blood collection. Plasma neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) were measured via Quanterix (Simoa HD-X). Exact logistic regression explored the association between predictors and delirium.

Results: Of 38 subjects, median age 78-years [interquartile range (IQR) 70-84], 27 (71%) women, 9 (24%) had cognitive impairment, and 19 (50%) had history of any TBI. Five (13%) subjects had TBI concurrent with HF (arrival Glasgow Coma Scale 13-15; imaging negative acute). Eight (21%) subjects had delirium preoperatively. Those with concurrent TBI (vs without) had similar ages, cognitive impairment rates, and higher odds of delirium [odds ratio (OR) 7.7, 95% confidence interval (CI) 0.7-1115.5, P=0.05]. Sixteen subjects (31% with concurrent TBI, 38% delirious) had NfL and GFAP data available. No difference in median NfL nor GFAP by TBI. Delirious subjects (vs without) had higher median NfL [93pg/mL (IQR 29-323) vs 19pg/mL (IQR 17-29)] but similar median GFAP. NfL remained associated with delirium after adjusting for cognitive impairment [OR 1.1, 95% CI 1.0-1.6; P=0.009].

Conclusions: Delirium is common in older adults with HF, those with concurrent TBI, and is associated with elevated NfL. Whether NfL elevations represent pre-existing neuropathology (marker of heightened delirium risk) or acute neurological injury requires further study.

Support: National Institute on Aging, Hillblom Foundation, Doris Duke Foundation.

Dr. Michele Diaz Nelson¹, Senior Research Coordinator Domenico Lombardi¹, Research Coordinator Katherine Kuang¹, Justin Wong¹, Ava Puccio², David Okonkwo², Amber Nolan³, Esther Yuh¹, Kristine Yaffe¹, John Boscardin¹, Sabrina Taylor⁴, Geoffrey Manley¹, Raquel Gardner⁵

¹UCSF, San Francisco, United States, ²University of Pittsburgh Medical Center, Pittsburgh, USA, ³ University of Washington, Seattle, USA, ⁴MedRhythms, Portland, USA, ⁵Sheba Medical Center, Tel Hashomer, Israel

Background: Caregivers of older adults (OAs) with traumatic brain injury (TBI) face unique challenges adapting to new physical, cognitive, and behavioral changes—exacerbated by the effects of aging. These challenges may cause caregiver strain, role shifts, and provoke fears about the future. Our aim was to understand caregivers’ experiences of managing their care, navigating healthcare systems, and uncertainties regarding recovery post-injury. Methods: OAs aged 65y+ with TBI were recruited from our trauma center and co-enrolled with a study partner (SP). SPs who provided financial, emotional, or physical support were invited to participate in an optional semi-structured interview. Purposive sampling was based on patient’s baseline cognition, functional status, relation to the SP, hospitalization, and time since injury. Interviews were conducted by phone, transcribed, and thematically analyzed for emerging themes. Results: All 11 SPs approached agreed to participate in the interviews. Mean SP age was 63y(range: 23-82y), with 4 being spouses, 5 adult children, and 2 friends of TBI participants. Average time since injury was 165(range 58-440) days. Average interview duration was 43 minutes. Identified themes included varied types of support provided and received post-injury, effect of TBI on relationship with TBI participant, and difficulties in navigating healthcare systems, managing care transitions, and advocating for unmet healthcare needs.

Conclusion: Caregivers of OAs with TBI face a complex array of challenges that vary based on diverse needs. Identifying and designing interventions to meet their distinct needs post-injury is crucial in bridging the care gaps that impact both the patient and their caregiver.

Mr. David Ellis¹, Dr. Madeleine Nowak², Mr. Osamudiamen Ogbeide¹, Dr. Jiancheng Hou¹, Dr. Hu Cheng¹, Dr. Sharlene Newman³, Dr. Keisuke Kawata¹

¹Indiana University, Bloomington, United States, ²Boston University, Boston, United States, ³University of Alabama, Tuscaloosa, United States

This single-site intervention trial aimed to investigate localized, neighboring, and whole brain neuronal activity in athletes with ADHD (n=30) and age and sex-matched controls without ADHD (n=30) using resting-state fMRI. To replicate subconcussive head impacts (SHI), a soccer heading paradigm, which excludes extraneous variables such as fatigue and exercise, was implemented. Both groups underwent 10 acute soccer headings. Participants were scanned at three timepoints: pre-SHI, 2-hour post-SHI, and 24-hour post-SHI. fMRI data were analyzed using fractional-amplitude-of-low-frequency-fluctuation (fALFF), regional homogeneity (ReHo) and resting-state functional connectivity (rs-FC) with a dorsolateral pre-frontal cortex (DLPFC) seed. We then conducted ANOVA F-tests, followed by post-hoc t-tests to determine within and between group differences. At the 2-hour timepoint, the ADHD group displayed significant increases in fALFF in the left middle temporal gyrus, and significant increases in ReHo within the left precuneus, right central gyrus, precentral gyrus, and Rolandic’s operculum. At the 24-hour timepoint the ADHD group showed an increase in ReHo in the left middle orbitofrontal gyrus and right middle-frontal gyrus. A decrease in ReHo within the left thalamus and precuneus was also observed at the 24-hour timepoint. Rs-FC analysis revealed hypoconnectivity in the ADHD group’s left superior parietal lobule compared to controls. Our data suggest changes in neural activity coherence occurred in both groups, where the ADHD group exhibited less fluctuation in fALFF and ReHo compared to controls.

Dr. Hilaire Thompson¹, Dr. Frederick Rivara, Dr. Nancy Temkin, Dr. Kyra Becker, Dr. Ronald Maier

¹University Of Washington, Seattle, United States

Purpose: Determine association between selected cellular immune (Th1) and inflammatory plasma biomarkers and outcomes at 3 and 6 months post-injury for older adults (> 55 years) with mild traumatic brain injury (mTBI).Methods: Prospective cohort design. Symptoms and function were assessed and blood drawn at day 0, day 3, day 7, and 1-, 3- and 6-months post-injury. PBMC Th1 responses were assessed using ELISpot. Multiplex cytokine assays were used to quantify protein inflammatory marker concentrations. Analyses included multivariate linear regression and ordinal logistic regression. Results: In older adults following mTBI (N=82), there was a significant association between higher IL-1-beta levels and a)lower mental health (SF-36) b)lower satisfaction with life scores, c)lower neuropsychological function (RAVLT and Trails Test A). Similar findings were seen for IL-6,-7,-8 and TNF-alpha levels and SF-36, Trails A/B and WAIS, and satisfaction with life. These cytokines were also associated with higher somatization scores on the BSI-18. Higher IL-6 level was associated with higher symptom severity, while higher fractalkine was associated with lower severity and number of symptoms. Higher IL-8 and leptin levels in the first week were negatively associated with 6 month GOS-E. Higher acute post-injury IL-13 levels were associated with improved satisfaction with life and WAIS scores at 6 months. No significant associations were seen among Th1 responses and outcome, nor were acute phase levels predictive of later outcome.

Conclusion: Several markers of the immune response were associated with symptom severity, day-to-day functioning and quality of life and predicted 6-month outcome in older adults post-TBI.

Dr Aleksander Bogucki¹, Ivo John¹, Łukasz Zinkiewicz¹, Michał Jachura¹, Michał Świątek¹, Damian Jaworski^2,3, Karolina Suwała^2,4, Mr. Hugo Chrost¹, Michal Wlodarski¹, Jakub Kałużny^2,4, Doug Campbell⁵, Paul Bakken⁵, Shawna Pandya⁵, Radosław Chrapkiewicz¹, Sanjay G. Manohar¹

¹Solvemed Inc., Lewes, United States, ²Oftalmika Eye Hospital, Bydgoszcz, Poland, ³Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland, ⁴Department of Sensory Organ Studies, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland, ⁵International Institute for Astronautical Sciences, Boulder, USA

Pupillometry is crucial in assessing neurological health, especially for prognosis and monitoring in intensive care. While quantitative pupillometry has introduced pupil reactivity indices, it faces challenges with ambient light variations. To address this, we developed a machine-learning-based method to estimate lighting-invariant pupillometric parameters and the open-sourced Pupil Reactivity (PuRe) score.

We present enhancements in the PuRe score’s performance using new data, evaluating its performance across lighting conditions, age, and biological sex. Ethical approval was granted by the Research Bioethics Committee at Nicolaus Copernicus University (KB 42712021).

In a dataset of 309 recordings, pupil reactivity scores were modelled as a linear function of ambient illumination in log(lux). The Pearson correlation between illumination and PuRe was r=0.064 (p=0.26), indicating robustness of the PuRe score across a wide range of lighting conditions (5 to 11,800 lux). In a separate dataset (N=26, 5 male), PuRe score values did not vary significantly with age (Pearson r<0.001, p=0.981) nor did they differ significantly for biological sex: mean 4.37+/-0.06 [s.e.m] for males and 4.38+/-0.03 for females (Mann Whitney U=52.0, p=1.00).

Quantitative pupillometry’s resilience in diverse environments is vital for clinical and point-of-care use. Pupil reactivity, measured with a smartphone-based AI Pupillometer and quantified with the open-sourced PuRe score, showed no relationship with ambient light, age, or biological sex. These results support the score’s versatility and robust performance in diverse environmental conditions, essential for pupil testing across hospital and pre-hospital care, including outdoor settings.

Dr. John Yue¹, Mr. Rithvik Ramesh¹, Dr. Geoffrey Manley¹, Dr. Phiroz Tarapore¹, Dr. Anthony DiGiorgio¹

¹University Of California, San Francisco, San Francisco, United States

Objectives: Despite profound medico-socio-legal consequences of traumatic brain injury (TBI) from intimate partner and domestic violence (IPV/DV), incidence and outcomes of concurrent IPV/DV-TBI are not well-understood. We examined United States IPV/DV patients with/without TBI (IPV/DV-TBI; non-TBI) using the National Trauma Data Bank.

Methods: IPV/DV patients aged≥18-years were extracted from NTDB Trauma Quality Program Participant Use Files (2018-2021) using ICD-10 external-cause codes. TBI/non-TBI was defined using ICD-10 diagnosis codes. TBI severity was defined by Glasgow Coma Scale (GCS; severe=3-8/moderate=9-12/mild=13-15). Outcomes were intensive care unit (ICU) admission, in-hospital mortality, length of stay (LOS), and discharge home. Multivariable regressions examined TBI-related associations, controlling for sociodemographic and injury severity variables.

Results: Of 3,891 IPV/DV-related cases, 31.1% were IPV/DV-TBI. Cranial injuries included skull fracture=30.2%, subdural=19.8%, subarachnoid=13.4%, and epidural=1.1% hemorrhage, contusion=8.1%, cerebral edema=3.3%. In IPV/DV-TBI, mild/moderate/severe TBI comprised 87.4%/4.3%/8.3%, with mean LOS 11.5±10.9/14.4±27.3/5.0±7.7-days, and mortality 0.9%/22.5%/28.6%, respectively. Compared to non-TBI, IPV/DV-TBI had more female (77.2%/64.6%) and fewer Black patients (28.9%/36.6%), more ICU admissions (20.9%/7.5%) and mortality (4.1%/1.8%; all p<0.001), longer LOS (5.3±9.5/4.5±6.4-days, p=0.008), and decreased discharge home (79.8%/83.8%, p=0.005). Regressions confirmed the associations between TBI and ICU admission (adjusted odds ratio (aOR)=4.29, 95%CI [3.46-5.33]), mortality (aOR=3.20 [1.99-5.15]), LOS (adjusted mean difference=+1.22 [0.68-1.76]), and inability to discharge home (aOR=0.57 [0.46-0.71]).

Conclusions: One-third of US IPV/DV-related trauma cases have TBI, comprising predominantly female patients. IPV/DV-TBI had increased ICU admissions, LOS, in-hospital mortality, and inability to discharge home compared to non-TBI. Investigating morbidity risk factors and providing socio-medical resources during acute care are critically needed in this vulnerable population.

Dr. Divya Jain¹, Emily Carter², Andrew P Cwiek², Katherine Dorman¹, Dr. Amelia J Hicks¹, Dr. Frank G Hillary^2,3, Dr. Inga K Koerte^4,5,6,7, Dr. Alexander P Lin^5,6,7, Dr. Amy D Marshall², Sklyer McComas^6,7, Adriana P Méndez-Fernández², Emma N Read^8,9, Elizabeth Rebuck², Philine Rojczyk^4,5, Dr. David F Tate^8,9, Carmen Velez⁸, Dr. Elisabeth L Wilde^8,9, Dr. Carrie Esopenko¹

¹Department of Rehabilitation and Human Performance, Icahn School of Medicine at Mount Sinai, New York, USA, ²Department of Psychology, Pennsylvania State University, University Park, USA, ³Social Life and Engineering Sciences Imaging Center, University Park, USA, ⁴cBRAIN, Department of Child and Adolescent Psychiatry, Psychosomatics, and Psychotherapy, Ludwig-Maximilians-University, Germany, ⁵Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Massachusetts General Brigham, Harvard Medical School, Somerville, USA, ⁶Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA, ⁷Center for Clinical Spectroscopy, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA, ⁸Traumatic Brain Injury and Concussion Center, University of Utah School of Medicine, Salt Lake City, USA, ⁹George E. Wahlen VA Salt Lake City Healthcare System, Salt Lake City, USA

Approximately 1 in 4 women who experience intimate partner violence (IPV) also experience IPV-related head trauma (IPV-HT), including non-fatal strangulation (IPV-NFS). More work understanding the injury characteristics of IPV-HT (e.g., injury mechanisms, frequency) is needed to improve language within IPV-HT screening tools. A semi-structured interview was developed for a larger on-going study to obtain in-depth contextual information about IPV-HT, IPV-NFS, and non-HT injury characteristics from women with severe IPV exposure. Data from 45 women 18-60 years (mean age = 40.2, 71.1% White) were analyzed using a mixed qualitative-quantitative methods approach. The number of lifetime injuries experienced due to an intimate partner and the proportion of participants who experienced at least one: 1) IPV-HT injury, 2) IPV-NFS injury, 3) non-HT injury, and 4) period of repeated IPV-related injuries, was extracted from interview transcripts. Interview quotes were used to understand injury characteristics and abuse context in the participants’ own words. Most participants (64.5%) experienced ≤4 lifetime IPV-related injuries, followed by 20% experiencing “too many to count.” Nearly all (91.1%) participants experienced at least one IPV-HT event, and 55.6% reported at least one IPV-NFS event. In addition, 62.2% reported at least one period of repeated IPV-related injuries that occurred, on average, over 4 years. Selected quotes from interviewees highlight the unique combinations of mechanisms and frequencies of IPV-related injuries experienced. The quantitative data about IPV-related injury characteristics and descriptive language about these injuries used by women who experienced severe physical IPV may help inform development of improved IPV-HT screening tools.

Mr. Peter Ngum^1,2,3,5, Dr. Harri Merisaari^1,3,4, Dr. Jussi Posti^1,2,3, Dr. Olli Tenovuo^1,2,3

¹University Of Turku, Turku, Finland, ²Turku Brain Injury Center, Turku, Finland, ³Turku University Hospital, Turku, Finland, ⁴Turku Brain and Mind Center, Turku, Finland, ⁵Johns Hopkins University, Baltimore, USA

Objective: This study evaluates the efficacy of Feedforward Neural Networks (FFNN) and Long Short-Term Memory (LSTM) networks in predicting Glasgow Outcome Scale Extended (GOSE) scores in patients with traumatic brain injuries (TBI) of all severities. FFNNs are well-suited for recognizing complex patterns in multivariate data, making them ideal for initial analyses where temporal dynamics are less critical. On the other hand, LSTMs are designed to effectively process sequential data due to their ability to remember information for long periods, which is essential in capturing the temporal progression inherent in biomarker evolution post-TBI.

Methods: Utilizing data from 200 TBI patients and 40 controls within the Finnish TBIcare dataset, we analyzed FDA-approved GFAP and UCHL1 biomarkers (days 0,1,3,5,7, 90) alongside age, motor Glasgow Coma Scale (GCS), and pupil reactivity. The cohort predominantly consisted of mild TBI cases (70.72%), with severe (19.34%) and moderate (10.94%) cases. Both models were tested using a stratified 5-fold cross-validation approach to enhance prediction accuracy and reduce overfitting.

Results: The LSTM model, which leverages temporal data better due to its recurrent architecture, achieved a training accuracy of 64.0% and a validation accuracy of 56.5%. In contrast, the FFNN model showed a training accuracy of 58.6% and a validation accuracy of 52.2%. Despite LSTM’s slightly higher mean validation loss (1.510 vs. 1.454 for FFNN), its superior handling of sequential data underscores its advantage in this application.

Conclusion: LSTM networks offer a promising avenue for enhancing TBI outcome predictions through their adept handling of biomarker time series, demonstrating a significant improvement over FFNN models. These results highlight the potential of advanced, time-aware modeling techniques in prognosticating TBI outcomes, although the study’s relatively small sample size may limit generalizability. Future research should aim to refine model architectures to optimize prediction accuracy and expand external validation.

Mikaila Cutone-Dion, Domenico Lombardi, Michele Nelson, Katherine Kuang, Leila Etemad, Yael Rozen, Justin Wong, Esther Yuh, Kristene Yaffe, John Boscardin, Geoffrey Manley, Pratik Mukherjee, Phiroz Tarapore, Raquel Gardner

¹University Of California San Francisco, San Francisco, United States, ²Sheba Medical Center, Tel Hashomer, Israel

Background: Older adults (aged 65+) have high incidence of traumatic brain injury (TBI) globally. Older military Veterans presenting to Veteran’s Affairs (VA) emergency departments (EDs) with acute TBI may be at higher risk for TBI because of prior military-relevant exposures (MREs). We aim to phenotype military, clinical and biological features using TBI Common Data Elements (CDEs).

Methods: TRACK-VA aims to enroll 70 older veterans with acute TBI,70 co-enrolled study informants, and 30 controls at the San Francisco VA Medical Center (SFVA). Participants are enrolled in the ED or by telephone after discharge. Participants and study partners complete pre-injury health/MRE assessments and multi-domain geriatric and TBI CDE follow-up assessments at 2 weeks, 3, 6, and 12 months. Blood for proteomic biomarkers and genetics are collected at baseline, 6, and 12 months and optional MRI at 2 weeks, 6, and 12 months.

Results: 15 participants (mean age=79, 100% male, 13% non-White) were enrolled between 10/2022-2/2024. <1% were head CT+, 73% injuries were due to ground level falls, 53% had a prior TBI, 45% had normal cognition, and 55% had mild cognitive impairment/dementia pre-injury. 1 participant expired (non-TBI related). Follow-up completion rates were 73% at 2-weeks, 73% at 3-months, 20% at 6-months, and 50% at 12-months.

Conclusion: TRACK-VA is a novel study of TBI in a highly burdened, understudied, vulnerable population. It has successfully initiated a consecutive sample of older Veterans presenting to the SFVA with acute TBI. Retention is a particular challenge, and its optimization is critical for this longitudinal study.

Dr. Hemika Vempalli¹, Katherine Snedaker², Nabeeha Affan³, Yu-Fu Michael Chen⁴, Erin Skotzke Fishman⁵, Stefanie Hollenbach⁶, Leon Ruiter-Lopez⁷, Michele D. Levine⁸, Celestin Niyomugabo⁹, Martina Anto-Ocrah^1,3

¹Department of Medicine, Division of General Internal Medicine, University of Pittsburgh School of Medicine, Pittsburgh, United States, ²PINK Concussions, Norwalk, United States, ³Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, United States, ⁴JSI Research & Training Institute, United States, ⁵Department of Occupational Therapy, Galaxy Brain and Therapy Center, United States, ⁶Department of Obstetrics and Gynecology, University of Rochester Medical Center, United States, ⁷Department of Neuroscience, Dietrich School of Arts & Science, University of Pittsburgh, Pittsburgh, United States, ⁸Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, United States, ⁹VONSUNG, Rwanda

Although concussion symptoms resolve within 4-6 weeks, for a “miserable minority” of patients, persistent post-concussion symptoms (PPCS) such as headaches, fatigue, & mood disturbances, persist for months, if not years. Rehabilitation of this group-who are often female-is crucial for reducing health and gender disparities in concussion recovery. A recent report by the National Center for Complementary and Integrative Health, showed that the use of complementary health approaches e.g., yoga & meditation, has increased substantially in the last two decades. Little is known, however, about the acceptability of these health approaches for female concussion patients, who are most vulnerable to PPCS. In this study, we evaluate the acceptability of a brain-injury tailored yoga and meditation program for female concussion patients.

An online survey of women in PINK Concussions, a peer-ran social media support network for female concussion patients, was conducted. Along with demographic and concussion-related questions, participants were asked about their interest and reasons for participating in the tailored program. Responses were reviewed and categorized into themes.

There were 434 respondents to the survey, of which 117 (26.96%) completed all survey questions. A majority (n=97;82.9%) were interested in the tailored program, for reasons including prior yoga experience (n=30), health/wellbeing benefits (n=27), and balance/healing/mindfulness (n=23). For disinterested participants (n=14;11.9%), reasons included: physical disabilities (n=6), time constraints (n=3), and enrollment in similar programs (n=5).

The majority of the PINK Concussion participants were interested in a tailored yoga and meditation program, indicating high acceptability of the complementary health approach for this group of patients.

Dr. John Yue¹, Mr. Nishanth Krishnan¹, Mr. Christopher Toretsky^2,3,4, Dr. Renee Hsia^5,6, Dr. Geoffrey Manley¹, Dr. W. John Boscardin^2,4,7, Dr. Anil Makam^2,4, Dr. Anthony DiGiorgio^1,4

¹University Of California, San Francisco, San Francisco, United States, ²Department of Medicine, Division of Hospital Medicine, Zuckerberg San Francisco General Hospital and Trauma Center, University of California, San Francisco, San Francisco, United States, ³Center for Clinical Informatics and Improvement Research, University of California, San Francisco, San Francisco, United States, ⁴Philip R. Lee Institute for Health Policy Studies, University of California, San Francisco, San Francisco, United States, ⁵Center for Vulnerable Populations, University of California, San Francisco, San Francisco, United States, ⁶Department of Emergency Medicine, University of California, San Francisco, San Francisco, United States, ⁷Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, United States

Objectives: Hospital length of stay (HLOS) is a metric of injury severity, resource utilization, and quality. How Medicaid managed care organization (MCO) or fee-for-service (FFS) models affect HLOS after traumatic brain injury (TBI) requires investigation.

Methods: California Department of Health Care Access and Information Patient Discharge Database (2017-2019) were queried for TBI patients aged≥18-years using ICD-10 (S06.0-S06.9/A). Patients with FFS/MCO/private insurance (PI), not expired/to-hospice within 5-days were included. Competing risk regression models accounting for in-hospital mortality evaluated time-to-discharge by insurance. Hazard ratios (HR)<1 for discharge signified longer HLOS. Sensitivity analyses were performed in severe TBI (intracranial pressure monitor/craniotomy=Yes). Medians/quartiles/[95% confidence intervals] reported.

Results: Overall (N=39384; FFS=24.2%/MCO=33.2%/PI=42.6%), FFS was associated with younger age (median: FFS=37y/MCO=45y/PI=44y) and males (80.1%/70.8%/68.8%). Hispanic ethnicity was highest in FFS and lowest in PI (51.6%/35.0%/24.6%), while the reverse was observed for English-language (74.0%/89.3%/93.9%). HLOS was longer in FFS/MCO (FFS=4d [2-11], MCO=4d [2-9], PI=3d [1-7]). Charges were highest in FFS (median: FFS=$120062/MCO=$100297/PI=$91863). All comparisons were p<0.0001. Findings were conserved in severe TBI (N=2077; FFS=31.8%/MCO=32.8%/PI=35.3%; median HLOS 26/22/17d; charges $724225/$629625/$607082).

Competing risk regressions showed Medicaid models (vs. PI) predicted HLOS overall (FFS: HR=0.81 [0.78-0.83]; MCO: HR=0.92 [0.89-0.94]) and in severe TBI (FFS: HR=0.65 [0.57-0.74]; MCO: HR=0.71 [0.62-0.81]). On direct comparison, FFS predicted longer HLOS vs. MCO (HR=0.88 [0.85-0.91]).

Conclusions: Medicaid models predicted longer TBI HLOS across California-licensed hospitals. MCO (vs. FFS) was associated with decreased HLOS and charges. Investigating reasons for efficacy differences in care delivery and reimbursement for Medicaid models is needed to reduce disparities and inform policy.

Ms. Judith Nwaiwu¹, Daramola Oluwatosin¹, Vishal Sandilya¹, Cristian Gutierrez-Reyes¹, Sarah Sahioun¹, Waziha Purba¹, Mojibola Fowowe¹, Professor Firas Kobeissy², Professor Stefania Mondello³, Dr Ava Puccio⁴, Yehia Mechref¹

¹Texas Tech University, Lubbock, United States, ²Morehouse School of Medicine, Atlanta, United State, ³University of Messina, Messina, Italy, ⁴University of Pittsburgh, Pittsburgh, United state

Metabolomics, a powerful analytical approach in systems biology, has become instrumental in unraveling the complex biochemical changes associated with Traumatic Brain Injury (TBI). TBI is a multifaceted condition resulting from external force or impact on the head, leading to a cascade of molecular events that influence the brain’s metabolic profile. Metabolomic changes would provide insights into the complex mechanisms of TBI and also contribute to the development of diagnostic tools. This study aims to profile metabolites from biofluids after TBI to enhance our understanding of the complex molecular mechanism involved in TBI. Human serum and Cerebrospinal fluid (CSF) from TBI patients collected on days 1, 3, and 5 were analyzed and profiled using LC-MS/MS. A total of 797 metabolites were identified in the CSF samples, and 1113 metabolites were identified in the serum samples. In the CSF, 88 metabolites were significant across the days. While in the serum analysis, a total of 385 metabolites were significant across the days. In CSF, pathway analysis showed serotonin degradation, Noradrenaline, and Adrenaline degradation pathways, and the anandamide degradation pathway were all enriched. In serum pathway analysis, the phenylalanine degradation IV pathway, acetylcholine receptor signaling pathway, choline degradation, glutamine receptor signaling, and acetyl-CoA biosynthesis 1 were enriched. Further research is needed to determine which pathway and metabolites would be the most instrumental in developing diagnostic tools for improving outcomes following a TBI.

This work was supported by grants from the Robert A. Welch Foundation (No D-0005) and The CH Foundation.

Ms. Eujung Park¹, Ms. Annie Pico¹, Ms. Haley Kenner¹, Mr. Robert Unger¹, Mr. Kevin Vo¹, Mr. Jacob Saunders¹, Mr. Harrison Feerst¹, Mr. Alex Thompson¹, Ms. Elika Azizi¹, Dr. Peter Nakaji²

¹University Of Arizona, College Of Medicine - Phoenix, Phoenix, United States, ²Department of Neurosurgery, Banner University Medical Center - Phoenix, Phoenix, United States

Objectives: Previous literature has correlated social determinants of health (SDoH) and traumatic brain injuries. This study aims to characterize relationships between the social determinants of health (SDoH) and basilar skull fracture (BSF), which can have devastating adverse sequalae.

Methods: Patients (>17yrs) diagnosed with BSF at a single institution between 2017-2022 were identified through an IRB-approved internal database search. Outcomes of interest included mechanism of injury (MOI) and concurrent injuries (subarachnoid hemorrhage (SAH), subdural hemorrhage (SDH), or SAH + SDH).

Results: 172 patients were included, 77% male. Average age was 43.4yrs [95%CI: 40.6, 46.3]. 149 identified as white; 41 as Hispanic; 20 as unhoused. Medicare/Medicaid insured 107 patients, private insurance covered 51, and 14 had other payment.

The most common MOI for patients <50yrs was motor vehicle accident (18-30yrs 47.5%; 31-50yrs 59.3%, p<0.05) compared to fall in older patients (51-70yrs 56.3%; >70yrs 72.7%, p<0.05). Non-Hispanic patients experienced a higher incidence of assault than Hispanic patients (13.0% vs 7.3%, p<0.05). Patients on Medicaid/Medicare experienced a higher incidence of assault compared to privately insured (15.0% vs 5.9%, p<0.05) and higher rates of concurrent injuries (SAH 59.8% vs 49.0%; SDH 59.8% vs 39.2%; SAH+SDH 44.9% vs 29.4%) (p<0.05). Unhoused patients also had higher rates of concurrent injuries compared to housed (SAH 65.0% vs 55.0%; SDH 60.0% vs 51.0%; SAH+SDH 50.0% vs 37.6%) (p<0.05).

Conclusions: These results will assist clinicians in having a higher index of suspicion for BSF in certain age groups based on MOI and for concurrent injuries in certain demographic groups.

Miss. LeeAnne Tunstall^1,2, Miss C.Lexi Baird^1,2, Miss Nino Nadareishvili³, Dr. Robert Turner II³, Dr. Rajendra Morey^1,2

¹Duke-UNC Brain Imaging and Analysis Center, Durham, United States, ²Department of Veteran Affairs (VA) Mid-Atlantic Mental Illness Research, Education and Clinical Center, Durham, United States, ³George Washington University, Washington D.C., United States

Background: Concern in former professional athletes about memory performance may arise due to long-term health indications, concussion history, age, physical health, and public awareness. As a result, performance on neurocognitive tests of memory may be negatively affected. Cognitive performance can be influenced by several other factors beyond actual subjective concern. In the present study, we investigated the relationship between subjective concern about memory and neurocognitive test performance.

Methods: Former male athletes (N=52, Mage=47.83) who participated in professional football and/or NCAA-Division I football (n=41), and non-contact sports (n=11), were assessed for subjective memory concern and cognitive performance (Brief Visuospatial Memory Test retention, Rey Auditory Verbal Learning Test retention, and Controlled Oral Word Association Test). Regression modeling was used to test the relationship between subjective concerns about memory and neurocognitive test performance on memory retention, while adjusting for age and years of education.

Results: We found retired football athletes reported significantly higher worry scores about memory compared to the non-contact athletes (t=3.93, p=0.023). Concerns about memory had a negative trend association with RAVLT retention scores. (t= -1.96, p=0.057), a significant association with age (t=-2.93, p=0.006), whereas BVMT scores were only influenced by age.

Conclusion: We found a relationship between subjective concern that athletes had about memory and neurocognitive test performance as well as age. Education had no direct influence on memory performance. Among all former athletes, worries about their memory were reflected in their retention scores.

¹University of CO School of Medicine, Fort Collins, United States

Pediatric traumatic brain injury research should expand to encompass perinatal exposures and events associated with complicated childbirth, including the concept of Perinatal Neurotrauma. Studies suggest a detrimental impact on child neurodevelopment stemming from overlapping events, emphasizing the significance of considering intrapartum complexities during labor and delivery as correlating with increasing child neurodevelopmental outcomes. Elevated maternal gestational obesity may interact, owing to diminished uterine contractility. Prevalent conditions of ADHD and Autism, with unclear etiologies, show associations with complicated childbirth dynamics. Cognitive, emotional, and social issues often persist into adulthood.

While genetics may contribute, exposures during sensitive developmental periods affect fetal brain development, leading to downstream effects on child neurodevelopment. Birth complications often involve measures aimed at expediting childbirth, with synthetic oxytocin assisting over 50% of U.S. childbirths, despite unclear fetal impacts. Concerns include prolonged exposure and dosage inconsistencies. Perinatal repercussions include measured fetal distress, low Apgar scores, and NICU admissions. Plausible neuropathophysiological models include fetal dose-specific tolerance, neuro- hyperstimulation, neuroinflammation, endocrine impact, and hypoxia.

Maternal adiposity, a modifiable factor, increases odds for uterine stimulation inducing or augmenting childbirth, potentially impacting fetal neurodevelopment. The interaction between maternal obesity, chemically expedited labor, and their potential impact on offspring neurodevelopment warrants interrogation. Examining neuropathogenic mechanisms involved in these overlapping factors to pediatric brain injury, through the timely lens of Perinatal Neurotrauma, is essential. Recent epidemiological research suggests complex perinatal factors contribute to child functional and behavioral impairments, compelling aggressive future studies in the domain of pediatric brain injury as a critical public health issue.

Ms. Bridget Mayrer², Ms. Madeline Peterson², Dr. Amy Wagner^1,4,5, Dr. David Barton³, Mr. Nabil Awan⁶, Dr. David Wright⁹, Dr. Michael Frankel⁸, Dr. Jenna Carlson², Dr. Raj Kumar¹

¹Department of Physical Medicine and Rehabilitation, University Of Pittsburgh, Pittsburgh, United States, ²Department of Biostatistics, University Of Pittsburgh, Pittsburgh, United States, ³Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, United States, ⁴Department of Neuroscience, University of Pittsburgh, Pittsburgh, United States, ⁵Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, United States, ⁶Department of Biostatistics, University of Wisconsin-Madison, Madison, United States, ⁷Department of Rehabilitation, Icahn School Of Medicine, New York, United States, ⁸Department of Neurology, Emory University, Atlanta, United States, ⁹Department of Emergency Medicine, Emory University, Atlanta, United States

In addition to secondary injury cascades in the central nervous system (CNS), Traumatic Brain Injury (TBI) disrupts systemic endocrine homeostasis. Our prior work suggests that TBI-induced changes in the aromatization of Androstenedione-to-Estradiol may contribute to the systemic injury response and global outcome. Our goal was to use K-means clusters to delineate if/how patient with unique aromatization-derived hormone patterns might map to distinct patient characteristics and inform CNS-derived biomarker profiles as well as long-term outcome via a secondary analysis of the ProTECT III multi-center randomized clinical trial cohort. Serum Samples (n=447 samples, n=536 patients) collected at 0-, 24- and 48-hours post-injury were assayed (Progesterone, Androstenedione, Testosterone, Estrone, Estradiol) to generate unique aromatization-derived patient clusters based on hormone patterns at each time-point. In addition to demographic, progesterone treatment, and injury severity characteristics, CNS markers SBDP, GFAP, UCHL-1, S100b, and TNF-α) were assessed by cluster group membership at each time point. 24-hour hormone levels identified 3 distinct groups with significantly different characteristics. A high-risk cluster included 118 patients (55% progesterone-treated, 45% placebo) with higher estrone, estradiol, testosterone, and androstenedione levels than the progesterone-treatment-only cluster or placebo-dominant cluster. This high-risk cluster also had significantly higher CNS biomarker levels, mortality rates, and non-neurological organ dysfunction scores than other 24-hr clusters. 24-hr cluster analysis also suggests that lower estradiol and higher estrone levels may be associated with reduced mortality and favorable outcome (measured via GOSE). Future work will delineate the predictive capacity of aromatization-derived hormone clusters using multivariate techniques.

Ms. Leila L. Etemad^1,2,3, Mr. Lawrence Chyall^2,3, Mrs. Sara Cole^2,3, Mrs. Gabriela G. Satris^1,2,3, Ms. Joye X. Tracey^1,2,3, Ms. Christine J. Gotthardt^1,2,3, Ms. Bukre C. Coskun^1,2,3, Dr. Cathra Halabi^3,4, Dr. Anthony M. DiGiorgio^1,2,3,5, Dr. Phiroz E. Tarapore^1,2,3, Dr. Michael C. Huang^1,2,3, Dr. Geoffrey T. Manley^1,2,3, Dr. John K. Yue^1,2,3

¹Department of Neurological Surgery, University of California San Francisco, San Francisco, United States, ²Brain and Spinal Injury Center, Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, United States, ³Weill Institute for Neurosciences, University of California San Francisco, San Francisco, United States, ⁴Department of Neurology, University of California San Francisco, San Francisco, United States, ⁵Philip R. Lee Institute for Health Policy Studies, University of California San Francisco, San Francisco, United States

Objectives: Helmets reduce head injury severity secondary to non-motorized vehicular and roller sport accidents. Furthermore, prevention of a single head injury reduces lifetime risk of head injuries. We present a novel clinical care quality improvement initiative (QII) to improve helmet usage, education, and safety awareness in head injury patients presenting to a Level 1 trauma center.

Methods: Head injury patients presenting to a single-institution emergency department (ED) after non-motorized vehicular or roller sport accidents without helmets, or with lost/damaged helmets, were provided helmets free-of-charge and in-person review of traumatic brain injury (TBI) education/resources consisting of injury statistics, publicly available TBI facts/figures, and post-discharge/follow-up care information. Semi-structured interviews querying patient perspectives on helmet use were conducted on day-of-injury and at ≥1 telephone follow-ups between 2-weeks to 1-year.

Results: In fifteen TBI patients aged 36.7±12.4-years, 67% were male, 53% reported prior TBI, and 33% were head CT-positive. Mechanisms included bicycle (47%), scooter (40%), and skateboard (13%) accidents; 80% were un-helmeted. All patients endorsed improved understanding of risk reduction strategies and helmet use after undergoing our QII on day-of-injury. Of 11 patients who completed follow-up, 91% did not operate non-motorized vehicles/roller sports post-injury, 55% used the helmet, and 9% (1/11) reported a subsequent TBI.

Conclusions: In-person provision of helmets, education, and resources for ED TBI patients is an effective and low-cost intervention to improve safety awareness and reduce reinjuries, contrasting with the high cost of one TBI (ED admission: >$6000 vs. helmet=$60). Our next steps include expanding QII implementation and refining evaluation metrics.

Mr. Gabriel Nah^1,2, Mrs. Lauren Rooks^1,3, Dr. Jonathon Crystal^1,2, Dr. Nicholas Crystal^1,3

¹Program in Neuroscience, Indiana University, Bloomington, United States, ²Dept. of Psychological and Brain Sciences, Indiana University, Bloomington, United States, ³School of Optometry, Indiana University, Bloomington, United States

Objective: The purpose of this study is to rigorously evaluate the memory performance of athletes by following various cognitive assessments. Design: Cohort prospective study. Setting: Collegiate athletics and military service academies. Participants: 47,411 athletes and cadets enrolled in the NCAA/DOD CARE consortium; 5,075 were diagnosed with a concussion. Assessments: The memory components of several manual and computerized concussion assessments: ANAM, SAC, CNS Vital Signs, and IMPACT. Main Result: Comparing the concussed group to the control group (baseline measures of the CARE consortium), small to medium effects on memory were found for SAC Immediate and Delayed memory (Cohen’s d = 0.29 & 0.33), ANAM Visual Memory (d = 0.75), ANAM Delayed Memory (d = 0.64), CNS Vital Signs Composite Memory (d = 0.36), CNS Vital Signs Verbal Memory (d = 0.82), CNS Vital Signs Visual Memory (d = 0.72), ImPACT Verbal Memory (d = 0.37), and ImPACT Visual Memory (d = 0.4). The null hypotheses of the aforementioned comparisons were all rejected (KS Test p < 0.001). The ANAM Working Memory test had a very small non-significant effect size of d = 0.16 (p = 0.5). Conclusions: Concussion/mTBI consistently produces small transient memory deficits, however the effect size of all memory tests is sufficiently small to not warrant their use in clinical decision making.

Dr. Juliet Haarbauer-Krupa¹, Dr. Jeffrey Berliner², Dr. Deanna Claus², Ms. Tracey Wallace¹, Dr. William Neihaur², Dr. Denise Crow³, Dr. Sunil Kothari Kothari³

¹Georgia RSVP Clinic, Atlanta, USA, ²Colorado RSVP Clinic, Engleton, USA, ³Texas RSVP Clinic, Houston, USA

Objectives: Insurance status determines a person’s ability to access healthcare services, ranging from emergency care to preventative services. Following a brain or spinal cord injury, uninsured persons are more likely to be discharged home and less likely to go to rehabilitation facilities. The aim of this session is to describe the population of uninsured patients with brain and spinal cord injuries served by free rehabilitation clinics in three states.

Methods: Colorado, Georgia, and Texas have formed free clinics whose mission is to provide outpatient rehabilitation care, each called the Rehabilitation Services Volunteer Partnership (RSVP) Clinic. Each state will review the demographics of individuals attending the free clinic and describe the population of individuals who have experienced catastrophic injury, yet do not have insurance or access to resources.

Results: The states of Texas, Colorado and Georgia have developed a clinic model to provide care to individuals who experience brain or spinal cord injuries and do not have insurance. Each state will describe the patients attending these clinics and state policies related to Medicaid expansion and injury waivers.

Conclusions: The RSVP Clinic offers opportunity to observe the “invisible” population of individuals who experience brain and spinal cord injuries but are unable to access necessary rehabilitation services. A free volunteer-run outpatient rehabilitation clinic is feasible and can contribute to improved outcomes for uninsured individuals with brain and spinal cord injury. Further research to understand the impact on patient outcomes is needed.

¹HHS/ASPR/BARDA, Washington, United States

In March 2024, a State of the Technology meeting focused on neurotrauma was co-hosted by the Biomedical Advanced Research and Development Authority (BARDA), within the HHS Administration of Strategic Preparedness and Response, and the U.S. Army Medical Research and Development Command (USAMRDC). The two-day event included over 300 participants and 40 speakers from healthcare, government, and academia. The findings will inform future investment strategies for the development of medical countermeasures to address limitations and bottlenecks in delivery of care to mitigate threats for military and civilian populations. The meeting identified major barriers and knowledge gaps that impede progress and opportunities for investment in new technologies. Results are based on the following key aspects:

- End user needs in clinical care environments from point of injury to definitive care

- Impact of new recommendations for TBI classifications of severity

- Commercial sustainability

- Ability to leverage artificial intelligence

- Regulatory considerations

The meeting identified needs in addressing the challenges in the current standard of care for neurotrauma patients. Partnerships within U.S. government agencies remain vital to drive innovation to develop and field new technologies that improve patient care. Meeting participants identified candidate technologies for management of TBI. BARDA and USAMRDC aim to take lessons learned from end users and those with lived experience to address some of the challenges in implementing these new technologies in partnership with product developers.

Dr. James Stone¹, Dr. Brian Avants¹, Dr. Nicholas Tustison¹, Dr. Elisabeth Wilde², Dr. Jacob Resch¹, Ms. Abby Lyons¹, Ms. Leslie Gladney¹, Dr. Stephen Ahlers³

¹University of Virginia, Charlottesville, USA, ²University of Utah, Salt Lake City, USA, ³Naval Medical Research Command, Silver Spring, USA

Repeated exposure to low-intensity blast is recognized as a potential cause of neurological changes in operational personnel. Studies of experienced breachers demonstrate blast-related alterations in brain structure and function. Blast associated increases in neuroinflammation have been seen in special operators. Concern has emerged regarding brain health effects in personnel exposed to artillery. The current study is the first to comprehensively examine the neurological correlates of repeated artillery exposures. Data from 100 service members were analyzed. The Blast Exposure Threshold Survey (BETS) was acquired to determine blast history. Neurocognitive measures and MR neuroimaging were acquired. Data were processed through ANTsX and SiMLR. Critical thresholds were determined for the generalized blast exposure value (GBEV) derived from the BETS and the 3BEC, an artillery BETS subcomponent. Cognitive assessments and brain structure and function relate to blast exposure. Common effects include midbrain cerebral blood flow, alteration in resting connectivity and structural effects in cholinergic brain regions and temporal lobe. Brain regions more strongly related to artillery exposure include orbitofrontal cortex, internal capsule, and corpus callosum. Total GBEV exhibits alterations in the entorhinal cortex and resting brain activity within limbic and cognitive control regions. Repeated artillery exposures are associated with alterations in white matter central to coordination, integration and processing. Conversely, GBEV is relatively more associated with alterations in cortical and resting brain activity. These results suggest unique changes as a function of weapon system and highlight the role of advanced imaging in elucidating the multifaceted nature of exposures on brain structure and function.

Dr. Ronald Alvarado-Dyer¹, Dr. Ali Mansour², MS. Plamena Powla², Dr. Farima Fakhri², Dr. Paramita Das², Dr. Peleg Horowitz², Dr. Fernando Goldenberg², Dr. Christos Lazaridis²

¹OU Health Oklahoma University Medical Center, Oklahoma City, United States, ²University of Chicago Medical Center, Chicago, United States

Penetrating brain injury (PBI) remains underrepresented in evidence-base knowledge and research efforts. We utilized data from the National Trauma Data Bank(NTDB) to investigate outcomes of PBI compared to clinical-severity matched blunt TBI.

A retrospective observation from the NTDB over 3-years including patients 16 years-old, with a Glasgow Coma Scale(GCS) of 3-12 and at least one reactive pupil was performed. Patients were divided into penetrating vs blunt injury. An inverse propensity score weighting approach was used to create a subgroup of patients within which covariates of interest (age, initial GCS-M, initial SBP, initial pulse oximetry, presence of midline shift, injury severity score, and pupillary reactivity) were represented in a balanced manner. Outcomes were mortality, rate of withdrawal of life supporting therapy (WOLST), and dispositional outcome.

1765 patients with PBI were 1:1 propensity score matched for clinical severity with blunt TBI patients. Mortality was significantly more common in PBI than in the blunt cohort (33.9% vs.14.3%,p<0.001) as was unfavorable outcome. Mortality was mediated by WOLST 30% of the time, and WOLST occurred earlier (median 3days vs.6days, p<0.001) in PBI. Increased rate of mortality was observed with GCS of <11 in PBI as compared to <7 in blunt TBI.

In conclusion, PBI patients exhibited higher mortality rates and unfavorable outcomes; 1/3 of excess mortality was mediated by WOLST. The study also brings into question the applicability of the traditional GCS classification in PBI. We emphasize the need to address these disparities and understand the distinctive mechanisms underlying PBI outcomes to improve patient care.

Dr. Krupa Savalia¹, Dr. Samantha Zuckerman², Bethany Young², Morgan Sikandar³, Aliza Narva²

¹University of California - Davis, Sacramento, United States, ²University of Pennsylvania Perelman School of Medicine, Philadelphia, United States, ³Hospital of the University of Pennsylvania, Philadelphia, United States

Victims of neurotrauma may require a prolonged length of stay in the intensive care unit (ICU) but are often deprived of the ability to make autonomous decisions regarding their care. In the absence of an advance directive, surrogates are expected to implement substituted judgment or a best interest standard to make decisions for their loved ones in the context of their previously expressed wishes. The unpredictability of neurologic recovery and outcomes after injury makes it hard to prognosticate and guide decision-making. Tensions may arise when there is a difference in the perceived values of the patient, their family, and members of the healthcare team. Thus, we propose a framework for providing ethically compassionate care with five strategies: identifying stakeholders early, involving an ethics consultant if indicated, clarifying proxy decision-making standards, creating a continuity team to help navigate discontinuity of care in the ICU, and establishing ethical and medically appropriate care. We discuss this framework in the context of a clinical case where our patient progressed to a persistent vegetative state, requiring a prolonged hospitalization given her surrogate’s request to continue life-sustaining measures despite a poor prognosis. Our goal is to provide a framework for how to intentionally approach patients requiring prolonged hospitalizations, particularly in the context of neurologically devastated injury that requires surrogate involvement, to ultimately deliver ethically compassionate and appropriate medical care.

Mrs. Katie Brecker¹, Dr. Rachel Thomas¹, Dr. Catherine Demos², Dr. Nikhil Padmanabhan², Dr. Taron Gorham², Dr. George Sigal², Dr. Jacob Wohlstadter², Dr. Sonia Jain³, Dr. Xiaoying Sun³, Dr. Joseph Giacino⁴, Dr. Michael McCrea⁵, Dr. David Okonkwo⁶, Dr. Claudia Robertson⁷, Dr. Nancy Temkin⁸, Dr. Pratik Mukherjee⁹, Dr. Kevin Wang¹⁰, Dr. Ava Puccio⁶, Dr. Andrea Schneider¹, Dr. Danielle Sandsmark¹, Dr. Geoffrey Manley⁹, Dr. Ramon Diaz-Arrastia¹

¹University of Pennsylvania, Philadelphia, United States, ²MesoScale Discoveries, Gaithersburg, US, ³University of California, San Diego, San Diego, US, ⁴Massachusetts General Hospital, Boston, US, ⁵Medical College of Wisconsin, Milwaukee, US, ⁶University of Pittsburgh, Pittsburgh, US, ⁷Baylor College of Medicine, Houston, US, ⁸University of Washington, Seattle, US, ⁹University of California, San Francisco, San Francisco, US, ¹⁰Morehouse University, Atlanta, US

Objective: Describe the relationship of vWF with TBI severity, CT findings, and 6-month outcomes.

Methods: A subset of the TRACK-TBI cohort consisting of adults with TBI (n=334), orthopedic injury controls (OI, n=86), and healthy controls (HC, n=64) was analyzed. Plasma was collected day 1 (D1), 2 weeks (W2), and 6 months (M6) after injury. vWF, Glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL) levels were measured using Meso Scale Discovery (MSD) U-PLEX or Neurology panel S-plex assays. Logistic regression models assessed the association of vWF levels with incomplete recovery (Glasgow Outcome Scale-Extended, GOSE<8) and unfavorable outcome (GOSE<5) at M6.

Results: The mean age of the TBI participants was 39.9 years and 49.4% had GCS 3-12. D1 vWF levels (median [IQR]) in TBI cases were 11.6 [6.7–16.5] μg/mL, compared to 4.7 [3.4–7.0] μg/mL in HC and 8.6 [6.1–12.4] μg/mL in OI (p<0.005 for both comparisons). vWF remained elevated at W2 in GCS 3-12 cases (13.0 [7.0–21.2] μg/mL), but returned to normal by M6. Higher levels on D1 and W2 are associated with TBI severity. Higher vWF levels on W2 were associated with both incomplete recovery (aOR=1.65 per log unit increase, 95%CI 1.06-2.58) and unfavorable outcome (aOR=2.36, 95%CI 1.19-4.68) after adjusting for age, sex, CT, GCS, log[GFAP], and log[NfL].

Conclusion: vWF is increased after TBI, and in severely injured cases higher levels persist for 2 weeks. vWF is a biomarker of traumatic microvascular injury and shows promise as a prognostic biomarker in moderate-severe TBI of a potentially treatable endophenotype.

Prof. Wilco Peul¹, Dr. Thomas van Essen¹, Dr. John Yue, Dr. Angelos Kolias, Dr. Hadie Adams, Prof. Hester Lingsma, Prof. Ewout Steyerberg, Prof. Andrew Maas, Prof Peter Hutchinson, Prof. Geoffrey Manley

¹Leiden University Neurosurgical Center Holland, Leiden, Netherlands

Surgical evacuation of a traumatic acute subdural hematoma (ASDH) is one of the most frequently performed acute surgical intervention within the skull but its effectiveness and determinants rely on limited evidence. Therefore, we propose to assess the effect of acute surgery in ASDH and to predict the effect for individual patients.

The contemporary hitherto largest studies CENTER-TBI in Europe, TRACK-TBI in Amerika and RESCUE-ASDH in the United Kingdom will be merged and harmonized to allow individual participant data meta-analysis. We will first estimate the overall effect of acute surgery for ASDH through multiple analyses to mitigate confounding (including multivariable regression, propensity score techniques and instrumental variable analysis). Second, we will devise a framework to disentangle the different effects of surgery vs conservative treatment in ASDH, using (a) conventional subgroup analyses of baseline characteristics, and (b) a multivariable outcome prediction model to estimate benefit for individual patients. Our evaluation of heterogeneous treatments effects will include determining the absolute risks of unfavorable functional outcome conditional on known and new risk factors. Finally, if successful, we aim to implement the prediction model in a tool to support decision making for surgery for ASDH.

We expect to provide clear surgical indications for ASDH, thereby personalize neurosurgery in ASDH, with the ultimate goal to improve survival and decrease disability among patients with ASDH.

Dr. Rawad Daniel Arja^1,2, Prof. Firas Kobaissy^1,2, Mr. Guangzheng Cai^1,2, Michele D. Nelson³, Moyinoluwa Adeniyi³, Oluwatosin Daramola³, Sherifdeen Onigbinde³, Prof. Yehya Mechref³, Prof. Raquel C. Gardner^4,5, Prof. Kevin Wang^1,2

¹Center for Neurotrauma, MultiOmics & Biomarkers (CNMB), Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, United States, ²Morehouse School of Medicine, Atlanta, United States, ³Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, United States, ⁴Brain and Spinal Injury Center, University of California, San Francisco, United States, ⁵Department of Neurosurgery, University of California, San Francisco, United States

In this work, we present the development of the Dried Plasma Biosampling Lateral Flow (DPB-LF) device that aims to revolutionize Traumatic Brain Injury (TBI) diagnostics through a minimally invasive method for multi-omic biomarker identification. This study evaluates the DPB-LF device’s efficacy in biomarker recovery and stability, focusing on GFAP, NFL, Tau, UCH-L1 from dry plasma samples. Utilizing this lateral flow assay technology, biomarker stability and recovery were assessed under various storage conditions (4°C, room temperature, and 40°C) over a 21-day time period, employing ELISA and western blot for protein quantification, in addition to proteomics and metabolomics assessment. Results indicate significant efficacy, reproducibility and compatibility for biomarker recovery, with optimal stability observed at 4°C, where biomarker levels in rehydrated samples remained comparable to those in fresh plasma, suggesting minimal degradation. The device’s performance highlighted the importance of storage conditions, with refrigerated conditions not only preserving but potentially enhancing biomarker stability over time. Conclusively, the DPB-LF device offers a significant advancement in TBI biomarker analysis, providing a reliable, efficient, and minimally invasive diagnostic tool that aligns with the evolving needs of global health crises, setting a new standard for TBI research and clinical practice by significantly reducing the biosample burden on patients and streamlining the diagnostic process.

Dr. Deborah Shear¹, DR. Krista Caudle², DR. Kenneth Curley², DR. James Phillips³, DR. Bradley Dengler⁴, DR. Damien Hoffman³, DR. Anke Scultetus¹, DR. Lou Jasper², DR. Janice Gilsdorf¹, COL Kara Schmid⁵

¹Walter Reed Army Institute of Research, Silver Spring, USA, ²U.S. Army Medical Materiel Development Activity, Fort Detrick, USA, ³Combat Casualty Care Research Program, Fort Detrick, USA, ⁴Uniformed Services University of the Health Sciences, Bethesda, USA, ⁵U.S. Army Headquarters, Dept of the Army, Arlington, USA

The inception of DoD involvement in the TBI blood-based biomarkers space began with a partnership formed between scientists at WRAIR and the University of Florida at a Military Medical Conference breakfast meeting on the morning of 9/11. Several years later, WRAIR and USAMMDA established the Laboratory Assay for Traumatic Brain Injury Integrated Product Team (LATBI IPT) to develop an acquisition strategy for detecting concussion on the battlefield.

The FDA clearance for the TBI blood test system took two decades and involved multiple government, academic, and industry partners. The test was based on data generated from plasma samples obtained from the ALERT-TBI clinical study (Bazarian et. al. 2018; Lancet Neurol). This study population included a cohort of 1901 mild TBI patients, and the test accurately identified 115 of the 120 CT+ subjects as “elevated”. This effort resulted in Abbott Point of Care obtaining FDA clearance in 2021 for marketing the i-STAT Alinity™ plasma blood test using GFAP and UCH-L1 to aid in evaluating TBI. On March 7, 2023, the FDA cleared Abbott’s blood test for commercial distribution. The TBI blood test introduces objectivity into the DoD/Army’s TBI point-of-injury assessment space. The incorporation of the blood test early in patient triage gives clinicians an extra data point in making evacuation and treatment decisions and may be valuable for monitoring the progression of brain injury throughout all stages of care. Moreover, results from the TBI blood test will become part of the patients’ medical records and may inform longitudinal treatment and recovery.

Prof. Gerry Shaw^1,2, Professor David Fuller², Professor David Borchelt², Professor Jose Abisambra², Professor Eduardo Candelario-Jalil², Ms Marda Jorgensen, Ms Anna Fusco², Ms Irina Madorsky¹, Dr Ying Li¹, Dr YongSheng Wang¹

¹EnCor Biotechnology Inc., Gainesville, United States, ²University of Florida, Gainesville, United States

Loss of axons is a key problem in serious human neurological disorders. Since neurofilaments (NF) are major components of axons, the detection of NF subunits or their breakdown products in blood or CSF is expected to reveal ongoing axonal loss. Recently much interest has focused on detection of the NF light chain, NF-L, using antibodies marketed originally by Uman Diagnostics Inc. We have shown that the Uman antibodies bind to the center of Coil II of the NF-L α-helical “rod” region. We developed monoclonal and polyclonal antibodies to this region and found that the original NF-L reagents and our novel antibodies do not recognize assembled NF in sections of normal CNS material. However the epitopes for all these antibodies are exposed on degeneration due to damage induced proteolysis. Antibodies to the homologous Coil II region of NF-M and NF-H and also antibodies to the N-terminus of NF-L Coil II also exhibit this degeneration induced immunoreactivity. We conclude that most of Coil II of NF-L, NF-M and NF-H is inaccessible to antibodies in assembled NF but revealed by proteolysis on degeneration. We have further characterized a protease resistant fragment of NF-L which we believe is the core of the NF-L biomarker. Antibodies to these degeneration specific forms of NF subunits are excellent markers of traumatic axonal damage and Wallerian degeneration. We also demonstrate their utility in a variety of models of neurodegeneration including spinal cord injury, traumatic brain injury, stroke and animal models of ALS, Pompe disease and others.

CPT Robert Bruce¹, SSG Brenda Hawkins¹, SGT William Hertzman¹, Weihong Yang¹, Ying Cao¹, Figiel Caitlin¹, Fang Zhou Yang¹, Xiaofang Yang¹, Intisar Diwani¹, Linda Huynh¹, Deborah Shear¹, Starlyn Okada-Rising¹, Anke Scultetus¹

¹Walter Reed Army Institute of Research, Forest Glen, United States

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in operational environments. Serum biomarkers including glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase-L1 (UCH-L1) have been FDA-approved to aid in the evaluation of mild TBI. However, the extent to which serum availability of these proteins is influenced by injury etiology and severity remains poorly characterized. The current study aims to evaluate the post-injury kinetics of 4 key neurotrauma biomarkers in rat models of penetrating TBI (pTBI) and controlled cortical impact (CCI). Isoflurane anesthetized adult Sprague-Dawley rats (10 per group; pTBI, CCI, or sham) underwent jugular vein catheterization 24h prior to injury. Animals received unilateral surgical pTBI or CCI targeting the frontal cortex under anesthesia. Blood was collected for serum chemistry 24h prior to injury (baseline) and at 2, 4, 6, 24, 48, 72 hours and 7 days following injury. Terminal cerebrospinal fluid (CSF) and blood samples were collected at 7 days post-injury. Proteins within the serum and CSF samples were quantified utilizing the Quantrix Neurology 4-Plex Assay. Preliminary results suggest marked elevations in serum GFAP and UCH-L1 acutely following injury in CCI compared to both pTBI and sham. Although serum neurofilament light and tau levels were elevated in pTBI and CCI, there appears to be no significant differences between the groups. These findings suggest that availability of the serum-based biomarkers may be affected by the mechanism of injury and/or the degree of intracranial hemorrhage.

Dr. Saul Datwyler¹, Paula Bernander¹, Raj Chandran¹, Jaime Marino¹, Karla Grasso¹, Jennifer Yen¹, Swati Pradhan-Bhatt², Krista Caudle³, Beth McQuiston¹

¹Abbott Laboratories, Abbott Park, United States, ²Abbott Laboratories, Princeton, United States, ³US Army Medical Materiel Development Activity, Fort Detrick, United States

Objective: The objective is to assess the performance of blood based biomarkers glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) for predicting intracranial lesions in subjects presenting to the emergency department with a suspected mild traumatic brain injury (TBI).

Methods: Analysis of archived plasma specimens from a prospectively collected multicenter study was performed to establish the performance of the Alinity i TBI test; a panel of GFAP and UCH-L1 immunoassays. Specimens were collected from individuals aged ≥18 presenting within 12 hours with suspected TBI who had an initial Glasgow Coma Scale score of 13-15 and a head CT scan performed per standard of care.

Results: Of the 1899 subjects available for testing and analysis, 1331 met the ACRM (American Congress of Rehabilitation Medicine) criteria for mild TBI. 103 had positive CT scan results. The TBI test had a sensitivity of 97.1% (95%CI: 91.8%,99.0%). Of the 1228 subjects with negative CT scan results, 508 had a negative TBI test interpretation (Specificity 41.4%; 95%CI: 38.6,44.1). The negative predictive value (NPV) of the test was 99.4% (95%CI: 98.3%,99.8%).

Conclusions: The Alinity i TBI test demonstrated high sensitivity and high NPV to assist in determining the need for a head CT scan in subjects presenting with suspected mild TBI. The results support use of blood biomarkers to provide supportive evidence of brain injury.

Funding: This study was funded by Abbott Laboratories in collaboration with the US Army Medical Materiel Development Activity, US Army Medical Research and Development Command CRADA 20-1266-CRA.

Dr. Claudia Robertson¹, Dr. Spyridoula Tsetsou¹, Dr. David Barton², Ms. Leah McQuillon², Dr. John Williamson³, Dr. Damon Lamb³, Dr. Firas Kobeissy⁴, Dr. Guangzheng Cai⁴, Dr. Richard Rubenstein⁵, Dr. Kevin Wang⁴, Dr. Amy Wagner²

¹Baylor College Of Medicine, Houston, United States, ²University of Pittsburgh, Pittsburgh, United States, ³University of Florida, Gainsville, United States, ⁴Morehouse School of Medicine, Atlanta, United States, ⁵SUNY Downstate Health Sciences University, Brooklyn, New York City, United States

Background: Multiple reports suggest that neurofilament light (NfL) is associated with axonal damage after traumatic brain Injury (TBI), with our prior work suggesting high specificity for subacute/chronic injury. However, NfL utility in understanding clinical course in the Intensive Care Unit (ICU) and associations with outcome have not been studied.

Methods: We analyzed stored serum samples (Simoa, Quanterix) collected over the first 10 days post-injury for 97 subjects with moderate-severe TBI. NfL values were examined using group-based trajectory (TRAJ) analyses to identify unique patient subgroups with similar NfL patterns over time. We then examined TRAJ associations with ICU course and outcome.

Results: TRAJ analysis identified two distinct subgroups with high (n=34) vs low (n=63) NfL levels over time; both groups exhibited increasing levels over the 10-day monitoring period. The high TRAJ group had worse Glasgow coma scale (GCS) scores (p=0.0009 all comparisons). High TRAJ group members more frequently had compressed basal cisterns on brain CT (p=0.03) and prehospital hypotension (p=0.046). High TRAJ group members also had more prolonged cerebral hypoperfusion (p=0.01) and higher ICP values (p=0.01) that required more frequent barbiturate coma (p=0.01) or decompressive surgery (p=0.02) for treatment, ICU factors that are associated with poor outcome. Finally, high TRAJ group members had worse 6-month outcomes and higher mortality (p=0.001).

Conclusion: Higher serum NfL temporal profiles are associated with worse injury severity and refractory intracranial hypertension and cerebral hypoperfusion during ICU stay, factors which are also associated with long-term outcome after moderate-severe TBI.

Dr. Alana Conti¹, Tanja Jovanovic¹, Seth Norrholm¹, Antonia Seligowski⁴, Oliver Holmes², Thomas Neylan⁵, Gari Clifford⁶, Sarah Linnstaedt², Jennifer Stevens⁸, Stacey House⁹, Kerry Ressler⁷, Ronald Kessler³, Xinming An², Samuel McLean²

¹Wayne State University, Detroit, United States, ²UNC School of Medicine, Chapel Hill, United States, ³Harvard Medical School, Boston, United States, ⁴Mass General Research Institute, Boston, United States, ⁵UCSF School of Medicine, San Francisco, United States, ⁶Georgia Institute of Technology, Atlanta, United States, ⁷Mass General Brigham McLean Hospital, Belmont, United States, ⁸Emory University School of Medicine, Atlanta, United States, ⁹Washington University School of Medicine in St. Louis, St. Louis, United States

Substantial evidence suggests that both traumatic brain injury (TBI) and stress exposure/stress system activation cause acute and persistent somatic and stress symptoms. However, past challenges with identifying individuals with TBI, and separating out the influence of TBI from other factors on adverse outcomes after trauma exposure, have limited the identification of vulnerability to acute symptoms and functional decline. Our Discovering DIagnostics, SubtypEs, and NaTurAl history of traumatic brain iNjury (TBI) vs. non-TBI Recovery to Gain MiLitary advantagE (D2ISENTANGLE) Focused Program Award addresses these critical knowledge gaps. GFAP was used as a blood-based TBI severity assessment biomarker for D2ISENTANGLE and we assessed trauma-related sympathetic reactivity across several GFAP cutoffs. SNS reactivity to trauma was assessed using skin conductance response (SCR) during an emergency department visit in which individuals reported head injuries. SCR and GFAP data were available for N=1354 individuals. Using American Congress of Rehabilitation Medicine clinical criteria or a lower GFAP cutoff of 268 pg/ml did not result in group differences in SCR. However, GFAP cutoffs of 360 pg/ml and 695 pg/ml showed increased SCR in the TBI+ group compared to the TBI-group, F=4.16, p<.05 and F=18.73, p<.0001, respectively. These results indicate that blood-biomarkers of higher levels of neural deterioration are associated with SNS hyperactivity after trauma and may point to potential early identification of vulnerable individuals. Supported by Department of Defense Congressionally Directed Medical Research Programs (CDMRP) W81XWH22C0122.

Mr. Peter Ngum^1,2,3,5, Dr Harri Merisaari^1,3,4, Dr Jussi Posti^1,2,3, Prof Olli Tenovuo^1,2,3

¹University Of Turku, Turku, Finland, ²Turku Brain Injury Center, Turku, Finland, ³Turku University Hospital, Turku, Finland, ⁴Turku Brain and Mind Center, Turku, Finland, ⁵Johns Hopkins University, Baltimore, USA

Objective: In this study, we assess the efficacy of various machine learning models in predicting 6-month mortality, CT findings, admission status, and binary Glasgow Outcome Scale Extended (GOSE)-based recovery for traumatic brain injury (TBI) patients using admission data.

Methods: We utilized a prospective Finnish TBI dataset of all injury severities comprising 240 records, refined to 180 after addressing missing data based on target variable data availability. To ensure the thoroughness and reliability of our analysis, we used a domain-specific data dictionary with clinically defined ranges for outlier handling and mean/median/mode for missing values. The dataset featured clinical scores, demographics, and biomarkers, analyzed using logistic regression, random forest, gradient boosting, SVM, and XGBoost, with performance validated through stratified 5-fold cross-validation to ensure robust model validation and mitigate overfitting.

Results: Biomarkers (GFAP, UCHL1, NFL) and age were key predictors in our analysis. XGBoost and random forest models excelled, achieving ROC-AUC scores of 0.881 for mortality and 0.893 for binary recovery predictions. The dataset consisted of patients with mild TBI (70.72%), complemented by moderate (19.34%) and severe cases (10.94%), reflecting a broad spectrum of TBI severity. 69.61 % were male with a median age of 51.

Conclusion: We demonstrated the efficacy of machine learning methods, notably XGBoost and random forest algorithms, in predicting various binary outcomes for TBI patients. These results highlight the potential of evolving our approach into an AutoML framework. AutoML automates the process of applying machine learning models to real-world problems, significantly speeding up hypothesis testing across various clinical variables and conditions. Although our initial results are promising, the pipeline is still under development and requires further refinement. Validating these methods in larger and more diverse external datasets is crucial to confirm their generalizability and reliability.

Ms. Joy Solomon¹, Cristian Gutierrez-Reyes¹, Sherifdeen Onigbinde¹, Moyinoluwa Adeniyi¹, Mojibola Fowowe¹, Md Mostofa Al Amin Bhuiyan¹, Oluwatosin Daramola¹, Judith Nwaiwu¹, Firas Kobeissy², Stefania Mondello³, Ava Puccio⁴, Yehia Mechref¹

¹Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, United States, ²Center for Neurotrauma, MultiOmics & Biomarkers (CNMB) Morehouse School of Medicine, Atlanta, United States, ³Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy, ⁴Neurotrauma Clinical Trials Center, University of Pittsburgh, Pittsburgh, United States

Glycans are crucial for neurological functioning and their importance in many neurological conditions is becoming more acknowledged. The specific glycomic patterns associated with TBI have just started to be explored, pointing out the high relevance of N-glycosylation to brain diseases and its potential for discovering novel markers. This study seeks to analyze the glycome in biofluids after TBI to further understand the complex pathogenic pathways associated with TBI, which could contribute to improved management strategies and help reduce the occurrence of post-traumatic complications. Utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS), we analyzed Serum and cerebrospinal fluid (CSF), from healthy individuals and TBI patients on day 1, day 3, and day 5 post-injury. We identified 86 and 102 glycans in CSF and Serum, respectively, covering different glycan types such as high mannose, fucosylated, sialylated, sialofucosylated, and others. Fucosylated glycans were predominant in the CSF, while sialylated glycans were prevalent in the blood. In the CSF, 27 glycans were significantly altered on Day 1, 26 on Day 3, and 14 on Day 5 when compared to controls. In HBS, 78, 68, and 63 significant glycans were identified for the same respective comparisons. Brain structures like HexNAc5Hex3DeoxyHex0NeuAc0 exhibited significant upregulation throughout the days compared to controls, while HexNAc8Hex6DeoxyHex0NeuAc0 showed downregulation over time. This study emphasizes the potential of glycomics in investigating glyco-biomarkers for improving therapy strategies.

This work was supported by grants from the National Institutes of Health, NIH (1R01GM130091-04), the Robert A. Welch Foundation grant number D-0005 (YM), and The CH Foundation.

Ms. Grace Recht¹, Ms. Claire Buddenbaum¹, Mrs. Taylor Zuidema^1,2, Ms. Adriana Rodriguez¹, Dr. Keisuke Kawata^1,2

¹Department of Kinesiology, Indiana University, School of Public Health, Bloomington, United States, ²Program in Neuroscience, The College of Arts and Sciences, Indiana University, Bloomington, United States

Brain-injury blood biomarkers (neurofilament light [NfL], glial fibrillary acidic protein [GFAP], ubiquitin C-terminal hydrolase-L1 [UCH-L1], and tau) have been utilized to gauge effects of head impact exposure in high school, collegiate, and professional contact sport athletes. However, there is a significant gap examining these biomarkers in retired, amateur level contact athletes. The present study aimed to determine if there were differences in brain-injury blood biomarkers in retired amateur contact athletes as compared to non-contact athletes. This study included 58 retired, amateur athletes between the ages of 30 and 60 (38 contact athletes, 20 age and sex matched non-contact athletes) with at least 10 years of organized contact or non-contact sport experience. For analysis, 4mL of venous blood was collected into an EDTA vacutainer, and plasma samples were analyzed for NfL, GFAP, UCH-L1, and Tau using the Human Neurology 4-Plex assay on a Quanterix SR-X system. No significant group differences in all 4 biomarker levels were observed. However, secondary analysis revealed that number of concussions significantly modulated Nf-L, GFAP, UCH-L1, and tau levels in the contact group, such that greater number of previous concussions were associated with higher levels of biomarker expressions. Conversely, no such relationship was observed in the non-contact group. These data suggest that while there are no significant group differences in brain-injury blood protein levels, number of concussions endured may influence biomarker expressions in contact athletes, suggesting that biomarker expressions may be reflective of cumulative neurological burden from concussive and subconcussive head impact exposure.

Ms. Makda Mulugeta¹, Dr. Andrew Reisner^1,2, Dr. Laura Blackwell^1,2

¹Children’s Healthcare of Atlanta, Atlanta, United States of America, ²Emory University, Atlanta, United States of America

Background: GFAP and UCH-L1 are validated as aids in the management of adult TBI, including assessing need for a head CT. For pediatrics, a non-invasive marker of intracranial injury would reduce unnecessary radiation resulting from CT. Understanding how blood biomarkers differ across types of head CT findings is important for management of these children.

Objective: To examine the association of GFAP and UCH-L1 with head CT findings defined as only intracranial injuries, only skull fractures, combined findings (both intracranial and skull), and negative findings.

Methods: Patients admitted to the ED for TBI (GCS 3-15) with head CTs (n=384) from 2018-2021, part of a larger prospective study. Plasma samples taken ≤6 hours of ED arrival were analyzed using the Quanterix SiMoA platform. GFAP/UCH-L1 were obtained. Kruskal-Wallis-H/Dunn’s post-hoc tests were used.

Results: The sample ranged in age (0-18, x̄=8.3±5.3), gender (65.6% male; 34.4% female), and race (49% White; 33.9% Black; 11.2% Hispanic). 18.8% (n=72) had only intracranial injuries, 11.5% (n=44) had only skull fractures, 33.9% (n=130) had combined findings, and 35.9% (n=138) had negative findings.

Significant differences in GFAP values across head CT categories were found (H(3)=42.10,p<0.001). Post-hoc tests revealed that GFAP differed between negative findings and intracranial only, skull only, and combined findings each (p<0.001). UCH-L1 values differed across head CT categories (H(3)=11.24,p=0.011), but only between negative findings and combined findings (p<0.001).

Conclusion: This study suggests that blood biomarkers can differentiate between various findings on head CT following pediatric TBI. Further investigation into the clinical utility of these markers is warranted.

Dr. Phillip Bonney^1,2, Dr. John Kanter^1,2, Dr. Anthony DiGiorgio^1,2, Dr. Phiroz Tarapore^1,2, Dr. Michael Huang^1,2, Dr. Geoffrey Manley^1,2

¹University Of California, San Francisco, San Francisco, United States, ²Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, United States

Our institutional venous thromboembolism (VTE) prophylaxis protocol in traumatic brain injury (TBI) patients calls for early enoxaparin 30 milligrams twice daily. We report VTE prophylaxis initiation data and VTE events in a cohort of ventriculostomy-treated TBI patients. TBI patients from August 2019 through October 2023 treated with ventriculostomies within 24 hours of arrival and admitted for at least 7 days were included. Date and location of VTE were recorded in addition to other hospitalization data. Clinically significant VTE was defined as lower extremity deep venous thrombosis (DVT-LE) or pulmonary embolism (PE). The cohort consisted of 111 patients (mean age 48 ± 19 years) presenting with median GCS 7 (interquartile range [IQR] 3 to 12). Length of stay was median 30 days (IQR 18 to 49 days). Sixteen patients (14.4%) were diagnosed with clinically significant VTE on median hospital day 8 (IQR 5 to 13 days). Twelve patients had DVT-LE and 8 had PE (4 had both). VTE prophylaxis was initiated at median 58 hours after hospital arrival (IQR 49 to 64 hours), with most patients (82.9%) receiving enoxaparin 30 milligrams twice daily, including 14 of 16 VTE patients (87.5%). There was no difference in time to VTE prophylaxis initiation in those with and without clinically significant VTE (54.0 vs. 61.3 hours). Mortality was similar in patients with and without clinically significant VTE (25% vs. 22%, p = 0.746). No deaths were directly attributable to VTE. Despite early, effective VTE prophylaxis, VTEs are common in ventriculostomy-treated TBI patients.

Ms. Peyton McIntyre¹, Dr. Sarah Svirsky¹, Ms. Olivia Raymond¹, Ms. Chelsea Wagner², Dr. Jessica Gill², Dr. Ava Puccio¹

¹University Of Pittsburgh, Pittsburgh, United States, ²John Hopkins University, Baltimore, United States

Background/Objective: The sports medicine community and society at large have recognized concussion as a major public health concern. It is estimated that more than 150 million youths have played football in the United States, with approximately 100 documented cases of CTE in former gridiron athletes (0.00007%). Sweat is a potential source of non-invasive biomarker collection, to provide objective measures for safety guidelines. This study explores sweat as a means of measuring protein biomarkers of brain injury following a football season.

Methods: Football players from a NCAA Division III college enrolled under an approved IRB protocol were included. Pre- and post- season assessments were conducted, including application of a noninvasive sweat patch (PharmChem, Forth Worth, TX) for 12-24-hours, Rivermead Post Concussion Questionnaire (RPQ), Ohio State Concussion Questionnaire, and analysis of sweat biomarker proteins tau, Neurofilament Light Protein[Nf-L], Glial Fibrillary Acidic Protein[GFAP], and Ubiquitin C-Terminal Hydrolase-L1[UCHL-1]) via immunoarray (Simoa™, Quanterix Corporation, Lexington, MA). Paired, two-tailed Student’s t-test were performed.

Results: 32 football players were assessed pre-season, with 18 returning post-season for analysis. Sweat patches were worn for a 12-24 hour period. Sweat was extracted and run for the above analytes. Paired, two-tailed Student’s t-test showed a significant increase in sweat biomarkers tau, GFAP and UCHL-1 protein expression from pre- to post-season (p=0.0049; p=0.0471; p=0.0371, respectively), with no significant change in Nf-L.

Discussion: Characteristic TBI proteins tau, Nf-L, GFAP, and UCHL-1 were detectable from this sweat analyses. Tau showed to be the most indicative measure of TBI exposure throughout a football season.

Mr. Vishal Sandilya¹, Mrs. Mojgan Atashi¹, Ms. Thu Nguyen¹, Ms. Joy Solomon¹, Mr. Md Mostofa Al Amin Bhuiyan¹, Mr. Cristian Gutierrez¹, Mrs. Waziha Purba¹, Mr. Mojibola Fowowe¹, Ms. Judith Nwaiwu¹, Dr. Firas Kobeissy², Dr. Stefania Mondello³, Dr. Ava Puccio⁴, Dr. Yehia Mechref¹

¹Texas Tech University, Lubbock, United States, ²Morehouse School of Medicine, Atlanta, United States, ³University of Messina, Messina, Italy, ⁴University of Pittsburgh, Pittsburgh, United States

The heterogeneous nature of severe traumatic brain injury (sTBI), primarily related to the different pathophysiological mechanisms and complex molecular cascades triggered by the initial injury, poses daunting challenges in diagnosis and treatment. Several protein biomarkers change over time post-injury, which can be associated to the underlying pathobiophysiology and can be used as potential diagnostic and treatment target tools. This study involves the comparative proteomics analysis of blood serum and cerebrospinal fluid (CSF) obtained from adult sTBI patients at post-injury intervals with a focus on low-abundance proteins. The serum samples were subjected to depletion to enhance the presence of lower-abundance proteins. Both sets of samples were then digested using trypsin in a 25:1 protein-to-enzyme ratio. Then the proteins were reconstituted in HPLC-grade water and 0.1% formic acid and analyzed via LC-MS/MS. A total of 38 paired serum and CSF samples were analyzed, comprising an even distribution of 19 controls and 19 TBI cases. The protein expression changes were tracked over days 1, 3, and 5 post-injury. The preliminary results displayed that multiple pathways linked to neurodegenerative diseases such as Alzheimer’s disease were significantly altered. The altered pathways in serum include LXR/RXR activation pathway and 24-dehydrocholestrol reductase signaling pathway. Similarly, the CSF samples also displayed significant alterations in pathways associated with neurodegenerative diseases, including pathways leading to amyloid fibril formation. These findings pose intriguing questions regarding the potential relationship between TBI and the risk of developing neurodegenerative diseases.

This work was supported by grants from the National Institutes of Health, NIH (1R01GM130091).

Ms. Madeline Peterson², Bridget Mayrer², Dr. David Barton³, Nabil Awan⁶, Dr. Raj Kumar⁷, Dr. Michael Frankel⁸, Dr. David Wright⁹, Dr. Jenna Carlson², Dr. Amy Wagner^1,4,5

¹Department of Physcial Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, United States, ²Department of Biostatistics, University of Pittsburgh, Pittsburgh, United States, ³Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, United States, ⁴Department of Neuroscience, University of Pittsburgh, Pittsburgh, United States, ⁵Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, United States, ⁶Department of Biostatistics, University of Wisconsin-Madison, Madison, United States, ⁷Department of Rehabilitation Medicine, Icahn School of Medicine, New York, United States, ⁸Department of Neurology, Emory University, Atlanta, United States, ⁹Department of Emergency Medicine, Emory University, Atlanta, United States

There are no approved neuroprotective treatment options for individuals with moderate-to-severe traumatic brain injury (TBI). However, knowledge gaps exist regarding the development and use of early prediction tools that incorporate biomarkers and clinical features reflecting aspects of both central nervous system (CNS) and Systemic Injury for identifying likely responders to potential neuroprotective treatments. Thus, we conducted a secondary analysis of the ProTECT III multi-center randomized clinical trial utilizing data from N=536 patients who also enrolled in the BioProTECT biosampling protocol (samples collected 0-, 24-, and 48-hr post-injury). We utilized baseline clinical measures [age, sex, race, Rotterdam CT score, index GCS (iGCS)], assayed systemic injury biomarkers and hormones (serum progesterone, androstenedione, estrone, testosterone, estradiol, and TNFα) and assayed CNS biomarkers (SBDP, S100B, UCHL-1, GFAP) to predict TBI overall favorable vs. unfavorable outcome using the Glasgow Outcome Scale-Extended (GOS-E) at 6-months, 6-month mortality status, and GOS-E outcome among survivors only. Classification and Regression Tree (CART) models, were employed to predict outcome, and findings were compared to logistic regression. Overall, logistic regression outperformed CART modeling; however, both methods identified some consistent baseline predictors. Features common to both GOS-E models included GFAP, age, Rotterdam, iGCS, progesterone, and S100B. Features common to both mortality models included GFAP, age, Rotterdam, and TNFα. Features common to both survivor models include age, iGCS, race, UCHL-1, GFAP, Rotterdam, and androstenedione. Future work will examine the moderating effects of progesterone treatment on baseline model outcome prediction and develop models using biomarker information collected at later time points.

Dr. Denis Bragin¹, Dr. Edwin Nemoto², Dr. Howard Yonas³

¹Lovelace Biomedical Research Institute, Albuquerque, United States, ²Department of Neurology, University of New Mexico, Albuquerque, USA, ³Department of Neurosurgery, University of New Mexico, Albuquerque, USA

Fifty years of neuroprotection clinical trials in both acute ischemic stroke (AIS) and severe traumatic brain injury (sTBI) at great expense and effort, failed with a critical unmet clinical need. Neuroprotection tacitly assumes that there is salvageable tissue to be rescued. Yet, in neither AIS nor sTBI clinical trials was the presence of salvageable tissue evaluated before enrollment. This failure has been noted for AIS [Transl Stroke Res. 2010; 1:220–9.] but not for sTBI. In AIS, specific imaging criteria were developed to qualify for FDA-approved treatment of large vessel occlusion (LVO) ischemic stroke by thrombolysis with recombinant tissue plasminogen activator (rTPa) or endovascular thrombectomy (EVT). Perfusion-weighted (PWI) and diffusion-weighted (DWI) imaging by magnetic resonance imaging (MRI) using the RAPID software [Stroke. 2011; 42:1608–14.], specified a penumbra/core volume ratio of at least 1.6 and a core volume of 70 ml or less, and an Alberta stroke program early CT score (ASPECTS) of >6 to qualify for treatment. In a rat AIS model, we quantitated voxel volumes of penumbra and core [Transl Stroke Res. 2010 Sep 1;1(3):220-9] by cross-correlating cerebral blood flow (CBF) and apparent diffusion coefficient (ADC) that eliminated the regional heterogeneity of CBF and ADC values in PWI and DWI image volumes. Enrollment in sTBI neuroprotection clinical trials has all been based solely on a Glasgow Coma Score (GCS) of 8 to 3. The verified imaging criteria to qualify for neuroprotection in sTBI as in AIS have yet to be established.

Mr. Andrew Geoly¹, Dr. John Coetzee^1,2, Dr. Wiebke Struckman¹, Dr. Derrick Buchanan¹, Dr. Azeezat Azeez¹, Dr. Bora Kim¹, Dr. Kirsten Cherian¹, Dr. Nimrod Keynan¹, Dr. Maheen Adamson^2,3,4, Dr. Nolan Williams¹

¹Dept. of Psychiatry and Behavioral Sciences, Stanford University, Stanford, United States, ²Dept. of Rehabilitation, VA Palo Alto Health Care System, Palo Alto, United States, ³WRIISC-WOMENCOE, VAPAHCS, Palo Alto, United States, ⁴Dept. of Neurosurgery, Stanford University, Stanford, United States

Introduction: Traumatic brain injury (TBI) is common among US Veterans, leading to a range of neuropsychiatric symptoms, including accelerated brain aging. Ibogaine, a naturally occurring psychoactive alkaloid, has demonstrated neuroplasticity-promoting properties. It may help improve function in Veterans with TBI.

Methods: We conducted an observational study with 30 Veterans with TBI and complex clinical problems who received supervised ibogaine treatment. At baseline, immediate post, and 1-month, we performed clinical assessments and structural MRIs, and derived cortical thickness (CT) measures. To evaluate longitudinal changes in CT and volume across ROIs, we employed linear mixed effects (LME) models. We used brainageR to predict brain age using T1s.

Results: A Χ2 test of regional LME models revealed a significant (pFDR<0.05) effect of study visit on CT in 13 ROIs. Posthoc t-tests demonstrated significant (pholm<0.05) increases in CT immediately following treatment in 11 ROIs. For subcortical volume, a Χ2 test of subcortical LME models revealed a significant (pFDR<0.05) effect of study visit on the Right Ventral Diencephalon at 1-month. A Χ2 test of LMEs revealed a significant change in brain age across timepoints [Χ2(2)=10.64, p=0.0049]. Post-hoc t-tests revealed a significant (pholm< 0.05) reduction of 1.60 years in predicted brain age relative to baseline at 1-month (t=3.18, p=0.0082, d=1.035).

Dr. Xiaojian Kang^1,2, Dr. Byung Yoon³, Dr. John Coetzee^2,4, Dr. Maheen Adamson^1,2,5

¹WRIISC-WomenCOE, VA Palo Alto Health Care System, Palo Alto, United States, ²Rehabilitation Service, VA Palo Alto Health Care System, Palo Alto, United States, ³Department of Radiology, Stanford University School of Medicine, Stanford, United States, ⁴Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, United States, ⁵Department of Neurosurgery, Stanford University School of Medicine, Stanford, United States

Background. TBI is a frequent cause of disability. Structural (SC) and functional (FC) connectivity were used to evaluate network properties in TBI. The aim of the study was to test for differences in SC and FC between TBI patients and controls.

Methods. 46 participants were divided into 3 groups: Control group (CG) n=13; n=16 TBI patients without chronic symptoms (TBIncs); n=17 TBIs with self-reported chronic symptoms (TBIcs). For each participant, one high-resolution T1W image and two DWI scans were acquired. One resting state functional MRI (rsfMRI) scan was also acquired. T1W anatomical images processed using FreeSurfer, which provides 34 cortical parcels from DK parcellations per hemisphere. DWIs processed using Mrtrix3. SC data collected for all connections between 68 parcels. RsfMRI data processed using CONN toolbox. FC were obtained for the same DK parcels. SC and FC compared between groups. Benjamini-Hochberg algorithm applied to perform false discovery rate (FDR) correction.

Results. Correlation between SC and FC is 11.5% and 11.9% stronger for TBIncs, and TBIcs compared to CG, respectively. SC reduction was observed in 4 parcels and 6 parcel clusters for TBIcs but only one cluster for TBIncs compared to CG. FC reduction was observed only in one cluster for TBIncs but in one parcel and two parcel clusters for TBIncs compared to CG, respectively.

Conclusions. Abnormal FC may be the result of damage to specific functional areas, or damage to the SC between functional areas. Combined assessment of SC and FC may provide a predictive model for clinical outcomes.

Holly J. Freeman², Alexander S. Atalay², Jian Li², Natalie Gilmore^2,8,9, Samuel B. Snider³, Holly Carrington¹, Enna Selmanovic¹⁰, Ariel Pruyser¹, Lisa Bura¹, Bram R. Diamond², Alan C. Seifert⁵, David Hunt⁴, Yelena G. Bodien^2,7, Jeanne Hoffman⁶, Christine L. Mac Donald⁴, Dr. Kristen Dams-O’Connor^1,11, Brian L. Edlow²

¹Department Of Rehabilitation And Human Performance, New York, United States, ²Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, United States, ³Department of Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, United States, ⁴Department of Neurological Surgery, University of Washington, Seattle, United States, ⁵Department of Diagnostic, Molecular and Interventional Radiology, Biomedical Engineering and Imaging Institute, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, United States, ⁶Department of Rehabilitation Medicine, Division of Rehabilitation Psychology, University of Washington School of Medicine, Seattle, United States, ⁷Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital and Harvard Medical School, Charlestown, United States, ⁸Tampa Veterans Research and Education Foundation, Tampa, United States, ⁹James A. Haley Veteran’s Hospital, Tampa, United States, ¹⁰Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, United States, ¹¹Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, United States

Traumatic brain injury (TBI) is a risk factor for neurodegeneration and cognitive decline, yet the underlying pathophysiologic mechanisms are incompletely understood. This gap in knowledge may be related to the lack of analytic methods to account for cortical lesions in prior studies of brain volumetrics. The objective of this study was to identify longitudinal changes in brain structure among individuals with chronic TBI who had cortical lesions on magnetic resonance imaging (MRI). We identified 25 individuals with chronic moderate-to-severe TBI enrolled in the Late Effects of TBI (LETBI) study who had cortical lesions detected by T1-weighted MRI at two time-points. We manually traced lesion voxels (1 mm3) using Voxel Edit, a tool available in the standard FreeSurfer pipeline. To determine if lesion volume change was statistically significant, we built a null distribution for the manual tracing error using inter-rater lesion tracings from 3 raters (2 physicians, 1 technician) in a lesion dataset with 20 subjects. We tested the difference between the lesion volume change in the longitudinal LETBI cohort and the null distribution from the inter-rater cohort using a Wilcoxon Rank Sum test. Initial MRI scans were performed at least 1-year post-injury and follow-up scans were performed 3.1 (IQR=1.7) years later. Lesion volume significantly increased between time points with a median volume change of 3.2 (IQR=5.9) mL (p<0.001). Inter-scan duration was not associated with the magnitude of lesion growth. Integration of lesion-tracing into MRI processing workflows is feasible and creates opportunities to investigate mechanisms of post-traumatic neurodegeneration in chronic TBI.

Dr. Raj Kumar¹, Ms Enna Selmanovic^1,2, Dr Natalie Gilmore^3,4, Dr. Lisa Spielman¹, Dr. Lucia Li⁵, Dr. Jeanne Hoffman⁶, Dr. Yelena Bodien⁷, Dr. Samuel Snider⁸, Ms. Holly Freeman^3,4, Dr. Nicola De Souza¹, Dr. Christine Mac Donald⁹, Dr. Brian Edlow^3,4, Dr. Kristen Dams-O’Connor¹⁰

¹Department of Rehabilitation and Human Performance, Icahn School Of Medicine At Mount Sinai, New York, United States, ²Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, United States, ³Center for Neurotechnology and Neurorecovery, Department of Neurology, Boston, United States, ⁴Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Charlestown, United States, ⁵Department of Brain Sciences, Imperial College London, London, United Kingdom, ⁶Department of Rehabilitation Medicine, University of Washington School of Medicine, Seattle, United States, ⁷Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital and Harvard Medical School, Charlestown, United States, ⁸Department of Neurology, Brigham and Women’s Hospital and Harvard Medical School, Boston, United States, ⁹Department of Neurological Surgery, University of Washington, Seattle, United States, ¹⁰Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, United States

Accumulating evidence for heterogeneous long-term outcomes after traumatic brain injury (TBI) has challenged traditional paradigms of TBI outcome classification. The present study leveraged multimodal data from 281 participants in the Late Effects of TBI (LETBI) Study who were at least 1-year post-injury. For our primary objective, we used principal components analysis to reduce the dimensionality of 41 multidimensional TBI clinical outcomes, and then used hierarchical cluster analysis on principal components to identify distinct phenotypes with shared clinical traits. For our secondary objective in a subset of 168 participants, we evaluated total cortical volume within 7 networks of the Yeo 7 atlas by phenotype. We observed four phenotypes which qualitatively represented: 1) mixed trait deficits (11.8% in the training dataset; 15.1% in the validation set); 2) predominant cognitive deficits (20.5%; 23.3%); 3) predominant mood and behavioral (27.7%; 22.1%); and 4) few deficits (40%; 39.5%). Those with a predominant cognitive deficit phenotype had lower volumes in executive control, dorsal attention, default mode, and visual networks, relative to participants with few deficits (all p-values <0.007 after multiple comparisons adjustment). Participants with predominant mood/behavioral deficits had lower volumes in limbic, dorsal attention, and visual networks (all p<0.007), relative to participants with few deficits. There were no significant differences in network volumes between participants with a mixed trait phenotype versus those with few deficits. The present study adds to the literature by illustrating four distinct clinical phenotypes, and their neuroanatomical correlates in selected networks, in a well-characterized cohort of patients living with chronic TBI.

Dr. Kelly Standifer¹, Dr. Zachary Smith², Dr. Yong Zhang¹

¹College of Pharmacy, OU Health Sciences, Oklahoma City, United States, ²College of Medicine, OU Health Sciences

Mild TBI (mTBI) from repeated impacts in military combat and sports can result in long-term neurological consequences secondary to the injury. Mild TBI often goes undiagnosed, and there are no consistent standards for follow-up care. However, it is difficult to detect damage by CT and conventional MRI. The infarct-avid (PET) agent, 18F-FGA, accumulates in ischemic tissue. Enhanced PET imaging is a feasible screening tool to capture patients who would need close follow-up.

Male SD rats (N=12; Charles River Labs) placed on a foam bed in stereotaxic apparatus unfixed, received an intact head impact at days 0, 2 and 4 (each 48 h apart) using a Neuroimpactor. Sham rats received anesthesia. The PET scan was acquired 50-70 min after 18F-FGA iv injection, followed by a CT scan (Vector 6 machine, MI Labs, Utrecht, Netherland). Images were reconstructed using MI Labs software. 18F-FGA uptake was quantified for the region of injury. Results were analyzed by unpaired t-test and were considered significant if p < 0.05.

Rats subjected to repeated mTBI accumulated significantly more 18F-FGA as % injected dose (ID; p = 0.034) and % ID/g (p = 0.0071) compared to sham. This is consistent with modified neurological severity score that places the TBI in the mTBI range. Background labeling in sham rats was minimal.

18F-FGA has the potential to become an important screening tool that can enhance our ability to identify patients with mild head injuries, as such a tool does not currently exist. Congressionally Directed Medical Research Program Award No.: HT94252310340.

Dr. Xiao Liang¹, Dr. Li Jiang¹, Ms. Rosy Linda Njonkou Tchoquessi¹, Mr. Steven Roys¹, Dr. Muhammad Saleh^2,3, Dr. Prashant Raghavan¹, Dr. Rao Gullapalli¹, Dr. Neeraj Badjatia¹, Dr. Jiachen Zhuo¹

¹University of Maryland School of Medicine, Baltimore, United States, ²Children’s Hospital of Philadelphia, Philadelphia, United States, ³University of Pennsylvania, Philadelphia, United States

Excessive thalamic iron deposition is linked to elevated later-life neurodegenerative risks. The antioxidant glutathione (GSH) and pro-oxidant iron level play a crucial role in regulating oxidative stress following TBI. However, the trajectory of thalamic iron deposition in mild TBI (mTBI) remains elusive. We used Quantitative Susceptibility Mapping (QSM), a recent MRI method to estimate brain iron from magnetic susceptibility, and edited MR spectroscopy (MRS) to investigate thalamic iron and antioxidant levels up to one year post-mTBI. In 9 control, 16 acute (within 14 days), and 21 chronic (6-12 months) patients, we measured susceptibility and R2* values from 13 thalamic nuclei based on the Morel Atlas. Additionally, GSH levels from the bilateral thalamus were assessed. Acutely post-injury, mTBI patients exhibited a significant increase in R2* value within the ventral anterior (VA) nucleus (p=0.04), suggesting heightened iron level potentially contributing to early oxidative stress. Chronically, we observed a positive correlation of thalamic GSH level with the susceptibility in ventral posterolateral (VPL) (p=0.01, r=0.53) and anterior pulvinar (PUA) (p=0.02, r=0.50) nuclei. Our findings highlight altered thalamic iron-GSH dynamics in mTBI. These findings imply that thalamic iron dynamics may trigger adaptive antioxidant responses, potentially mitigating oxidative damage over time. The identification of specific thalamic nuclei involved (VA, VPL, and PUA) may indicate region-specific vulnerability and adaptation. Our ongoing study will expand the sample size to confirm our findings. The study is supported by NIH 5R01NS105503.

Dr. Linda Robayo Riofrio¹, Julian Dallmeier², Dr. Teddy Salan³, Dr. Varan Govind³, Dr. Eva Widerstrom-Noga^1,4

¹The Miami Project to Cure Paralysis, University of Miami, Miami, United States, ²Brain Endowment Bank, Department of Neurology, University of Miami, Miami, United States, ³Department of Radiology, University of Miami, Miami, United States, ⁴Department of Neurological Surgery, University of Miami, Miami, United States

Traumatic brain injury (TBI) can disrupt the structural integrity of brain parenchyma and cause macro- and microstructural alterations. These changes may significantly impact pain perception and modulation, ultimately contributing to the development of chronic pain. In this study, we aimed to evaluate the microstructural integrity of pain-related white matter tracts in individuals with TBI, both with (n = 17) and without (n = 18) chronic pain, compared to healthy controls (n = 30). We utilized diffusion tensor imaging (DTI), a powerful MRI technique that provides insights into the diffusion properties of water molecules within brain tissue. Data were acquired using a 3T MRI scanner with 1000 and 2000 s/mm² b-values. Fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) metrics were obtained from specific pain-related tracts (corticothalamic, cingulum, medial lemniscus, and spinothalamic) using the Human Connectome Project (HCP842) atlas available in DSI studio. Our findings indicated significantly (p < 0.05) lower FA and higher MD, AD, and RD in the corticothalamic and cingulum tracts in individuals with TBI without chronic pain; and lower FA and higher MD and RD in the cingulum tract, as well as higher MD at the corticothalamic tract in individuals with TBI and chronic pain compared to healthy controls. These results suggest underlying microstructural alterations in pain-related brain regions in people with TBI, with and without chronic pain, associated with demyelination and axonal damage or loss. Interestingly, there were no statistically significant correlations between DTI metrics and clinical pain variables.

Mr. Jackson S. Hamersly¹, Dr. Ho-Ching Yang², Dr. Yomna Takieldeen², Mrs. Kirsten Adams², Dr. Steven P. Broglio³, Dr. Michael A. McCrea⁴, Dr. Thomas W. McAllister⁵, Dr. Yu-Chien Wu^2,6

¹Indiana University School of Medicine, Indianapolis, United States, ²Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, United States, ³Michigan Concussion Center, University of Michigan, Ann Arbor, United States, ⁴Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, United States, ⁵Department of Psychiatry, Indiana University School of Medicine, Indianapolis, United States, ⁶Stark Neurosciences Research Initiative, Indiana University School of Medicine, Indianapolis, United States

Introduction: Sport-related concussion (SRC) is a serious public-health issue. Diffusion MRI (dMRI) allows researchers to postulate microstructure alterations in white matter tracts (WMTs). Nevertheless, limited studies look at relationships between advanced dMRI approaches, e.g., neurite orientation dispersion and density imaging (NODDI), and post-concussive pain symptoms. This study aimed to characterize these relationships in collegiate contact-sport athletes 24-hours post-SRC.

Methods: Sixty-nine concussed athletes underwent dMRI scans and the Sport Concussion Assessment Tool (SCAT), which evaluates self-reported neck pain and headache. The NODDI metrics, including intracellular volume fraction (ICVF), isotropic volume fraction (ISOVF), and orientation dispersion index were averaged from the SRC-related WMTs, including the anterior thalamic radiation (ATR), para-hippocampal part of cingulum (CGH), cingulate gyrus part of cingulum (CGC), corticospinal tract (CST), and forceps minor (FMI). Partial correlations between the diffusion metrics and pain severity were examined after adjusting for age and sex, as well as multiple comparisons by controlling the false discovery rate (FDR).

Results: The severity of neck pain was significantly associated with ICVF in the bilateral CST, left CGC, and right CGH (rs≥0.50, ps<0.05) and with ISOVF in the bilateral CGC, CGH, and right ATR and CST (rs≥0.48, ps<0.05). Higher ICVF and ISOVF were associated with higher pain severity.

Conclusion: The results suggest that neck pain could be an indicator for changes in WMT microstructural organization, particularly in parts of the limbic system controlling both pain and behavior regulation and the CST controlling voluntary movement.

Disclosure: This research was supported by DOD (W81XWH1420151/W81XWH1820047) and NIH R01 NS112303.

Maxwell Wang^1,2, Shawn Eagle², Regan Shanahan², Anna Slingerland², Shovan Bhatia², Michael Kann², Tyler Augi², Ava Puccio², David Okonkwo²

¹Carnegie Mellon University, Dept. of Machine Learning, Pittsburgh, United States, ²University of Pittsburgh, Dept. of Neurological Surgery, Pittsburgh, United States

Introduction: While severe traumatic brain injury (TBI) can result in disruption to various metabolic and physiological control loops, current studies on severe TBI in humans typically focus on either the hyper-acute injury phase (changes within the first 24 hours) or in their chronic response (changes over months to years post-injury). Here we investigate the sub-acute time period connecting the two: the days to weeks post-injury when many TBI survivors make meaningful gains in recovery.

Methods: Using blood samples and vitals collected every several hours during the first two weeks post-admission of 240 severe TBI patients, we trained random forest models to detect dynamic trends in several physiological markers (such as heart rate, carbon dioxide levels, sodium, platelet count, and more) that predicted long-term outcomes (GOSE at six-month post-injury). We connect these fluctuations to endocrinological markers to suggest potential drivers of these changes.

Results/Discussion: Several markers destabilized and recovered in the days to weeks post-injury according to consistent trends across participants. Of these, glucose and sodium levels during the first few days post-injury negatively correlated to six-month outcomes (Spearman’s R: -0.2 to -0.4). Rises in platelet levels from three to nine days post-injury positively correlated (Spearman’s R 0.17 to 0.3). Fluctuations in glucose and platelet levels correlated to cortisol levels, suggesting a stress response (Spearman’s R: 0.25 to 0.32 for glucose, -0.27 to -0.4 to platelets). Fluctuations in sodium levels were primarily driven by choice and rate of administered IV-fluids (z-statistic 2.2).

Dr. Ana Mikolic^1,2, Shuyuan Shi¹, William Panenka^3,4, Jeffrey Brubacher⁵, Frank Scheuermeyer⁵, Lindsay Nelson⁶, Noah Silverberg^1,2

¹University Of British Columbia, Vancouver, Canada, ²Rehabilitation Research Program, Centre for Aging SMART, Vancouver Coastal Health, Vancouver, Canada, ³Department of Psychiatry, University of British Columbia, Vancouver, Canada, ⁴British Columbia Provincial Neuropsychiatry Program, Vancouver, Canada, ⁵Department of Emergency Medicine, University of British Columbia, Vancouver, Canada, ⁶Department of Neurosurgery and Center for Neurotrauma Research, Medical College of Wisconsin, Milwaukee, USA

Our recent improved understanding of traumatic brain injury (TBI) comes largely from cohort studies of TBI patients with indication for computed tomography (CT). Using CT head as an inclusion criterion may overestimate poor outcomes after TBI with GCS=13-15. We aimed to compare outcomes after TBI in adults who had a head CT scan performed (with negative findings) versus those who had no CT when presenting to emergency department.

This was a secondary analysis of a trial that recruited adults with GCS=13-15 after TBI in Vancouver, Canada. We included 498 participants, after removing n=15 with acute intracranial CT findings. Outcomes were 6-month Glasgow Outcome Scale Extended (GOSE), Rivermead Postconcussion Symptoms Questionnaire (RPQ), Patient Health Questionnaire (PHQ)-9 and Generalized Anxiety Disorder (GAD)-7.

Half (55%) of participants received a CT. At 6 months, 54% of participants with CT and 49% without CT had functional limitations on GOSE; 33% with CT and without CT reported severe postconcussion symptoms (RPQ≥16); 22% (CT) and 20% (without CT) screened positive for depression (PHQ-9≥10), and 29% (CT) and 35% (without CT) screened positive for anxiety (GAD-7≥7). In regression adjusted for personal variables, participants with CT had somewhat higher odds of worse GOSE (1.4, 95% CI 1.0-2.1) but similar odds of severe symptoms (1.1, 95% CI 0.7-1.7), depression (1.1, 95% CI 0.7-1.7) and anxiety (0.9, 95% CI 0.6-1.3).

Adults with and without head CT have mostly comparable outcomes from TBI with GCS=13-15. Requiring CT by clinical indication for study entry may not create problematic selection bias for outcome research.

Dr. Ho-Ching Yang¹, Dr. Mario Dzemidzic^1,2, Dr. Steven P. Broglio³, Dr. Michael A. McCrea⁴, Dr. Thomas W. McAllister⁵, Dr. Jaroslaw Harezlak⁶, Dr. Yu-Chien Wu^1,7

¹Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, United States, ²Department of Neurology, Indiana University School of Medicine, Indianapolis, United States, ³Michigan Concussion Center, University of Michigan, Ann Arbor, United States, ⁴Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, United States, ⁵Department of Psychiatry, Indiana University School of Medicine, Indianapolis, United States, ⁶Department of Epidemiology and Biostatistics, School of Public Health, Indiana University, Bloomington, United States, ⁷Stark Neurosciences Research Initiative, Indiana University School of Medicine, Indianapolis, United States

Introduction: Sport-related concussion (SRC) has acute and long-term effects on the brain. Diffusion MRI could non-invasively identify these changes. Nevertheless, groupwise analyses lack sensitivity to cross-subject heterogeneity. Given the unique biomechanical forces involved in SRC, a subject-specific approach (SSA) is warranted. Here, we employed SSA on diffusion tensor imaging (DTI) to investigate longitudinal changes in white matter microstructure post-SRC.

Materials and Methods: Ninety-seven concussed and 111 matched non-contact-sport-control collegiate athletes received diffusion MRI at four timepoints (i.e., 24-48-hours post-SRC, asymptomatic, seven-days-post-unrestricted return-to-play, and six-months post-SRC). The preprocessed DTI metrics for the concussed participants were first Z-transformed using the normal distribution template created from the non-contact sport controls and then clustered. Later, they were clustered to form extreme Z-maps. To assess the longitudinal trajectories of the concussed brains, we averaged the Z-scores of the extreme voxels at the 24-48-hours timepoint and the Z-scores of the same voxels at the following timepoints for each DTI metric of each concussed athlete.

Results: The heterogeneity of SRC was evident from scattered white matter locations of the extreme Z-clusters in the concussed athletes. Additionally, certain concussed athletes showed more noticeable extreme Z-clusters in corpus callosum and internal capsule. Significant longitudinal alterations were observed in the distributions of averaged Z-scores across timepoints and across all DTI metrics.

Conclusion: SSA unveiled post-SRC brain heterogeneity with respect to anatomical locations and longitudinal trajectories. Specific white matter regions appeared more prone to the injury.

Disclosure: This research was supported by the DOD (W81XWH1420151/W81XWH1820047) and NIH R01 NS112303.

Dr. Mahta Karimpoor¹, Dr. Marios Georgiadis¹, Sohrab Sami¹, Brian Mills¹, Narvin Phouksouvath¹, Dr. Nick Cecchi¹, Jessica Towns¹, Dr. Maged Goubran², Nicole Mouchawar¹, Dr. Max Wintermark¹, Dr. Charles Liu³, Dr. Jack Van Horn⁴, Dr. Gerald Grant¹, Dr. David Camarillo¹, Dr. Michael Zeineh¹

¹Stanford University, Stanford, United States, ²University of Toronto, Toronto, Canada, ³University of Southern California, Los Angeles, United States, ⁴University of Virginia, Charlottesville, United States

Repetitive head impact exposure during contact sports may increase the risk of cognitive decline and neurodegenerative disease. We compared resting state functional connectivity (rsFC) networks and ImPACT cognitive tests between high-contact and low-contact collegiate athletes from two institutions, consisting of multiple sports and both sexes. A linear model for each institution was applied to assess rsFC differences between sports (high-contact vs. low-contact). Across both institutions, rsFC in the high-contact compared to low-contact was significantly increased (hyperconnectivity) between the default mode network (DMN) and the dorsal attention network. Low-contact athletes performed significantly better in visual-motor-speed task, and this improvement in performance was correlated to decreased connectivity between the dorsal attention and visual network compared to high-contact athletes. High-contact athletes performed worse under reaction-time testing and showed increased connectivity between the DMN and fronto-parietal network and decreased connectivity between the dorsal attention and fronto-parietal networks as well as between cingulate-operculum and hand sensorimotor/ventral attention networks. High-contact athletes with prior history of concussion exhibited decreased rsFC within sensorimotor/auditory networks and increased rsFC in the frontoparietal-visual network, both patterns overlapping with the same directionality with global functional connectivity differences between high- vs. low-contact sports. Finally, greater head impact/concussion incidence risk with player’s position in football was associated with increased rsFC within sensorimotor networks. These findings suggest that participation in high-contact sports can influence the rsFC with altered DMN, dorsal attention, frontoparietal, and sensorimotor network connectivity.

Dr. John Yue¹, Dr. Esther Yuh², Dr. Mahmoud Elguindy¹, Ms. Xiaoying Sun³, Dr. Thomas van Essen⁴, Dr. Hansen Deng⁵, Dr. Patrick Belton¹⁴, Ms. Gabriela Satris¹, Mr. Justin Wong¹, Dr. Alex Valadka⁶, Dr. Frederick Korley⁷, Dr. Murray Stein¹⁰, Dr. Ramon Diaz-Arrastia¹¹, Dr. Claudia Robertson⁸, Dr. Michael McCrea⁹, Dr. Kevin Wang¹², Dr. Nancy Temkin¹³, Dr. Anthony DiGiorgio¹, Dr. Phiroz Tarapore¹, Dr. Michael Huang¹, Dr. Amy Markowitz¹, Dr. Ava Puccio⁵, Dr. Pratik Mukherjee², Dr. David Okonkwo⁵, Dr. Sonia Jain³, Dr. Geoffrey Manley¹

¹Department of Neurological Surgery, University Of California, San Francisco, San Francisco, United States, ²Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, United States, ³Biostatistics Research Center, Herbert Wertheim School of Public Health and Human Longevity Science, University of California, San Diego, San Diego, United States, ⁴Department of Neurological Surgery, Leiden University Medical Center, Leiden, The Netherlands, ⁵Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, United States, ⁶Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, United States, ⁷Department of Emergency Medicine, University of Michigan, Ann Arbor, United States, ⁸Department of Neurological Surgery, Baylor College of Medicine, Houston, United States, ⁹Department of Neurological Surgery, Medical College of Wisconsin, Milwaukee, United States, ¹⁰Department of Psychiatry, University of California, San Diego, San Diego, United States, ¹¹Department of Neurology, University of Pennsylvania, Philadelphia, United States, ¹²Department of Neurobiology, Morehouse School of Medicine, Atlanta, United States, ¹³Departments of Neurological Surgery and Biostatistics, University of Washington, Seattle, United States, ¹⁴Department of Neurological Surgery, University of Wisconsin-Madison, Madison, United States

Objectives: Isolated traumatic subarachnoid hemorrhage (tSAH) after traumatic brain injury (TBI) on head computed tomography (CT) is often regarded as “mild”, with reduced need for workup. However, tSAH is a predictor of poorer outcomes. This study evaluated CT-occult intracranial injuries on magnetic resonance imaging (MRI) in a prospectively-enrolled 18-center United States TBI cohort with isolated tSAH on head CT.

Methods: The TRACK-TBI Study (2014-2018) enrolled patients who received a clinically-indicated head CT within 24-hours of TBI. A subset underwent blood draw within 24-h for glial fibrillary acidic protein (GFAP) level, and 2-week MRI. TRACK-TBI subjects aged≥17-years, with emergency department (ED) presenting Glasgow Coma Scale (GCS)=13-15, isolated tSAH on CT, plasma GFAP level, and 2-week MRI were analyzed.

Results: In 57 subjects, median age=46-years [IQR=34-57] and 53% were male. At ED discharge, 12% went home, 62% were admitted to hospital ward, and 26% to intensive care unit (ICU). MRI identified CT-occult traumatic intracranial lesions in 46% (1 additional lesion type=32%; 2 types=14%), and of 26 subjects with CT-occult lesions, 65% had axonal injury, 42% subdural hematoma, and 23.1% intracerebral contusion. GFAP was associated with CT-occult MRI lesions (median=631pg/ml, IQR=[172-941] vs. 226 [106-436], p=0.049), and axonal injury (no: median=227pg/ml [110-435], yes: 828 [204-1194], p=0.009).

Conclusions: Isolated tSAH on CT is often not the sole intracranial injury in GCS 13-15 TBI. Forty-six percent of our cohort had CT-occult traumatic lesions on MRI. Plasma GFAP may be an important biomarker for identifying CT-occult injuries, including axonal injury. These findings await validation in larger studies.

Ms. Alexandra Stan¹, Aleks Penev¹, Rhonda Mittenzwei¹, Kathryn Scherpelz¹, Caitlin Latimer¹, Dirk Keene¹, Amber Nolan¹

¹University Of Washington, Seattle, United States

Chronic traumatic encephalopathy (CTE) pathology is currently defined as accumulation of perivascular phosphorylated tau in neurons with or without astrocytes at the sulcal depth. However, how the distribution of tau in cell types within CTE ranges across an individual or cohort has not been systematically investigated. In addition, while there has been much emphasis on examining selective neuronal vulnerability to tau pathology in other neurodegenerative diseases, such as Alzheimer’s disease, there has been little analysis of CTE. Therefore, we analyzed 28 cases of CTE obtained from community brain donors to assess how many perivascular sulcal pathognomonic lesions contain both astrocytic and neuronal tau versus neuronal tau alone and have started to explore which neuronal types, focusing on inhibitory neurons show vulnerability to tau pathology. One to 16 CTE sulcal lesions were observed per case and when we examined the incidence of astrocytic tau in canonical CTE lesions, only 44% of lesions exhibited both astrocytic plus neuronal tau, while the majority of lesions (56%) exhibited neuronal only. At the donor level, 16 donors (57.1%) had co-occurrence of tau in both neurons and astrocytes (N+A), while 12 had only neuronal tau (42.9%). Interestingly, the presence of N+A versus neuronal only was independent of age, vascular disease, Thal, C-score or LATE stage. Preliminary analysis of tau and inhibitory neuronal markers suggests that parvalbumin-, but not somatostatin-expressing neurons can exhibit tau aggregation. These findings further our understanding of the cell types involved in CTE that may contribute to therapeutic development in the future.

Ms. Jennifer Merk¹, Dr. Meagan Chambers, Maiya Pacleb, Dr. Caitlin Latimer, Dr. Dirk Keene, Dr. Amber Nolan

¹University of Washington, Seattle, United States

Traumatic brain injury is a risk factor for neurodegenerative disease through unknown mechanisms. Furthermore, how localized brain injury alters pathologic peptide aggregation has not been systematically evaluated. Towards this end, we evaluated if hyperphosphorylated tau (p-tau) and beta-amyloid deposition are modified in brain parenchyma adjacent to chronic contusion. Cases with a diagnosis of chronic contusion from the University of Washington Neuropathology Core were stained with beta-amyloid and phosphorylated tau (p-tau) immunohistochemistry adjacent to contusion and in a section from the same contralateral lobe without contusion (internal control). Semi-quantitative evaluation of neuritic plaques for beta-amyloid and neurofibrillary tangles for p-tau were evaluated along with quantitative analysis of the percent area of staining using HALO imaging software. In our preliminary analyses, neurofibrillary tangles were significantly higher in sections with contusion compared to the internal control (p=0.0188, paired t-test), and neuritic plaques showed a similar trend with higher counts in 8 of 9 cases (p= 0.0723, paired t-test). Overall increased deposition for both proteins occurred in the contusion compared to the control section (p=0.0391 for p-tau, p=0.0391 for beta-amyloid, Wilcoxon-signed rank tests). These results support an interaction of brain injury with protein aggregation that may contribute in driving neurodegeneration.

Dr. Ashley Russell^1,2, Lara Nasser^1,2, Julie Scott^1,2, Vincent Vagni^2,3, Devin Henry⁴, Dr. Penelope Morel⁴, Dr. Milan Rusnak⁵, Dr. John Wu⁵, Dr. Patrick Kochanek^2,3, Dr. Amy Wagner^1,2,6

¹Department of Physical Medicine & Rehabilitation, University Of Pittsburgh, Pittsburgh, United States, ²Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, United States, ³Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, United States, ⁴Department of Immunology, University of Pittsburgh, Pittsburgh, United States, ⁵Department of Gynecologic Surgery and Obstetrics, Uniformed Services University of the Health Sciences, Bethesda, United States, ⁶Department of Neuroscience, University of Pittsburgh, Pittsburgh, United States

The biological burden of repeated, chronic life stress and TBI dysregulates neuroendocrine and immune allostasis. The cumulative effect of life events and TBI is not well understood. We determined the impact of chronic variable stress (CVS) preceding TBI on behavioral, immune and neuroendocrine responses. Male and female mice were exposed to 2-weeks of twice daily stressors (9 distinct physical/psychological stressors). After 2-weeks of CVS, mice received sham or CCI (6.0±0.2m/sec, 2mm depth, 50-60ms duration). Behavioral assessments interrogated a PTSD-like profile including activity, anxiety, sociability, anhedonia, and fear learning/extinction. Tissue was analyzed 21-days-post-CCI. The CVS phenotype reflected high vigilance and compulsive-like behaviors, including more grooming bouts and risk-taking behaviors. In males, CCI induced bodyweight loss, increased activity, anxiety, reduced inhibition and impaired fear learning. When CVS preceded CCI, bodyweight gain and fear learning were further impaired. CVS increased adrenal weight, but not after CCI alone or CVS+CCI, suggesting possible TBI-associated adrenal failure due to elevated pre-injury allostatic burden. CVS decreased spleen cell viability and increased IL-6 receptor expression in dendritic cells, with CCI further exacerbating this effect. Females have similar behavior profiles in that CVS increased compulsive-like behaviors and CCI increased bodyweight loss, activity and anxiety. Taken together, CVS and CCI have distinct neurobehavioral, endocrine or immune features. CCI impaired the normal HPA-immune CVS response. Parallel studies are ongoing to compare findings by sex and TBI model (blast vs CCI). Future studies will explore neurological and neuroendocrine-immune allostasis after CVS and CCI, and test therapies to mitigate TBI and PTSD-related outcomes.

Dr Milan Rusnak¹, Dr Ashley Russell^2,3, Julie Scott^2,3, Devin Henry⁴, Dr Penelope Morel⁴, Dr Patrick Kochanek^3,5, Dr Amy Wagner^2,3, Dr. Milan Rusnak¹

¹Department of Gynecologic Surgery and Obstetrics, Uniformed Services University, Bethesda, United States, ²Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, United States, ³Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, United States, ⁴Department of Immunology, University of Pittsburgh, Pittsburgh, United States, ⁵Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, United States

Introduction: The biological burden of repeated, chronic life stress and traumatic brain injury (TBI) dysregulates neurological, endocrine, and immune allostasis, yet the underlying mechanisms and behavioral phenotypes are not well understood. Here, we determined the impact of chronic variable stress (CVS) preceding TBI on behavioral, immune, and endocrine responses utilizing the advanced blast system to simulate the blast (b) TBI.

Methods: Adult male mice were randomized to 2-weeks of twice daily stressors (9 distinct physical/psychological stressors) versus usual care. Afterward, mice received either mild bTBI (18-20 psi) or sham procedures. bTBI mice displayed a longer righting behavior versus shams. Behavioral assessments were designed to interrogate a PTSD-like profile including activity, anxiety, sociability, anhedonia, and fear learning/extinction. On D21 post-TBI, brain, adrenals and serum were collected.

Results: The CVS phenotype reflected high vigilance and compulsive-like behaviors, including more grooming bouts and risk-taking behaviors. When CVS preceded bTBI, body weight gain and fear learning were impaired. A persistent adrenal weight increase and thymus weight decrease occurred among CVS, but not bTBI, exposed mice. bTBI mice had greater fear responses (increased freezing; p<0.05) than shams regardless of CVS exposure. When CVS preceded bTBI, mice groomed more than non-stressed bTBI mice (p<0.05). Finally, we observed increased c-FOS neuronal activity among mice exposed to both CVS and bTBI.

Discussion: Together, the results show that bTBI may differentially alter responses to CVS and exacerbate select behavioral phenotypes. Future work will explore underlying neural circuitry, endocrine, and immune responses after CVS+/-TBI to understand their impact on allostasis.

Dr. Shaun Carlson¹, Jeremy Henchir¹, Youming Li¹, C. Edward Dixon¹

¹Department of Neurological Surgery, University Of Pittsburgh, Pittsburgh, United States

Traumatic brain injury (TBI) can result in cognitive, emotional, and somatic impairments, which are named as major contributors to reduced quality of life for TBI survivors. Impaired neurotransmission is implicated in contributing to dysfunction post-TBI. Monomeric alpha synuclein plays a critical physiological role in the regulation of synaptic neurotransmitter release. Our team previously demonstrated controlled cortical impact (CCI) results in reduced hippocampal and cortical monomeric alpha synuclein in the weeks post-injury. To further investigate the effect of alpha synuclein after TBI, we implemented a targeted genetic knockout of alpha synuclein (C57BL/129J-Snca[tm1Ros1]/J). Male alpha synuclein KO and wild-type (WT) littermate controls received either 1.8mm CCI or sham control surgery (Sham-WT, n=10; CCI-WT, n=10; CCI-KO, n=10). Beam balance and Morris water maze (MWM) assessments were completed on days 1-5 and 9-14, respectively. Assessment using the beam balance revealed CCI-KO mice exhibited a significant reduction in the latency to balance of the beam, as compared to Sham-WT mice (p<0.05, repeated measures one-way ANOVA). Testing of spatial acquisition and memory in the MWM task revealed significantly impaired performance of CCI-WT mice, as compared to Sham-WT mice (p<0.05; repeated one-way ANOVA and one-way ANOVA, respectively), but CCI-KO mice exhibited no difference from Sham-WT mice. Other reports utilizing the alpha synuclein KO mice suggest that compensatory mechanisms may play a role in attenuating potential alterations. Ongoing work is testing the effect of alpha synuclein KO on compensatory synaptic mechanisms and additional pathophysiological responses post-TBI.

Support: NIH NS091062 (CED), NS124730 (SWC), and Walter L. Copeland Fund (SWC).

Ms. Elnaz Pourasgari², Ms. Molly Smith, Ms. Mayumi Prins²

¹UCLA, David Geffen School of Medicine, Los Angeles, United States, ²UCLA Birc, Los Angeles, United States

Early life stress (ELS) heightens adolescents’ susceptibility to anxiety and risky behaviors, increasing the likelihood for a mild traumatic brain injury (mTBI) later in life. Adolescence is a critical time period for brain development, hypothalamic-pituitary-adrenal (HPA) axis changes, shaped by early-life stress history. However, the effects of ELS remain insufficiently studied in female adolescents post-mTBI on risk-taking behaviors. The study examined the impact of ELS and mTBI on anxiety and risk-taking behaviors in female adolescent rats. Adolescent female Sprague Dawley rats received four randomized stressors: confinement, cage tilt, water, and oscillation over 16 days. Plasma samples were collected 2, 10d post-stress, and 1, 5 days post injury for stress hormones and inflammatory cytokines (IL-1β and TNF-α). Both ACTH (50.63 to 2.93 pg/mL; p<0.02) and corticosterone (35983.32 to 5363 pg/mL; p<0.03) were significantly decreased, demonstrating an adaptive stress response. Using this randomized 16d stress model with CCI or sham injury open field and elevated plus maze tasks were conducted at 1 and 5 days post injury to test a secondary stress response. Female rats show increased risk-taking behaviors at PID1 (Time in open arms: 79.16 (s), 23.24 (s); p<0.02) and PID5 (Time in open arms: 31.86 (s), 25.42 (s); p<0.03) compared to shams. Anxiety levels decreased between PID5 and shams (Time in center: 5.46 (s), 2.44 (s); p<0.04). The data validates a 16d model of chronic unpredictable stress during adolescence post-mTBI, indicating the crucial period of HPA-axis development on stress reactivity.

This work was supported by NIH NS110757, UCLA BIRC, BrainSPORT

Ms. Cydney Martin¹, Dr. Laura Giacometti¹, Dr. Jessica Barson¹, Dr. Ramesh Raghupathi¹

¹Drexel University College Of Medicine, Philadelphia, United States

Mild traumatic brain injury (mTBI) is common among adolescents because of their participation in contact sports. Following mTBI, depression-related behaviors are more common in girls than boys. Using adolescent-age rats, this study compared the effects of single and repetitive mTBI on depression-like behavior and stress-related neuropeptide expression in the acute and chronic phase. Adolescent male and female Long-Evans rats were subjected to single or repetitive closed-skull impacts (single-injured males n=12, repetitive n=16, single-injured females n=26, repetitive n=18) or were anesthetized without injury (single-sham males n=11, repetitive n=15, single-sham females n=25, repetitive n=16). At 5-weeks, but not 2-weeks following injury, injured females but not males displayed increased immobility in the forced swim test compared to sham females (p<0.05), with this finding being estrous cycle-dependent following single-injury. In the paraventricular thalamic nucleus (PVT) mRNA expression of pituitary adenylate cyclase-activating polypeptide (PACAP), as assessed by quantitative real-time PCR, was increased in repetitive-injured females but not males at 2- (215%) and 5-weeks (162%, p<0.05) and reduced in single-injured females (-40%, p>0.05) compared to shams. In the nucleus accumbens (NAc), mRNA expression of corticotropin-releasing factor (CRF) was decreased only in single-injured females (-29%, p<0.05), particularly during estrus phase (-54%) compared to shams. These data suggest that depression-like behavior may emerge in the chronic phase following adolescent mTBI in females, being estrous cycle-dependent following single-injury. Moreover, PACAP in the PVT may contribute to depressive-like behavior in females following repetitive mTBI while CRF in the NAc may do so in an estrous cycle-dependent manner following single mTBI.

Dr. Javier Allende Labastida¹, Dr. Maria Paula Avalos¹, Dr. Preeti Vyas¹, Jinhuan Liu¹, Dr. Raymond C. Koehler¹, Dr. Sujatha Kannan¹

¹Anesthesiology and Critical Care Medicine, Baltimore, United States

Neuropsychiatric disorders are a significant cause of disability after traumatic brain injury (TBI). Prevalence of neuropsychiatric disorders post-TBI ranges from 34-50%; the most prevalent are major depressive disorder (13-77%), generalized anxiety, and post-traumatic stress disorder (3-28%), doubling in military personnel. The risk of suicide attempts increases in TBI with co-morbid post-traumatic depression (PTD). This pilot study uses the CHIMERA model to explore the generation of a PTD phenotype after repetitive closed-head injury.

Male Sprague Dawley rats, 10-11 weeks old, were randomly assigned to sham or repetitive TBI (rTBI) groups. The rTBI group received four impacts (∼10 m/sec) over two days (two on injury day one and two on day two, each day with one-hour inter-impact periods). Depressive-like symptoms were assessed behaviorally, including anhedonia (sucrose preference test), sociability and social novelty (social interaction test), and learned helplessness/despair (forced swim test). Rats from the rTBI group showed decreased sucrose preference from day three until day five of testing (19-22 days post-injury) and increased immobility in the forced swim test while displaying no motor deficits in the open field test.

These results suggest that rTBI induces a depressive-like phenotype characterized by anhedonia and learned helplessness or despair. Analysis of the social interaction test and histopathological exploration of anatomical behavior correlates, neuroinflammation and neurodegeneration in the medial prefrontal cortex, nucleus accumbens, and amygdala are ongoing.

Support: This work was partly supported by the Richard J Traystman professorship endowment (SK).

Ms. Jenna McCloskey¹, Ms. Mia Eleid¹, Dr. Cole Vonder Haar¹

¹The Ohio State University, Columbus, United States

Traumatic brain injury (TBI) results in cognitive-behavioral impairments such as risky decision-making, which correlate with a higher risk of developing addiction-related disorders such as problem gambling. TBI may generate novel neurological or behavioral mechanisms that contribute to this phenomenon. These complex behaviors require isolating the individual elements that may underlie heightened vulnerability. This study investigated how TBI affects sensitivity to probabilistic outcomes and whether it is linked to disordered decision-making in rats.

Male and female rats were given a severe bilateral, frontal CCI or sham procedure (N = 32). Rats were tested on a two-option probability discounting task (PDT) where they chose between a guaranteed small reinforcer or risky large reinforcer that degraded in probability throughout the session. Rats were then assessed on the more complex four-choice rodent gambling task (RGT), where they chose amongst options associated with varying probabilities and magnitudes of reinforcement or punishment.

TBI rats demonstrated lower preference for risky outcomes on the PDT, even when large reinforcement was guaranteed. The overall downshift of their discounting curve might suggest that TBI rats are risk-averse. However, TBI increased preference for risky options on the RGT which is more indicative of general suboptimal decision-making. Preliminary stains of ΔFosB, a transcription factor associated with learning and addiction, suggest dysregulation of the nucleus accumbens after TBI. These data highlight discrepant relationships with probabilistic decision-making after TBI. Continued research will evaluate the physiological basis of disordered decision-making and potentially identify novel mechanisms by which addiction may develop distinctly after TBI.

Ms. Mydirah Littlepage-saunders¹, DVM, PhD Milan Rusnak¹, PhD Mumeko Tsuda¹, PhD T. John Wu¹

¹Uniformed Services University, Bethesda, United States

Post-traumatic stress disorder (PTSD) has a lifetime prevalence of 1 in 13 people; about a quarter have delayed-onset PTSD where onset of symptoms occur at 6 months or later after experiencing a traumatic event. The development of PTSD is more prevalent in women than men. It is not fully understood why some are more vulnerable to developing PTSD. To enhance our understanding of the causal mechanisms, we designed a study with mice to compare the effect of sex on delayed fear incubation. We expected the female mice to show time-dependent increased fear response which would suggest more chronic delayed fear incubation than the male mice. To test this, adult male and female C57Bl/6J mice (7-8 weeks of age; n=16/group) underwent a delayed fear incubation behavioral assay. Animals were placed in a fear conditioning chamber for a 198 s acclimation period and then administered a single 2 s scrambled footshock of 1.5 mA via the metal grid floor. After an additional 60 s, animals were returned to their home cage. Animals were then placed back in the shock chamber for a total of 180 s without any additional footshocks for recall test (1 day, 14 days, and 28 days post shock). Data showed a significant effect of time on freezing (p<0.0001) and distance traveled (p<0.0001). There was no significant effect of sex or interaction between sex and time. Ongoing experiments will compare neuronal activation through cFos expression in different fear-associated brain regions.

Ms. Katherine J. Koontz¹, Ms. Lizza H. O’Connel¹, Mr. Alex B. Gentry¹, Ms. Jenna E. McCloskey¹, Dr. Travis R. Smith¹, Dr. Michael T. Bailey², Dr. Cole Vonder Haar¹, Dr. Kris M. Martens¹

¹The Ohio State University, Columbus, United States, ²Nationwide Children’s Hospital, Columbus, United States

Traumatic brain injury (TBI) leads to a wide spectrum of chronic deficits or disabilities, including increases in impulsivity and risky decision making. Changes in the intestinal microbiome following TBI have also been observed and correlate with decreased performance with various cognitive tasks. Given the connection between the digestive system and the brain through the gut-brain axis, it is possible that these microbial changes precipitated by TBI may influence cognitive performance and thus be a potential therapeutic target. Prebiotic manipulation of diet may preserve microbiome diversity after TBI, leading to improved cognitive outcomes. To test this, male and female rats were maintained on a diet containing 2% pure galactooligosaccharide (GOS) for six weeks while training on the Rodent Gambling Task (RGT), an assessment of risky decision making. Rats were then given a bilateral frontal CCI or sham procedure. Following recovery, rats were tested on a battery of tests including the elevated plus maze (EPM), forced swim test (FST), Morris water maze (MWM), and re-assessed on the RGT. Preliminary results show that GOS, compared to control, improves optimal choice on the RGT in rats with TBI. Clear diet effects were not observed on either the EPM, or MWM. Though the study is ongoing to fully power statistical analyses, initial inspection of the data indicate a beneficial effect of GOS diet on decision-making behavior, but no effects on other measures. Further work will evaluate specific bacterial species modified by GOS which may contribute to improved function.

Ms. Caiti-Erin Talty¹, Dr. Susan Murphy², Mr. Soham Desai³, Dr. Pamela VandeVord^2,4

¹Graduate Program in Translational Biology, Medicine & Health, Virginia Tech, Blacksburg, United States, ²Biomedical Engineering & Mechanics, Virginia Tech, Blacksburg, United States, ³Academy of Integrated Science, Virginia Tech, Blacksburg, United States, ⁴Veterans Affairs Medical Center, Salem, United States

Following a concussion, up to 50% of patients may suffer from chronic symptoms that significantly affect their quality of life. Prominent among these is depression, and this is especially prevalent in females according to clinical reports. Using a clinically-relevant closed-head impact model, we evaluated the emergence of depression-like behaviors up to three months post-injury in adult female rats. Injured animals exhibited elevated risk-taking behaviors in open field testing at one week (p=0.0047) and hypersocial behavior at one month (p=0.0596) which returned to sham levels over time. Interestingly, we observed an increase in grooming behaviors and decreased preference for social novelty at two months (p=0.0287). Frontal cortex and hippocampus were collected at three months and western blot was performed to evaluate changes in N-methyl-D-aspartate receptor (NMDAR) subunit and glutamate transporter expression as glutamatergic alterations represent a promising mechanistic link between concussion and depression. Expression of GluN1 (p=0.0049), GluN2A (p=0.0219) and GluN2B (p<0.0001) was upregulated in the injured frontal cortex, however the GluN2A:GluN2B ratio was decreased (p=0.0376), suggesting an increased total number of NMDARs and potential shift toward GluN2B signaling. GLAST was also elevated in the frontal cortex (p=0.0181) while GLT-1 increased in the hippocampus (p=0.0064). Together, these findings suggest females underwent dynamic changes in depression-related behavioral domains throughout the chronic post-injury period and core components of glutamatergic neurotransmission became chronically increased in a region-dependent manner. Future work should assess protein changes across multiple timepoints to better understand the timing of molecular changes as they relate to the development of behavioral deficits.

Mr. Zachary Zimomra¹, Mr. Sam Houle¹, Ms. Cindy Ren¹, Juan Peng¹, Dr. John Sheridan¹, Dr. Jonathan Godbout¹, Dr. Olga Kokiko-Cochran¹

¹The Ohio State University, Columbus, United States

Coordinated activation of the hypothalamus pituitary adrenal (HPA) axis results in production of corticosterone (CORT) in rodents. Traumatic brain injury (TBI) is associated with endocrine dysfunction, which can modulate the plasma CORT response to stress. We hypothesize that an impaired plasma CORT response to stress exaggerates post-injury inflammation through dysregulated glucocorticoid receptor (GR) signaling. To study this, C57BL/6 mice with jugular catheters were given a lateral fluid percussion TBI or sham injury. Mechanical sleep fragmentation (SF) served as a daily, transient stressor from ZT0-ZT4, 1-30 days post injury (DPI). Dexamethasone (DEX), a potent GR agonist, or vehicle was administered intraperitoneally 2 hours prior to SF 7, 14, 21, and 30 DPI. Blood was collected at 22ZT, 0ZT, 0.5ZT, and 1.5ZT at each time-point for plasma CORT analysis by enzyme immunoassay. qRT-PCR was performed on the hypothalamus, pituitary, and adrenal gland. Overall, TBI and SF significantly increased plasma CORT across the time-course compared to Sham and control mice. Administering DEX significantly lowered plasma CORT in both Sham and Sham SF mice; but DEX only significantly lowered plasma CORT in TBI control not TBI SF mice across days. qRT-PCR shows that coordinated communication within the HPA axis is uniquely compromised in TBI SF mice. These data confirm that post-injury SF increases plasma CORT with the DEX challenge revealing dysregulated GR signaling and HPA axis negative feedback following TBI. Therefore, environmental SF is sufficient to modulate stress signaling following TBI; and further investigation is needed to determine the neuroimmune consequences of this effect.

Dr. Tabitha Green^1,2, Mr Grant Mannino², Ms Nicole Couillard², Ms Dana Ritterbusch², Dr Sean Murphy³, Professor Mark Opp², Assistant Professor Rachel Rowe²

¹The University Of Glasgow, Glasgow, United Kingdom, ²The University of Colorado Boulder, Boulder, United States, ³Cumberland Biological and Ecological Researchers, Longmont, United States

Limited research exists on TBI-induced pubertal disruption and hypopituitarism. Male and female peripubertal rats (post-natal day 35) received diffuse TBI or sham surgery (n=56). We investigated growth, puberty, and function of the hypothalamic-gonadotropin-axis. We also investigated post-traumatic sleep because hypopituitarism results in sleep-wake disturbances that further complicate puberty. Brains were collected at 7 days post-injury (DPI) to histologically assess hypothalamic neuronal populations (GnRH, orexin, kisspeptin) and gliosis. We analyzed data using generalized linear mixed models; statistical and biological significance were determined based on p < 0.05 and standardized effect sizes (d) ≥0.5, respectively. Righting reflex times were similar between male and female rats subjected to TBI, males had longer apnea, however, females had a higher mortality probability. In both males and females, TBI caused biologically significant reductions in gonad weights and higher levels of circulating kisspeptin (plays a vital role in the onset of puberty) compared to respective shams. In females, TBI increased follicle-stimulating hormone, whereas in males, TBI impacted growth, with lower growth hormone and IGF-1 levels and lower terminal body weights compared to shams. Independent of TBI, significant sex differences existed in follicle-stimulating hormone, IGF-1, testosterone, and IL6. TBI increased sleep in both male and females at 1DPI but this increase was sustained to 5DPI in males only. A novel colocalization of kisspeptin and orexin neurons was identified in the hypothalamus and neuronal histology and analysis of gliosis is ongoing. Together, these results provide an improved understanding of hypopituitarism and pubertal disruptions following TBI.

Funding: R21NS120022.

Ms. Kyli Mcqueen^1,2, Ms. Karisa Louangprasert², Mr. Daniel Griffiths^1,2, Dr. Jonathan Lifshitz^1,2

¹University Of Arizona College Of Medicine - Phoenix, Phoenix, United States, ²Phoenix VA Health Care System, Phoenix, United States

Head injury can disrupt sleep; and repeated head injury may produce compounding effects. However, the cumulative effects of repeated closed head injury on sleep remains unclear. In our prior study, repeated closed head injury every other day indicated a possible conditioning effect on subsequent head injuries and sleep. In this follow-up study, we hypothesized that either once or twice daily closed head injury would disrupt sleep patterns, particularly during the mouse wake cycle, and effect sizes would be cumulative with subsequent injuries.

Male C57BL/6J mice (n=12) were randomly assigned to either once daily (ZT=3) or twice daily (ZT=3&6) weight drop head injury (Height: 94cm, Weight: 100g) allowing free head rotation daily for five consecutive days. Mice were anaesthetized and weight drop was administered upon normal respiration. Mice were immediately monitored for righting reflex recovery time and returned to non-invasive piezoelectric sensor sleep recording chambers. Sleep was recorded hourly from ZT=12 to ZT=2 and analyzed for sleep density, defined as sleep percentage per hour during the animal’s wake cycle.

No cumulative effects on righting reflex times or sleep were observed across the week for single or repeated injury. The righting reflex times for the second daily injury were longer than the first injury of the day. A decrease in sleep density was seen at three days post-injury (F(1,20)=52.816, p<0.001) compared to baseline. Sleep density was unaffected by injury number on day three (F(1,20)=0.375, p=0.547). Further studies will explore injury parameters and interactions between repeated head injuries.

Funding: Arizona Alzheimer’s Consortium, R21-NS131877.

Ms. Rebecca Boland¹, Samuel Houle¹, Shannon Dobres¹, Dr. John Sheridan¹, Dr. Jonathan Godbout¹, Dr. Olga Kokiko-Cochran¹

¹The Ohio State University, Columbus, United States

Recovery from traumatic brain injury (TBI) can be impeded by external stressors that elicit an immune response. We have shown that daily, mechanical sleep fragmentation (SF; ZT0-ZT4) after TBI increases neuroinflammation at 7 and 30 days post-injury. However, since the acute neuroimmune response mediates chronic recovery, we hypothesized that 3 days of SF would be sufficient to exacerbate neuroinflammation. Here, C57BL6/J mice received TBI or sham injury followed by 3 days of SF or control housing. As predicted, indices of sleep consolidation were impaired in TBI mice. Daily SF increased shorter bouts of sleep and total sleep in the active phase; however, TBI did not exaggerate this response. Flow cytometry revealed that brain infiltration of monocytes and neutrophils was increased after TBI. Contrary to expectations, post-TBI SF decreased many genes that were increased by SF and TBI alone. Genes with increased expression due to TBI that were suppressed by SF are involved in a variety of inflammatory mechanisms such as the regulation of microglial responses to injury (Tlr4, Aif1, Cd68, Csf1R, Cd84), interferon signaling (Stat1, Stat2, P3mbb, Tap1, Bax), and the complement cascade (C1q, C1r, Itgam, Cr3, C3ar1). Altogether, these data show that stress following TBI dampens the expression of genes and inhibits pathways that are typically activated as part of the TBI response. Taken together, these data emphasize the importance of acute post-injury care, as even a few days of stress exposure can substantially change the neuroimmune landscape after TBI.

Ms. Michaeala Breach¹, Mr. Ethan Goodman¹, Mr. Jonathan Packer¹, Dr. Marissa Smail¹, Ms. Alejandra Zaleta Lastra¹, Mr. Habib Akouri¹, Dr. Zoe Tapp¹, Dr. Cole Vonder Haar¹, Dr. Jonathan Godbout¹, Dr. Olga Kokiko-Cochran¹, Dr. Kathryn Lenz¹

¹The Ohio State University, Columbus, United States

Background: Adverse childhood experiences (ACEs), ranging from neglect to physical violence, increase psychiatric disorder risk. Pediatric traumatic brain injury (TBI) may be incurred during ACEs, and pediatric TBI also increases risk for neuropsychiatric dysfunction. We used a ‘two hit’ rat model to explore the mechanisms through which stress and pediatric TBI influence neurobehavioral development. Methods: Rats underwent 4 hr/day of maternal separation stress or handling from postnatal days (P)1-14, followed by lateral fluid percussion injury or isoflurane anesthesia on P15. At 7 days post injury (DPI), ipsilateral hippocampus was dissected. Pooled nuclei were barcoded, single nucleus RNA sequencing was conducted, and Ingenuity Pathway Analysis was performed on differentially expressed genes. Other rats underwent open field, spontaneous and spatial Y maze tests from 53-80 DPI. Results: Stress and Stress+TBI activated neuroplasticity and neuromodulator pathways. TBI activated plasticity-associated pathways in excitatory neurons only. In microglia, stress deactivated phagocytic and inflammatory pathways, an effect further enhanced by TBI. Upstream regulator analysis showed CSF3, GRIN3A, and MECP2 were shared regulators across perturbations, and DAG1 was implicated in neurons after Stress+TBI. Disease and function analyses showed unique signatures of perturbations in neurons, microglia, oligodendrocytes and oligodendrocyte precursor cells. Stress increased exploratory risk-taking behavior in the open field, but TBI had no effects. Conclusion: Early life stress profoundly impacts the juvenile hippocampal transcriptome, and pediatric TBI modulates these stress-induced effects. This work will inform future studies of adversity and injury-induced neurobehavioral dysfunction.

Funding: Ohio State Chronic Brain Injury Pilot Funds, CDMRP HT94252311003.

Dr. Ahmed Chenna¹, Dr. Christos Petropoulos¹, Dr. John Winslow¹

¹Monogram_LabCorp, S San Francisco, United States

Objective: Characterize levels of serum total-Tau (t-Tau), NF-L, GFAP, UCH-L1, and IL-6, IL-10, TNF-α within 16 hr following c/mTBI and compare to levels in healthy controls.

Background: Elevations of central nervous system (CNS) proteins (t-Tau, NF-L, GFAP, and UCH-L1) and inflammatory cytokines (IL-6, IL-10, TNF-α) in blood and cerebral spinal fluid (CSF) have been associated with c/mTBI. Recent studies suggest that markers of neuro-injury and inflammatory cytokines provide prognostic information regarding full recovery following c/mTBI.

Methods: Blood samples were collected from 30 subjects 1-4 hr and 8-16 hr post-c/mTBI injury, as well as 30 healthy controls. The SIMOA Neurology 4-plex A and Cytokine 3-plex A immunoassays (Quanterix) were used to measure t-Tau, NF-L, GFAP, UCH-L1 and IL-6, IL-10, TNF-α.

Summary: The mean levels of GFAP, NF-L, UCH-L1, and t-Tau in serum were significantly elevated 1-4 hr and 8-16 hr post-c/mTBI relative to healthy controls. Receiver Operating Characteristic (ROC) analysis of neuronal biomarkers indicated moderate discriminatory ability for c/mTBI vs controls (AUC = 0.7-0.76). IL-6, IL-10, and TNF-α were significantly elevated in the 1-4 hr and 8-16 hr post-c/mTBI serum relative to healthy controls (p <0.0001). ROC curve analysis indicated that each of the three inflammatory cytokines were discriminatory for c/mTBI vs healthy controls (AUC = 0.86-0.99).

Conclusions: The measurement of CNS proteins and inflammatory cytokines in serum as biomarkers of c/mTBI may enhance diagnostic and prognostic capabilities regarding the severity of, and recovery from, brain injury.

Mr. Daniel Griffiths^1,2, Mr. R. William Hack³, Ms. Kyli McQueen^1,2, Mr. Tyler Vail¹, Dr. Jonathan Lifshitz^1,2

¹University of Arizona College of Medicine-Phoenix, Phoenix, United States, ²Phoenix VA Health Care System, Phoenix, United States, ³Arizona State University, Tempe, United States

Microglia are the most dynamic cell in the brain, constantly surveying their microenvironment. In response to brain injury, microglia rapidly react to the primary injury and then mediate the secondary injury cascade, defined by changes in cellular morphology. Despite their dynamic morphology, research has been limited to analysis of static images. In this study, we developed a novel approach for timelapse imaging of fluorescent cortical microglia in freely behaving transgenic mice. We hypothesize that closed head injury drives dynamic changes in microglia morphology observed as changes in fluorescent intensity. Adult male CX3CR-1-GFP transgenic mice underwent surgery to secure miniscope hardware to the skull for time lapse imaging (20 images/hour). One week post-surgery, a miniscope was attached to acquire baseline images for three days. After baseline imaging, the miniscope was detached and replaced with a protective cap. Anesthetized mice received a weight drop head injury (Height: 94cm, Weight: 100g) that allowed free head rotation or a sham injury. After injury, the miniscope was reattached to image for three days. At the conclusion of imaging, brains were collected for histology. Qualitative results show increased background fluorescence representing changes in microglia morphology. Our study demonstrates that miniscope imaging, combined with closed head injury, has the potential to visualize and quantify dynamic microglia activity in the mouse brain in the acute post-injury period. Further studies are needed to investigate the relationship between injury parameters, long-term visualization of microglia activity, and behavioral function.

Funding: R21 NS131877, The Fraternal Order of Eagles, Arizona Alzheimer’s Consortium.

Marta Celorrio-Navarro¹, Stuart H. Friess¹

¹Washington University in St Louis, St Louis, United States

Hypoxemia after traumatic brain injury (TBI) is common within the first 24 hours after injury and is associated with morbidity and mortality. Neuroinflammation after TBI is a complex interaction between the peripheral and central immune cells which changes over time. We believe that a deeper mechanistic understanding of how hypoxemia after TBI exacerbates neuroinflammation and how its impact is modulated by age and sex is a knowledge gap in the field. In our previous work, by utilizing our clinically relevant murine model of TBI (cortical controlled cortical impact) and delayed hypoxemia, we characterized that hypoxemia exacerbates long-term neuropathology after TBI. In our new preliminary data, we randomized injured mice into three groups: normoxemia, and hypoxemia (8% O2) for one hour at 15 min or 6 hours after CCI and characterized the inflammatory response one week after injury with brain spectral flow cytometry. We found that mice subjected to hypoxemia 6 hours after injury had increased microglial number and activation and neutrophils (Ly6G) infiltration compared with hypoxemia 15 min after injury. Mice with hypoxemia 6 hours after injury had increased recruitment of T cells (CD3+CD4+), T regulatory cells (CD3+CD4+CD25), and delta-gamma T cells to the injured brain. Furthermore, we found a marked increase in CD3+ T cells in the brains of injured aged mice (1-year-old) with hypoxemia (6 hours after TBI) compared with young mice (2-months-old). Overall, our data demonstrates that the timing of hypoxemia after TBI and age at the time of injury influence the acute neuroinflammatory response.

Dr. Rex Jeya Rajkumar Samdavid Thanapaul^1,2, Dr Manoj Y Govindarajulu^1,3, Mr Gaurav Phuyal^1,3, Dr Joseph B. Long¹, Dr Peethambaran Arun¹

¹Blast-Induced Neurotrauma Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, United States, ²NRC Research Associateship Programs, National Academies of Sciences, Engineering, and Medicine, Washington, United States, ³Oak Ridge Institute for Science and Education, Oak Ridge, United States

Exposure to blast overpressure waves is implicated as the major cause of ocular injuries and resultant visual dysfunction in veterans involved in recent combat operations. No effective therapeutic strategies have been developed so far against blast-induced ocular dysfunction due to the lack of information on the mechanism of injury. Activation of toll-like receptors (TLRs) is known to trigger oxidative stress and neuroinflammation after brain injuries, and drugs targeting specific TLRs have shown efficacy in animal models of non-blast related brain injuries. We have shown upregulation of multiple TLRs in the ferret brain, but no such studies evaluated in the retina to determine the potential role of TLRs in the pathogenesis of blast-induced ocular dysfunctions. Our present study investigates the temporal profile of TLR expression in the retina of ferrets exposed to blast overpressure waves. Ferrets (n=48) were exposed to tightly coupled double blasts (20 psi) using an advanced blast simulator. Retinal tissues were collected at 4-, 24- hours, 7- or 28 days post-blast. Differential expressions of TLR1-10 were assessed using qPCR and compared to sham controls. TLR1, 4, 5, and 8 showed significant upregulation at 4 hours, while TLR7 exhibited substantial increases at both 4 hours and 7 days. Other TLRs exhibited varied expression patterns across the different time points. The results suggest that multiple TLRs are upregulated in the retina post-blast and that use of therapeutic agents which can inhibit multiple TLRs may be more broadly efficacious than using a single TLR inhibitor to treat blast-induced ocular dysfunction.

Mr. Pritom Kumar Saha¹, Mr. Adil Arman¹, Miss Nija White¹, Mr. Oleksii Shandra¹, Mr. Detlev Boison²

¹Florida International University, Miami, United States, ²Rutgers University, New Jersey, United States

Alzheimer’s disease and epilepsy, often triggered by traumatic brain injury (TBI), share symptoms like cognitive deficits and seizures. Both conditions involve astrogliosis and disrupted adenosine metabolism from elevated adenosine kinase (ADK) expression, where adenosine’s deficiency as an anti-epileptic neurotransmitter may cause seizures and cognitive deficits. Repetitive, diffuse TBI (rdTBI), frequent in contact sports and military, is the most common type of TBI, yet its impact on adenosine metabolism and its connection to post-traumatic Alzheimer’s and epilepsy remain elusive. We hypothesized that rdTBI leads to a progressive increase in brain ADK, causing early cognitive and seizure symptoms.

We used a weight drop model to induce rdTBI in 12-16-week-old male C57BL/6 mice and 4 months of electroencephalographic monitoring. Novel object recognition test was used to assess cognitive deficits at 7, 14, and 28 days post-TBI, with brain tissue analyzed for astrocyte ADK and pTau proteins. Sham mice underwent the same procedures except for the TBI.

rdTBI led to early and progressive cognitive and behavioral deficits demonstrated by reduced interactions and novel object exploration. Cortical and hippocampal astrocytes showed significant ADK overexpression at all timepoints correlating with cognitive deficits. 7/28 (25%) of mice had spontaneous seizures with average onset at 2 months post-TBI. These mice also had significantly greater ADK overexpression and pTau accumulation than non-seizure or sham mice.

Our data show that rdTBI alters adenosine metabolism, with increased ADK in areas affecting cognition and seizures, highlighting its role in post-traumatic epilepsy and potential Alzheimer’s via pTau, underscoring adenosine’s significance in related comorbidities.

Ms. Janeen Laabei¹, Dr. Nathan Ryzewski Strogulski¹, Dr. Gloria Vegliante¹, Ms. Carly Douglas¹, Mr. Sahil Threja¹, Dr. Andrew Pearson², Dr. Aurore Nkiliza², Dr. Marie Hanscom¹, Dr. Joseph Ojo², Dr. David Loane¹

¹Trinity College Dublin, Dublin 2, Ireland, ²The Roskamp Institute, Sarasota, USA

NADPH oxidase 2 (NOX2) is an enzyme complex responsible for phagocytic reactive oxygen species (ROS) production that acts as a priming signal for NLRP3 inflammasome activation. The goal of this study was to investigate the therapeutic potential of a small molecule NOX2 inhibitor, GSK2795039, in models of microglial activation in vitro and to translate findings to an experimental TBI model in mice.

Immortalised Microglial (IMG) or primary microglia from p1 Wistar rat pups were pre-treated with GSK2795039 or MCC950 (NLRP3 inhibitor) and stimulated with lipopolysaccharide (LPS) and Nigericin to induce NOX2/ROS and NLRP3 inflammasome activation. ROS and cell viability were measured using CM-H2DCFDA and MTT assays, respectively, while conditioned media was analysed by ELISA for cytokines, and lactate dehydrogenase (LDH) to measure pyroptosis. Protein expression of NLRP3, cleaved-Caspase-1, cleaved-IL-1β and ASC were assayed by Western immunoblot. Our in vitro studies demonstrated that GSK2795039 attenuated LPS/nigericin-induced microglial NOX2 activity, ROS, LDH, IL-1β and IL-18 release, as well as NLRP3 and cleaved-caspase-1 expression.

In vivo studies using controlled cortical impact in adult male C57Bl/6J mice and flow cytometry demonstrated increased infiltration of NOX2/ROS/Caspase-1/IL-1β+ inflammatory monocytes compared to sham. Systemic administration of GSK2795039 (100mg/kg; IP) starting at 2 hours post-injury attenuated NOX2/IL-1β+ microglia/macrophage activation. In addition, GSK2795039 reduced numbers of IL-1R+CD4+ and IL-1R+CD8+ T cells indicating that microglial-T cell crosstalk was altered by treatment. These neuroimmune changes were associated with improved motor function recovery post-TBI. Thus, our translational studies indicate that GSK2795039 may be a promising therapeutic drug for mitigating NOX2-mediated neuroinflammation post-TBI.

Mr. Frank Mobilio¹, Prof. Peter Crack¹, Dr. Juliet Taylor¹

¹The University of Melbourne, Parkville, Australia

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. We have previously shown that mice lacking interferon regulatory factor 7 (Irf7) display a reduced lesion size and altered neuroimmune response in a mouse model of mild TBI (mTBI). With increasing interest in the chronic effects of TBI, this study explored the implications of elevated Irf7-mediated neuroinflammation on long-term behaviour post-TBI, using an array of behavioural paradigms. C57BL/6 wildtype (WT) and Irf7-/- male mice (8-10-week-old, n=9-14 per group) were subjected to a controlled-cortical impact (CCI) mouse model of mTBI. At 6 months post-TBI, Irf7-deficient mice displayed reduced anxiety compared to injured WT mice (21.72±1.72% vs. 15.15±2.10% time in open arms, p=0.031), as assessed via the Elevated Zero Maze. Using the Novel Object Recognition test, improvements in cognition and memory were observed in injured Irf7-/- mice, through a significant increase in novel object exploration time when compared to sham mice (70.46±3.31% vs 56.88±3.64%, p=0.036), with no changes observed in wildtype mice. Additionally, in a fear conditioning paradigm, injured Irf7-/- mice extinguished fear more rapidly when compared to their sham controls (Block 3: 46.29±4.78% vs 60.73±4.54% freezing, p=0.020), with no changes observed between sham and injured WT mice, further supporting the notion of reduced anxiety. This study confirms a key role for Irf7 in regulating the detrimental long-term neuro-behavioural responses following mTBI. Current studies are focused on understanding Irf7’s specific role in microglial function and its contribution to the neuro-inflammatory response that drives the secondary damage following a TBI.

Dr. Savannah Kounelis-Wuillaume¹, Andrew Frank², Dr. Emilie Goguet³, Camille Alba⁴, Gauthaman Sukumar⁴, Dr. Matthew Wilkerson⁵, Dr. Clifton Dalgard^4,6, Dr. Joseph McCabe⁶, Dr. Martin Doughty⁶

¹Uniformed Services University, Bethesda, USA, ²The Henry M. Jackson Foundation (HJF), Uniformed Services University, Bethesda, USA, ³Department of Microbiology, Uniformed Services University, Bethesda, USA, ⁴The American Genome Center (TAGC), Uniformed Services University, Bethesda, USA, ⁵Center for Military Precision Health (CMPH), Uniformed Services University, Bethesda, USA, ⁶Department of Anatomy, Physiology and Genetics, Uniformed Services University, Bethesda, USA

Traumatic brain injury (TBI) results from a primary injury that impacts the brain in a spatially-dependent manner to influence long-term outcomes, but current understanding of the topography of TBI molecular responses is lacking. Using spatial transcriptomics, we mapped early post-injury transcriptional responses in a well-characterized mouse model of focal TBI using controlled cortical impact (CCI). We compared gene expression in the injured neocortex (CTX) and underlying corpus callosum-external capsule (CC-EC) and striatum (STR) at the rostro-caudal point of impact. Molecular pathways driving neuroinflammation, neuronal cell death, and risk factor genes for neurodegenerative disease were found to be enhanced across the CTX, CC-EC and STR with structure-specific differences. These include the activation of TNF and IFNγ signaling in the CTX while the STR had enhanced TGFβ signaling post-injury. In the CC-EC, genes for neutrophil degranulation and chemotaxis were enriched. Unbiased spatial clustering identified an injury-specific CTX cluster enriched for genes involved in regulation of the inflammatory response, particularly cytokine and chemokine genes stimulating granulocyte chemotaxis and activation, plus neuronal apoptosis and stress pathways. We therefore depleted circulating neutrophils to map molecular responses to neutrophil infiltration in the injured brain. Attenuated neutrophil infiltration into the brain downregulated axonal remodeling and synaptic transmission gene pathways in the CC-EC but did not significantly alter gene expression in the spatially-identified injury cluster within the CTX. These results demonstrate transcriptional responses to injury are influenced by tissue cytoarchitecture, proximity to the initiating physical force, and by neutrophil infiltration into the injured brain.

MS Jing Ju¹, BS Collin Ocampo³, MD Biraj Patel^3,4, BS Xia Wang¹, Dr. Michelle Theus^1,2

¹Department of Biomedical Sciences and Pathobiology, Department of Biomedical Sciences and Pathobiology, Blacksburg, United States, ²Center for engineered Health, Blacksburg, United States, ³Virginia Tech Carilion School of Medicine, Roanoke, United States, ⁴Neurointerventional Surgery, Department of Radiology, Roanoke, United States

Background: Pial collateral vessels serve as distal arterial anastomotic channels within the leptomeninges, facilitating retrograde reperfusion to ischemic tissue following cerebral ischemia. Arteriogenesis, triggered by collateral vessels post-thrombotic occlusion, entails significant vascular remodeling, vital for averting blood hypoperfusion in ischemic penumbra and limiting tissue damage. While peri-vascular macrophages have been implicated in collateral vessel remodeling, the role of peripheral derived immune (PDI) cells, particularly EphA4, in arteriogenesis remains unknown.

Methods: Using GFP bone marrow chimeric knockout mice undergoing permanent middle cerebral artery occlusion (pMCAO), we investigated the PDI cell-specific role of EphA4. We assessed circulating immune cell populations, infarct volume, functional recovery, characterized infiltrating immune cell subtypes, and quantified collateral vessel diameters through vessel painting. Furthermore, we explored the Tie2-mediated PI3K signaling pathway in peripheral-derived monocyte/macrophages (PDM) using soluble Tie2-Fc and a PI3K p110α inhibitor.

Results: Loss of PDI cell-specific EphA4 enhanced collateral remodeling, associated with reduced infarct volume, improved blood flow, and functional recovery within 24 hours post-pMCAO. Crosstalk between EphA4-Tie2 signaling in PDM, mediated through PI3K regulation, suppressed pial collateral remodeling.

Conclusions: Our findings suggest that PDM-specific EphA4 negatively regulates collateral growth and remodeling by inhibiting Tie2 function via the PI3K signaling pathway. Peripheral myeloid-derived EphA4 emerges as a novel mediator of cerebral vascular damage and neuroinflammation post-acute ischemic stroke.

Acknowledgments: We acknowledge grant support from NIH NINDS R01 NS112541.

Ms. Michelle Taylor¹, Dr. Kirsty Dixon

¹Virginia Commonwealth University, Richmond, United States

Apolipoprotein E4 (ApoE4) and traumatic brain injury (TBI) are two well established risk factors for developing Alzheimer’s disease (AD), but how they may act synergistically to increase an individual’s likelihood of developing AD remain unknown. Both ApoE4 and TBI increase neuroinflammation, specifically the proinflammatory cytokine tumor necrosis factor (TNF). Soluble TNF preferentially binds to TNFR1, furthering neuroinflammation by increasing NF-ΚB activity. Lipoprotein receptor-related protein 1 (LRP1), a receptor for apoE, reduces neuroinflammation by internalizing TNFR1, preventing its downstream signaling. However, when apoE is misfolded by the ApoE4 allele, LRP1’s ability to remove TNFR1 from the membrane may be impaired, thus furthering TBI-induced TNFR1 signaling to accelerate AD pathophysiologies.

C57BL6 and humanized ApoE4 mice underwent either sham or TBI (CCI model) and were survived up to 7 days, undergoing the novel object recognition test (NORT) 3dpi. At 12 hours or 7 dpi, the ipsilateral hippocampus was collected and processed for Western blotting.

Preliminary data shows that ApoE4 mice have increased Shc*, TNFR1* and NF-ΚB** expression as early as 12 hours following TBI (cf. WT levels), suggesting an increase in LRP1 and TNFR1 activity, which ultimately leads to increased amyloid precursor protein (APP)* levels. While Shc* and NF-ΚB* levels have reduced to baseline levels by 7 DPI in WT mice, the presence of ApoE4 sustains the expression of these proteins, leading to increased amyloidosis* and cognitive deficits (NORT).

These results suggest that ApoE4 sustains TBI-induced TNFR1 activity through an LRP1- mediated mechanism to accelerate and exacerbate AD pathophysiologies. (n=3-5; *=p<0.05, **=p<0.01).

Dr. Deepak Subramanian¹, Mr. Erick Contreras¹, Dr. Krista Marrero¹, Dr. Iryna Ethell¹, Dr. Vijayalakshmi Santhakumar¹

¹University Of California - Riverside, Riverside, United States

Increased levels of Matrix Metalloproteinase-9 (MMP-9), a potent Zn+ activated endopeptidase that degrades extracellular matrix, is commonly observed in humans and animal models after Traumatic Brain Injury (TBI) and has been implicated in the development of post-traumatic epilepsy and cognitive deficits. However, the factors that regulate MMP-9 levels after TBI are not fully understood. Here we examined the contribution of innate immune signaling mediated by Toll-Like Receptor 4 (TLR4) in regulating MMP-9 activity after concussive brain injury. Juvenile rats (p24) were subjected to a moderate lateral Fluid Percussion Injury (FPI) or sham injury and were evaluated for changes in MMP-9 levels, altered synaptic physiology, network excitability and plasticity in the hippocampal dentate gyrus (DG). In situ zymography revealed an increase in MMP-9 activity in the DG 48 hours after FPI. Remarkably, blocking TLR4 signaling early after FPI limited this increase demonstrating a novel immune regulation of MMP-9 activity (n=5 animals/group, p<0.05 by TW-ANOVA). Patch clamp recordings revealed an increase in the frequency of excitatory inputs to DG granule cells 1-week after injury that was reduced by early inhibition of TLR4 or MMP-9 after injury suggesting a role for TLR4:MMP-9 signaling cascade in this process (n=7-8 cells/group, p<0.0001 by Kolmogorov-Smirnov test). Post-injury inhibition of TLR4 or MMP-9 prevented trauma induced changes in DG network excitability and long-term potentiation in urethane anesthetized rats in vivo (n= 5 animals/group, p<0.05 by TW-ANOVA). Overall, our results identify a novel TLR4 dependent regulation of MMP-9 activity that contributes to the early physiological changes after TBI.

Ms. Chenxing Li^1,2, Ms Sydney Triplett², Ms Anna Silverio¹, Mr Martin Griffin¹, Mr Felix Moctezuma¹, Dr Erin Buckley^1,2, Dr Levi Wood^1,2

¹Georgia Institute of Technology, Brookhaven, United States, ²Emory University, Atlanta, United States

Backgrounds: Repetitive mild traumatic brain injury (rmTBI) sustained within a window of vulnerability can result in persistent functional deficits (i.e., cognitive decline, depression). We previously reported that acute phosphorylation of the pro-inflammatory signaling molecule p38 MAPK was linked to worse functional outcomes following a weight-drop model of repetitive mTBI. Given the known immunomodulatory role of p38 MAPK, we investigated the effect of acute p38 MAPK inhibition on microglial markers and cytokine expression after rmTBI.

Methods: Male and female C57/BL6 mice were intraperitoneally injected with the p38 MAPK inhibitor SB239063 or vehicle 30 min after each of 5 once-daily weight-drop closed head injuries or sham. Brain tissues were collected at 4hr or 4w after the final injury; assessment of microglial/phagocyte markers and cytokines were performed via ELISA and Luminex.

Result: In females, SB239063 treatment attenuated injury-upregulated cytokines (MIP-1a, G-CSF, IL-5, Eotaxin; p < 0.05) at 4hr post-injury. However, SB239063 had less effect on injury-increased cytokine (IL-1a; p < 0.05) in males. Similar sex disparities were observed in microglial response. In females, injury resulted in increases in the microglial-specific marker Tmem119 at 4hr and decreases at 4w, (suggesting acute microglial recruitment) along with increases in CD68 at 4w (p < 0.05), suggesting sustained mononuclear phagocyte activation. Importantly, both Tmem119 and CD68 changes in females were attenuated by SB239063 treatment (p< 0.05). In contrast, p38 MAPK inhibition only normalized injury-induced increases in CD68 at 4h in males.

Conclusion: These findings reveal that transient inhibition of p38 MAPK attenuates injury-induced response differentially by sex.

Mr. Daniel Zhang¹, Ms. Alexis Pulliam², Dr. Michelle LaPlaca²

¹School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, United States, ²Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, United States

Traumatic brain injury (TBI) has been shown to reduce glymphatic clearance. This study aims to quantify glymphatic clearance and determine brain-to-blood permeability post-TBI. Male Sprague Dawley rats (sham, n=4; injured, n=5) received 3 head impacts (5 m/s, displacements 5, 2, and 2mm, 2-minute intervals). Radiolabeled tracers (0.05μCi each, 14C-inulin carboxyl (5000 Da) and 3H-sucrose (342 Da) in 5 μL aCSF) were injected into the striatum 24 hrs post-injury or sham conditions. Blood was collected at 30, 60, 90, and 120 min; cervical lymph nodes, brains, and CSF were extracted 120 min post-infusion. Brains were sectioned coronally into 5mm sections anterior-to-posterior (BR1, BR2, BR3, BR4). Samples were solubilized and counted in a liquid scintillation counter. Preliminary results showed a significant increase in 14C-inulin in the BR2 section for TBI compared to sham (p=0.04), indicating reduced glymphatic flux from the injection site. There were no significant differences in the other sections, lymph nodes, or blood between injured and sham animals for either 14C-inulin or 3H-sucrose. Interestingly, we observed 14C-inulin in the blood, which was intended to be a brain reference, and no 3H-sucrose for both injured and sham conditions. Additionally, there were significant levels of both 14C-inulin and 3H-sucrose in the CSF (n=2 injured, n=2 sham), which suggests preferential glymphatic clearance for smaller molecules over the blood brain barrier (BBB). Overall, these results show a small injury effect and point to the need for additional animals and time points. Future directions include modeling glymphatic flow among the relevant compartments.

Support: R01NS101909.

Dr. Tyler Nguyen^1,2, Ms. Reem El Jammal¹, Ms. Ashlyn G Cochran¹, Mr. Michael T Fletcher¹, Mr. Andrew Brumett¹, Dr. Edward M. Campbell³, Dr. Makram Obeid¹, Dr. Fletcher White^1,2

¹Indiana University School Of Medicine, Fishers, United States, ²Richard L. Roudebush VA Medical Center, Indianapolis, United States, ³Loyola University Stritch School of Medicine, Chicago, United States

Hemorrhage is a significant risk factor for mild traumatic brain injury (mTBI)-related neurological sequalae but studying it in animal models is hindered by rodents’ rapid blood coagulation system compared to humans. In this study using repeated closed-head mTBIs, we promoted bleeding by subjecting transgenic mice constitutively expressing the caspase-1 biosensor to anticoagulant heparin injection prior to controlled cortical impact injury. As the caspase-1 biosensor is activated in response to various inflammatory stimuli, we were able to monitor the spatiotemporal dynamics of caspase-1 activation and in vivo onset of inflammation in individual animals following injury alone and injury in combination with heparin injection. We established that there was a significant increase in caspase-1 mediated inflammation in mice with heparin/injury compared to injury only animals that lasted at least one week post injury. Furthermore, ex vivo brain slice imaging revealed considerable enhancement in heparin/injury neuroinflammatory response, which could be altered with MCC950, a NLRP3-specific inhibitor and the TLR4 inhibitor, Tak242. We also observed that heme (ferroprotoporphyrin IX), a biproduct of traumatic intracranial hemorrhages, has a profound impact on the inflammatory response which could be attenuated with exposure to Tak242. Overall, these findings suggest that hemorrhage potentiates mTBI-related inflammatory responses. Ongoing work by our team is examining the role of heme iron, an activator of NLRP3, in such responses, and in the potentially associated neurological sequalae of mTBI.

Ms. Kylee Smith¹, Dr. Linda Noble¹, Dr. Michael Donovan¹, Dr. Romona Von Leden¹

¹University Of Texas At Austin, Austin, United States

Young brain-injured mice show a prolonged recruitment of neutrophils over the first two weeks post-injury (PI). Here we tested the hypothesis that neutrophil recruitment, limited to the acute phase PI, alters the local microenvironment and contributes to neurological deficits at adulthood. First, we validated systemic depletion of neutrophils via their quantification in blood and the injured cortex of Catchup-IVM mice which, through modulation of Ly6G locus, allows for fluorescent imaging-based tracking of neutrophils. At p20-21, male and female mice were administered either Ly6G or IgG control antibody (N=7-8/group) at 1d prior to injury and immediately after injury for acute depletion. Males (92.3%) and females (91.6%) showed a significant reduction in both circulating neutrophils (p<0.001) and in the injured cortex (p<0.001), compared to controls at 1d PI . Next, we determined if neutrophil depletion influenced microglial recruitment and activation in the injured brain. Although there was no overall difference in microglial density in the injured cortex in either sex, compared to IgG controls, neutrophil-depleted male mice showed a reduction in activated microglia (p<0.05), while no change was apparent in brain injured females. Lastly, we evaluated learning and memory (Barnes Maze and Novel Object Recognition) at adulthood. Preliminary findings suggest that early depletion of neutrophils rescues deficits in learning and memory in males only. Together, these findings suggest complex interactions between neutrophils and microglia in the injured young brain, which may influence extent of recovery after an early age TBI. Supported by the Depts. of Psychology and Neurology, Univ. Texas, Austin.

Ms. Erika dlRM Cabrera Ranaldi¹, Mr. Leo I. Levine¹, Dr. Juliana Sanchez-Molano¹, Ms. Ofelia E. Furones-Alonso¹, Dr. Oliver Umland³, Dr. Robert W. Keane^1,2, Dr. Juan Pablo de Rivero Vaccari^1,2, Dr. Helen M. Bramlett^1,4, Dr. W. Dalton Dietrich¹, Dr. Nadine A. Kerr¹

¹Department of Neurological Surgery and The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, USA, ²Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, USA, ³Cell Transplant Center, Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, USA, ⁴Bruce W. Carter Department of Veteran Affairs Medical Center, Miami, USA

Traumatic brain injury (TBI) results in long-lasting impairment and disability, in part due to exacerbated inflammation. A contributor to immune dysfunction after TBI is the inflammasome. When activated, the inflammasome leads to interleukin (IL)-1β and IL-18 release and to pyroptotic cell death via Gasdermin-D (GSDMD) cleavage. Extracellular vesicles (EVs) can transport inflammasome components to advance systemic inflammation after TBI. As inflammasome proteins have been established to increase after TBI and associate with worse outcomes, we sought out to determine whether targeting pyroptosis through GSDMD knockout (KO) can improve inflammatory signaling and pathology after TBI. GSDMD KO mice and C57BL/6 controls (WT) underwent sham or moderate controlled cortical impact and were sacrificed after 3 days. Cortical lysates were collected for electroluminescence and EVs for flow cytometry. Cerebral blood perfusion rates were compared and cognitive function was measured through the open field maze. KO TBI mice had significantly lowered levels of the pro-inflammatory cytokines IL-6 (p < 0.05) and IL-1β (p < 0.01) compared to WT TBI in the cerebral cortex. Further, neuronal-derived EVs were decreased (p < 0.01) in KO TBI compared to WT TBI. IL-1β-labeled EVs were also reduced (p < 0.01) in KO TBI mice. Overall, our results indicate that GSDMD inhibition can reduce pro-inflammatory cytokine expression in the cerebral cortex after TBI. Additionally, GSDMD KO can decrease inflammatory-associated and brain-derived EVs after TBI. Thus, inflammasome inhibition via GSDMD targeting presents a promising prospect for neurological recovery after TBI. We acknowledge NIH/NINDS 4RF1NS125578 and NIH/NINDS 1R37NS133195 for their support.

Mr. Jonathan Packer¹, Mrs. Samantha Gianno¹, Mrs. Lynde Wanger¹, Mrs. Amara Davis¹, Dr. Jonathan Godbout¹

¹The Ohio State University, Columbus, United States

Neuropsychiatric complications including depression and cognitive decline develop, persist, and even worsen in the years after traumatic brain injury (TBI), negatively affecting quality of life. TBI-induced alterations lead to reduced neuronal dendritic complexity, reduced excitability, and suppressed homeostatic gene expression. As previous work by the Godbout lab showed TBI-induced neuronal dysfunction, we sought to better understand deficits in neuronal homeostasis after TBI. In our recent report, single nuclei RNA-seq data 7 dpi showed evidence that phosphatase and tensin homolog (PTEN)-mediated pathways were decreased in cortical neurons 7 dpi. Here, we provide more insight from this sn-RNAseq data where specific genes associated with the PTEN pathway increased (Pten, Gsk3b, Rock1, Rock2) while genes associated with the PI3k/AKT growth and survival pathway (Akt3, Igf1r, Mapk1) were suppressed. Moreover, PTEN directly acts on the PI3K/AKT signaling pathway to inhibit neuronal homeostasis. Thus, PTEN was targeted for inhibition following TBI using Bisperoxovanadium ho(PIC) (BPV). This specific PTEN inhibitor was administered 1h following TBI, then every 24h for six days. We confirmed that TBI increased PTEN protein expression within the cortex and that this was attenuated by BPV intervention. Notably, PTEN intervention had limited effects on TBI-induced neuroinflammation and gliosis in male and female mice. Nonetheless, TBI induced cortical injury with reduced Neun+ cell counts and percent area. This was attenuated by PTEN inhibition 7 dpi. Furthermore, TBI-induced cognitive deficits 7dpi in the NOL/NOR were also reversed by the PTEN inhibition. Taken together, reducing PTEN signaling after TBI effectively reduced neuronal dysfunction and cognitive impairment.

Mr. Cody Hubbard¹, Mr. Gabriel Nah¹, Dr. Nicholas Port¹, Dr. Andrea Hohmann¹, Dr. Jonathon Crystal¹

¹Indiana University, Bloomington, United States

Objective: The purpose of this study is to assess astrocyte and microglia morphology at different time points following a mild traumatic brain injury (mTBI).

Methods: 30 Sprague Dawley rats received either mTBI or a sham injury using the Wayne State University modified weight drop model in which a 450g weight is dropped from a height of 1m on an anesthetized animal with the skin and skull intact. Head landmarks were used with a guide tube to aim the weight. This mTBI model recapitulates key elements of sports-related injury. Immunohistochemistry staining was performed using GFAP for astrocytes, IBA1 for microglia, and DAPI for cell nuclei. Rats were euthanized at the following time points post-injury: 1, 4, and 8 days. A sham group was studied 4 days after the procedure. A naive group was studied following minimal handling. All groups consisted of 3 male and 3 female rats. The hippocampus was imaged at 20x using a Leica Model X confocal microscope. Custom written morphology software was written in Matlab to segment cells and calculate their area of staining. Cells were only accepted if they contained a nucleus identified with the DAPI stain.

Results: There was no effect of group (1, 4, 8 day, sham, naive) on astrocyte and microglia cell area (Kruskal-Wallis ANOVA, p = 0.66).

Conclusion: These results suggest the 450g weight drop model of mTBI is truly mild, producing subtle transient (4 day) deficits in spatial working and episodic memory, while simultaneously producing no microscopic changes to astrocytes or microglia.

Dr. Morgan Taylor^1,2,3, Samuel Houle^1,2,3, Dr. Zoe Tapp^1,2,3, Dr. John Sheridan^2,4, Dr. Jonathan Godbout^1,2,3, Dr. Olga Kokiko-Cochran^1,2,3

¹OSU Department of Neuroscience, Columbus, United States, ²Institute for Behavioral Medicine Research, Columbus, United States, ³OSU Chronic Brain Injury Program, Columbus, United States, ⁴OSU College of Dentistry, Columbus, United States

Traumatic brain injury (TBI) is a global source of injury-related death and disability, and survivors suffer functional and psychiatric consequences that often persist for years. Neuroinflammation, mediated in part by microglia, perpetuates chronic dysfunction after TBI, including dysregulated stress response. Previous data shows that 30 days of mechanical sleep fragmentation (SF) aggravates microgliosis and neuroinflammation, impairing recovery after TBI. We hypothesized that the combined effects of TBI and SF would also result in robust transcriptional changes in microglia. We used RNA-seq to analyze gene expression in microglia and coronal slice brain tissue of C57BL/6J mice who received TBI or sham injury followed by 30 days of SF or control housing. We analyzed the independent effects of TBI and SF on differentially expressed genes (DEGs) within each tissue type and compared microglial DEGS to those of coronal slice. Furthermore, we identified a set of DEGs which are uniquely dysregulated by the combination of TBI and SF. Gene set enrichment analysis reveals numerous pathways and ontologies correlating to these DEGs. We find distinct subsets of olfactory genes that are differentially dysregulated by TBI and SF in the coronal slice, as well as significant enrichment of cell-cell communication pathways that are disrupted in microglia compared to the rest of the brain. Through in-depth transcriptional analysis we identify potential molecular targets that will shed light on the mechanisms of TBI-induced microglial activity and reveal how post-TBI SF alters the microglial response, which could inform the development of better therapeutics.

Ms. Radina Lilova¹, Sean Regan¹, Rana Ansari¹, Audrey Lafrenaye¹

¹Virginia Commonwealth University, Richmond, United States

Secondary sequelae from traumatic brain injury (TBI) can result in glial alterations. Our previous studies showed regional morphological astrocyte changes following central fluid percussion injury (cFPI) and buprenorphine (bup) administration, however, what these morphological changes indicate remains enigmatic. Therefore, this study aimed to investigate the influence of bup on astrocyte protein expression post-cFPI. At 4w post-cFPI and saline or bup treatment, cortical, hippocampal, and thalamic tissue from adult male rats was assessed for protein levels of the intermediate filament, GFAP, the volume reducing channel, SWELL1, and the ion channel associated with astrocyte cell swelling, TRPM4. Using multi-factor analyses across injury, region, and treatment we found regional, injury-dependent differences in all three proteins. There was a trend toward increased GFAP protein levels following cFPI compared to sham. There were interactions among injury, region, and treatment in which bup reduced GFAP in the cortex and hippocampus following cFPI, but not the thalamus or in sham animals. There were significant regional differences in both SWELL1 and TRPM4. There was a significant interaction between region and treatment and a trend toward interactions among region, injury, and treatment for SWELL1, in which TBI animals treated with bup had lower SWELL1 in the cortex but higher in the thalamus. There was an interaction among region, injury, and treatment for TRPM4 in which TBI animals treated with bup had lower TRPM4 in the cortex.

This work was funded by NINDS grants R01NS096143.

Dr. Guoxiang Xiong¹, BS Anthony Farrugia¹, Dr. Akiva Cohen¹

¹Children’s Hospital Of Philadelphia, Philadelphia, United States

Traumatic brain injury (TBI) is a leading cause of death and disability in the American population. When the brain gets traumatized, damage can be identified around the impact site (coup injury), and/or at the opposite site to the impact (contrecoup injury). Anatomical and functional abnormalities arising from the coup injury have been extensively studied. However, pathology associated with contrecoup injury is frequently overlooked. In the present study we focused at determining contrecoup pathology in the cerebellum caused by traumatic injury to the mouse forebrain. Lateral fluid percussion injury was used to deliver a TBI and multiple biomarkers were used to determine pathological changes. Fluoro-Jade C staining revealed damaged Purkinje cell bodies and deformed dendrites in cerebellar cortex after injury. APP antibody Y188 immunostaining demonstrated axonal blebs from Purkinje cells, but not granule cells. Unlike the forebrain that holds patches of Y188-stained puncta in white matter bundles, the cerebellum showed no punctate staining by Y188 in its white matter. NeuroSilver staining detected Purkinje cell bodies and deformed dendrites, together with diffuse Wallerian degeneration (of axons) in cerebellar cortex, nuclei and peduncles. With all these markers, we demonstrated no damages in climbing and parallel fibers. We also used Thy1-YFP and PV/Tomato transgenic mice, and successfully detected damages in mossy fibers and Purkinje cell axons, respectively. The present study has demonstrated extensive contrecoup pathological changes, which may be the cellular bases underlying the cerebellar dysfunctions reported in TBI patients.

Dr. Samuel Shin¹, Dr. Angela Viaene², Mr. Kevin Browne¹, Dr. Kacy Cullen¹, Dr. Misun Hwang², Dr. Todd Kilbaugh²

¹University of Pennsylvania, Philadelphia, United States, ²Children’s Hospital of Philadelphia, Philadelphia, United States

Objective: Contusional traumatic brain injury (TBI) induces significant hemorrhage and iron deposits in pericontusional tissue. Given the role of iron in generating reactive oxygen species (ROS) we investigated the role of iron induced neuronal and glial injury following TBI. Methods: Using a pig model of TBI, we compared the degree of iron deposition in pig brains after controlled cortical impact (CCI) and rotational acceleration injury (RAI). Then, we investigated the role of iron by comparing the neuronal and glial cells that were stretch injured with in-vitro injury device compared to those that were stretched injured in the presence of excess iron. Cytotoxicity, caspase activity, and mitochondrial ROS levels were compared using chemiluminescent assays as well as immunohistochemistry. Results: When excess iron was present at the time of stretch injury cytotoxicity, caspase activity, and mitochondrial ROS levels were accentuated. This effect was more pronounced in oligodendroglia compared to neuronal cell cultures. Additionally, pharmacological inhibitors of ferroptosis such as Ferrostatin-1 and mitochondrial protectant Cyclosporine A attenuated these injury markers. Moreover, there was cell type dependent vulnerability to ferroptosis and apoptosis. Conclusion: Hemorrhage at the time of injury significantly enhances injury via ferroptosis and apoptosis in a cell type dependent manner.

Dr. Zachary Weil¹, Bailey J. Whitehead¹, Deborah Corbin¹, Megan L. Alexander¹, Jacob Bumgarner¹, Ning Zhang¹, Kate Karelina¹

¹West Virginia University, Morgantown, United States

Mild-moderate traumatic brain injuries (TBIs) are prevalent, and while many individuals recover, there’s evidence that a significant number experience long-term health impacts, including increased vulnerability to neurodegenerative diseases. These effects are influenced by other risk factors, such as cardiovascular disease. Our study tested the hypothesis that a pre-injury reduction in cerebral blood flow (CBF), mimicking cardiovascular disease, worsens TBI recovery. We induced bilateral carotid artery stenosis (BCAS) and a mild-moderate closed-head TBI in male and female mice, either alone or in combination, and analyzed CBF, spatial learning, memory, axonal damage, and gene expression. Findings showed that BCAS and TBI independently caused a ∼10% decrease in CBF. Mice subjected to both BCAS and TBI experienced more significant CBF reductions, notably affecting spatial learning and memory, particularly in males. Additionally, male mice showed increased axonal damage with both BCAS and TBI compared to either condition alone. Females exhibited spatial memory deficits due to BCAS, but these were not worsened by subsequent TBI. Gene expression analysis in male mice highlighted that TBI and BCAS individually altered neuronal and glial profiles. However, the combination of BCAS and TBI resulted in markedly different transcriptional patterns. Our results suggest that mild cerebrovascular impairments, serving as a stand-in for preexisting cardiovascular conditions, can significantly worsen TBI outcomes in males. This highlights the potential for mild comorbidities to modify TBI outcomes and increase the risk of secondary diseases.

¹Ucla Neurosurgery, Los Angeles, United States

Traumatic brain injury (TBI) has been shown to induce early increases in cerebral glucose metabolic (CMRg), followed by prolonged metabolic depression. The magnitude and duration of the hypometabolism is correlated with the duration of cognitive dysfunction. What causes this CMRg depression? Evidence of dietary changes impacting brain metabolism inspired the hypothesis that TBI induces gut microbiome changes that contribute to CMRg depression. Male PND45 rats were given lateral controlled cortical impact (CCI) injury. Fecal samples were collected before and daily after injury for 3 days. Fecal samples were processed for 16S rRNA sequencing (Michigan Microbiome Project). Sham animals either received 3 days of fecal matter transplant (FMT) from the pre-injury (SS) or post injury days (SI) from CCI rats. On day 3 all groups were cannulated for 14C-2DG injection to measure CMRg. CCI injury induced 19% decrease in cortical and 9% decrease in hippocampal CMRg at day 3, consistent with prior publications. This coincided with the maximal decrease in Firmicutes phyla of the microbiome. SS rats that received pre-injury FMT for 3 days showed cortical (144µmol/100g/min) and hippocampal (89µmol/100g/min) CMRg rates consistent adolescent male sham rats. However, SI rats that received post injury FMT for 3 days showed bilateral cortical (15%) and hippocampal (14%) CMRg depression relative to the SS group. This study demonstrates that the alterations in gut microbiome from TBI do contribute to cerebral metabolic depression and would suggest that treatment of the gut could improve brain metabolism and recovery of function.

Mrs. Tala Curry-Koski^1,2,3, Liam Curtin^1,3, Mary-Eunice Barrameda^1,3, Caitlin Bromberg^1,2,4, Gokul Krishna^1,2, Zackary Sabetta¹, Mitra Esfandiarei^1,2,3, Theresa Currier Thomas^1,2,3,4

¹University of Arizona College of Medicine-Phoenix, Phoenix, USA, ²Barrow Neurological Institute at Phoenix Children’s Hospital, Phoenix, USA, ³Midwestern University, Glendale, USA, ⁴Arizona State University, Tempe, USA

Traumatic brain injury (TBI) can chronically increase transforming growth factor-β (TGF-β), a cytokine implicated in cerebrovascular dysfunction underlying blood-brain barrier (BBB) permeability and neuroinflammation. Fibrillin-1 (Fbn1+/-)-mutation, associated with connective tissue disorders, increases TGF-β systemically, generating vascular dysfunction by 6-months (6M) in mice. Cerebrovascular dysfunction is also elicited, with decreased posterior cerebral artery (PCA) blood flow velocity in 6M-Fbn1+/- mice, similar to middle-aged 12M-C57BL/6 mice, indicative of an aging-associated phenotype. We hypothesized that Fbn1-mutation is associated with altered microvascular density, BBB permeability, neuroinflammation, neurobehavior, and glutamate neurotransmission in the PCA-perfused hippocampus, increasing vulnerability to mild-TBI (mTBI). Male and female 6M-Fbn1+/-, WT-1-day-post-injury (1DPI), and 6M-Fbn1+/--1DPI mice (n=5-10/group) were compared to C57BL/6(WT). Midline fluid percussion injury required a 15% lower force of injury to provoke righting reflex times (5-10 minutes) in 6M-Fbn1+/- mice (p=0.004) and displayed increased cortical neuropathology and cavitation. 6M-Fbn1+/-, WT-1DPI, and Fbn1+/--1DPI displayed 29-47% decreased hippocampal microvascular density (p=0.002) and 47-53% increased BBB permeability (p=0.0002). Ionized calcium-binding adaptor molecule-1 (iba-1) immunohistochemistry showed 56-65% increased microglial cell counts and reactive morphology in 6M-Fbn1+/-, WT-1DPI, and Fbn1+/--1DPI hippocampi, indicating reactive microglial saturation (p=0.017). Neurobehavioral severity scale (NSS) scores were elevated in 6M-Fbn1+/-, WT-1DPI, and Fbn1+/--1DPI (p<0.0001). In vivo hippocampal electrochemical recordings showed elevated baseline glutamate levels in 6M-Fbn1+/-, WT-1DPI, and Fbn1+/--1DPI (p=0.016) in the dentate gyrus. These findings indicate neuropathology in 6M-Fbn1+/- mice, and despite similarities in 1DPI hippocampal outcomes, 6M-Fbn1+/--1DPI mice displayed cortical neuropathology and sensitivity to force of injury, supporting vulnerability to mTBI. Funding-Valley_Research_Partnership-P1A-5012,_NIH-R36AG083385,_NIH-R15HL145646,_NIH-R01NS100793,_Midwestern_Graduate_Funds.

Ms. Sydney Bennett¹, Dr. Zoe Teton¹, Dr. Mayumi Prins¹

¹UCLA, Los Angeles, United States

Traumatic brain injury (TBI) remains the leading cause of death among adolescents in the US. The most definitive treatment option for intracranial hypertension remains the hemicraniectomy (HC, removal of half of the skull). The recently discovered cerebral glymphatic system describes a brain-wide pathway of perivascular CSF channels that promote a system of CSF-ISF exchange during sleep that cleanses the brain of metabolic waste products. Anterograde CSF movement through this system is partially dependent on the pulsatility of the brain against the closed cranial vault, pulsatility that is lost following HC. Glymphatic dysfunction has been demonstrated in many neurological pathologies, but has yet to be investigated in severe adolescent TBI. We hypothesized that severe TBI in adolescent rats will impair glymphatic influx and that this will be exacerbated by HC. Adolescent male rats (PND 40) received severe controlled cortical impact (CCI) injuries (n=3), CCI followed by a HC (n=2) or sham injuries (n=4). At 5 days post-injury, fluorescent dye was injected into the cisterna magna and allowed to circulate for a total of 30 minutes, to measure glymphatic inflow. The brain was sliced and imaged to analyze mean fluorescence. Results: Fluorescence intensity in the sham group was more than twice that of the TBI group (p=.024) and more than triple the HC group (p=.008). Conclusion: Severe TBI causes significant glymphatic dysfunction in the adolescent rat and this dysfunction is magnified by HC.

This work was supported by NIH NS110757, the UCLA BIRC, BrainSPORT, and Easton Labs.

Miss. Farrah Mohammed¹, Declan McGuone², Dr. Sacit Bulent Omay³, Dr. Zeynep Erson Omay³, Dr. Jiangbing Zhou^1,3

¹Yale School of Engineering and Applied Science, Department of Biomedical Engineering, New Haven, United States, ²Yale School of Medicine, New Haven, United States, ³Department of Neurosurgery, Yale School of Medicine, New Haven, United States

To improve traumatic brain injury (TBI) outcomes, we must understand the spatiotemporal dynamics of secondary injury processes to engineer interventions that modulate physical, cellular, and biochemical neurodegenerative processes. Yet, the spatial patterning of such mechanisms is unknown. This pilot study presents the spatial transcriptomic profiling of a controlled cortical impact TBI model at two acute time points.

Male C57BL/6 mice aged 10-12 weeks underwent sham treatment or unilateral moderate or severe TBIs on the somatosensory cortex. 24 or 48 hours post-surgery, ipsilateral samples were sequenced following the Fresh-Frozen Visium Spatial Protocols. Using the Seurat v4 spatial exploration pipeline and implementing cell/spot characterization through integrating publicly available single-cell data, we achieved high-resolution spatiotemporal profiling, reaching subspot resolution via Bayesian computational methods.

Unbiased transcriptomic characterization of our cohort (24hr-sham, 24hr-moderate, 24hr-severe, and 48hr-severe) displayed differential spatiotemporal co-expression of canonical markers of synaptic plasticity including Bdnf, Nptx2, and Ppp3ca. Cell-type matched analysis near the site of injury identified that CREB, Synaptogenesis, and Netrin signaling pathways were significantly (p≤.00058) upregulated 24 hours after impact, reflecting a neuroplastic response to the physical and oxidative stress. Histopathological and reference-guided analysis exposed structural disruption including focal loss of cortical layer 2/3 in injured animals.

To our knowledge, this is the first exploratory TBI experimental design to elucidate complex molecular and cellular dynamics at a high spatial resolution. We observed a striking, quantitative, and spatial differential expression across injury severity and temporal dimensions. Ongoing extended cohort studies include contralateral hemispheric data and expanded time points.

Ms. Nishell Savory¹, Mr. Ryan DeSanti, Ms. Tiffany Briscoe, Mr. Ramesh Raghupathi

¹Drexel University College Of Medicine, Philadelphia, United States

Traumatic brain injury (TBI) is a leading cause of mortality and morbidity in children below the age of 3. TBI sustained in childhood can lead to psychosocial and cognitive deficits. Clinical evidence demonstrates that the progression of pathophysiological alterations and behavioral deficits differs between adult and pediatric TBI patients. Additionally, therapies that have been shown to be effective in adults may be ineffective or dangerous in children who sustain TBI. Most current models of pediatric TBI that have been developed to determine the cellular mechanisms underlying long-term behavioral deficits are translationally relevant to children older than 3 years. Although a rat model of neonate TBI has been extensively characterized, there are certain advantages to having a mouse model of neonate (infant) TBI which was the primary goal of the present study. Fifty-three neonate (11-day-old) male and female C57BL/6 mice underwent closed head injury (n=26) or sham injury (n=27). At 3 days, traumatic axonal injury and glial activation was evident in multiple white matter tracts as well as the thalamus in the injured hemisphere. Further assessments conducted at 4-5 weeks post-injury (adolescent age) showed significant impairments in spatial learning and an increase in risk-taking behaviors in brain-injured mice (p<0.05). However, axonal injury and glial activation were not apparent at 6 weeks. These data provide evidence of a working model of TBI in the neonate mouse that will allow us to use genetic tools to investigate the cellular and circuit mechanisms underlying long-term deficits caused by TBI.

Dr. Sarah Svirsky¹, Matthew Dain¹, Dr. Yuefang Chang¹, Dr. James Castellano², Dr. David Okonkwo¹, Dr. Yvette Conley³, Dr. Ava Puccio¹, Dr. Shaun Carlson¹

¹Dept. of Neurological Surgery, University Of Pittsburgh SOM, Pittsburgh, United States, ²Dept. of Neurology, University Of Pittsburgh SOM, Pittsburgh, United States, ³School of Nursing, University Of Pittsburgh, Pittsburgh, United States

Post-traumatic epilepsy (PTE) occurs in up to 1/3 of severe traumatic brain injury patients (sTBI). PTE is independently associated with impoverished long-term outcomes. Alterations in synaptic neurotransmission have been linked to the development of PTE, however underlying genetic etiologies remain unknown. We hypothesize that single nucleotide polymorphisms (SNPs) of synaptic genes are associated with PTE and/or functional outcomes in sTBI patients. Participants were prospectively enrolled under an approved IRB between 2002-2013, with corresponding PTE status from electronic medical records. DNA was extracted from 385 patients. SNPs from AP2M1, CLTA, CLTC, and SYT1 were genotyped using the Human Core Exome. Outcome up to 24mo post-injury was measured using Glasgow Outcome Scale (GOS) and Disability Rating Scale (DRS). PTE occurred in 28% (n=57) of patients. 38 SNPs across 4 genes were identified. Multivariate logistic regression, controlling for sex age, and initial severity found AP2M1 rs8478 and rs2231224 minor allele variants significantly increased the odds of PTE (p<0.05, OR=2.21 and 2.19, respectively). CLTA rs4879960 major allele variant significantly reduced odds of poor outcome on 6-24mo DRS (p<0.05, OR<0.6). 6 Syt1 minor allele variants significantly reduced odds of poor outcome on 12mo GOS (rs1405499, rs1918193, rs1918191, rs1245804, rs1245824 and rs2272500, p<0.05, OR<0.5). This study found an association between three synaptic neurotransmission genes and PTE or long-term outcome in a sTBI population. Identification of these genetic variants may improve early identification of patients at high-risk for PTE. Further work aims to determine the implication of these polymorphisms on protein function and pathological mechanisms. (NIH-NS124730-SWC).

Ms. Odunayo Oluokun¹, Joy Solomon¹, Moyinoluwa Adeniyi¹, Sherifdeen Onigbinde¹, Mojibola Fowowe¹, Federico Moro², Teresa Ravizza², Firas Kobeissy³, Pavel Klein⁴, Elisa Zanier², Kevin Wang³, Yehia Mechref¹

¹Texas Tech University, Lubbock, United States, ²Mario Negri Institute for Pharmacological Research IRCCS, Milan, Italy, ³Center for Neurotrauma, Multiomics and Biomarkers (CNMB), Neuroscience Institute, Morehouse School of Medicine (MSM), Atlanta, United States, ⁴Mid-Atlantic Epilepsy and Sleep Center, Bethesda, United States

Epileptogenesis, the process leading to recurrent, unprovoked seizures, emerges as a critical complication following traumatic brain injury (TBI). Evidence suggests a direct link between the severity of TBI and the increased risk of developing post-traumatic epilepsy (PTE). Glycans are crucial for neurological functioning, thereby accruing attention over time due to the roles they play. This study aims to shed light on glycome alterations accompanying PTE, which could improve the development of targeted treatments. Utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS), we analyzed serum samples from three groups: “healthy” individuals, TBI patients without PTE (PTE-), and TBI patients with PTE (PTE+). Our analysis revealed significant alterations across these groups. Between the control and PTE+ groups, 49 glycans showed significant changes: 19 were upregulated, and 30 were downregulated (p-value < 0.05). The comparison between control and PTE- individuals identified 66 significantly altered glycans, with 27 upregulated and 39 downregulated. Notably, the direct comparison between PTE+ and PTE- groups highlighted fewer changes, with 18 glycans significantly differing with four upregulated and 14 downregulated. Five significant glycans were observed to be downregulated across all comparisons while two significant glycans were observed to be upregulated across all comparisons. These findings give insight into changes in the glycans in serum from PTE patients, which could further enhance the understanding of the complex pathological process of TBI progression to PTE.

This work was supported by grants from the National Institutes of Health, NIH (1R01GM130091), the Robert A. Welch Foundation grant number D-0005 (YM), and The CH Foundation.

Dr. Kali Burke¹, Dr. Athanasios Alexandris², Dr. Vassilis Koliatsos², Dr. Amanda Lauer^1,3

¹Department of Otolaryngology – Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, United States, ²Department of Pathology – Neuropathology, Johns Hopkins University School of Medicine, Baltimore, United States, ³Department of Neuroscience Johns Hopkins University School of Medicine, Baltimore, United States

Traumatic brain injury (TBI) often leads to changes in hearing sensitivity, tinnitus, and hyperacusis. This may be due to trauma to the temporal bone caused by blunt force, traumatic axonal injury (TAI) from impulse loading, or acoustic overexposure at the time of injury. Our experiments characterized the changes in auditory system structure and function caused by a diffuse model of TBI (impact acceleration TBI) in two mouse genotypes. We first measured auditory sensitivity in male and female CBA/CaJ mice before and up to 3 months after IA-TBI using auditory brainstem response (ABR) evoked potentials. At randomly assigned endpoints, we defined pathology in the central and peripheral auditory after injury. These first results demonstrate that diffuse TBI causes an elevation of auditory thresholds, a decrease in ABR wave amplitudes, a delay in ABR wave latencies, TAI in nerves innervating cochlear hair cells, and degeneration in auditory nuclei of the brainstem and midbrain. We repeated the same study in Sterile alpha and TIR motif containing 1 (SARM1) knock-out (KO) mice that are resistant to Wallerian degeneration and compared with C57 wildtype (WT) littermate controls. We found that SARM1 KO mice do not show the physiological and pathological changes observed in WT mice in the central and peripheral auditory system, suggesting that negating SARM1 signaling may offer structural and functional protection after IA-TBI in the auditory system in diffuse TBI. This work provides valuable insights into our understanding of the structure-function link between TBI and auditory loss and raises important translational therapeutic prospects.

Dr. Daniela Lecca¹, Dr. Balaji Krishnamachary¹, Dr. Zhuofan Lei¹, Dr. Yuanyuan Ji², Niaz Khan¹, Dr. Liwen Lei¹, Dr. Hui Li¹, Dr. Jace W. Jones², Dr. Junfang Wu¹

¹University of Maryland School of Medicine, Baltimore, United States, ²University of Maryland School of Pharmacy, Baltimore, United States

Traumatic brain injury (TBI) in the elderly population results in worsened neurological outcomes and increased mortality. Cellular senescence has been linked to chronic neurodegeneration after TBI. Recent advances have identified extracellular vesicles (EVs) as a critical mediator of cellular senescence. EVs contain proteins, lipids, and microRNAs from their originating cells, which when delivered to recipient cells can alter their function and contribute to both physiological and pathophysiological processes. Here we investigated the impact of TBI on EVs and the effects of circulating EVs in aged mice. Young adult or aged male mice received controlled cortical impact (CCI) surgery. After 24h, plasma EVs were isolated by ultracentrifugation and EV cargoes were examined. In vivo, plasma EVs derived from young (sham or TBI) or aged (sham or TBI) mice were systemically administrated into naïve aged mice; neurological functions were then assessed. We demonstrated that EVs from TBI-challenged aged mice expressed different proteins, lipids, and microRNAs compared to young TBI animals. Specifically, these changes related to components associated with cell cycle perturbation and cell senescence. While intact aged mice receiving young EVs showed improvement in physical strength and working memory indicating rejuvenation, TBI-derived EVs from both young and aged animals impaired overall well-being and cognitive function of intact aged mice. Moreover, TBI-derived EVs priming aggravated naïve aged mice in response to a subsequent mild brain injury. These results are the first to describe changes in circulating EVs after TBI and in aged animals and support a potential EV-mediated mechanism for TBI-induced systemic changes.

Ms. Erin Anderson¹, Mr. Daunel Augustin¹, Mr. Taehwan Kim¹, Ms. Anastasia Georges¹, Dr. David Issadore¹, Dr. David Meaney¹

¹University Of Pennsylvania, Philadelphia, United States

Although blood-based biomarkers can rapidly and noninvasively diagnose concussion, they provide poor prognostic value. Moreover, these blood-biomarkers offer no insight into the history of injury exposure, which can significantly affect diagnostic accuracy. In this study, we examined differences in miRNA expression from neuron-derived extracellular vesicles (NDEVs) to distinguish between complex factors affecting head injury outcome. To do so, we used closed-head CCI to deliver sham, simple concussion, or subconcussive-preconditioned concussion to adult male mice. At 9 days post injury, we performed contextual fear conditioning and collected blood serum for miRNA sequencing from NDEVs. Twelve (12) miRNAs survived FDR correction (Q<0.1) to distinguish either concussion or preconditioned concussion from sham. Of those 12 miRNAs, only miR-206-3p distinguished both simple concussion and preconditioned concussion from each other and sham (q<0.1), suggesting its utility in differentiating between exposure histories. An additional 3 miRNAs (miR-146a-3p, miR-187-3p, miR-200b-3p) associated with fear conditioning response (Pearson correlation; r = 0.44 to 0.58, p < 0.05). After depleting microglia prior to injury, 3 of the 12 original differentially expressed miRNAs (miR-184-3p, miR-3535, and miR-8117) were no longer significantly different, indicating an indirect relationship between microglia and neuron-derived biomarkers. Intriguingly, 8 new miRNAs emerged which correlated with fear conditioning response (Pearson correlation, p < 0.05), possibly reflecting microglia’s role in fear memory. Together, these results demonstrate both the initial brain exposure state, and interactions among cellular populations, can be inferred from miRNAs in NDEVs.

Dr. Aliyah Anderson, Ms. O’lisa Waithe, Mr. Saravanakumar Muthusamy, Ms. Gabriela Seplovich, Dr. Binu Tharakan

¹Morehouse School of Medicine, Atlanta, United States

The blood-brain barrier (BBB) is a semi-permeable and protective barrier of the brain, separating the circulating blood and brain parenchyma. The BBB is composed of densely connected endothelial cells held together by tight junction proteins. In pathological conditions, such as traumatic brain injury (TBI), disruption of the BBB causes leakage of solutes and fluids into the brain parenchyma, leading to cerebral edema formation and intracranial pressure elevation. Recent studies from our lab show evidence for the involvement of NLR family pyrin domain containing 3 (NLRP3) inflammasome in promoting BBB dysfunction following traumatic brain injury. Extracellular ATP via its purinergic receptor, P2X7R, promotes NLRP3 inflammasome activation. Once activated, the NLRP3 inflammasome recruits proinflammatory caspase-1 and subsequent activation of matrix metalloproteinase-9 (MMP-9), which disrupts tight junction proteins. The objective of this study was to determine if melatonin, previously established as an MMP-9 inhibitor in our lab, will inhibit ATP-NLRP3 inflammasome pathway. Benzyl ATP (BzATP) was used to activate P2X7 receptors and subsequently activate the NLRP3 inflammasome. Rat and human brain endothelial cells were utilized. Bz-ATP treatment induced BBB tight junction disorganization evidenced by zonula occludens-1 (ZO-1) immunofluorescence and monolayer hyperpermeability (FITC-dextran extravasation) without affecting ZO-1 protein (immunoblot) or gene expression (RT-PCR analysis). Pharmacological inhibition of this pathway via melatonin resulted in the protection of the tight junctions and barrier functions/permeability. Furthermore, melatonin inhibited Bz-ATP-induced MMP-9 activity (fluorometric assay) significantly. These results suggest that one of the mechanisms by which melatonin protects the BBB, is via inhibiting purinergic signaling and NLRP3 inflammasome pathway.

Dr. Nurul Sulimai¹, Mr Jason Brown, Professor David Lominadze

¹University Of South Florida, Tampa, United States

Oxidative stress has been implicated in neural dysfunction and degeneration during traumatic brain injury (TBI). TBI is an inflammatory disease that is associated with an increased blood level of proinflammatory factor fibrinogen (Fg). We have previously shown that Fg induced an increase in the generation of reactive oxygen species (ROS) and nitric oxide in astrocytes and neurons, with an addition of enhanced production of mitochondrial superoxide in neurons in vitro. These effects of Fg were ameliorated by inhibiting Fg’s interaction with these cells. In the current study, we tested the specificity of Fg-induced generation of ROS in cultured neurons and the effects of a reduced blood level of Fg on neuronal oxidative damage during TBI. Inhibiting the generation of ROS with caffeic acid phenethyl ester (CAPE) significantly reduced the Fg-induced generation of ROS and neuronal death in vitro. A TUNEL assay and staining with NeuN showed less apoptosis and cell death in brain samples from transgenic heterozygous Fg γ-chain-deleted (Fg γ+/-) mice during TBI compared to those in control C57BL/6J wild type (WT) mice. This effect was further decreased in mice treated with CAPE. Short-term memory assessed with the novel object recognition test was also better in Fg γ+/- mice 14 days after head injury compared to that in WT mice. Treatment with CAPE also had an ameliorative effect. Combined, our results suggest that an elevated blood level of Fg has a significant effect in neurodegeneration during TBI through enhanced formation of ROS in the brain cells.

Ms. Kathryn Jacobson¹, Hailong Song¹, Yue Qiu¹, Doulgas Smith¹

¹University Of Pennsylvania, Philadelphia, United States

Large-scale tissue deformation occurs during traumatic brain injury (TBI) and is known to physically injure brain cells (i.e. diffuse axonal injury). Along with cellular injury, the dynamic deformations from TBI may cause physical damage to the structural networks surrounding the cells, commonly referred to as the interstitial extracellular matrix (ECM). In other tissue injuries (e.g. tendon rupture, skin wound healing), damaged ECM networks undergo remodeling as part of the tissue repair response. However, the process of ECM remodeling in the brain induced by TBI remains unknown. Here, we conducted preliminary studies to assess the murine brain for changes in the ECM immediately and 24-hours after fluid percussion injury. Specifically, we used immunohistochemistry to examine changes in distribution of thrombospondin-4, an adhesive glycoprotein associated with ECM remodeling, 24-hours after injury. Thrombospondin-4 was broadly distributed throughout the gray and white matter in both injured and sham animals (n=3). Interestingly, there was increased enrichment of thrombospondin-4 surrounding select cells in the gray matter of injured brain tissue, indicating that this ECM might be synthesized after injury. Additionally, thrombospondin-4 outlined axons in the white matter of sham brains, but these cellular structures were generally less defined after injury. We suspect this is associated with ongoing axon degeneration, but the persistence of thrombospondin-4 could indicate that these networks are interstitial and do not degrade with cell degeneration. Additional experiments will map the ECM composition of the gray and white matter as a function of injury and recovery.

Dr. Mojtaba Golpich¹, Dr. Zhihui Yang^2,3, Dr. Haiyan Xue^2,3, MD. Rawad Daniel Arja¹, Dr. William Haskins⁴, Dr. Federico Moro⁵, Dr. Rossella Di Sapia⁵, Dr. Annamaria Vezzani⁵, Dr. Teresa Ravizza⁵, Dr. Elisa R. Zanier⁵, Dr. Kevin K. Wang^1,2,3,6, Dr. Firas Kobeissy^1,2,3,6

¹Center for Neurotrauma, MultiOmics & Biomarkers (CNMB), Department of Neurobiology, Neuroscience institute, Morehouse School of Medicine, Atlanta, United States, ²Department of Emergency medicine, University of Florida, Gainesville, United States, ³Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, North Florida / South Georgia Veterans Health System, 1601 SW Archer Road, Gainesville, United States, ⁴Gryphon Bio, Inc., 611 Gateway Blvd. Suite 120 #253, South San Francisco, United States, ⁵Department of Acute Brain and Cardiovascular Injury, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy, ⁶Center for Visual & Neurocognitive Rehabilitation (CVNR), Atlanta VA Health Care System 1670 Clairmont Rd, Decatur, United States

Post-traumatic epilepsy (PTE), a serious consequence of traumatic brain injury (TBI), accounts for a substantial proportion of epilepsy cases. The prediction and diagnosis of PTE remain challenging due to the lack of reliable tools, underscoring the importance of identifying predictive biomarkers. In this study, we investigated the role of microRNAs (miRNAs) as indicators of epileptogenesis, the process leading to epilepsy utilizing a TBI mouse model. We collected cortical tissue and blood samples from TBI-induced mice at six months post-injury. We conducted miRNA analyses focusing on a panel of miRNAs relevant to neurology, aiming to differentiate between mice that developed PTE (PTE+) and those that did not (PTE-). Our study identified significant discrepancies in five cortical miRNAs and four in plasma when contrasting PTE+ with PTE- mice. Notably, in the ipsilateral cortex of PTE+ mice, mir-342 levels were lower compared to PTE- mice and controls, whereas mir-125-5p levels were diminished in PTE- compared to PTE+ mice. Similar patterns of miRNA expression were found in the contralateral cortex and in plasma, with certain miRNAs being reduced in PTE+ mice and one miRNA being elevated. These altered miRNAs are linked to pathways critical to cell survival and stress responses, including apoptosis and oxidative stress. These pathways are integral to epileptogenesis, suggesting the miRNAs could serve as potential biomarkers. By identifying miRNAs that differ in expression between PTE+ and PTE- mice, the study offers a promising direction for monitoring and potentially predicting PTE following TBI, illuminating potential targets for therapeutic intervention.

Dr. Hailong Song¹, Ms. Alexandra Tomasevich¹, Mr. Andrew Paolini¹, Mr. Kevin Browne¹, Dr. Kathryn Wofford¹, Dr. Brian Kelley¹, Mr. Eashwar Kantemneni¹, Mr. Justin Kennedy¹, Ms. Yue Qiu¹, Dr. Andrea Schneider¹, Dr. Jean-Pierre Dolle¹, Dr. D. Kacy Cullen¹, Dr. Douglas Smith¹

¹University Of Pennsylvania, Philadelphia, United States

Although human females appear be at a higher risk of concussion and suffer worse outcomes than males, underlying mechanisms remain unclear. With increasing recognition that damage to white matter axons is a key pathologic substrate of concussion, we used a clinically relevant swine model of concussion to explore potential sex differences in the extent of axonal pathologies. At 24 hours post-injury, female swine displayed a greater number of swollen axonal profiles and more widespread loss of axonal sodium channels than males. Axon degeneration for both sexes appeared to be related to individual axon architecture, reflected by a selective loss of small caliber axons after concussion. However, female brains had a higher percentage of small caliber axons, leading to more extensive axon loss after injury compared to males. Accordingly, sexual dimorphism in axonal size is associated with more extensive axonal pathology in females after concussion, which may contribute to worse outcomes.

Mrs. Michaela Breach¹, Brooke Schatz², Habib Akouri², Dr. Zoe Tapp¹, Alejandra Zaleta-Lastra¹, Ashley Walters², Dr. Cole Vonder Haar^3,4,5, Dr. Olga Kokiko-Cochran^3,4,5, Dr. Kathryn Lenz^2,3,4,5

¹Neuroscience Graduate Program, The Ohio State University, Columbus, United States, ²Department of Psychology, The Ohio State University, Columbus, United States, ³Department of Neuroscience, The Ohio State University, Columbus, United States, ⁴Chronic Brain Injury Program, The Ohio State University, Columbus, United States, ⁵The Institute for Behavioral Medicine Research, The Ohio State University, Columbus, United States

Traumatic brain injury (TBI) in the pediatric period increases the risk for long-term physical, cognitive, and psychosocial impairment. There are sex differences in long-term outcomes following pediatric TBI. The mechanisms through which pediatric TBI impacts sex-specific brain and behavioral development are not well understood. Methods: In this study, male and female Sprague Dawley rats received a lateral fluid percussion injury (1.2 atmospheres), sham surgery, or were undisturbed (naïve) on postnatal day 15. We assessed long-term behavioral outcomes and select neuroimmune and neuroanatomical endpoints that could be linked to behavioral alterations, including gliosis, brain mast cell number, oxytocin neurons and fibers, and perineuronal nets. Results: TBI increased mast cells relative to naïves at 3 days post-injury (DPI). By 7 DPI, TBI females had elevated mast cells relative to shams. Surgery increased microgliosis at 3 DPI and had sex-specific effects on astrogliosis. No effects were found on oxytocin or perineuronal nets. Regarding behavior, surgery increased rearing and had sex- and session-specific effects on play and allogrooming in juveniles. In adulthood, TBI reduced sociability relative to naïves in both sexes. Social avoidance was significantly increased in TBI females and reduced in TBI males. Conclusions: Pediatric TBI impairs adult social behavior in rats, and some acute and chronic outcomes may be more impacted in females.

Funding: R01NS130517 (KML); Brain Injury Association of America seed grant (KML); OSU Chronic Brain Injury Program Pilot Award (KML; OKC); NSF GRFP DGE-130 (MRB).

Mr. Adam Rayfield¹, Dr. Taotao Wu², Kyulee Kim¹, Daunel Augustin¹, Anastasia Georges¹, Jared Rifkin³, Dr. David Meaney¹

¹University Of Pennsylvania, Philadelphia, United States, ²University of Georgia, Athens, United States, ³University of Virginia, Charlottesville, United States

While modern brain imaging has been used to associate patterns of brain network differences with cognitive outcomes after TBI, a model which can describe how damaged brain connectivity causes functional impairment remains unclear. Recently, we applied a simplified computational model of brain dynamics in the mouse to simulate functional connectivity disruptions caused by lesions to different brain regions. Using these results, we hypothesized that the degree of cognitive impairment after brain lesions in mice may be predicted by simulated functional connectivity disruptions. We targeted four different mouse brain regions in vivo for ibotenic acid lesions or sham injections, then measured behavior in all individual mice using the open field test, spatial object recognition, novel object recognition, and contextual fear conditioning. Next, we applied principal component analysis to these behavioral features and used a support vector machine classifier to identify individual mice as lesion or sham condition. We examined how differences in leave-one-out cross validation accuracy varied among target regions and how these differences related to our simulations. We found that we could classify lesions accurately for CA1 injections (Accuracy = 1.00), but less accurately for frontal pole cortex (Accuracy = 0.84), lateral entorhinal cortex (Accuracy = 0.70), and caudoputamen (Accuracy = 0.65) lesions. These values correlated strongly with simulated functional connectivity disruptions to hippocampal regions (R² = 0.94, p = 0.03), suggesting that the degree to which brain injuries impair cognition involving other regions of the brain is dependent on network-level communication.

DR. Hiren Modi¹, DR. Sudeep Musyaju¹, MS. Meaghan Ratcliffe¹, DR. Deborah Shear¹, DR. Anke Scultetus¹, DR. Jignesh Pandya¹

¹Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, USA

Traumatic brain injury (TBI) is a major global health problem that affects both the military and civilian populations worldwide. Post-injury acute and chronic progressive secondary injury processes may contribute to neurodegeneration. Currently, there are no FDA-approved therapeutic options available for TBI to curb its progressive pathophysiology. Antioxidant therapy may serve as one potential therapeutic, as it has shown promise in improving overall health conditions. Recent advances in TBI preclinical research have identified depletion of endogenous antioxidant levels and mitochondrial functions following TBI, suggesting that antioxidant supplementation may mitigate secondary injury progression. Natural antioxidants are capable of alleviating TBI oxidative stress pathology progression, thereby preserving mitochondrial and cerebral functional integrity. Efforts are underway to evaluate synthetic antioxidants, which may offer targeted drug delivery and enhance bioavailability. This comprehensive review analysis mitochondria-targeted antioxidant therapy for TBI, compiling neuroprotective antioxidants to add potential therapeutic value in TBI management by targeting mitochondria. These antioxidants include natural vitamins and minerals (alpha-Tocopherol, Vitamins A, C, and E, Selenium), antioxidant precursors (cysteine, N-acetylcysteine), phytochemicals (flavonoid, curcumin, quercetin, resveratrol), and synthetic targeted compounds (e.g., MitoQ, dendrimer-tagged N-acetylcysteine, Mito-Vit K, Mito-tempol, Edaravone, Plastoquinone). Scientific interest has transitioned from traditional antioxidant vitamins and minerals to a stronger focus on synthetic antioxidants, endogenous signaling pathways activators, and mitochondria-targeted therapy, including compounds like Omaveloxolone, Dimethyl Fumarate, and Sulforaphane. The listed mitochondria-targeted antioxidants, both natural and synthetic, may serve as pipeline products for FDA approval and potential treatment options for point-of-injury and TBI management.

Support: US_Army_CCCRP_H_001_2018 and CO240012_WRAIR.

DR. Jignesh Pandya¹, DR. Sudeep Musyaju¹, DR. Hiren Modi¹, DR. Deborah Shear, DR. Anke Scultetus

¹Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, USA

Targeting drugs to the mitochondrial level shows excellent promise for acute and chronic treatment of traumatic brain injury (TBI) in both military and civilian sectors. The greatest obstacle to successfully delivering therapies to the central nervous system (CNS) is the blood-brain barrier (BBB) permeability. The intranasal drug delivery approach holds a great promise for treating CNS disorders, as this route is non-invasive, bypasses the BBB, enhances bioavailability, and reduces systemic adverse effects. Herein, based on a literature search spanning the past several decades, we highlighted the advantages of intranasal administration over conventional routes for TBI. We searched research articles exclusively published in peer-reviewed journals. The keywords used in the literature search were “Intranasal drug AND Mitochondria AND Traumatic Brain Injury AND CNS Disease”. Approximately 18200 articles were identified based on keyword search. After filtering through the layers of inclusion criteria, 24 potential compounds were identified. Our findings suggest that the most considerable promise lies in the intranasal delivery of antioxidants such as nicotinamide mononucleotide, resveratrol, and mitoquinone. The intranasal route could offer a solution to poor oral absorption of neuroprotective compounds like quercetin, curcumin, gallotannin, and tetrandrine. Additionally, compounds with a short half-life, like insulin, apelin-13, ginsenoside Rg3 and cyclin D1 may achieve better bioavailability following intranasal administration. Further, clinically relevant drug administration route for mitochondria-targeting compounds is warranted to optimize pharmacological properties of neuroprotection therapeutics using animal models of TBI.

Support: US_Army_CCCRP_H_001_2018 and CO240012_WRAIR.

Dr. Kimberly Byrnes¹, Dr. Karin Pedemonte¹, Alison Gregor¹, Dr. William H. Frey II²

¹Uniformed Services University, Bethesda, United States, ²Neuroscience Center, HealthPartners Institute, Minneapolis, United States

Intranasal insulin (INI) can rapidly enter the central nervous system to increase glucose uptake and improve functional outcomes in models of traumatic brain injury (TBI) and Alzheimer’s Disease. We have previously shown that acute administration of INI improved outcome after moderate and mild TBI. However, the therapeutic window of INI in these models was unclear. We therefore assessed the effects of INI in a mild, open skull model of lateral fluid percussion (LFP) injury in young adult Sprague Dawley rats. Young adult (3 month) male Sprague-Dawley rats underwent a mild (1atm) LFP and received 7 daily intranasal administrations of insulin or saline starting at 4 hours, 7 days or 28 days post injury. Assessment of INI target engagement acutely after administration showed elevated phosphorylation of AKT and IRS2. While the mild LFP model did not significantly affect motor function or learning and memory, significant increases in anxiety-like behavior were noted in the TBI group treated with saline. However, administration of INI at 4 hours or 7 days post-injury significantly ameliorated this injury response, restoring or improving outcomes toward naïve-like function on the Open Field task, Light Dark Box, and Nesting score. Preliminary analysis showed that INI also led to marked reductions in microglia/macrophage presence in the corpus callosum, hippocampus, and hypothalamus by 28 days post-injury. No significant improvement in any measure was found in the 28 day treatment group. These data demonstrate that INI significantly improves outcome with a therapeutic window up to at least 7 days post-injury.

Katelyn Martino¹, Laura Milovic¹, Joe Kalish¹, Sarah Marcum¹, Ashley Thayaparan¹, Maurice Linder-Jackson¹, Arush Nakhre¹, Dr. Renee Demarest¹, Dr. David Devilbiss¹

¹Rowan-Virtua School of Translational Biomedical Engineering & Sciences, Stratford, United States

Mild traumatic brain injury (mTBI), or concussion, is a critical health and economic issue affecting approximately 3 million Americans each year. Mild TBI is a complex pathophysiological process resulting in behavioral and cognitive deficits including impaired arousal, attention, decision-making, and other executive functions. Repeated mTBI can produce more severe, longer-lasting cognitive impairments and brain damage than single injuries and can result in outcomes similar to severe TBI. Although symptoms can resolve within a week, evidence indicates that symptoms can persist for 3 months or more. Moreover, chronic impairment of these higher cognitive processes are central to patient difficulties returning to work and activities affecting quality-of-life.

Dihexa is an angiotensin IV-derived peptide that acts as a positive modulator of the hepatocyte growth factor/c-Met (HGF/c-Met) receptor system. Dihexa has previously been shown to stimulate neurogenesis, be neuroprotective, and enhance cognitive function in rodent models of neurodegenerative disease. We hypothesize that following mTBI, enhancing c-Met signaling can improve cognitive impairment and act as a neuroprotectant. We found procognitive effects of dihexa on performance in the T-maze test of working memory and observed changes in markers of axonal integrity following dihexa treatment. Together these data support the hypothesis that activating the HGF/c-Met system can improve cognitive impairments after mTBI. These findings provide critical insight into a new therapeutic strategy for repeated mild TBI and support for the role of the HGF/c-Met system in rescuing the cognitive deficits resulting from repeated injury.

Dr. Karen-amanda Irvine^1,2, Dr. David Clark^1,2

¹Stanford University, Stanford, United States, ²Palo Alto Veterans Institute for Research, Palo Alto, United States

Chronic pain is one of the most challenging and debilitating symptoms to manage after traumatic brain injury (TBI). The disruption of normal endogenous pain control mechanisms has been linked to several forms of chronic pain and may play a role in pain after TBI. In rodent models, changes in nociceptive signaling after TBI manifest in two distinct phases. The initial serotonin-dependent phase occurs within 24hrs of TBI and involves mechanical allodynia of the hindlimbs dependent on spinal 5-HT3 receptors that resolves within a month of injury. This is followed by a more slowly developing second phase characterized by the failure of a critical endogenous pain control mechanism known as diffuse noxious inhibitory control (DNIC). Enhancement of descending serotonergic signaling was shown to restore the DNIC response in male TBI rats via the 5-HT7 receptor. To address the possibility of sex differences, we repeated these TBI studies in female rats. We observed that the nociceptive changes after TBI in female rats also manifested in two distinct phases and that the initial phase was also serotonin-dependent. In contrast to the males, however, the second phase was not restored by enhancing serotonergic signaling via treatment with the selective serotonin reuptake inhibitor, escitalopram. Enhancement of descending noradrenergic signaling via the noradrenalin reuptake inhibitor, reboxetine, restored the DNIC response in female TBI rats but failed to do so in male TBI rats. These studies provide evidence of sexual dimorphism in pain mechanisms after TBI. Sex-specific approaches to treatment of pain after TBI may be required.

Dr. Carlos A. Dallera¹, Dr. Patrizzia Mastromatteo-Alberga¹, Dr. Fabiola Placeres-Uray¹, Maria Dominguez Torres¹, Dr. Ying Xu², Dr. Coleen M. Atkins¹

¹University of Miami Miller School of Medicine, Miami, United States, ²Rutgers, The State University of New Jersey, Newark, United States

The mechanisms underlying learning and memory deficits associated with traumatic brain injury (TBI) and Alzheimer’s disease (AD) remain poorly understood. Inhibition of phosphodiesterase 2A (PDE2A), a signaling molecule involved in synaptic plasticity and inflammation, has been demonstrated to improve memory in mouse models of AD. Administration of the selective PDE2-inhibitor Bay60-7550 has also shown protective effects from β-amyloid neurotoxicity. In this study we explored the effects of Bay60-7550 in rescuing learning deficits after mild TBI in a presymptomatic AD mouse model. At age 2-months wild-type C57BL/6 and APP/PS1 mice received mild controlled cortical impact (mCCI: 2m/sec, 0.55mm depth) or sham surgery followed by treatment with vehicle (5% DMSO, 5% saline solution) or Bay60-7550 (3 mg/kg, i.p.) for 14 days. Study endpoints were assessed 2 months post-injury. Cognition was assessed via cue and contextual fear conditioning. APP/PS1+mCCI+Vehicle mice exhibited significantly less cue and contextual fear memory retention compared to APP/PS1+Sham+Vehicle, WT+mCCI+Vehicle, and WT+Sham+Vehicle mice (Context p<0.001; Cue p<0.05). Treatment of APP/PS1+mCCI mice with Bay60-7550 significantly improved retention in both cue and contextual fear memory (p<0.001). Electrophysiology recordings of the Schaffer collateral-CA1 synapse in the ipsilateral hippocampus were obtained. There was a significant long-term potentiation (LTP) deficit in APP/PS1+mCCI+Vehicle mice compared to WT+Sham+Vehicle (p<0.01) and APP/PS1+mCCI+Bay (p<0.001) groups. LTP in APP/PS1+mCCI+Bay animals was significantly improved as compared to APP/PS1+mCCI+Vehicle (p<0.001) and similar to WT+Sham+Vehicle and APP/PS1+Sham+Vehicle groups. These results demonstrate that PDE2 inhibition improves learning and memory and reverses hippocampal synaptic plasticity deficits in a mouse model of AD following mild TBI.

Dr. Ramesh Raghupathi¹, Ms Tiffany Briscoe, Dr Dana Lengel, Ms Joya Maser, Ms Dayani Pillai, Dr Jimmy Huh

¹Drexel University, Philadelphia, United States

Long-term deficits in psychosocial and cognitive behaviors are a significant consequence of traumatic brain injury (TBI) in children under the age of 3. Previous treatment approaches in animal models aimed at reducing inflammation and neurodegeneration in the acute phase (hours to days) following TBI have shown limited success or exacerbated the pathophysiology in the chronic period. Administration of progesterone in the first week after neonate TBI improved object recognition memory (ORM) in adolescence which was associated with reversal of deficits in the excitation/inhibitory balance in the medial prefrontal cortex but did not affect risk-taking behaviors. We extended this observation to assess social behavior deficits and examined whether delaying progesterone treatment until adolescence would be effective in reducing psychosocial and cognitive deficits. Male and female rat pups received a TBI at 11 days of age (n=88) with sham animals not receiving an injury (n=62). When either sesame oil (vehicle) or progesterone (16mg/Kg/injection) was administered over the first 7 days after injury, both sham- and brain-injured animals exhibited deficits in social recognition memory (SRM) when tested at 5 weeks after injury (p<.05 compared to naïve animals). Delaying progesterone administration until the 4th week after injury reduced both SRM deficits (p<.05) and risk-taking behaviors (p<.03); however, progesterone impaired ORM in both sham- and brain-injured animals (p<.03). Evaluation of microglial activation revealed a modest reduction of ED-1 labeled cells in white matter tracts and thalamus below the impact site. These findings underscore the complexity of treatment strategies targeting the developing brain after traumatic injury.

Dr. Regina Armstrong¹, Xiaomei Zi, Dr. Kryslaine Radomski

¹Uniformed Services University Of The Health Sciences, Bethesda, United States

Traumatic brain injury (TBI) is a significant public health concern, with axonal injury being a pivotal contributor to its long-term sequelae. No available treatments mitigate the progression of axonal injury processes that can lead to dysfunction of neural circuits. Based on our findings of disrupted axon-myelin interactions after TBI, we evaluated repurposing of the potassium channel blocker, 4-aminopyridine (4-AP), to mitigate early TBI-induced axonal damage. Adult mice received a closed skull concussive TBI followed by 4-AP (0.5 mg/kg, i.p., b.i.d) treatment initiated at 24 hours continuing until day 7. Experiments in male and female mice were blinded and randomized with controls for sham injury and vehicle treatment. Two forms of axon damage were evaluated using measures applicable in mouse and human neuropathology. 4-AP therapy significantly reduced axonal injury in the corpus callosum based on β-APP immunolabeling (p = 0.0004), as the clinical neuropathological “gold standard”, and node of Ranvier disruption (void nodes p = 0.0115; heminodes p = 0.0001), which identifies a potentially reversible early phase of axon damage. The clinically used Simoa® biomarker assay of serum neurofilament light (NfL) protein levels effectively detected axonal injury (p < 0.0001), but was not a sensitive measure of the 4-AP therapeutic effect. Low-dose 4-AP did not induce seizures, which is a potential adverse effect that may have increased risk after TBI. These findings of acute 4-AP efficacy and safety using translational measures support further evaluation for 4-AP repurposing to TBI as a new clinical indication. (Support from CDMRP W81XWH-21-2-0040).

Dr. Ping Wang¹, Dr. Joseph Dwyer¹, Xiaofang Yang¹, Ying Cao¹, Alan Giglio³, Fangzhou Yang¹, DR. Ping Wang¹, Alexandru Korotcov², Dr. Zachary Bailey¹, Dr. Victor Rodgers³, Dr. Anke Scultetus¹

¹Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, USA, ²Biomedical Research Imaging Core at Uniformed Services University, Bethesda, USA, ³Department of Bioengineering, University of California, Riverside, Riverside, USA

A lack of effective therapeutics for traumatic brain injury (TBI)-induced cerebral edema represent a critical gap in triage situations. Animal studies show that an osmotic transport device (OTD) can reduce acute edema development by removing water via osmosis through surface treatment of edematous tissue. The objective of this study was to examine the effects of OTD treatment on cerebral edema, intracranial pressure (ICP) and neuropathology following penetrating TBI (pTBI). Using a rat model of pTBI (n = 8-10), ICP and mean arterial pressure (MAP) were measured prior to and following right unilateral pTBI, with or without OTD treatment, from 1 to 5hr post-injury. Cerebral edema was measured using the wet-dry method right after ICP recording. The impact of OTD on cerebral edema progression was characterized by MRI during and following a 72hr treatment while lesion volume, neuroinflammation, and neuronal damage were assessed by post-experimental histology. ICP was decreased in the hypertonic treated group compared to both isotonic and pTBI-only controls but change was not statistically significant. OTD treatment with isotonic or hypertonic fluid elicited a statistically significant reduction in brain water content in the ipsilateral hemisphere when compared to the injury only condition (p<0.05). Histological assessment demonstrated a significant reduction of IBA1 levels in the striatum (p<0.05), and silver stain analysis indicated a trending reduction of neuronal damage. These results provide preliminary evidence that OTD treatment following pTBI has the potential to reduce ICP and improve neuropathologies. This work was supported by a DOD grant from the USAMRDC/MTEC.

Dr. Meghan Blaya¹, Yelena Pressman¹, MaryLourdes Andreu¹, Dr. Nadine Kerr¹, Aisha Khan¹, Dr. Helen Bramlett^1,2, Dr. William Dietrich¹

¹University Of Miami Miller School Of Medicine, Miami, United States, ²Bruce W. Carter Department of Veterans Affairs Medical Center, Miami, United States

Traumatic brain injury (TBI) is a significant global challenge, encompassing a spectrum of debilitating cognitive and neurological impairments. There is a lack of effective treatments to address this public health concern. Exosomes are small, secreted vesicles that play crucial roles in intercellular communication. They have garnered significant attention for therapeutic applications given their ability to cross biological barriers, deliver bioactive molecules to target cells, and modulate cellular function to promote repair. Exosomes derived from human Schwann cells (hSC) are a potent option as they have shown to facilitate axonal regeneration and inhibit inflammatory responses. However, their contribution to neuroprotection and repair after TBI remains to be delineated. Our objective was to investigate outcomes in a rat model of moderate fluid percussion injury (FPI) with jugular infusion of hSC-exosomes 30min after trauma. We assessed inflammasome activation at 24h post-TBI, as well as brain edema, contusion volumes, and degree of activated microglia at 72h post-TBI. Using Western blotting, we found a significant attenuation of apoptosis-associated speck-like-protein (ASC), caspase-1, and interleukin-1β (IL-1β) proteins in the ipsilateral cerebral cortex with hSC-exosome administration. At 72h, there were significant reductions in brain water content with exosome treatment, indicative of decreased brain edema. Furthermore, using immunohistochemistry and automated stereological quantification, we found that hSC-exosomes reduced cortical contusion and mitigated proinflammatory microglia activation towards a more anti-inflammatory ramified state. Our results indicated that acute intravenous administration of hSC-derived exosomes after FPI is a viable and potent option to target the multifaceted pathophysiology of TBI.

Support: NIH/NINDS 4RF1NS125578; 1R37NS133195.

Dr. Brenda Bartnik Olson¹, Rhideeta Jalal², Maria Recio³, Margie Carson⁴, Khongmany Wells⁴, Kyrstle Salvador³, Duc Tran³

¹Department of Radiology, Loma Linda University, Loma Linda, United States, ²Department of Psychology, Loma Linda University, Loma Linda, United States, ³Department of Physical Medicine and Rehabilitation, Loma Linda University Medical Center, Loma Linda, Un, ⁴Department of Nutrition and Dietetics, Loma Linda University, Loma Linda, United States

Traumatic brain injury (TBI) is caused by rapid acceleration-deceleration shearing forces on the structural and functional components of the brain leading to progressive brain volume loss. The aim of this study is to investigate the therapeutic potential of a ketogenic diet (KD)/modified Atkin’s diet (MAD) in moderate-severe TBI patients when administered during the early sub-acute post-injury period of inpatient rehabilitation. The rationale for our approach lies in the success of KD/MAD as a therapy in experimental models. This study provides a “first-look” at the effect of KD/MAD on brain structure following moderate-severe TBI - determining whether its effects outlast the duration of the diet. We acquired 3D structural T1 weighted (MPRAGE) MR images in 11 moderate-severe TBI patients and 5 healthy age-matched controls at 3 time points spanning a 9-month period in the sub-acute post-injury stage. TBI subjects were randomized into regular diet (RD) or KD/MAD diet following their baseline imaging. The dietary intervention started 26-47 days post-injury and lasted for 18 days. Brain volume was measured using the FreeSurfer recon-all pipeline (https://surfer.nmr.mgh.harvard.edu/fswiki/recon-all). At 6-months post injury KD/MAD subjects had higher regional brain volumes, including the left hippocampus (p=.04), brainstem (p =.02), and left cerebral white matter (p=.05), compared to RD subjects. Preliminary findings suggest that the neuroprotective and anti-inflammatory effect of ketogenic and modified Atkin’s diets contributes to preserved grey and white matter volumes following TBI.

Ms. Emily H. Thomas¹, Lajos Z. Szabò², William J. Flerlage¹, Christorpher R. Apostol², Troy E. Smith², Shawn Gouty¹, Brian M. Cox¹, Robin Polt², Fereshteh S. Nugent¹

¹Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, United States, ²Department of Chemistry and Biochemistry, The University of Arizona, Tucson, United States

The vast majority of traumatic brain injury are mild (mTBI). Stress-related disorders are frequently present and have a potentially life-threatening impact on mTBI patients’ quality of life and perceived symptom severity. Enhancing the pituitary adenylate cyclase-activating polypeptide (PACAP) in the brain is shown to exert neuroprotective and neurotrophic effects in pathological conditions associated with PACAP deficiency such as aging, neurodegenerative disorders as well as traumatic brain injury. Whether PACAP can also provide neuroprotection on the negative effects of mTBI in mood-related brain circuits and associated affective and emotional dysregulation is unknown. In this study, we tested the preventive efficacy of a novel PACAP agonist with enhanced stability and blood-brain barrier penetration on long-term negative effects of mTBI on social and motivated behaviors through regulation of lateral habenula (LHb) activity (a critical brain region involved in pathophysiology of psychiatric illnesses including depression and anxiety) in male mice. Using an established preclinical repetitive closed head mouse model of mTBI in mice, we confirmed that mTBI resulted in LHb hyperexcitability in male mice a month after the injury. Moreover, our preliminary results show potential efficacy of the PACAP analogue in prevention of mTBI-induced LHb hyperexcitability and motivational deficits in self-care grooming behavior in sucrose splash test. Our study has the potential to provide translational validity for the use of novel PACAP agonists in prevention of mTBI-related reward circuit dysfunction and depression.

Support: USAMRAA Contract # HT94252320003.

Tiffany Sculthorpe¹, Achint Singh¹, Forum Mangrola¹, Ananya Nethikunta², Hana Choi², Dr. Mary Kosciuk³, Dr. Syed Ahmed⁴, Dr. Randel Swanson^5,6, Dr. Venkat Venkataraman^7,8, Dr. Robert Nagele^1,2,3,9, Dr. Jose Pascual⁴, Dr. Nimish Acharya^1,2,3,5,8,9

¹Rowan-Virtua School of Osteopathic Medicine (SOM), Stratford, United States, ²Rowan-Virtua Graduate School of Biomedical Sciences, Rowan University, Stratford, USA, ³Department of Geriatrics and Gerontology, NJISA, Rowan-Virtua SOM, Rowan University, Stratford, USA, ⁴Department of Neurosurgery, Center for Brain Injury and Repair, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA, ⁵Center for Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, USA, ⁶Department of Physical Medicine and Rehabilitation, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA, ⁷Department of Academic Affairs, Rowan-Virtua SOM, Stratford, USA, ⁸Department of Cell Biology & Neuroscience, Rowan-Virtua SOM, Stratford, USA, ⁹Rowan-Virtua School of Translational Biomedical Engineering & Sciences, Rowan University, Glassboro, USA

Background: The use of novel oral anticoagulants (NOACs) following traumatic brain injury (TBI) showed a reduced risk of TBI progression. In the controlled cortical impact (CCI) mouse model treated with NOAC Dabigatran (Pradaxa®), we observed significantly improved Garcia Neurological Test (GNT) scores. As Dabigatran is a thrombin-inhibiting anticoagulant, we investigated its role in modifying the expression of thrombin and its G-protein-coupled receptor, protease-activated receptor-1 (PAR-1). Since thrombin and PAR-1 are associated with inflammatory changes, we hypothesized that Dabigatran improved GNT scores through its anti-inflammatory effects. Therein, we also investigated the expression profile of GFAP, an astrogliosis marker.

Methods: Two-month-old male CD1 mice underwent CCI (impactor diameter-3mm, depth 1 mm, left hemisphere) and Dabigatran treatment (80 mg/kg, PO, TID, n=4) for two days and were euthanized. Brain tissues were harvested for routine paraffin embedding and immunohistochemistry along with controls: untreated (CCI-saline, n=5) and sham (craniotomy-saline, n=3). Sections comprising the hippocampus and cerebral cortex were probed with anti-thrombin, -PAR-1, and -GFAP antibodies. Blinded investigators conducted image analysis and comparisons between treatment groups.

Results: The Dabigatran-treated group demonstrated a significantly reduced number of PAR-1 immunoreactive neurons compared to the untreated group. On the contrary, we observed similar levels of thrombin and GFAP immunoreactivity in neurons and astrocytes, respectively, between the Dabigatran-treated and untreated groups.

Conclusion: Improved GNT scores in the Dabigatran-treated group may result from reduced PAR-1 expression and lowered PAR-1-mediated neuroinflammatory and neurodegenerative cellular signaling. Future studies using larger cohorts of PAR-1 knockout CCI mice are essential to validate these observations.

Ms. Helena Oft^1,2,3, Dr. Shamseldin Ayman Hassan Metwally^1,2, Mr. John P. Bielanin^1,2, Ms. Lin Lin^1,2, Ms. Victoria M. Fiesler^1,2,4, Ms. Lesley M. Foley⁵, Dr. T Kevin Hitchens⁵, Professor Shanshan Song^1,2,4, Professor Dandan Sun^1,2,4

¹University of Pittsburgh Department of Neurology, Pittsburgh, United States of America, ²Pittsburgh Institute for Neurodegenerative Disorders University of Pittsburgh, Pittsburgh, United States of America, ³Center for Neuroscience University of Pittsburgh, Pittsburgh, United States of America, ⁴Veterans Affairs Pittsburgh Health Care System, Pittsburgh, United States of America, ⁵Animal Imaging Center, University of Pittsburgh, Pittsburgh, United States of America

Over 55 million people globally suffer from mild traumatic brain injury (mTBI) each year. These injuries have been linked to chronic behavioral/cognitive deficits and to increased risk of developing neurodegenerative disease. However, the underlying mechanisms for mTBI-induced pathogenesis remain elusive. Oxidative stress and reactive oxygen species (ROS) have been shown to play key roles in repetitive (r-mTBI) pathogenesis. We previously reported that Na+/H+ exchanger protein 1 (NHE1) activity is associated with oxidative stress after ischemic stroke and mTBI. In this study, we sought to determine if NHE1 is critically involved in sustained white matter tissue damage, oxidative stress, and motor/cognitive deficits in a murine model of r-mTBI. C57BL/6J mice subjected to r-mTBI exhibited impaired motor learning and spatial memory performance 40 days post injury (dpi). These mice also show trends of reduced white matter tract integrity on ex vivo MRI/DTI. Increased NHE1 protein expression was detected across neuronal and glial cell types (astrocytes, microglia, oligodendrocytes) in cerebral cortex, corpus callosum, and hippocampus. These changes are accompanied by increased astrogliosis and degraded myelin. Compared to vehicle treated r-mTBI control, r-mTBI mice treated with NHE1 inhibitor HOE642 (at 9-15 dpi) displayed significantly improved motor/cognitive function. R-mTBI-induced astrogliosis and myelin damage were significantly reduced. MRI/DTI analysis revealed that HOE642 treatment restored white matter tract integrity. These findings suggest that NHE1 plays a critical role in r-mTBI pathogenesis. Targeting NHE1 represents a novel therapeutic strategy for mitigating mTBI-induced neuropathology and neurological function deficit.

Dr. Alexis Thompson¹, Manisha Ramprasad¹, Manda Saraswati¹, Paige Mathena¹, Dr. Shenandoah Robinson¹, Dr. Lauren L. Jantzie¹, Dr. C. David Mintz¹, Dr. Courtney Robertson¹

¹The Johns Hopkins Medical Institutions, Baltimore, United States

Following severe pediatric TBI, patients often have prolonged sedative exposure. Benzodiazepines can impair neurodevelopment and cognitive outcomes. We hypothesized that early, prolonged exposure to midazolam following pediatric TBI in immature rats would worsen cognitive, imaging and pathological outcomes.

Male Sprague-Dawley rats (postnatal day 17) were divided into four groups: naive, naive-sedation, TBI, and TBI-sedation (n=5-12/group). TBI groups underwent controlled cortical impact. Starting on post-injury day (PID) 1, sedation groups received 12 hours/day of midazolam with dosing based on a standardized sedation scale. Immunohistochemistry was performed on PID4. During PID60-100, rats completed a visual discrimination (VD) touchscreen task, and then ex-vivo brain MRI. Naïve, TBI and TBI-sedation were compared with one-way ANOVA test with p<0.05 considered significant.

Immunohistochemistry at PID4 showed reduced neuroinflammation (Iba-1, CD68 staining intensity) in ipsilateral thalamus (p<0.05, Tukey’s HSD), and reduced cell death (TUNEL, caspase-8) in ipsilateral peri-trauma cortex and dentate gyrus (p<0.05, t-test), in TBI-sedation rats compared to TBI alone. Compared to TBI, TBI-sedation rats had lower passing rates in VD (40 vs 20%). Preliminary MRI analyses demonstrated changes in white matter microstructure in both TBI groups, including abnormalities in fractional anisotropy and directional diffusivity compared to naïve rats.

Short-term studies suggested reduced neuroinflammatory and cell death markers with midazolam, which did not translate into improvements in executive function or white matter microstructure between the TBI and TBI-sedation groups. Future studies will include additional MRI and histologic analyses, and evaluation of synaptic integrity/density. Ultimately, these results could have implications on sedative choice following severe pediatric TBI.

Mr. Wenqian Shi^1,2, Mrs. Xinyue Wang^1,2, Mr. Pengzhan Zhao^1,2, Mr. Tian Wang^1,2, Mr. Yangfan Ye^1,2, Mr. Lei Xu^1,2, Mr. Honglu Chao^1,2, Mr. Jing Ji^1,2

¹Nanjing Medical University, Nanjing, China, ²The First Affiliated Hospital of Nanjing Medical University, Nanjing, China

Traumatic brain injury (TBI) is a great threat to human life, health and quality of life. However, there are still not enough effective drugs or treatments for TBI. Therefore, we aim to find one or more new therapeutic targets that can help TBI patients with neurological repair and functional rehabilitation. In this study, we used single nuclear RNA sequencing(snRNA-seq) to perform a detailed analysis of human brain tissue samples (TBI group: n=19; Control group: n=4) for TBI and controlled cortical injury (CCI) mice model. Because of neurons are more vulnerable after TBI, we selected neurons for differential expression gene analysis. In both human and mice tissues, the expression of NPAS4 after TBI significantly increased in neurons, especially in excitatory neurons, and was significantly different with the control group. Then, the results of qRT-PCR, Western Blot and immunofluorescence experiments were consistent. In vitro, glutamate was used to simulate the excitotoxic effects after TBI. The fluorescence intensity of Synaptophysin1 and PSD-95 demonstrated impaired synaptic function. The structure and function of synapses with NPAS4 knockdown were worse. In vivo, pAAV-hSyn-EGFP-shRNA (NPAS4) was injected to reduce NPAS4. Golgi staining and behavioral experiments showed sh-NPAS4+TBI group had less dendrite spine density and more severe cognitive impairment than sh-NC+TBI group. Next, CUT&Tag sequencing is to explore the downstream target genes of NPAS4. Therefore, we conclude that NPAS4 alleviates synaptic dysfunction and cognitive impairment after TBI, and it is expected to become a new and effective target for clinical treatment of TBI.

Dr. Fabiola Placeres-Uray¹, Dr Carlos A Dallera¹, Dr Patrizzia Mastromatteo-Alberga¹, Maria Dominguez-Torres¹, Alyssa F Balleste¹, Tyler Rahimzadeh¹, Aditi S. Gorthy¹, Isabelle Aliancin¹, Dr W. Dalton Dietrich¹, Dr Juan Pablo de Rivero Vaccari¹, Dr Michael A. Zeligs², Irwin C. Jacobs², Dr Coleen M. Atkins¹

¹Neurological Surgery Department and The Miami Project to Cure Paralysis University of Miami Miller School of Medicine, Miami, United States, ²Boulder BioScience, LLC, Boulder, United States

3,3’-Diindolylmethane (DIM) is a neuroprotective indole active in models of CNS hypoxia and stroke. Dispersed BR4044 formulation provides a nano-scale DIM suspension for treating brain injury. This study determined whether IV/IP BR4044 could curtail acute and subacute CNS damage, modify neuroinflammatory signaling, and improve neurobehavioral outcomes after fluid-percussion injury (FPI). Adult male Sprague Dawley rats received moderate to severe FPI under normoxic conditions (85-95mmHg). Rats received BR4044 (30mg/kg/DIM intravenously/10 min post-FPI, then 60mg/kg intraperitoneally at 4hr/24hr or 4hr/24hr/48hr/72hr). Vehicle rats received excipients at the same post-FPI timepoints. Sham animals received saline and were exposed to supplemental oxygen (100-180mmHg). At 1 day post-injury (DPI), FPI/BR4044 rats exhibited significantly reduced cortical (p<0.0005) and hippocampal edema (p<0.0001) with reduced serum-derived extracellular vesicle (EV) concentrations compared to FPI/Vehicle rats (p=0.0117). At 3 DPI, forelimb paw placement in a cylinder task was preserved with BR4044 treatment (p<0.0001). At 7-9 DPI, cue and contextual fear conditioning tests showed a significant interaction between trial and treatment (Cue: p=0.0001; Context: p<0.0001). BR4044 significantly improved cue and contextual fear conditioning in FPI rats compared to FPI/Vehicle rats (p<0.001). A significantly lower histopathology score at 9 DPI was seen with BR4044 treatment. At 9 DPI, NeuN+ cell counts in the CA3 region (p<0.0001) and the parietal cortex (p=0.0003) were greater following BR4044 versus Vehicle treatment. These results demonstrate that DIM from BR4044 effectively reduces brain edema, lowers acute EV release, preserves cortical and hippocampal neurons, and promotes sensorimotor and cognitive recovery post-TBI in male rats.

Support: Boulder BioScience, LLC.

Mr. Daunel Augustin¹, Ms. Anastasia Georges¹, Mr. Kevin Browne^1,2, Ms. Jillian Wachira¹, Mr. Srijan Kalva¹, Dr. Daniel Kacy Cullen^1,2, Dr. David F. Meaney¹

¹University of Pennsylvania, Philadelphia, United States, ²Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, United States

Blast-induced traumatic brain injury (bTBI) is a prevalent cause of traumatic brain injury (TBI) for military personnel and can cause significant long-term morbidity. Although murine models are frequently used to simulate the effects of bTBI, the behavioral responses across different mice strains have not been extensively studied, presenting a crucial area for investigation into the underlying genetic factors. This study observes the behavioral characteristics following bTBI at 10% lethality thresholds across six mouse strains (A/J, 129S1/SvlmJ, NOD/LtJ, NZO/HILtJ, C57BL/6, and CAst/EiJ), which collectively represent over 90% of genetic variation in commonly used laboratory mice. We utilized a comprehensive battery of mouse behavioral assessments including Elevated Zero Maze, Open Field (OF), Novel Object Recognition, Contextual Fear Conditioning (CFC), and Fear Extinction, to evaluate cognitive and motor deficits up to one month after injury. Using the blast overpressure levels corresponding to 10% lethality thresholds in each strain, bTBI causes only mild changes in most behavioral measures. For motor deficits, only the NOD/LtJ and 129S1/SvlmJ showed a significant change after bTBI in average movement speed during the Open Field test (t-test, p = 0.0096, p = 0.045). In comparison, cognitive deficits appeared in NZO/HILtJ mice during Contextual Fear Conditioning testing after bTBI (t-test, p = 0.042). Interestingly, behavioral differences across strains were more significant than the effect of the studied blast overpressure levels. This study emphasizes the need for continued exploration into the genetic aspects of bTBI and offers valuable insights for future research.

Keywords blast, traumatic brain injury, genetic strains, behavior, cognition

Dr. Shaun Carlson^1,2, Mr. Jeremy Henchir¹, Kristina Schwab², Youming Li¹, Dr. Yijen Wu², Dr. C. Edward Dixon^1,3

¹University Of Pittsburgh, Dept. of Neurological Surgery, Pittsburgh, United States, ²University of Pittsburgh, Department of Pediatrics, Pittsburgh, United States, ³Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, United States

Blast traumatic brain injury (bTBI) is a prominent health concern among military personnel and can result in debilitating long-term sequalae. Axonal injury has been identified as a contributing factor to development of impairments after blast exposure, and alterations in the dopamine (DA) and acetylcholine (ACh) systems have been implicated to contribute to post-injury dysfunction. An approach to visualize changes in the DA and ACh circuits may be helpful in the identification of pathological responses and potential identification of therapeutic strategies. To address this, we implemented a diffusion tensor imaging (DTI) with MRI approach followed by graph theory to delineate brain network architecture with high definition specifically for the DA and ACh systems. We examined regional connectivity between the substantia nigra, diagonal band, ventral tegmental area (VTA), medial septum, medial forebrain bundle (MFB) and the striatum after bTBI. We hypothesized this approach would identify bTBI-induced changes in the DA and ACh connectivity. Male Sprague Dawley rats were subjected to single bTBI (30psi peak overpressure) using an Advanced Blast Simulator (n=4/group). Sham control rats received equivalent anesthesia exposure (n=4/group/sex). At 30 days post-injury the rats were euthanized and ex vivo DTI and MRI imaging were completed. Rats exhibited reduced fiber density in the VTA and MFB as compared to sham controls but not in the medial septum, diagonal band, hippocampus, medial septum striatum and substantial nigra. Ongoing immunohistochemical studies will confirm the DTI findings and assess the implications on cognitive function post-bTBI.

Ms. Makenzie Patarino^1,2,3,4,5,6, Dr. Tami Wolden-Hanson⁵, Mr. Mathew Sevao^3,6, Dr. Garth Terry^1,3,6, Dr. Bryan Schuessler^5,6, Ms. Renata Daniels^5,6, Ms. Monica Tschang^1,2,3,4,5,6, Ms. Alexandria Murry^4,8, Dr. Samantha Keil^3,6, Dr. Sam Golden^2,4,8, Dr. Jeffrey Iliff^1,3,6,9, Dr. Abbie Schindler^{1,2,3,4,5,6,7}

¹University Of Washington; VAPSHCS, Seattle, United States, ²Graduate Program in Neuroscience; UW, Seattle, United States, ³Department of Psychiatry and Behavioral Sciences; UW, Seattle, United States, ⁴Center for the Neurobiology of Addiction, Pain, & Emotion, Department of Psychiatry and Behavioral Sciences; UW, Seattle, United States, ⁵Geriatric Research Education and Clinical Center; VAPSHCS, Seattle, United States, ⁶VISN 20 Mental Illness Research Educational and Clinical Center; VAPSHCS, Seattle, United States, ⁷Division of Gerontology and Geriatric Medicine; UW, Seattle, United States, ⁸Department of Biological Structure; UW, Seattle, United States, ⁹Department of Neurology; UW, Seattle, United States

Mild traumatic brain injury (mTBI), commonly called the “hallmark injury” of the Iraq/Afghanistan wars, is an established risk factor for Alzheimer’s Disease and related dementias (ADRD). Alcohol use disorder (AUD) can also increase the risk of ADRD, and is often comorbid with mTBI. However, the interaction of mTBI and AUD in contributing to ADRD remains understudied. The current study investigates how chronic alcohol after blast-induced mTBI affects development of ADRD and aging related behaviors and biomarkers. Male mice were exposed to repetitive (3x) blast or sham using a translationally relevant shock tube. Following recovery, group-housed mice were allowed intermittent access to multiple doses of alcohol (2-20%) in our novel Socially Integrated Polysubstance cages for three, four week periods. Behavioral outcomes (spatial working memory, thermal sensitivity, blast-conditioned aversion, hyperreactivity) were assessed prior to initial alcohol exposure and again after each access period. Fluid and imaging-based biomarkers were assessed, including peripheral cytokines, gut microbiome, liver, brain glucose metabolism (FDG-PET), and glymphatic function (3D histology). Behavioral results show higher alcohol dose preference in blast-exposed mice and a combined effect of blast-exposure and alcohol on hyperreactivity. Early biomarker analyses suggest high alcohol preference impairs brain glucose metabolism and glymphatic clearance. Interestingly, only blast-exposed mice show impairments after low levels of chronic alcohol. These results provide a holistic characterization of how aging is affected by trauma and alcohol over the lifespan, highlight new biomarkers to predict adverse outcomes, and ultimately provide potential clinical targets to combat adverse comorbid outcomes in the aging population.

Dr. Jake Aronowitz^1,2,3, Kyle Manetz⁴, Dr. Susan Schwerin^1,3, J Okwesili^1,3, Dr. Sharon Juliano^1,2

¹Department of Anatomy, Physiology, & Genetics, Uniformed Services University of the Health Sciences, Bethesda, USA, ²The Military Traumatic Brain Injury Initiative (MTBI2), Bethesda, USA, ³The Henry M. Jackson Foundation Inc., Bethesda, USA, ⁴The School of Medicine, Uniformed University of the Health Sciences, Bethesda, USA

Traumatic brain injury (TBI) is a global public health concern and leading cause of disability worldwide. Blast TBIs, which result from exposure to overpressure, rather than direct impact to the head, are common in military service members and often lead to persistent neurocognitive and neuropsychiatric difficulties. Data from animal and human studies of blast-injured brains show reduced glucose metabolism, white matter injury, and scattered Purkinje cell loss in the cerebellum, a brain structure important for motor coordination, balance, and cognition, but with only limited investigation. We exposed adult male ferrets to blast TBIs and rotational head injuries (CHIMERA) with or without stress over a 2 week period. At two different survival points (4 weeks or 6 months post-injury) we evaluated the cerebellum with immunohistochemistry. Our analyses showed damage to the axons of Purkinje cells, using myelin basic protein (MBP) as a marker, and a reduction in their terminations surrounding the deep cerebellar nuclei, demonstrated with calbindin as a marker. The colocalization of calbindin and MBP also reduced by >50% (and decreased with survival time) in the injured ferrets. The number of calbindin-immunoreactive Purkinje cells in injured animals also decreased with survival time, suggesting progressive Purkinje cell loss following injury. Finally, using Sox2 to identify Bergmann glia, an appreciable loss of these specialized glial cells occurred within the Purkinje cell layer. Taken together, our findings indicate that exposure to blast injury in gyrencephalic animals leads to progressive cerebellar damage, which may impair motor and/or cognitive function.

Funding: MTBI-70-13490 and CDMRP W81XWH-13-2-0018.

Ms. Madison Kilgore^1,2, Sarah Tran^1,2, Sushant Prajapati^1,2, Gopal Velmurugan^1,2, Jaycie Gard^1,2, Stephen Dundon³, David Powell³, W. Brad Hubbard^1,2,4

¹Spinal Cord & Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, United States, ²Department of Physiology, University of Kentucky, Lexington, United States, ³Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, United States, ⁴Lexington VA Healthcare System, Lexington, United States

Instances of mild traumatic brain injury (mTBI) surpass those of moderate-to-severe TBI within the US military, with blast exposure as the leading cause. Blast-induced mTBI is linked to cerebral perfusion and vasculature alterations, along with psychological deficits. There is a specific need to understand the pathological effects of low-level blast (LLB) exposure on cerebral blood flow (CBF), blood-brain barrier (BBB) dysfunction, and behavioral outcomes. To model repeated mild blast TBI (rmbTBI), male rats (N=6-8/group) were exposed to two 11 psi static peak overpressure blast waves at a 24h interval. Two animal cohorts were used for acute (1w) and chronic (14w) time points. The chronic cohort underwent social interaction testing at 7w, pseudo-continuous arterial spin labeling (pCASL) MRI to measure CBF at 8w, and elevated plus maze (EPM) testing at 12w post-injury. Animals were euthanized at 1w or 14w post-injury, and hemibrains were collected for immunohistochemistry, western blot, and brain capillary analysis. Acutely, the rmbTBI group exhibited significantly lower levels of pericytes (PDGFRβ), tight junction proteins (zonula occludens-1 (ZO1) and occludin), and aquaporin-4 (AQP4) compared to sham. Chronically, rmbTBI animals displayed decreased social novelty, spending significantly less time in novel stranger rat zones than sham. rmbTBI animals showed no CBF changes in the hippocampus or cortex but a nonsignificant decrease in the amygdala compared to sham. No anxiety-like differences were apparent between rmbTBI and sham groups. Future studies will determine chronic BBB deficits post-rmbTBI. Our findings demonstrate that rmbTBI leads to ongoing changes in cerebral vasculature and abnormalities in social behavior.

Ms. Kathleen Murray^1,4, Dr. Fernando Velloso^3,5, Dr. Arun Reddy Ravula⁶, Dr. Maryann Swain¹, Dr. Vedad Delic^1,4,5, Dr. Kevin Beck^2,4,5, Dr. Bryan Pfister^7,8, Dr. Steven Levison^3,4,5, Dr. Bruce Citron^1,4,5

¹Laboratory of Molecular Biology, Research & Development, VA New Jersey Health Care System, East Orange, United States, ²Neurobehavioral Research Laboratory, Research & Development, VA New Jersey Health Care System, East Orange, United States, ³Laboratory for Regenerative Neurobiology, Department of Pharmacology, Physiology, and Neuroscience, Rutgers-New Jersey Medical School, Newark, United States, ⁴Rutgers School of Graduate Studies, Newark, United States, ⁵Department of Pharmacology, Physiology, and Neuroscience, Rutgers-New Jersey Medical School, Newark, United States, ⁶Department of Neuroscience, Mayo Clinic, Jacksonville, United States, ⁷Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, United States, ⁸Center for Injury Biomechanics, Materials and Medicine, New Jersey Institute of Technology, Newark, United States

Repetitive weaponry-type blast-induced traumatic brain injury (rwbTBI) can result in chronic cognitive impairments in military personnel from 0.50-caliber rifles, grenades, and breaching devices during training and active service. We are interested in understanding the impact of rwbTBI on neuronal cell-specific injury mechanisms and therapeutic targets to improve cognitive outcomes for Veterans and others. Male C57BL/6J mice (n=3/group) received five 70 kPa blast exposures at 1-min intervals modeling heavy weaponry followed by treatment with tert-butylhydroquinone (tBHQ), a Nrf2 activator, and pioglitazone, a PPARγ agonist, at 30 minutes post-injury. Single nucleus RNA sequencing (snRNA-seq) was performed from dissociated hippocampal samples at 24 hours post-injury to assess gene expression responses to injury and/or treatment. We identified dysregulated genes and pathways after rwbTBI and investigated whether modulation of neuroprotective and antioxidant transcription factors can help combat neurodegeneration by influencing gene expression profiles of cell populations within the hippocampus after injury. Preliminary analysis identified differential expression of genes of interest including a 2.6-fold upregulation of Nfe2l2, the gene that encodes Nrf2, in dentate granule cells due to injury (p=0.002) and a 1.7-fold downregulation of Camk2a in astrocytes (p<0.001) due to injury which was partially reversed by treatment (p<0.001). This study provides insight into potential mechanisms that underlie cell-specific neuropathological changes following repetitive weaponry-type blast exposure and provides a foundation for the identification of therapeutic targets that could be modulated to improve the health of Veterans and others with histories of occupational blast exposures.

Research supported by the VA, DOD, and Veterans Bio-Medical Research Institute.

Dr. Jason Gumbel¹, Emma G Iorio¹, Dr. Jacob A Davis¹, Cleopa Omondi¹, Dr. J. Russell Huie¹, Dr. Adam R. Ferguson¹

¹Ucsf, San Francisco, United States

Spinal cord injury (SCI) often causes autonomic dysfunction, including both urinary issues involving bladder and kidney, and the cardiovascular system such as coronary artery disease and dysregulation of blood pressure due to autonomic dysregulation. Together, these are among the leading issues that impact quality of life in the SCI population. However, little is known about how SCI impacts kidney health and function, which is important as kidneys help regulate blood pressure and electrolyte balance. It has been previously established that SCI results in the chronic alteration of key water/solute balance biomarkers in the kidney, such as vasopressin, atrial natriuretic peptide, aquaporin 2, and epithelial sodium channels. Given that these receptors are altered after SCI, combined with the inability to regulate blood pressure, we tested the hypothesis that acute SCI would generate kidney injury, contributing to cyclical autonomic dysfunction. We aimed to investigate the effect of SCI on kidney health, targeting kidney health/function biomarkers in rat kidney tissue. We have found that neutrophil-gelatinase-associated lipocalin (NGAL; a biomarker for kidney injury) was increased in SCI animals compared to a laminectomy only group in acute SCI, suggesting SCI negatively impacts kidney function. This project has strong translational potential since the kidneys are impacted after human SCI, as shown by the increased incidence in chronic kidney disease in the SCI population.

Acknowledgement: Supported by NIH: R01NS122888, UH3NS106899, U24NS122732; US VA: I01RX002245; Craig H. Neilsen Foundation; Wings for Life Foundation.

Dr. Iris Leister¹, Ms. Barbara Altendorfer², Dr. Doris Maier¹, Mr. Orpheus Mach¹, Dr. Christof Wutte¹, Dr. Andreas Grillhösl¹, Dr. Angel Arevalo-Martin³, Dr. Daniel Garcia-Ovejero³, Dr. Ludwig Aigner², Dr. Lukas Grassner²

¹BG Trauma Center Murnau, Murnau, Germany, ²Paracelsus Medical University, Salzburg, Austria, ³Laboratory of Neuroinflammation, Hospital Nacional de Paraplejicos, SESCAM, Toledo, Spain

Background: In acute spinal cord injury (SCI), neurological examination is often challenging, emphasizing the necessity for diagnostic biomarkers to objectively assess lesion severity. Also, because SCI is characterized by persisting neurological impairments, there is an additional demand for prognostic biomarkers to predict neurological recovery.

This study aimed to investigate the relationship between biomarkers of neurodegeneration and the presence and severity of SCI in the immediate post-injury phase, as well as their temporal dynamics during the transition from acute to chronic SCI.

Methods: Blood samples were prospectively collected from 41 individuals with traumatic SCI in the acute phase (1-4 days post-injury), and after 30 and 120 days. Serum levels of Glial Fibrillary Acidic Protein (GFAP), Neurofilament light protein (NfL), and Neuron-Specific Enolase (NSE) were determined using R-Plex Assays (Meso Scale Discovery). A group of 41 age- and sex-matched healthy individuals served as control group.

Results: NfL and GFAP are different among patients depending on SCI severity. Our analysis produced preliminary cut-off values for NfL (75.217 pg/ml) and GFAP (73.121 pg/ml) allowing a differentiation between individuals with SCI and healthy controls within the initial four days after SCI. Additionally, the trajectory of GFAP over time is significantly associated with the extent of neurological recovery.

Conclusion: NfL and GFAP qualify as diagnostic biomarkers in the acute post-SCI phase where the reliability of clinical exams is limited. Also, the trajectory of serum GFAP levels serves as a prognostic biomarker for neurological recovery, thereby facilitating monitoring of disease progression in the sub-acute post-injury phase.

Dr. Luisa M Rojas Valencia^1,2, Amy Song⁵, Prakruthi Amar Kumar^1,2, Emma G Iorio^1,2, Naoki Takegami^1,2, Esmeralda Mendoza^1,2, Abel Torres-Espin⁴, Adam R Ferguson^1,2,3, Jeannie Bailey⁶, Anastasia Keller^1,2,3

¹Department of Neurological Surgery, University of California San Francisco (UCSF), San Francisco, United States, ²Brain and Spinal Injury Center (BASIC), Weill Institute of Neurosciences, UCSF, San Francisco, USA, ³San Francisco Veterans Affairs Healthcare System, San Francisco, USA, ⁴School of Public Health Science, University of Waterloo, San Francisco, USA, ⁵Electrical Engineering and Computer Science program, College of Engineering, University of California Berkeley, Berkeley, USA, ⁶Department of Orthopaedic surgery, University of California San Francisco (UCSF), San Francisco, USA

One enduring feature of spinal cord injury (SCI) is central neuropathic pain. Recent evidence suggests that certain subtypes of chronic low back pain (cLBP) reflect a ‘mild’ SCI that is neuroinflammatory in nature. Spinal cord central sensitization represents a shared pathophysiological mechanism in both SCI pain and cLBP. Transcutaneous spinal cord stimulation (tSCS) is a novel neuromodulation technique pioneered for non-invasive lumbosacral spinal cord activation to enable motor functions in patients with chronic complete motor paralysis. We hypothesized that tSCS therapy could modulate central sensitization to control pain and sensorimotor outcomes in patients with non-specific cLBP. Eligible individuals had non-specific cLBP with duration >6 months, and Visual Analogue Scale (VAS) >5 at enrollment. Patients underwent a battery of assessments, including sit-to-stand full-body biomechanics with paraspinal and lower extremity surface electromyography (EMG) before/after therapy. Stimulation was administered via 3-4 surface (skin) electrodes over the lumbosacral spinal cord 3x/week, 30-min/session, 12-sessions. Daily VAS surveys tracked pain intensity for the study duration. Patients marked painful areas on a body map and rated their pain before and after each tSCS. Fourteen enrolled participants are undergoing treatment. The first 4 who completed treatment reported immediate reduction in cLBP intensity after tSCS. VAS scores one month after tSCS indicate a 56% reduction in cLBP compared to enrollment. Objective sensorimotor outcomes analysis is ongoing, while preliminary results suggest tSCS efficacy for pain relief. In the future, we will test tSCS efficacy for treatment of neuropathic pain following SCI.

FUNDING: UCSF-DOS-Seed-Award, UCSF-Catalyst, CDMI, VA-BRAVE, U19AR076737; U24NS122732, R01NS122888; VA-I01RX002245.

Dr. Toluyemi Malomo¹, Mr. Amardeep Singh Sekhon¹, Dr. Femke Streijger¹, Dr. Marcel F. Dvorak^1,2,3, Dr. Charles G. Fisher^1,2,3, Dr. Tamir Ailon^1,2,4, Dr. Scott J. Paquette^1,2,4, Dr. John T. Street^1,2,3, Dr. Nicholas Dea^1,2,4, Dr. Raphaële Charest-Morin^1,2,3, Dr. Charlotte Dandurand^1,2,4, Dr. Brian K Kwon^1,2,3

¹International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada, ²Vancouver Spine Surgery Institute, Vancouver General Hospital, Vancouver, Canada, ³Division of Orthopaedic Surgery, Department of Surgery, University of British Columbia, Vancouver, Canada, ⁴Division of Neurosurgery, Department of Surgery, University of British Columbia, Vancouver, Canada

Intraparenchymal hemorrhage (IPH) following acute spinal cord injury (SCI) is associated with poorer neurological outcomes. This study aimed to use serial MRIs to determine if routine clinical practices of mean arterial pressure (MAP) augmentation between 85-90 mmHg with the use of vasopressors and venous thromboembolism prophylaxis (VTEP) with the use of anticoagulants exacerbate IPH progression in acute SCI patients.

13 patients presenting with acute cervical SCI were enrolled in the ongoing CHASM trial (ClinicalTrials.gov: NCT04758377). MAP was kept between 85-90 mmHg with norepinephrine (NE) and was recorded every hour. VTEP was started at 49-68 hours for all patients. IPH was quantified on T2-weighted imaging taken at baseline (<24 hours post-SCI) and 2-, 4-, 7-, and 14-days post-SCI. Hemorrhage progression (delta IPH) was calculated between baseline-day 2 imaging, then from days 2-4, 4-7, and 7-14.

Simple linear regression demonstrated a significant correlation between time-weighted average MAP (TWA-MAP) and delta IPH at days 2 and 4 (p=0.0076 and p=0.0046). A multilinear regression model accounted for 94-98% of the variance observed between TWA-MAP, NE dosage, baseline IPH, and time to initiation of VTEP. The amount of IPH on baseline MRI was the strongest factor influencing delta IPH within the first 4 days post-SCI, as well as TWA-MAP. NE dosage and the time to initiation of VTEP were not found to be important predictors of delta IPH.

These findings suggest that there may be a rationale for tailoring our hemodynamic management goals in patients who present with severe hemorrhage at the time of injury.

Miss. Mayra Arellano^1,2, Xuan Duong-Fernandez^1,2, Nicole Lai^1,2, Dr. J Russell Huie^1,2, Dr. Anastasia Keller^1,2, Dr. Debra D Hemmerle^1,2, Dr. Vineeta Singh^1,2, Dr. Lisa Pascual¹, Dr. Jonathan Pan^1,2, Dr. William Whetstone^1,2, Dr. Jason Talbott^1,2, Dr. Anthony DiGiorgio^1,2, Dr. Rajiv Saigal^1,2, Dr. Philip Weinstein¹, Dr. Adam R Ferguson^1,2,3, Dr. Jacqueline C Bresnahan^1,2,3, Dr. Michael S Beattie^1,2,3, Dr. John Kramer⁴, Dr. Nikos Kyritsis^1,2

¹University of California, San Francisco, San Francisco, United States, ²Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, United States, ³San Francisco Veterans Affairs Healthcare System, San Francisco, United States, ⁴University of British Columbia, Vancouver, Canada

Neuropathic pain following spinal cord injury (SCI) is widely recognized as a significant secondary consequence impacting patient well-being. The prevailing belief suggests that neuropathic pain emerges weeks or months post-injury, persists indefinitely, and significantly reduces quality of life due to a lack of effective treatment. However, our understanding of neuropathic pain pathophysiology remains incomplete. This study from the Transforming Research and Clinical Knowledge in SCI (TRACK-SCI) database examines neuropathic pain development and progression in SCI patients. Of the 199 Zuckerberg San Francisco General Hospital (ZSFG) patients, 75 had long-term pain data. Results revealed varied neuropathic pain presentations: 34.7% had no neuropathic pain areas, 42.7% had one, and 22.7% had multiple. Acute pain data were available for 44.0% of patients, with 32.0% showing neuropathic pain at these early time points. Some patients exhibited acute neuropathic pain without chronic manifestation or lacked continuity in pain status over time. Pain treatment rates differed significantly, with 61.2% of neuropathic pain patients receiving treatment compared to 26.9% of non-neuropathic pain patients. These findings underscore the nuanced nature of neuropathic pain progression and challenge conventional views on its development post-SCI. Further research is essential for a deeper understanding of neuropathic pain pathophysiology and improving pain management strategies in SCI patients.

This work was supported by grants from the U.S. Department of Defense (W81XWH-22-1-0473) to N. Kyritsis, and U.S. Department of Defense (W81XWH-13-1-0297 and W81XWH-16-1-0497) and Craig H. Neilsen Foundation (University of California, San Francisco, Spinal Cord Injury Center of Excellence special project award) to M.S. Beattie.

Dr. Matthew Farley^1,2, Alex Benedetto^1,2, Dr. Charles J. Heckman^1,2, Dr. Monica Perez^1,2,3,4

¹Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, United States, ²Shirley Ryan AbilityLab, Chicago, United States, ³Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, United States, ⁴Edward Hines Jr., VA Medical Center, Chicago, United States

Transcutaneous spinal cord stimulation (tSCS) has been reported to reduce involuntary muscle activity and facilitate voluntary motor output in individuals with spinal cord injury (SCI) (Hofstoetter et., al 2014). The mechanisms contributing to these effects remain poorly understood. The purpose of this study was to examine the effect of a single session of lumbar tSCS applied between L1-L2 vertebral interspace (30Hz pulses with a 10kHz carrier frequency) on ankle clonus and the amplitude of the H-reflex in the soleus muscle (as a proxy for spinal cord excitability) in participants with incomplete or complete chronic SCI. tSCS was delivered at 50% of the intensity needed to elicit a 50 μV peak-to-peak posterior root reflex in the soleus muscle. We measured clonus duration, frequency, burst characteristics, and the soleus H-reflex before and after 20 min of tSCS in each participant. Following stimulation, clonus duration (average duration at baseline=45.4±53.0 s) was reduced (20.1±42.5s after stimulation) in 6/7 participants tested. In one out of the 7 individuals tested, clonus was completely abolished immediately after TESS. The frequency, burst duration, and interburst duration in the remaining clonus were not different to values obtained at baseline after the stimulation. The H-reflex amplitude was reduced 15 min after the stimulation in all participants (by 66.8±20.1%) and remained suppressed for up to 30 minutes (by 41.9±38.1%). These results suggest that tSCS attenuates clonus in humans with chronic SCI, likely by reducing spinal cord excitability.

Funding: M.A.P received funding from NINDS and VA. MF received funding from NIH.

Mr. Dexter Zamora^1,2, Dr. Carolyn Sparrey^1,2

¹Simon Fraser University, Surrey, Canada, ²International Collaboration on Repair Discoveries (ICORD), Vancouver, Canada

Precision of test platforms producing spinal cord injuries in animal studies and their ability to extract accurate injury biomechanics is crucial. These platforms are designed with a focus on technical specifications, but the user experience (UX) for non-engineers is cumbersome. We have developed a new large animal contusion system, but its current design requires someone with extensive engineering knowledge to operate, which hinders its potential for adoption by non-engineers. We aim to revise the system based on user feedback to address perceived UX barriers while retaining its capacity to provide accurate biomechanical data. A user-centered design framework was used to engage with potential users to gather their perceptions. Thematic analysis was used to identify key areas for improvement with extracted themes informing the proposed design revisions. Our preliminary results show that current UX barriers relate to operational complexities (number of user interactions to conduct experiments and need for subject-specific controls for large animal models) and non-intuitive user interface (UI) (cluttered, information-heavy design). The proposed system revisions include embedding automation capabilities within the existing control system to address operational complexities and designing an intuitive UI allowing subject-specific test parameters. Injury test platforms for large animal models require the capacity to tune and control each impact for the test subject. An effective UX that supports a variety of neurotrauma researchers becomes essential. Implementing these user-informed revisions into the test platform could transform it from an engineering prototype to a broadly adoptable system for neurotrauma research. This study was financially supported by NSERC.

Dr. Matthew Kercher¹, Dr. Allan R. Martin¹

¹UC Davis Health Department of Neurological Surgery, Sacramento, United States

Introduction: Traumatic spinal cord injury (SCI) is common with devastating impact. Incomplete (iSCI) vs complete SCI (cSCI) differ significantly. Morbidity depends significantly on fracture location, with high cervical fractures having the highest morbidity. All SCI patients are often studied together, despite their heterogeneity. There exists a need for detailed prevalence data for iSCI and cSCI.

Methods: A retrospective review of a single Level I trauma center SCI database was conducted. Of 2672 total records, 166 SCI patients were identified, of which 90 were iSCI and 76 were cSCI. The fracture incidence was calculated per level in the full, iSCI, and cSCI populations.

Results: 337 fractures in total occurred. 0 occipital condyle, 0 dens fractures, 113 cervical, 160 thoracic, 59 lumbar, and 5 sacral fractures occurred. The highest frequency fracture was C6 with 36 fractures (22%). C5 to T1 made up 108 fractures (32%). In the full population, C5-T1 were the top 4 most frequent fractures, followed by T12 at 20 fractures (12%). A bimodal distribution of fractures was shown with peaks at C6 and T12, more apparent in the iSCI group. cSCI had more fractures than iSCI at T8 and T9 (15 vs 2).

Conclusion: In our data, SCI shows a bimodal distribution with the major mode at C6 and minor mode at T12. iSCI may be more bimodal than cSCI, which shows a more uniform distribution appearance with skew to C6. At the apex of thoracic kyphosis at T8/9, cSCI is more common.

Mr. Austin Lui^1,2, Dr. Naoki Takegami², Dr. Nikos Kyritsis², Dr. Russell Huie², Dr. Debra Hemmerle², Dr. Alan Nima², Dr. Timothy Chryssikos³, Dr. Abel Torres-Espin⁴, Ms. Xuan Duong-Fernandez², Ms. Nicole Lai², Dr. Rajiv Saigal², Dr. Jacob Blitstein⁵, Dr. Jason Talbott², Dr. Jonathan Pan², Dr. Adam Ferguson², Dr. William Whetstone², Dr. Vineeta Singh², Dr. Philip Weinstein², Dr. Sanjay Dhall², Dr. Praveen Mummaneni², Dr. Lisa Pascual², Dr. Geoff Manley², Dr. Jacqueline Bresnahan², Dr. Michael Beattie², Dr. Anthony DiGiorgio²

¹Touro University California, Vallejo, United States, ²University of California, San Francisco, San Francisco, United States, ³University of Maryland, Baltimore, United States, ⁴University of Waterloo, Waterloo, Canada, ⁵Virginia Commonwealth University, Richmond, United States

The pathology and precise definition of central cord syndrome (CCS) remain controversial. Studies suggest similar treatments for CCS and non-central cord (non-CCS). We compare initial characteristics, surgical treatment, and short-term outcomes of CCS and non-CCS. We queried the Transforming-Research-and-Clinical-Knowledge-in-SCI registry to identify cervical-CCS-patients (ASIA C/D with lower-extremity-motor (LEM) scores > upper-extremity-motor (UEM) scores by at least 5 points) and those with cervical-SCI but not CCS (non-CCS). Forty-three CCS patients and 43 non-CCS-patients were included. There were no differences between age, sex, and SCI etiology. Injury severity scores were higher in CCS compared to non-CCS (19.1 vs 16.1, p=0.034). There were no differences in percent undergoing SCI-related neurosurgical interventions, decompression surgery, or fusion surgery. Time to surgery, ICU length of stay (LOS), and hospital LOS, were similar between the groups. CCS-patients had worse UEM-scores (27 vs 38.3, p<0.001) and LEM-scores (42.4 vs 35, p=0.028) compared to non-CCS patients at day-0 (+/- 2 days), but no differences in total motor scores at day-0. There were no differences in UEM, LEM, or total motor score at day-7 (+/- 2 days). Discharge location differed (p=0.001). Most non-CCS patients were discharged to either acute rehabilitation (32.6%) or home/hotel (39.5%). While most CCS patients were also discharged to acute rehabilitation (44.2%), a high percentage were also discharged to skilled nursing facility (30.2%). Our results indicate that CCS and non-CCS patients undergo similar neurosurgical interventions and have similar in-hospital outcomes. However, discharge disposition differed, possibly suggesting a difference in prognosis, social support, and resources for long-term recovery.

Mr. Adnan Ismail¹, Mr. Austin Lui², Dr. Debra D. Hemmerle^3,4,5, Ms. Xuan Duong-Fernandez^3,4,5, Ms. Nicole J. Lai^3,4,5, Dr. J. Russell Huie^3,4,5, Dr. Abel Torres-Espin^4,5, Dr. Nikos Kyristis^3,4,5, Dr. Vineeta Singh^3,4,5, Dr. Lisa U. Pascual^6,7, Dr. Jonathan Z. Pan^4,8, Dr. William D. Whetstone⁹, Dr. Jason F. Talbott^10,4, Dr. Anthony M DiGiorgio^5,10, Dr. Rajiv Saigal^5,10, Dr. John H. Kanter^5,10, Dr. Philip Weinstein^3,11,12,5,13, Dr. Adam R. Ferguson^3,4,5,14, Dr. Jacqueline C. Bresnahan^3,4,5, Dr. Michael S. Beattie^3,4,5

¹Tibor Rubin VA Medical Center, Long Beach, United States, ²College of Osteopathic Medicine, Touro University, Vallejo, United States, ³Weill Institutes for Neuroscience, San Francisco, United States, ⁴Brain and Spinal Injury Center, San Francisco, United States, ⁵Department of Neurological Surgery, UCSF, San Francisco, United States, ⁶Orthopaedic Trauma Institute, San Francisco, United States, ⁷Department of Orthopaedic Surgery, UCSF, San Francisco, United States, ⁸Department of Anesthesia and Perioperative Care, UCSF, San Francisco, United States, ⁹Department of Emergency Medicine, UCSF, San Francisco, United States, ¹⁰Zuckerberg San Francisco General Hospital Department of Radiology and Biomedical Imaging, San Francisco, United States, ¹¹Institute of Neurodegenerative Disease, San Francisco, United States, ¹²Spine Center, San Francisco, United States, ¹³Department of Neurology, UCSF, San Francisco, United States, ¹⁴San Francisco Veterans Affairs Healthcare System, San Francisco, United States

Traumatic spinal cord injury (SCI) can cause long-term psychosocial deficits and disproportionately prevails in marginalized groups. Little is known about the relationship between socioeconomic status and self-perceived stigma following SCI. We explored relationships between socioeconomic factors and self-reported stigma at 6-12 months post-SCI. Participants included 134 SCI patients (males: N=99, mean age = 41 years) from the prospective, longitudinal study Transforming Research and Clinical Knowledge in SCI (TRACK-SCI). Predictor variables included race (white vs. non-white), income (above vs. below median), insurance (public/uninsured vs. private), marital status, urbanity, and living situation. Self-perceived stigma at 6-12 months was measured using The Quality of Life in Neurological Disorders (Neuro-QoL) Stigma short form questionnaire (N=86). T-tests were used to assess mean differences between predictor groups and ANOVA to assess interactions of race and income with other predictors on stigma scores. Higher income was associated with lower self-reported stigma at 6-12 months (n=33, p=.034). Marital status, urbanity, and living situation were not significantly associated with self-reported stigma. Privately insured white participants (n=31) had lower stigma scores than public/uninsured white participants (n=18, p=.027). Higher-income white participants (n=19) reported lower stigma scores than lower-income non-white participants (n=33, p=0.031). Comparisons between race classes within the same income and insurance groups showed no significant results, nor did comparisons between different income groups of the same race class. Underinsurance and lower income levels are associated with higher perceived stigma in SCI. Our introductory results support the important consideration of intersectionality when designing patient-centered rehabilitation for SCI survivors.

Ms. Anakaren Romero Lozano¹, Dr. Wenliang Wang¹, Mr. Kai Wing (Kevin) Tang¹, Dr. Ilya Pyatnitskiy¹, Dr. Micheal Donovan², Dr. Linda Noble-Haeusslein^1,2,3, Dr. Huiliang (Evan) Wang¹

¹Department of Biomedical Engineering, Cockrell School of Engineering, The University Of Texas At Austin, Austin, United States, ²Department of Neurology, Dell Medical School, University of Texas at Austin, Austin, United States, ³Department of Psychology, College of Liberal Arts, University of Texas at Austin, Austin, United States

Recovery of bladder voiding is a top priority for those with spinal cord injury (SCI). Electrical stimulation is somewhat effective but poses significant limitations, including non-specificity and damage from invasive surgery. Optogenetics is a widely popular tool in neuroscience allowing for precise spatiotemporal control of neural circuits without off-target effects. However, clinical translation is hampered by the invasive implantation of an optical fiber. We have recently developed ‘sono-optogenetics’, where nanoparticles convert CNS-penetrant focused ultrasound (FUS) to localized light emission for non-invasive optogenetic stimulation. We report an improved version of self-amplifying mechanoluminescent nanoparticles to achieve blue light emission upon ultrasound stimulation. Chemiluminescence L012, sonosensitizer IR780, and sono-amplifier polyethylene glycol 200 coated calcium peroxide nanoparticles were loaded into lipids for FUS activation. The improved photon emission of these nanoparticles was demonstrated through a reward behavioral response. Male mice received a local injection of our liposome in the Ventral Tegmental Area and were allowed to self-administer FUS through a lever across 5 days. Only the experimental group that was administered all of ChR2, liposome, and FUS stimulation demonstrated increased lever pressing rates, while all other control groups did not (n=4). Previous studies have demonstrated the lumbar dorsal root ganglia (DRG) as a target for modulating voiding. We have confirmed this target through injection of retrobeads in the bladder wall which were retrogradely delivered to the DRG. These results have positioned us to approach projection-specific sono-optogenetic stimulation for restoring bladder function after SCI. This research is supported by the Craig H. Nielsen Foundation.

Dr. Tanya Barretto¹, Miss Vyshnavi Manohara¹, Dr. Judy Illes¹

¹University Of British Columbia, Vancouver, Canada

Objective: Clinical trials are the bedrock of medical research. For the millions of people living with spinal cord injury (SCI), clinical trials involving biologics, drugs, devices, and rehabilitation have improved quality of life although not a full solution to lost mobility. We examined criteria required for participation on this trials landscape.

Methods: Clinicaltrials.gov was mined for registered SCI trials from the inception of the registry to Dec 2022 using the search term “spinal cord injury” and variants. Inclusion and exclusion criteria for each trial were analyzed using a priori codes with a focus on ethics-related factors. We also conducted cross-theme analyses with intervention type.

Results: 37% of all studies (N=413) exclude participants on the basis of mental illness; 27% on the basis of substance use; and, 15% leave undefined exclusion criteria to the investigator’s discretion. Only 11% provide definitions for mental illness benchmarked to standardized assessments, and 3% for substance use. 44% (15/34) of biologic interventions and 43% (16/37) of device interventions exclude for mental illness. 34% (53/158) of drug interventions exclude for substance use.

Conclusions: Exclusion of participants without consistent assessments for mental illness or substance use or at the undefined discretion of investigators is a concern of justice. This ethics challenge is compounded by the high prevalence of these conditions in the SCI population and the reduced the pool of participants available to statistically power trials. Overall, review of participation criteria for future SCI trials is needed to meet the goals of both ethical and scientific rigor.

Dr. Johannes Dapprich¹, Dr. Amanda Ratajczak¹, Sophia Hertel¹, Elena Hertel¹, Dr. Jason Puchalla¹

¹NeuroPair, Inc., Princeton, United States

For spinal cord injury (SCI), trauma surgeons say ‘every injury is different’. Rapid treatment is essential to stabilize the patient, help prevent secondary damage and allow for at least partial functional recovery.

New axonal growth and the formation of functional circuits are possible in a favorable biophysical environment. The growth of spinal axons can be stimulated and enhanced, in particular with fiber-based guidance scaffolds.

However, it is currently impossible to place a scaffold that is minimally invasive and conforms to any shape of the injury site. Establishing direct molecular contact with surviving nerve endings across most of the rostral and caudal surfaces of the cavity is known to provide the greatest chance of recovery.

NeuroPair’s injectable scaffold allows for cellular contact of the entire scaffold with surrounding healthy tissue, the potential to induce guided growth, and the ability to include stem cells and bioactive factors.

Superparamagnetic particles in a hydrogel formulation are manipulated with a temporary, externally applied magnetic field to form aligned fibrous bundles, ‘Fiberguides’ (Fig. 1).

These adapt to and interact with the natural geometry of the lesion (Fig. 2), instead of having to surgically match the injured cord to an implant - a key difference versus rigid scaffolds.

Preliminary data:

1) Biocompatibility

- Viability of N1E-115 neuronal cells and rat dorsal root ganglia

2) Formation of stable Fiberguides

- Fibers remain stable over weeks after removal of the magnetic field

3) Guidance of neuronal growth

- Some axons extend over 0.5 mm and parallel to the Fiberguides

Dr. John Aldrich¹, Olivia Calderon³, Bianca Ford³, Sydney Lee¹, Ashley Scheinfeld¹, Jiacheng Ma³, Kalina Dusenbery¹, Fiona Bremner¹, Kang Le⁴, Michael Soth⁴, William Ray³, Sunil Goodwani³, Andrew Gaudet^1,2

¹Department of Psychology, College of Liberal Arts, University of Texas at Austin, Austin, United States, ²Department of Neurology, Dell Medical School, University of Texas at Austin, Austin, United States, ³Neurodegeneration Consortium, Therapeutics Discovery Division, The University of Texas MD Anderson Cancer Center, Houston, United States, ⁴Institute for Applied Cancer Science, The University of Texas MD Anderson Cancer Center, Houston, United States

Following spinal cord injury (SCI), secondary damage accompanied by neuroinflammation, oxidative stress, and excitotoxicity, can lead to the loss of otherwise viable neurons. This not only results in significant neuronal loss but exacerbates the inflammatory response, contributing to further secondary damage. The c-Jun N-terminal Kinase (JNK) pathway, initiated by Dual Leucine Zipper Kinase (DLK), regulates neuronal cell death during development and in response to extracellular stress or damage and is therefore a promising therapeutic target in a number of neurological injury and disease models. As such, we hypothesized that the JNK pathway would be activated in the lesion epicenter following SCI and that pharmacological inhibition of DLK would suppress this activation and promote neuronal cell survival. We found via western blot that levels of phosphorylated c-Jun, a direct target of JNK, and MEK4, an immediate upstream activator of JNK, are both significantly elevated as early as 4 hours in mice following a moderate T9 contusion SCI and that this effect lasts at least 7 days post-injury. Inhibition of DLK via oral delivery of IACS-825, a pre-clinical CNS-permeable drug, significantly reduced phosphorylated c-Jun levels at 24 hours post-SCI and up to 48 hours post-injury when delivered via intraperitoneal injection. Taken together, these results suggest that the JNK pathway is induced post-SCI and that targeting DLK via IACS-825 may be an effective way to reduce JNK-mediated neuronal cell death pathways. Further studies will determine if DLK inhibition has a positive effect on neuroprotection, functional locomotor recovery, and neuropathic pain-like symptoms following SCI.

Wenrui Qu¹, Xiangbing Wu¹, Wei Wu¹, Ying Wang¹, Yan Sun¹, Lingxiao Deng¹, Melissa Walker¹, Chen Chen¹, Heqiao Dai¹, Qi Han¹, Ying Ding¹, Yongzhi Xia¹, George Smith², Assoc. Prof. Nai-kui Liu¹

¹Indiana University School Of Medicine, Indianapolis, United States, ²Temple University School of Medicine, Philadelphia, United States

Schwann cell (SC) transplantation is one of the most promising cell-based therapies for repairing the injured spinal cord due to its unique growth-promoting and myelin-forming properties. An FDA-approved Phase I clinical trial has been conducted to evaluate the safety of transplanted human autologous SCs to treat patients with spinal cord injury (SCI). A major challenge for SC transplantation is that grafted SCs are confined within the lesion cavity, and they do not migrate into the host environment due to the inhibitory barrier formed by injury-induced glial scar, thus limiting axonal reentry into the host spinal cord. Here we introduce a combinatorial strategy by suppressing the inhibitory extracellular environment with chondroitinase ABC (ChABC) at the rostral and caudal borders of the lesion site and simultaneously leveraging the repair capacity of transplanted SCs in adult rats following thoracic contusive SCI. The results showed that when the glial scar was degraded by ChABC at the rostral and caudal lesion borders, SCs migrated for considerable distances in both rostral and caudal directions. Such SC migration led to enhanced axonal regrowth, including the serotonergic and dopaminergic axons originating from supraspinal regions, and promoted recovery of locomotor and urinary bladder functions. Importantly, the SC survival and axonal regrowth persisted up to 6 months after the injury, even when treatment was delayed for 3 months to mimic chronic SCI. These findings collectively show promising evidence for a combinatorial strategy in promoting remodeling and recovery of function following SCI.

DR. Ping Wang¹, Dr. Zachary Bailey¹, Linda Huynh¹, Intisar Diwani¹, Weihong Yang¹, Omar Ahmad², Dr. Irene Dris², Dr. Deborah Shear¹, Dr. Anke Scultetus¹

¹Brain Trauma Neuroprotection Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, USA, ²Cresilon, Inc, Brooklyn, USA

Hemostatic hydrogel technology may significantly improve traumatic brain injury (TBI) wound dressing beyond gauze, by providing benefits such as hemorrhage control, flexible wound coverage and potentially as a drug delivery platform. Cresilon Hemostatic Gel (CHG™), a 510(K) cleared hemostatic hydrogel comprised of crosslinking plant-based polymers form a strong mechanical barrier upon exposure to blood, ensuring both immediate and durable hemostasis. In this study, we evaluated the physiological effects and efficacy of CHG™ application acutely following TBI. Sprague-Dawley rats received lateral controlled cortical impact (CCI) under anesthesia and were divided into two groups: hydrogel-treated (HYG, 200uL) and untreated. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were recorded for 6hrs post-injury. Cerebral edema and brain hemoglobin levels were measured at 6 and 72hrs post-TBI using the wet-dry method and ELISA. Histology was assessed 3 and 7 days post-injury. ICP increased relative to baseline post-TBI and stabilized without group differences. CPP remained steady over time with HYG but controls increased slightly (not significant). Edema changes with HYG were not significant in perilesional brain sections but HYG-treated posterior sections had significant edema reductions versus controls at 6hrs. Hemoglobin concentrations were lower in perilesional brain sections with HYG than untreated (not significant). Overall, direct CHG™ application to the injured brain didn’t have adverse physiological effects. Superficial application tended to decrease acute hemorrhage in the brain after injury which is promising. Future directions include examining suitability for an intracerebral hemorrhaging brain injury such as a penetrating brain injury or supplemented with a drug treatment.

Emma G. Iorio¹, Dr. Alireza Khanteymoori², Dr. Kenneth A. Fond¹, Dr. Anastasia V. Keller¹, Lex Maliga Davis¹, Prof. Jan M. Schwab^3,4, Prof. Adam R. Ferguson^1,5, Dr. Abel Torres-Espin^6,7, Dr. Ralf Watzlawick²

¹Department of Neurological Surgery, University of California, San Francisco, United States, ²Department of Neurosurgery, Neurocenter, Faculty of Medicine, University of Freiburg, Freiburg, Germany, ³Departments of Neurology and Neurosciences, The Ohio State University, Columbus, United States, ⁴Belford Center for Spinal Cord Injury, The Ohio State University, Columbus, United States, ⁵San Francisco Veterans Affairs Healthcare System, San Francisco, United States, ⁶Department of Physical Therapy, University of Alberta, Edmonton, Canada, ⁷School of Public Health, University of Waterloo, Waterloo, Canada

This study aims to bridge the gap between preclinical and clinical evidence by evaluating the feasibility of generating ‘class I evidence’ through meta-analysis and individual subject data (ISD) extraction. Despite advancements in understanding spinal cord injury (SCI) at the molecular and cellular levels, effective pharmacological interventions for humans remain elusive, highlighting the gap between preclinical and clinical evidence evaluation.

By applying modified clinical meta-analysis methods to interventional effect sizes in preclinical models, the study compares pooled effect sizes extracted from published literature to raw source data on individual subjects. This innovative approach uses the Collaborative Approach to Meta-Analysis and Review of Animal Data in Experimental Studies (CAMARADES) methods and demonstrates the feasibility of combining ISD analysis with traditional publication-based meta-analysis to explore effect size reproducibility in SCI.

Through systematic review and data extraction from 25 published articles from the Open Data Commons for SCI (ODC-SCI) repository and individual subject data from the Visualized Syndromic Information and Outcomes for Neurotrauma-SCI (VISION-SCI), including N=1841 subjects, and individual subject data from the same articles, including N=2441 subjects, the study compares meta-analysis findings with archived data to assess predictors of functional improvement.

The analysis shows significant differences in effect sizes across subject classifications, indicating variations in therapeutic responses between severe and mild injuries. As a result, this study underscores the importance of data sharing and transparency in improving the robustness of translation in SCI research. It highlights the potential for combining individual subject data analysis with traditional publication-based meta-analysis to improve preclinical SCI research.

Dr. Shun Okuwaki¹, Dr. Hiroshi Takahshi¹, Dr. Kotaro Sakashita¹, Dr. Masao Koda¹

¹University Of Tsukuba, Tsukuba, Japan

Background: Efficient clearance of apoptotic cells is crucial in preventing secondary injury expansion after spinal cord injury (SCI). The phosphatidylserine receptor CD300a is an immunoreceptor expressed on the dendritic cells and macrophages that regulate efferocytosis. A recent report indicated that CD300a deficiency enhanced efferocytosis by myeloid cells and treatment with an anti-CD300a neutralizing antibody ameliorated the neurological deficit in a rodent model of ischemic stroke.

Objective: This study investigates to evaluate the effect of CD300a blockade with an anti-CD300a neutralizing antibody in acute SCI.

Methods: Female mice underwent laminectomy at T10 and their spinal cords were injured. The antibody group (Group A) received 400 μg/200 μl of anti-CD300a neutralizing antibody immediately after SCI, and the control group (Group C) received normal saline. Hindlimb motor function was assessed up to 6 weeks after SCI using the Basso Mouse Scale (BMS). Histological analysis of the spinal cord for evaluating injury and residual myelinated areas.

Results: At 6 weeks after SCI, BMS was 4.3±0.3 in group A and 3.1±0.3 in group C. Group A demonstrated significant behavioral improvement compared to group C over 6 weeks after SCI (repeated major ANOVA, p<0.05). Histological examination revealed a smaller injured area, and the high percentage of residual myelinated area in group A.

Conclusion: In a SCI mice model, anti-CD300a antibody administration enhanced hindlimb motor function after SCI, reducing the injured area and preserving the myelin. The results suggest that CD300a blockade has neuroprotective effects in acute SCI and relieves the secondary injury to the spinal cord.

Mr. Alex Benedetto^1,2,3,4, Ms. Sophie T. Jenz^1,2, PT, PhD Bradley S. Heit², DPT Matthew T. Farley^1,2,3, PhD James A. Beauchamp^1,2,6, PhD Sina Sangari³, PhD Charles J. Heckman^1,2,3, PT, PhD Monica A. Perez^1,2,3,4, PhD Gregory E. Pearcey^1,5

¹Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, United States, ²Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, United States, ³Shirley Ryan AbilityLab, Chicago, United States, ⁴Edward Hines, Jr. VA Hospital, Hines, United States, ⁵School of Human Kinetics and Recreation, Memorial University of Newfoundland, Canada, ⁶Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, United States

Motor commands are comprised of excitatory, inhibitory, and neuromodulatory components, and disruptions in descending tracts caused by spinal cord injury (SCI) affect all three of these components. We hypothesized that disruptions alter motor unit (MU) discharge patterns in the upper limb muscles following cervical SCI, and that alterations in MU discharge would be associated with the extent of motor impairment. Individuals with chronic, incomplete SCI (n=18), and age-matched non-injured (NI) participants (n=18) performed maximal voluntary isometric contractions (MViC), submaximal holds to 20, 60, and 60% of maximum, and triangular ramp contractions to a peak of 30% of maximum with their elbow flexors and extensors. High-density surface electromyograms were collected from biceps and triceps brachii, and signals were decomposed into MU spike times. Mean discharge rates during each hold were computed to determine if rates were modulated with effort, and persistent inward current magnitudes were estimated using the paired-MU analysis technique (ΔF). Due to heterogenous strength deficits, the participants with SCI were categorized into high-functioning (HFSCI) and low-functioning (LFSCI) sub-groups based on their MViC values. Linear mixed effects models revealed that discharge rates were higher in NI than both SCI groups, and NI and HFSCI modulated rates across efforts but the LFSCI did not. Estimates of PICs in LFSCI were less than half of both the HFSCI and NI groups. These results suggest that motoneuron function is associated with the extent of motor impairment after SCI, and that the preservation or restoration of motoneuron excitability after SCI may enhance functional recovery.

Ms. Kayli Colpitts¹, Rafael Elejalde¹, Shriya Patil¹, Travis Johnston², Katherine Sanchez³, Erin Giles³, James Grau¹

¹Texas A&M University, College Station, United States, ²McGovern Medical School at UT Health Houston, Houston, United States, ³University of Michigan, Ann Arbor, United States

SCI is often accompanied by other tissue damage (polytrauma), which engages pain fibers. In a preclinical model, noxious stimulation a day after a lower thoracic (T10-11) injury impairs long-term recovery in male rats. This adverse effect has been related to pain-induced hemorrhage at the site of injury (Grau, 2017, J Neurotrauma, 34, 1873). Comparable results were observed with female rats (Baine, 2022, Neurotrauma Rep, 3.1). However, the magnitude of the effect varied with estrous cycle; noxious stimulation had less effect on animals injured during the proestrus stage. We hypothesized that this was due to variation in sex hormones. To evaluate this possibility, we first verified that noxious stimulation induces acute hemorrhage and a disruption in locomotor performance in ovariectomized rats. We then assessed the effect of hormone replacement in two separate experiments. The first evaluated the effect of estradiol, which was given either before ovariectomized rats received a thoracic contusion injury and/or 24 hrs later, prior to noxious stimulation. The second used the same design to test the effect of progesterone. In both experiments, locomotor performance was assessed prior to, and after, stimulation and tissue was collected 3 hrs later. We found that estradiol given prior to injury had a protective effect that lessened the impact of pain on locomotor performance. Two injections of progesterone appeared to adversely affect locomotor recovery. The results are consistent with other studies which suggest that estrogen has a neuroprotective effect.

Dr. Preeja Chandran¹, Anton Odarenko¹, Lindsay Cates¹, Dr Zin Khaing¹

¹University Of Washington, Seattle, United States

Spinal cord injury (SCI) leads to motor and sensory function loss, and currently there are no approved therapies for SCI patients. Although extensive vascular alterations occur at the lesion site, the extent of vascular remodeling in distant areas remains unclear. Recent research suggests that there may be a significant reduction in spinal cord oxygenation levels leading to a hypoxic state caudal to the injury. Loss of brainstem serotonin projections are thought to play a crucial role in this hypoxia. Here, we aim to determine how injury severity influence caudal spinal cord blood flow. Female Long Evans rats underwent contusion injuries at T8/9 with different severities (200kdyne + 2s dwell time (200/2s) and 250Kdyne + 2s dwell time (250/2s)) and a novel ultrafast ultrasound imaging was performed at baseline, acute, and at 6-8 weeks post injury (wpi) to visualize blood volume and flow velocities in both gray matter (GM) and white matter (WM). Ultrasound imaging showed a significant reduction in blood flow in GM at 6-8 wpi (27% decrease and 54% in 200/2s and 250/2s groups respectively; n=5). Histology results showed a significant reduction in 5HT fibers (83% and 93% fiber loss in 200/2s and 250/2s respectively; n=5). Combined, our data showed that there is a significant hypoperfusion after SCI in areas caudal to the injury, and this may be correlated with the extent of 5HT innervation loss. Strategies that can improve intraspinal blood flow are likely to be good therapeutic strategies to enhance functional improvements in chronically injured patients.

Ms. Rui-Yi Chen¹, Dr. Kun-Ze Lee¹

¹National Sun Yat-sen University, Kaohsiung, Taiwan

The present study was designed to investigate the therapeutic efficacy and mechanism of norepinephrine on cardiorespiratory function following cervical spinal cord injury. Non-invasive blood pressure analyzer and double chamber plethysmography were used to examine cardiorespiratory function of awake rats underwent cervical spinal cord contusion and implantation with saline or norepinephrine (125 μg/kg/hr for 1 week) osmotic pump. The result demonstrated cervical spinal cord injury caused a reduction in the mean arterial pressure and tidal volume. The hypotension response was significantly reversed in contused rats received norepinephrine (1 day: 90 ± 20 mmHg; 2 week: 96 ± 13 mmHg) compared with rats received saline (1 day: 71 ± 15 mmHg; 2 week: 82 ± 10 mmHg). Norepinephrine also significantly improved the tidal volume at 1 day post-injury (norepinephrine: 0.7 ± 0.2 ml; saline: 0.5 ± 0.1 ml). Immunofluorescent staining revealed that injury-induced reductions of thoracic noradrenergic and glutamatergic fibers were significantly improved by norepinephrine. Spinal cord blood flow and oxygenation of anesthetized rats at 1 week post-injury were not significantly modulated by norepinephrine, but spinal hemorrhage was mitigated as reflected by a lower spinal hemoglobin content in rats received norepinephrine (24 ± 4 mg/dL) vs. saline (45 ± 12 mg/dL). Next-Generation Sequencing of spinal cord showed that cervical spinal cord injury is associated with significant alterations of genes, which could be partially alleviated by norepinephrine treatment. These results indicate acute hemodynamic management using norepinephrine can improve cardiorespiratory function by mitigating neural pathway damage and spinal hemorrhage following cervical spinal cord injury.

Brittany Avonts¹, Ms. Daniela Garcia Prada¹, Dustin Kim, Dr. Brian T. David, Dr. Richard G. Fessler

¹Rush University, Chicago, United States

Central neuropathic pain (CNP) commonly develops in individuals after spinal cord injury (SCI), causing debilitating symptoms and sensory abnormalities to mechanical and thermal stimuli. The biological variability of pain phenotypes in these individuals has limited the number of positive outcomes. Thus, it is necessary to investigate the physiological processes contributing to sensory changes that develop over time. Using the tail flick and von Frey tests, we performed hierarchical clustering to determine the subpopulation of rats that developed thermal and mechanical sensory abnormalities. To measure inflammation as a potential mediator of CNP phenotypes, we used flow cytometry and immunohistochemistry. Lastly, to assess the secondary effects on locomotor recovery, up to 8 weeks after injury, we used the CatWalk test to assess multiple parameters of gait. The von Frey test showed a subpopulation of SCI rats which were hyposensitive to mechanical stimuli from 6-8 weeks following injury. The tail flick test showed a subpopulation of SCI rats that were hypersensitive to thermal stimuli at 1 week and 3-8 weeks after injury. While there were no differences in inflammatory cells between subpopulations, we did see significant changes in locomotor recovery between rats with and without sensory abnormalities. The overall myeloid cell population is not affected by mechanical or thermal phenotypes of pain in this model. However, locomotor recovery is impaired depending on the pain phenotype present. Further investigation into acute inflammatory cells may be insightful for predicting the development of pain phenotypes.

This work is funded by the Daniel and Ada Rice Foundation.

Dr. Natalie Scholpa^1,2, Dr. Epiphani Simmons², Dr. Justin Snider², Dr. Rick Schnellmann^1,2

¹Department of Veterans Affairs, Tucson, United States, ²University of Arizona, Tucson, United States

Following spinal cord injury (SCI), there is an inherent recovery phase that is short-lived and ultimately plateaus. Understanding the physiological differences within the spinal cord over time could facilitate targeted approaches aimed at preventing and/or reversing this plateau, allowing for continued recovery. Metabolomics were used to characterize the metabolic profile within the injured cord during the recovery (7 DPI) and plateau (21 DPI) periods in a mouse model of severe contusion SCI. Analysis revealed that alterations in 183 lipid metabolites, including those involved in phospholipid metabolism, largely contributed to overall differences in metabolic profile. Phospholipids are hydrolyzed to yield lysophospholipids and fatty acids (FAs). Phospholipid metabolites decreased between 7 and 21 DPI, while lysophospholipids increased at 21 DPI, suggesting amplified phospholipid metabolism during the plateau phase. In support of this, expression of various phospholipases A2 (PLA2), which catalyze phospholipid metabolism, were increased 21 DPI versus 7 DPI. Increased FAs promote inflammation, mitochondrial dysfunction and neuronal damage. These effects can be attenuated by binding FA with carnitine to form acylcarnitines, which translocate into the mitochondria for beta-oxidation. While FAs were increased in the injured cord regardless of timepoint, carnitine and acylcarnitines were increased at 7 DPI and then decreased 21 DPI. These data suggest that adverse FA effects may be inhibited 7 DPI via carnitine-mediated pathways, which could contribute to the observed recovery phase. In contrast, the consistently high levels of FAs and decreased carnitine during the plateau phase may augment FA-induced dysfunction, preventing continued recovery following SCI.

Dr. Yun Li¹, Dr. Rodney Ritzel¹, Dr. Junyun He¹, Simon Liu¹, Dr. Li Zhang¹, Dr. Junfang Wu¹

¹University of Maryland, School of Medicine, Baltimore, United States

Spinal cord injury (SCI) causes sensorimotor deficits and neuropathic pain, with no effective treatment. In part, this reflects incomplete understanding of the secondary pathobiological mechanisms involved. Microglial/macrophage activation has distinct pro-inflammatory or inflammation-resolving phenotypes, which potentiates tissue damage or functional repair. However, little work has addressed underlying mechanisms that determine phenotype. Identifying such pathways could provide novel targets for therapeutic intervention. The major integrin Mac-1 (CD11b/CD18), a heterodimer consisting of CD11b and CD18 chains, is expressed by multiple immune cells of the myeloid lineage. Here, we examined the effects of genetically manipulating CD11b on neuroinflammation and functional outcomes after SCI. Young adult female CD11b knockout (KO) mice and their wildtype (WT) littermates were subjected to moderate thoracic contusion. qPCR analysis showed a rapid and persistent upregulation of CD11b mRNA starting from 1d after injury, which persisted up to day 28. At 1d post-injury, increased expression levels of genes that regulate inflammation-resolving processes were observed in CD11b KO mice. Flow cytometry analysis of CD45intLy6C-CX3CR1+ Tmem119+ microglia and CD45hiLy6C+G-CD83+CX3CR1+ Tmem119+ monocytes revealed significantly lower cell counts and decreased reactive oxygen production in CD11b KO mice at d3 post-injury. Further examination of the injured spinal cord with NanoString and RNAseq showed downregulation of pro-inflammatory genes. Importantly, CD11b KO mice exhibited significantly improved locomotor function, reduced cutaneous mechanical/thermal hypersensitivity, and limited tissue damage at 8 weeks post-injury. Together, our data suggest an important role for CD11b in regulating tissue inflammation and functional outcome following SCI, which makes it a potential target for novel therapeutic strategies.

Dr. Alireza Khanteymoori¹, Roza Atamny¹, Prof. Jürgen Beck¹, Dr. Ralf Watzlawick¹

¹Department of Neurosurgery, Neurocenter, Faculty of Medicine, University of Freiburg, Freiburg, Germany

This study aims to systematically review experimental Chondroitinase ABC (ChABC) treatments after spinal cord injury (SCI) and assess their efficacy for locomotor function. The formation of glial scars after injury impedes axonal growth, posing a major obstacle in developing effective therapies for nerve cell regeneration and functional restoration. ChABC offers a potential approach to restore locomotor function by degradation of the forming scar at the injury site. Efficacy was assessed by measuring the percentage of improvement on neurobehavioral scales compared to control groups.

Overall, ChABC treatment demonstrated a 15.9% improvement in locomotor outcomes. Subgroup analyses were performed to investigate various experimental factors, including animal type, strain, sex, sample size, injury models, level of injury, and treatment duration. The results of the subgroup analyses did not reveal any significant effects for treatments longer than 7 weeks. Additionally, the number of animals used did not significantly influence the outcomes. However, the quality analysis indicated a larger effect size in studies that did not report randomization, underscoring the importance of improving animal allocation practices.

In conclusion, these results provide evidence of an improvement in locomotor behavior among animals with spinal cord injuries following ChABC treatment. However, it is important to acknowledge the presence of inter-individual variations, heterogeneity, publication bias, and methodological weaknesses within the included studies. These factors should be taken into consideration when interpreting the findings.

Dr. Lisa Baker^1,2, Dr. Adam Kramer^1,2, Dr. Rayna Birnbaum², Dr. Kimberly Byrnes³, Dr. David Sharp²

¹Microcures, Inc., Bronx, United States, ²Dept. of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, United States, ³Dept. of Anatomy, Physiology, and Genetics, Uniformed Services University, Bethesda, United States

We previously identified the microtubule severing enzyme Fidgetin-like 2 (FL2) to be a novel regulator of cell motility and axonal growth and demonstrated that targeted depletion of FL2 accelerates wound healing in multiple rodent injury models, including peripheral nerve injury. Based on these studies, we hypothesized that targeted depletion of FL2 after spinal cord injury (SCI) may promote healing and functional recovery. We conducted a pilot study in which male rats underwent moderate thoracic contusion injury followed by delivery of nanoparticles containing FL2 siRNA (SiFi2) or scrambled siRNA (siCon) to the intrathecal space. Basso, Beattie, Breshanan (BBB) scores showed that SiFi2 enhanced locomotor function compared to controls by 21 days (SiFi2 mean BBB=17; siCon=10; n=3/group, p<0.01). To understand how SiFi2 promotes healing after SCI, we are testing the effects of FL2 depletion on multiple cell types involved in CNS repair, including neurons and endothelial cells. FL2 depletion of dissociated mouse neonatal cortical neurons increased mean neurite length compared to controls (p=0.002; 20% increase; n=140 neurons/group). Human umbilical vein endothelial cells (HUVECs) transfected with FL2 siRNA formed endothelial tube networks more rapidly than controls (60% increase in mesh and segment number over 12 hours) and migrated faster in an in vitro scratch assay (p<0.001, 16% increase in mean velocity, n=30-31 cells/group). These studies indicate that FL2 is a promising therapeutic target for treating SCI and identify neurons and endothelial cells as two possible cell types through which SiFi2 may promote healing.

Funding Source(s): NIH/NINDS R21 (NS126890-01A1); NIH/NIDDK RO1 DK109314.

¹University Of Miami, Miami, United States

Gliosis and fibrosis are essential wound-healing processes after spinal cord injury (SCI), but they result in scar tissue that impedes axon and oligodendrocyte regeneration. In its mature form, the two scars occupy distinct regions with reactive glia surrounding the fibrotic scar that occupies the lesion center and is comprised mainly of macrophages and fibroblasts. The interface between the glial and fibrotic scar is thought to be especially inhibitory to regeneration, but the cellular and molecular composition of these regions is still poorly understood, especially during the early stages of SCI when a distinct scar has yet to form. Thus, we used spatial transcriptomics of the mouse spinal cord injury site at 3 days post contusion injury to gain a better understanding of the cellular and molecular mediators of scar formation at its early stages. A dimension reduction analysis revealed distinct clusters that were associated with different regions of the injury site. Notably, our analysis identified a cluster that was located in between infiltrating immune cells and neural tissue. This “scar interface” cluster contained high expression of genes associated with leukocytes and myelin, and Gene Ontology analysis identified antigen presentation as a biological process highly enriched in this region. Using our previous single-cell RNA-seq datasets, we found that antigen presentation genes associated with this scar interface cluster were highly specific to dendritic cells. Taken together, our spatial transcriptomics analysis of the early spinal cord injury site revealed antigen presentation by dendritic cells as a possible mechanism that contributes to scar formation.

Ms. Shelby Reid¹, Miranda Leal¹, Megan Kirchhoff¹, Nicole Rehtmeyer¹, Alyson Narvaez¹, Isha Shirvaikar¹, Dylan McCreedy¹

¹Texas A&M University, College Station, United States

After traumatic spinal cord injury (SCI), inflammation and other reactive processes exacerbate tissue damage and impair long-term motor recovery. Extracellular traps (ETs) are an immune effector function first described in neutrophils wherein chromatin is decondensed, decorated with cytotoxic granule enzymes, and expelled from the cell body. Recently, ETs have been linked to poor functional outcomes in SCI; however, translatable agents to prevent ET-mediated damage after SCI have yet to be explored. We assessed recombinant human (rh) DNase (trade name Pulmozyme) as a potential therapeutic that could be repurposed to break down ETs after SCI. To determine the timing of treatment, we characterized the timeline of ET formation in a thoracic contusion model of SCI in mice. We found that ETs levels increased in the injured spinal cord by 4 hours post injury (hpi), peaking within 24 hpi. When rhDNase was administered at 1 hpi, DNase activity in the serum remained elevated for 24 hpi with a corresponding increase in circulating ET fragments. At 6 hpi, blood spinal cord barrier permeability was attenuated in rhDNase-treated animals. Long-term functional hind limb recovery, as assessed by the ladder rung walking test, was improved at 35 dpi in rhDNase-treated animals compared to vehicle-treated controls. RhDNase-treated animals also exhibited shorter SCI lesion lengths and improved white matter sparing at 35 dpi. All together, our data demonstrate the potential of rhDNase as an anti-ET therapeutic to improve long-term SCI outcomes.

Mrs. Miranda Leal-Garcia¹, Mrs. Shelby Reid², Miss Mia Pacheco², Miss Victoria Tseng¹, Dr Dylan McCreedy^1,2

¹Biology Department - Texas A&M University, College Station, United States, ²Texas A&M Institute for Neuroscience, College Station, United States

During the acute phase of spinal cord injury (SCI), neutrophils infiltrate in large numbers and can exacerbate inflammation, promote secondary tissue damage, and worsen long-term functional outcomes. We have previously shown that augmenting the cleavage or shedding of L-selectin, an adhesion and signaling receptor on neutrophils, can reduce secondary injury and improve neurological recovery after SCI. However, it remains unclear how L-selectin shedding regulates neutrophil function following SCI. To determine the role of L-selectin shedding in neutrophil responses to SCI, we utilized L(E) mice, which express a non-cleavable version of L-selectin. Using in vitro stimulation assays, we observed sex- and genotype-dependent differences in neutrophil effector functions in the absence of L-selectin shedding, including decreased degranulation in neutrophils from L(E) females compare to WTs and increased ROS production in neutrophils from L(E) mice of both sexes. In vivo, we observed sex- and genotype-dependent differences in neutrophil accumulation at 1, 3 and 35 days post-injury (dpi) in a thoracic contusion model of SCI. At 1 dpi, we observed greater neutrophil accumulation in male mice compared to females. At 35 dpi, neutrophil accumulation was greater in L(E) females compared to WTs, but no differences were observed between L(E) and WT males. We observed impaired long-term hindlimb recovery in L(E) female, but not male, mice compared to WTs. Interestingly, there was a marked reduction in spared white matter in L(E) mice from both sexes when compared to WT mice. Our data demonstrates sex-dependent roles for L-selectin shedding in attenuating pathogenic neutrophil response after SCI.

Ashley Tran, Dr. Dylan McCreedy

¹Texas A&M University, College Station, United States

The acute phase of spinal cord injury (SCI) is marked by rapid and extensive accumulation of neutrophils, which may worsen long-term outcomes. Despite their commonly short lifespan (∼1-2 days), neutrophils can adopt heterogeneous phenotypes and functions that could be dependent on cellular maturation state. However, neutrophil heterogeneity and maturation is poorly understood in the context of SCI. We tracked neutrophil maturation by flow cytometry in the bone marrow, blood, and spinal cord tissue at 1, 3, 7, and 35 days post-injury (dpi). Although immature neutrophils are commonly thought to be functionally inactive or dysfunctional, we observed a sex-dependent shift from predominantly mature neutrophils (CD101+) circulating in the blood to mostly immature neutrophils (CD101-) at 1 dpi before returning to a predominantly mature phenotype by 7 dpi. In the spinal cord, we observed an increase in mature neutrophils at 1 and 3 dpi before returning to a predominantly immature phenotype by 7 dpi. Our data indicates that SCI triggers immature neutrophil release into circulation and that neutrophil maturation states change over time in the injured spinal cord. We also injected EdU at 1 day prior to SCI to label immature neutrophils recently derived from proliferating neutrophil progenitors. At 35 dpi, about 10% of both immature and mature neutrophils in the spinal cord were EdU+, suggesting that some neutrophils remain in injured spinal cord tissue for weeks after SCI. Our findings are the first to characterize neutrophil maturation after SCI and to identify long-lived neutrophils in the injured spinal cord tissue.

Mr. Frank Jalufka¹, Mr. Jack Kubaney¹, Ms. Margaret Hruska², Dr. Dylan McCreedy^1,3

¹Department of Biology, Texas A&M University, College Station, United States, ²Department of Public Health, Texas A&M University, College Station, United States, ³Texas A&M Institute for Neuroscience, Texas A&M University, College Station, United States

Neutrophils are the first immune cell type to invade the injured spinal cord in large numbers, however, the spatiotemporal pattern of neutrophil accumulation hasn’t been well characterized. While tissue clearing and 3D lightsheet imaging could provide critical insight into neutrophil distribution following spinal cord injury (SCI), we found that Ly6G (a well-validated marker for neutrophils in mice) is removed during tissue clearing. To create an alternative method for labeling neutrophils, we bred Ly6G-Cre mice with Ai14 reporter mice, which led to robust expression of tdTomato in ∼66% of neutrophils. However, we also observed extensive background neuronal labeling that hindered quantification of neutrophils in the injured spinal cord. Using publicly available scRNA-sequencing datasets, we identified S100a8 (MRP8) as a potential secondary marker to help distinguish neutrophils. By combining our Ly6G-Cre x Ai14 reporter mouse with an anti-MRP8 antibody, we were able to visualize co-localization of the tdTomato and MRP8 in neutrophils within the spinal cord with minimal co-localization in other cell types. Interestingly, an additional discovery from our scRNAseq analysis was the identification of a novel population of neutrophils associated with the uninjured spinal cord. This population is phenotypically distinct from circulating neutrophils and closely resembles immature neutrophils found in the bone marrow. Our scRNAseq analysis of later timepoints suggests that intraspinal neutrophils revert back to this immature state in the subacute phase of SCI. Using our new labeling strategy, we are now characterizing the localization and distribution of this novel neutrophil population in the uninjured and sub-acutely injured spinal cord.

Mr. Anthony Alfredo¹, Dr. Matthew Goodus¹, Ms. Kaitlin Carson¹, Dr. Jan Schwab¹, Dr. Xiaokui Mo¹, Dr. Richard Bruno¹, Dr. Dana McTigue¹

¹The Ohio State University, Columbus, United States

Individuals with spinal cord injury (SCI) are disproportionately affected by metabolic syndrome (MetS), a collection of co-morbidities such as abdominal obesity. Our previous studies revealed SCI causes hyperlipidemia, insulin resistance, and “neurogenic” non-alcoholic steatohepatitis (nNASH), the hepatic manifestation of MetS. A possible driver of nNASH after SCI is the accumulation of visceral white adipose tissue (WAT). Excess WAT triggers macrophages to infiltrate and form crown-like structures (CLS) around dying adipocytes. CLS produce pro-inflammatory adipokines, stimulating adipocyte lipolysis via phosphorylation of hormone-sensitive lipase (pHSL). Currently, no experimental studies directly assess the relative changes in post-SCI adipose compared to obesity. Thus, we hypothesize that SCI increases inflammation and lipolysis in WAT and that this effect will be exacerbated by premorbid obesity. To test this, male rats were fed a high-fat diet causing diet-induced obesity (DIO) or low-fat (LF) diet for 8w prior to SCI and then given a moderate T8 contusion. Animals continued with their respective diets and were sacrificed at 56d post-injury (dpi). Epididymal (eWAT) and retroperitoneal (rWAT) adipose was collected. Histological analysis of eWAT and rWAT revealed LF+SCI, DIO, and DIO+SCI animals had comparably increased CLS formation versus LF controls. SCI animals had elevated pro-inflammatory adipokines TNF and IL-1b in eWAT versus LF controls. pHSL was significantly elevated in eWAT and rWAT of LF+SCI and DIO+SCI animals compared to LF and DIO controls. Thus, SCI causes visceral WAT inflammation and lipolysis independent of premorbid obesity. Identifying mechanisms driving post-SCI WAT dysregulation are therefore expected to improve cardiometabolic health following SCI.

Dr. Zihui Wang¹, Dr. Zhuofan Lei¹, Dr. Yun Li¹, Dr. Balaji Krishnamachary¹, Dr. Hui Li¹, Dr. Long-Jun Wu², Dr. Junfang Wu¹

¹Department of Anesthesiology & Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, United States, ²IMM-Center for Neuroimmunology and Glial Biology, University of Texas Health Science Center at Houston, Houston, United States

The voltage-gated proton channel Hv1 is highly expressed by resting microglia but not neurons or astrocytes in the mouse brain. Microglial Hv1 regulates intracellular pH and aids in NOX2-dependent generation of reactive oxygen species (ROS). Thus, Hv1 is a unique target for controlling multiple NOX activities and ROS production. In mouse models of spinal cord injury (SCI), our studies point to an acute neuroprotection phenotype when Hv1 is genetically deleted including infiltrating immune cells. Here, the goal was to test the impact of microglial Hv1 on SCI-mediated neuropathology. In cultured mouse primary microglia, ELISA analysis showed that inhibition of Hv1 by its inhibitor 2-guanidinobenzimidazole significantly reduced pro-inflammatory cytokines and chemokine secretion stimulated by lipopolysaccharide in a dose-dependent manner. In vivo, young adult age-matched global Hv1 KO and WT male mice were subjected to SCI. At 28 days post-injury, the transcriptional changes in the injured spinal cord were assessed by a NanoString nCounter Glia panel. Nanostring analysis revealed decreased gene expression of cytokines, inflammasomes, and astrocyte markers in Hv1 KO mice. To dissect the function of microglial Hv1 in SCI, Hv1flox/flox mice were crossed with CX3CR1CreER mice to generate microglia-specific conditional Hv1 KO (Hv1 cKO) mice. After 4 weeks of tamoxifen induction, a moderate contusion SCI at T10 of the male mice was performed in both Hv1 cKO and their WT littermates. Hv1 cKO mice exhibited significantly improved locomotor function and reduced histopathology. Together, the present data suggest an important role for microglial Hv1 in regulating SCI-mediated secondary injury processes.

Dr. Patrick Belton¹, Dr. Abel Torres-Espin, Mr. Justin Wong, Dr. Hannah Radabaugh, Dr. John Yue, Dr. J. Russell Huie, Mr. Jason Barber, Dr. Nancy Temkin, Dr. Sonia Jain, Ms. Xiaoying Sun, Dr. Benjamin Lee, Dr. John Kanter, Mr. Mattice Harris, Mr. William McDaniels, Amy Markowitz, Dr. Adam Ferguson, Dr. Geoffrey Manley

¹University Of Wisconsin - Madison, Madison, United States

Clinical traumatic brain injury (TBI) studies have often housed collected data either in on-site servers or with a commercial clinical data management system (CDM). While commercial CDMs are regarded as secure and reliable, cost can be substantial. An on-site server can be supplemented with advanced analysis tools such as bespoke statistical or machine learning applications, but server maintenance and security can require substantial staff time. In addition, there has been interest in aggregating data from multiple clinical TBI studies in order to increase sample size, improve expected generalizability, and capture effects not evident in a smaller pool. Combining identified data from studies performed in different countries can require extensive legal agreements and inhibit collaborative research using identified human data. Federated analysis, where analysis routines are run on local servers and then abstracted data transmitted for central re-processing, holds promise to both preserve subject privacy and allow maximal research utility for collected data. We describe the design and implementation of a highly protected cloud-based version of the open-source data warehouse Opal, the associated federated analysis toolset Datashield, and the transfer and validation of data from clinical trials to that warehouse. Primary data sources are the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) clinical trials. We describe a network architecture which allows secure interface with multiple points of interdiction for use of federated analysis tools to perform research on the study data without need for explicit data sharing.

Ms. Anushka Sheoran¹, Kenneth A Fond², Lex Maliga Davis², J Russell Huie², Romana Vavrek³, PJ Fairbairn², Vance Lemmon⁴, John L Bixby⁴, Ubbo Visser⁵, John C Gensel⁶, Karim Fouad³, Adam R Ferguson², Jeffrey S Grethe⁶, Anita Bandrowski⁹, Maryann E Martone¹, Abel Torres-Espin¹⁰

¹University Of California San Diego, La Jolla, USA, ²Department of Neurological Surgery, Weill Institute for Neurosciences, Brain and Spinal Injury Center, University of California San Francisco, San Francisco, USA, ³Department of Physical Therapy, Faculty of Rehabilitation Medicine, Institute for Neuroscience and Mental Health, University of Alberta, Edmonton, Canada, ⁴Miami Project to Cure Paralysis, Department of Neurological Surgery and Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, USA, ⁵Department of Computer Science, University of Miami, Coral Gables, USA, ⁶Department of Physiology, Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, USA, ⁷San Francisco Veterans Affairs Health Care System, San Francisco, USA, ⁸Center for Research in Biological Systems, University of California San Diego, San Diego, USA, ⁹SciCrunch Inc., San Diego, USA, ¹⁰School of Public Health Sciences, Faculty of Health, University of Waterloo, Waterloo, Canada

Data interoperability is crucial for effectively combining data for scientific inquiry. To facilitate interoperability, data standards such as a common definition of variables are often developed. The Open Data Commons for Spinal Cord Injury (ODC-SCI, odc-sci.org) has established an initial set of community-based data elements (CoDEs) to promote data interoperability in SCI research, aligning with FAIR (Findable, Accessible, Interoperable, and Reusable) data principles. We sought to understand the use of CoDEs by the SCI community to inform current standards adherence and future standards development. We systematically analyzed 39 public datasets in relation to 17 required CoDEs and found variations between reported data and the structure specified by the CoDEs. Overall, we found that the enforcement of data standards improved reporting rates of CoDEs variables. Notably, different variables were found to require different levels of curation to ensure semantic equivalence among datasets. We also uncovered specific reporting habits of researchers such as formatting and naming patterns. A need for different data standards based on the nature of the study (e.g., human study, secondary study) was realized alongside a detailed list of issues that should be addressed when implementing such standards. Among the various approaches to develop data standards, ODC-SCI adopted a semi-formal approach by creating standards that are easy to adopt by the user. Our data driven evaluation on actual reporting behavior shows that this flexibility can lead to subsequent problems in harmonization. This study serves as a baseline analysis of reporting behaviors for shaping and facilitating data standards.

Dr. Ina Wanner^1,2, Dr. Raymond Koehler³, Dr. Neil Harris^1,2, Dr. Russell Huie⁴, Dr. Timothy Van Meter⁵, Dr. Javier Allende Labastida³, Dr. Hannah Radabaugh⁴, Mr Anthony Tobar¹, Mrs Chloe McMann-Chapman¹, Dr. Mark Burns⁶, Dr. Alexandru Korotcov⁷, Dr. Marcelo Febo⁸, Dr. Jinyuan Zhou⁹, Mrs Jieru Wan³, Dr. Adam Ferguson⁴, Mrs Esmeralda Mendoza⁴, Mrs Lex Maliga Davis⁴, Dr. Firas Kobeissy¹⁰, Dr. Jiepei Zhu¹⁰, Dr. Kevin Wang¹⁰, Dr. Hibah Awwad¹¹, Dr. Joseph McCabe¹²

¹UCLA, Semel Institute, IDDRC, Los Angeles, United States, ²UCLA, Brain Research Injury Center, BIRC, Los Angeles, United States, ³John Hopkins University, Department of Anesthesiology and Critical Care Medicine, Baltimore, United States, ⁴UCSF, Brain and Spinal Injury Center, BASIC, San Francisco, United States, ⁵Brain Box Solutions Inc., Richmond, United States, ⁶Georgetown University Medical Center, Center for Neural Injury and Repair, Washington DC, United States, ⁷Uniformed Services University, Department of Radiology and Radiological Sciences, Bethesda, United States, ⁸University of Florida, Department of Psychiatry, Advanced Magnetic Resonance Imaging and Spectroscopy Facility, Gainesville, United States, ⁹John Hopkins University, Department of Radiology and Radiological Science, Baltimore, United States, ¹⁰Morehouse School of Medicine, Department of Neurobiology, Center for Neurotrauma, Multiomics and Biomarkers, Atlanta, United States, ¹¹NIH, National Institute of Neurological disorders and Stroke, NINDS, Division of Neuroscience, Bethesda, United States, ¹²Uniformed Services University, Department of Anatomy, Physiology and Genetics, Bethesda, United States

TOP-NT aims to test noninvasive, clinically-relevant assessments in three rat TBI models, controlled cortical impact, fluid percussion injury and CHIMERA, to determine reproducibility between sites (Kislik, NNS2024), and cross-domain validation. Primary outcomes included diffusion-weighted and amide proton transfer imaging, functional MRI, and biomarkers glial fibrillary acidic protein, neurofilament light, aldolase-C and tau/P-tau. Here we report necessary prospective harmonization product’: (1) a jointly formulated and applied compendium of standard operating procedures (SOPs), (2) a dictionary of 477 preclinical TBI CDEs derived from these SOPs, (3) a CDE taxonomy, (4) practical steps for data curation among sites and domains, and (5) an a-priori analysis plan. New CDEs for CHIMERA, anesthesia, apnea, estrous cycle, temperature, Barnes, and Y-mazes were added to pre-existing ones. New domains were biomarkers, volumetric multimodal MRI, and unbiased quantitative histopathology (Tong, NNS2024). CDEs defined acquisition specifications, measurements, metadata, and quality controls. An organizing CDE taxonomy bridged existing and ongoing CDE-creation efforts and documented preclinical-to-clinical similarities. We identified canonical, core CDEs used by all domains including quality controls, identifiers and metadata that linked heterogeneous datasets. Practical data curation and organizing steps handled repeated measures, technical replicates, missingness, outliers, and pooling for centralized analytics. An univariate general linear model ANOVA assesses main and interaction effects of group, sex, time, injury setting and site (Harris, Cai, Zhou, Tong, NNS2024). This TOP-NT structural framework serves to evaluate reproducibility addresses multiple covariates simultaneously, and enables multivariable analyses to arrive at a higher level, syndromic understanding of TBI signatures for preclinical and clinical TBI research.

Ms. Emily Lin^1,2, Professor Pratik Mukherjee^1,2, Professor Gabriela G. Satris^1,2, Dr. John K. Yue^1,3, Sabrina R. Taylor^1,3, Editor and Program Manager Amy J. Markowitz^1,3, Professor Christine L. Mac Donald⁴, Professor David O. Okonkwo⁵, Professor Joseph T. Giacino⁶, Professor Michael W. McCrea⁷, Professor Murray B. Stein^8,9, Professor Nancy R. Temkin⁴, Professor Ramon Diaz-Arrastia¹⁰, Professor Claudia S. Robertson¹¹, Professor Geoffrey T. Manley^1,3, Professor Esther L. Yuh^1,2

¹Brain and Spinal Injury Center, UC San Francisco, San Francisco, United States, ²Department of Radiology and Biomedical Imaging, UC San Francisco, San Francisco, United States, ³Department of Neurological Surgery, UC San Francisco, San Francisco, United States, ⁴Department of Neurosurgery, University of Washington, Seattle, United States, ⁵Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, United States, ⁶Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, United States, ⁷Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, United States, ⁸Department of Psychiatry, UC San Diego, San Diego, United States, ⁹Veterans Affairs San Diego Healthcare System, San Diego, United States, ¹⁰Department of Neurology, University of Pennsylvania, Philadelphia, United States, ¹¹Department of Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston, United States

In recent years there has been interest in automated intracranial hemorrhage detection and segmentation on head CT. As with other clinical applications of machine learning, high performance on external data, or CT exams performed at hospitals not represented in the training data, is essential. We use CT exams from the multicenter Transforming Research and Clinical Knowledge in Traumatic Brain Injury (“TRACK-TBI”) study to demonstrate a deep learning model that detects and segments subarachnoid hemorrhage (SAH), subdural hematoma (SDH), contusion, epidural hematoma (EDH), traumatic microbleeds, and intraventricular hemorrhage (IVH) with excellent performance on “unseen” external CT exams. The model was trained on a corpus of 3348 clinical CT examinations from a single U.S. medical center, and validated on 835 CT examinations performed on TRACK-TBI participants across 13 outside U.S. medical centers. CT examinations were pixel-labeled by a U.S. board-certified neuroradiologist. The model achieved strong binary classification, with area under curve (AUC) receiver operating characteristic (ROC) of 0.971 for identification of exams positive for intracranial hemorrhage. The model also achieved strong performance on multiclass classification, with AUC ROCs of 0.959 for SAH, 0.963 for SDH, 0.833 for contusion, 0.837 for EDH, 0.748 for petechial hemorrhage, and 0.831 for IVH. Finally, the model achieved a high mean Dice coefficient of 0.557 compared to manual expert segmentation. Deep learning can achieve strong performance on multiclass detection and segmentation of intracranial hemorrhage on “unseen” external CT exams that embody the diversity of real-world clinical data.

Mr. Benjamin Burch¹, Ms. C. Lexi Baird^1,2, Mr. Ahmed Hussain^1,2, Ms. Alexandra Dwulit^1,3, Dr. Rajendra Morey^1,2

¹Duke University, Durham, United States, ²Durham VA MIRECC, Durham, United States, ³North Carolina State University, Raleigh, United States

Background: As sample sizes increase from consortium studies sourced from multiple cohorts, the effect of errors on results is increasingly important to characterize. Neuroimaging studies of TBI patients are particularly susceptible to imaging artifacts. While various strategies (imputation, etc) can address missing data, corrupt data is challenging to address because it may remain undetected.

Methods: Python was used to create a tool that simulates the effects of corrupt elements in clinical data and structural neuroimaging data. Given user input, the tool introduces iterations of corrupt entries into datasets used in regression modeling. The simulation returns a data table with p-values and beta coefficients corresponding to each iteration. This tool was tested on a dataset of ROI-level cortical surface area (N = 241).

Results: We found a non-linear relationship between the potential for noise and dataset reliability. The most significant results were found with altering data points by changing its value by a specified percentage. The results of our simulations showed the effects of 135 datapoints corrupted by 5% of the original value, or 100 datapoints corrupted by 10% of the original value. The age regressor ceases to be statistically significant when 135 datapoints are corrupted by 5%, 100 datapoints are corrupted by 10%, or 75 datapoints are corrupted by 20%. Our tool is useful for determining how robust a data set is.

Conclusion: Our tool provides valuable feedback that researchers can use to understand the relationships between the variables in their data sets and simulate corrupt neuroimaging and clinical data.

Mr. Gregory Kislik^1,2, Ms. Rachel Fox^1,2, Dr. Alex Koroctov, Dr. Jinyuan Zhou, Dr. Marcelo Febo, Dr. Raymond Koehler, Dr. Mark Burns, Dr. J. Russell Huie, Dr. Joseph McCabe, Dr. Adam Ferguson, Dr. Kevin Wang, Dr. Ina Wanner^1,2, Dr. Neil Harris^1,2, TOPNT Consortium Participants

¹UCLA Department of Neurosurgery, Los Angeles, United States of America, ²Brain Injury Research Center, Los Angeles, United States of America

Multi-site neuroimaging studies have become increasingly common in order to verify reproducibility and to increase group sizes for questions with smaller effect sizes. The data harmonization model NeuroCombat has been shown to remove site effects introduced by differences in site-related technical variance, while maintaining group differences, yet its effect on data harmonization and statistical power in pre-clinical models of CNS disease is unclear. The present study examined fractional anisotropy data computed from diffusion weighted imaging data at 3 and 30 days post-controlled cortical impact injury from 337 adult rats across 4-sites as part of the Translational-Outcome-Project-in-Neurotrauma Consortium. Findings confirmed prior clinical reports that NeuroCombat fails to remove site effects in data containing a high proportion-of-outliers (>10%) and skewness, which introduced significant variation in non-outlier sites. After removal of 1 site, the impact of harmonization at the voxel level after image co-registration was analyzed with Bland Altman plots, which confirmed improved cross-site alignment of whole-brain voxel distributions. This was characterized by movement toward similar distributions (Kalmogorov-Smirnov <<0.001 to >0.01), stable variability (delta standard deviation) and statistical power increases within ipsilateral cortex. Harmonization with NeuroCombat removed or reduced the effect of site (P>0.05), but retained the effect of group (p< 0.01) for univariate high and low FA volumes of pathology, white/gray matter regions-of-interest and, whole-brain-computed FA values (p<0.01). These findings indicate the data-dependent utility of NeuroCombat in multi-site harmonization, where biological differences can be accurately revealed to allow for greater reproducibility in neuroimaging studies.

¹Uniformed Services University of the Health Sciences, Bethesda, United States, ²Henry Jackson Foundation, Bethesda, United States

Early detection of traumatic brain injury (TBI) is essential for early intervention and accurate diagnoses. Serum-detectable biomarkers are key for diagnosing and assessing mild TBI. We have modified a novel 3D human tissue culture system to form a discovery platform for identifying novel human biomarkers following blast TBI. 3D tissue cultures (tricultures) were grown from iPSC-derived neuronal precursors, human astrocytes, and HMC3 microglia-like cells. Following 5 weeks of growth and integration into the scaffold matrix, tricultures were subject to blast injury. Media taken from tricultures at several timepoints were analyzed through SomaLogic’s aptamer array and Nanostring’s nCounter miRNA expression panel. Bulk RNA seq was also performed. Traditional bioinformatics analysis of these datasets has provided promising information on hundreds of potential human biomarkers; pairing these initial exploratory analyses with a categorical machine learning approach has narrowed down the list of most-relevant targets to 17 proteins 6 hours following blast. We have confirmed the induction of several biomarkers in independent samples. These blast biomarkers will be compared to biomarkers produced from tricultures injured by impact injury. These detailed analyses of proteins and miRNAs generated in injured triculture media may suggest unique biomarkers produced by blast or impact injuries.

This work was funded by a grant from the Department of Defense (DoD) Technology for the Warfighter Program. The opinions and assertions expressed herein are those of the author(s) and do not reflect the official policy or position of the Uniformed Services University or the DoD.

Mr. Ori Zaff¹, Dr. Alexa Walter¹, Mr. Drew Parker¹, Ms. Stefanie Darnley¹, Ms. Priyanka Kalyani¹, Mr. Griffin Anderson¹, Ms. Abbie Chan¹, Dr. Jeffrey Ware¹, Dr. Ragini Verma¹, Dr. Ramon Diaz-Arrastia¹

¹University of Pennsylvania, Philadelphia, United States

Objective: Traumatic axonal injury (TAI) is not necessarily irreversible, and stretched axons may recover or begin Wallerian degeneration. We aim to assess the 6-month evolution of TAI using diffusion tensor imaging (DTI).

Methods: Participants with traumatic brain injury (TBI) received scans at 2-weeks and 6-months post-injury. Glasgow Outcome Scale-Extended (GOSE) was collected at 6-months. Free water-corrected fractional anisotropy (fwFA) and volume fraction (VF) were measured in 156 regions from the JHU-DTI Eve atlas. Z-scores were calculated by comparing against age/gender matched uninjured controls. fwFA z-scores below -2.0 and VF above 2.0 were considered abnormal.

Results: 41 participants with TBI (28 male, age (mean [SD]) 37 [15]) were included.;For fwFA, the volume of abnormal regions at 2-week was 46.6 [78.8] mm3. By 6-months, it increased to 79.5;[21.9] mm3. Of regions with initial low fwFA, recovery was noted in 20.5;[41.4] mm3, while abnormalities developed in 51.9;[19.8] mm3 by 6-months. For VF, the volume of abnormal regions at 2-weeks was 81.0;[19.3] mm3, which increased to 110.8;[248.2] mm3 at 6-months. Of regions with initial high VF, improvement was noted in 41.6;[101.6] mm3, while elevated VF developed in 70.0 [224.0] mm3. fwFA abnormalities did not correlate with GOSE, but there was a trend towards higher volume of abnormal VF in participants with incomplete functional recovery (GOSE < 8).

Conclusions: TAI apparent at 2-weeks was not necessarily irreversible, as some regions appear to normalize. However, regions of disrupted white matter at 6-months were not always detectable at 2-weeks.

Dr Hailong Song¹, Dr Jingwen Tan¹, Ms Yoonjung Kim¹, Dr. Mariana Ilha¹, Mr Frank Rauscher¹, Dr Gisele Hansel¹, Dr Jean-Pierre Dolle¹, Dr Douglas Smith¹

¹University of Pennsylvania, Philadelphia, United States

Concussion is a major health concern and leads to long-lasting neurological impairments. Such neurological deficits often reflect the disruption of normal brain networks, which are formed by connecting different brain regions, or nodes, via white matter axons. Mounting evidence suggests that selective mechanical damage to axons, referred to as traumatic axonal injury (TAI), is a key contributor to the clinical manifestation of concussion. Yet, how localized TAI contributes to the disruption of the global nodal network remains unclear. In order to better understand injury induced network disruption, we designed and generated a simplified culture system with four distinct micropatterned primary rat cortical neuronal nodes interconnected by parallel tracts of axons. We first confirmed nodal network synchrony in vitro by monitoring/ measuring synchronized Ca2+ activity. Notably, synchronized Ca2+ events across the entire network were disrupted by dynamic stretch injury of axons connecting just two of the four network nodes. Further, this localized TAI caused selective axonal transport interruption leading to accumulation of amyloid precursor protein in damaged axons. Surprisingly, loss of synchrony could be reversed by pre-injury administration of the sodium channel blocker tetrodotoxin (TTX). These findings provide potential molecular substrates of localized TAI underlying global brain network disruption following concussion and adds potential targets for modulating and restoring brain synchrony.

Mr. Xianghao Zhan¹, Dr. Yuzhe Liu², Dr. August G. Domel¹, Dr. Michael Fanton¹, Dr. Zhou Zhou³, Dr. Samuel J. Raymond¹, Dr. Hossein Vahid Alizadeh¹, Dr. Nicholas J. Cecchi¹, Dr. Svein Klevin³, Dr. Michael M. Zeineh¹, Dr. Gerald G. Grant⁴, Dr. David B. Camarillo¹

¹Stanford University, Stanford, United States, ²Beihang University, Beijing, China, ³KTH Royal Institute of Technology, Stockholm, Sweden, ⁴Duke University, Durham, United States

This work presents a comprehensive study on the effects of different inertial force components on brain strain during head impacts, computationally validating the longstanding Holbourn hypothesis and exploring the limits of the hypothesis with novel head impact datasets collected from real-life scenarios. We utilized non-injurious head kinematics data (n=118) collected from on-field American football to simulate brain strain arising from various inertial force components. The findings showed that the Euler force primarily determines brain strain within this dataset, which agrees with the hypothesis. However, the centrifugal force and the Coriolis force were at a similar level to the Euler force, which contradicts the hypothesis. Additionally, we utilized a model of head movements with high rates of angular and linear acceleration, known as synthetic sinusoid head kinematics, to assess the validity of the Holbourn hypothesis under conditions of more extreme head impacts. Our findings indicate that the level of brain strain resulting solely from linear forces exceeds 0.093 (the average level of brain strain found in 118 non-harmful head impacts in American football) when linear acceleration ranges between 116 and 248 g. Similarly, brain strain resulting solely from rotational forces exceeds 0.093 when angular velocity ranges between 195 and 216 rad/s. To conclude, this study shows that in the majority of measured head impacts, Holbourn hypothesis holds with Euler force contributing the most to the brain strain. In impacts with extremely high angular velocity and/or linear acceleration, the contributions from linear force, centrifugal force and Coriolis force are not negligible.

Ms. Shahrzad Shiravi¹, Ms. Alexandra Yufa¹, Ms. Maria Jose Quezada Valladares², Dr. Colin Franz³, Dr. John Finan¹

¹University of Illinois at Chicago, Chicago, United States, ²Northwestern university, Chicago, United States, ³Shirley Ryan ability lab, Chicago, United States

Human induced pluripotent stem cell (hiPSC)-derived brain organoids have exciting potential as pre-clinical trauma models because they can reproduce human pathophysiology. However, traumatizing these cultures consistently is non-trivial because they vary in size. We mechanically compressed dorsal cortical organoids at biofidelic strain magnitudes and rates and measured the resulting pathology. The first step in our compressive injury protocol was measuring the height of the organoid and adjusting the depth of compression so that the % compression was independent of height. In the first experiment, 24 organoids at day 73 were compressed by either 0%, 30% or 60% of their initial height and released in a period of 30 milliseconds. Calcium dynamics were measured 4 hours after injury by time series imaging of CalBryte 520 AM fluorescence on a confocal microscope. These cultures were also stained with tetramethylrhodamine (TMRM) to detect changes in mitochondrial membrane potential. Calcium dynamics declined with increasing depth of compression (R2=0.41, p-value:0.0008) as did TMRM intensity (R2=0.32, p-score:0.004). The second experiment involved repeating the mitochondria assay with a narrower range of compressions (0%, 15%, 25%,35% and 45%) with 20 organoids at the same age.

TMRM fluorescence intensity declined linearly with increasing compression (R2=0.856, p-score:5.22E-09). Taken together, these results show that dynamic compression of cortical organoids can reproduce important TBI phenotypes in a human pre-clinical model.

Dr. Cole Vonder Haar¹, Robert Pafford¹, Eric Schwegler¹, Kazuki Hayashi¹, Elizabeth Wu¹, Saeedeh Ziaeefard¹

¹Ohio State University, Columbus, United States

Pigs are increasingly employed as models for traumatic brain injury given the similarity of their physiology and neuroanatomy to humans. However, behavioral outcomes are rarely assessed due to a lack of standardized equipment and behavior protocols. Recently, our lab published the design for a pig touchscreen device to assess cognitive function and performed and proof-of-concept behavior studies (Ao et al., 2022). However, varying experimental needs may necessitate the ability to record responses or delivery rewards at locations away from the touchscreen unit. Thus, the current project designed a wireless input/output printed circuit board capable of handling up to 8 inputs and 8 outputs via Molex connectors. The circuit board accepts 12V to 48V inputs for maximum versatility with existing operant standards (12V, 28V). The circuit board interfaces with a controlling computer via Bluetooth pairing and a simple Python library allows for control of outputs and detection of inputs. Testing verified that the Bluetooth signal could record and control events at least 20 feet away and through obstacles. A 3D-printed housing was also developed to hold the circuit board which then integrates with a wall-mounted pellet dispenser. Testing with initial Yorkshire pig subjects is ongoing to evaluate any potential unforeseen consequences of pig interaction. This new I/O interface combined with the touchscreen unit could significantly lower barriers to cognitive research in pigs and increase interest in studies on traumatic brain injury, Alzheimer’s disease and other neurological conditions.

Dr. Anna Oeur^1,2, Mackenzie Mull^1,2, Harry Torp², Susan Margulies^1,2

¹Emory University, Atlanta, United States, ²Georgia Institute of Technology, Atlanta, United States

Severity of head loading and presence of blood are important risk factors for early posttraumatic seizures and have been associated with poorer outcomes. In this study, we measured resting state-EEG in 4-week old Yorkshire swine (N=13) after five repeated head rotations in a High – Medium (HM) order and a Medium – High (MH) order. Six piglets received 1x100 rad/s rotation followed by 4x60 rad/s rotations (HM), spaced 8 minutes apart. Seven animals received rotations in the reverse order (MH: 4x60 rad/s and 1x100 rad/s). Resting state was captured using a 32-electrode net for 1 minute in the anesthetized animal before and 6 hours after the first head rotation. EEG data were Fourier transformed to yield the average power in the alpha (8-12 Hz), beta (16.5-25 Hz), delta (1-3 Hz), and theta (4-7.5 Hz) bands. Animals were necropsied at 6 hours, and craniectomy performed to visualize and estimate extent of subdural bleeding (IH) over the cortical surface area. Two-way ANOVA revealed significance for order and time, and post hoc tests showed HM had greater EEG activity than the MH at electrodes encompassing the front (alpha, beta, theta), left (beta) and right (alpha and beta) regions (P<0.05). Within region, IH was significantly higher for HM than MH in the front and left regions. Regions with increased EEG power were the same with regions with increased IH. Future work will investigate the relationship between presence of IH and cortical activity in the injured brain.

Supported by NIHR01NS097549 and Georgia Research Alliance.

Mr. Benjamin Baskin¹, Dr. Alexandra Hochstetler^1,2, Ms. Ya’el Courtney^2,3, Ms. Tawny Stinson¹, Dr. Maria K. Lehtinen^2,3, Dr. Beth Costine-Bartell¹

¹Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, United States, ²Department of Pathology, Boston Children’s Hospital, Harvard Medical School, Boston, Boston, United States, ³Graduate Program in Neuroscience, Harvard Medical School, Boston, Boston, United States

Introduction: Homeostasis of brain ions and fluids is essential for typical neurodevelopment in children and may be disrupted following traumatic brain injury (TBI). We previously reported that seizures and subarachnoid hemorrhage (SAH) drive damage in an age-dependent manner in swine. One explanation for these differences is the “GABA switch” from excitatory to primarily inhibitory GABA in neurons, characterized by phosphorylation of cation chloride cotransporters NKCC1 and KCC2. In severe TBI, we hypothesize activation of NKCC1 and KCC2 may be differentially disrupted.

Methodology: Our validated model includes cortical impact, midline shift, SAH, seizures, and brief apnea and hypoventilation. Male Yorkshire piglets (N=22) aged 7 days (“infant”) and 30 days (“toddler”) underwent severe TBI/sham injuries plus ICU, or no injury/ICU. Brain tissue was collected for histology and biochemical assays.

Results: We created a map of NKCC1 and KCC2 expression and activation during immaturity in piglets with spatial and temporal resolution. Toddler piglets were more susceptible to disruptions in the balance of NKCC1 and KCC2 following TBI, with a greater effect correlated with cortical hypoxic-ischemic damage versus sparing of subcortical structures.

Conclusions: We demonstrated evidence of the postnatal GABA switch in swine between 7 and 30 days of age and acute disruption of NKCC1 and KCC2 activation following severe TBI in an age-dependent manner. This has key implications regarding the clinical management of children with severe TBI and opens the doors for novel therapeutic paradigms.

Funding: T32NS007473 (AH), Pappendick Family Therapeutic Acceleration Award (MKL), NIH NICHD K01HD083759, and R01 HD099397 (BCB).

Dr. Li Jiang¹, Dr. Molly Goodfellow¹, Dr. Su Xu¹, Dr. Xiao Liang¹, Steven Roys¹, Xin Li¹, Amanda Hrdlick¹, Boris Piskoun¹, Julie Proctor¹, Dr. Ulrich Leiste², Dr. William Fourney², Dr. Jiachen Zhuo¹, Dr. Gary Fiskum¹

¹University of Maryland School Of Medicine, Baltimore, United States, ²University of Maryland-College Park Department of Aerospace Engineering, College Park, United States

Under-vehicle blast (UVB) induces a distinct traumatic brain injury (TBI) with blast and impact injuries on the military battlefield. While the effects of low air pressure during flight (hypobaria; HB) on neurologic outcomes after TBI remain poorly understood, injured soldiers often undergo multiple flights, including aeromedical evacuation. We hypothesized that flight after TBI influences brain functional connectivity (FC).

The protocol was approved by the UMB IACUC and US Air Force General’s Office of Research Oversight and Compliance. Sedated male ferrets underwent UVB and controlled cortical impact under anesthesia (BCCI), followed by one or five 6-hour HB or normobaria (NB; sea level) exposure(s) over the 6 months post-injury. Treatment groups consisted of naïve, craniotomy+5HB, BCCI+NB, BCCI+1HB, and BCCI+5HB. Ferrets underwent T2-weighted and resting-state functional-MRI (rs-fMRI) scans under anesthesia, at baseline and 6 months post-injury. Behavioral assays confirmed that multiple flights post-injury increased anxiety-like behavior. Thus, ROI-to-ROI FC analysis was conducted to evaluate FC changes within the anxiety network.

FC was increased within the anxiety network in BCCI+5HB ferrets compared to all other groups. This suggests that multiple HB exposures exacerbate the neurological response within the brain regions, including prefrontal cortex, amygdala, and hippocampus, associated with anxiety regulation. Our findings highlight the potential impact of multiple flights on the neurobiological mechanisms underlying TBI-induced anxiety-like behavior. Additional analyses are in progress.

The views expressed are those of the authors and do not reflect the official guidance or position of the United States Government, the DOD or of the USAF. Supported by USAF FA8650-20-2-6H20.

Mr. Drew Parker¹, Dr. Victoria Johnson¹, Dr. John Wolf¹, Dr. Ragini Verma^1,2

¹Perelman School of Medicine, University of Pennsylvania, Philadephia, United States, ²Cohen Veterans Bioscience, New York, United States

Introduction: Pig models of traumatic brain injury (TBI) are considered translational because of their gyrencephalic brain structure and appropriate white-matter (WM)-to-grey-matter ratio. Increased free-water volume fraction (FW-VF) shown in humans and pig models following TBI may offer an opportunity to relate these findings to the underlying neuropathology.

Objective: To develop a framework for analyzing individualized WM-specific injury measures in a pig TBI model and their associations with histology.

Methods: 7 pigs underwent T1 and diffusion MRI, forming the uninjured normative sample. One pig underwent a single controlled cortical impact (CCI) injury and was imaged 3 days, 1 month, 3 months, and 6 months post-injury. Data were preprocessed with a customized pig-specific pipeline, including free-water-correction with FERNET and registration to an atlas of 58 Yucatan mini-pigs. Mean and standard deviation of FW-VF in uninjured pigs were used to calculate z-scores for the injured timepoints. A cubic region of interest (ROI) was placed 10mm beneath the craniotomy in the WM along with a comparative contralateral region that intersected with the atlas WM.

Results: Z-scores of FW-VF were elevated compared to the contralateral region at 3 days (ipsilateral: 3.9±2.8; contralateral: -0.5±1.0), 1 month (ipsilateral: 4.8±3.0; contralateral: 2.2±1.3), 3 months (ipsilateral: 8.3±4.1; contralateral: 2.7±1.5), and 6 months post-injury (ipsilateral: 6.8±3.5; contralateral: 0.4±0.8).

Conclusion: We created a subject-specific map that characterizes the CCI injury. In initial findings, FW-VF was higher in ipsilateral WM, but also elevated contralaterally post-TBI. This provides a useful subject-wise approach to examine the temporal course and pathological basis of neuroimaging findings.

Dr. Kathryn Wofford^1,2, Mr. Kevin Browne^1,2, Ms. Susan Shin¹, Dr. D. Kacy Cullen^1,2

¹University Of Pennsylvania, Philadelphia, United States, ²Corporal Michael J. Crescenz VA Medical Center, Philadelphia, USA

Closed-head diffuse traumatic brain injury (TBI) is the most common form of TBI, characterized by white matter damage. Microglia, resident immune cells of the brain, drive the resulting neuroinflammation and affect neuronal health. However, microglial contributions to white matter damage and resolution have yet to be fully investigated. Therefore, we employed a translational pig model of closed-head diffuse TBI to characterize microglia over time and injury severity. Female Yucatan minipigs were injured with a sham, low, or high angular velocity TBI and survived for 3 or 14 days. Coronal sections were stained for microglia (Iba1) at three levels across the rostral-caudal axis. We observed numerous Iba1+ microglia distributed throughout white matter tracts that, in many cases, were organized as multi-cellular aggregates. Iba1+ aggregates were observable 14 days after a low or high angular velocity TBI and 3 days after a high angular velocity TBI, with the number of clusters positively correlating to injury severity and survival time. Immunohistochemical staining suggests microglial clusters are not spatially localized with blood brain barrier damage (fibrinogen), do not contain myelin components (myelin basic protein), and do not co-localize with reactive astrocytes (glial fibrillary acidic protein). Together, these data suggest white matter microglia continue to change their morphology and distribution at least several weeks after a closed-head diffuse TBI in an injury-severity and time-dependent manner. Ongoing work seeks to understand what causes these cellular aggregates, how long they persist in the tissue, and if these clusters are beneficial or detrimental for axonal and neuronal health.

Ms. Sarah Schantz^1,3, Ms. Taylor Hillhouse^1,2, Ms. Stephanie Dubrof⁴, Mrs. Sydney Sneed^1,2, Mrs. Savannah Cheek^1,2, Dr. Holly Kinder^1,2, Dr. Kylee Duberstein^1,2, Dr. Jerry Stern⁵, Dr. Alexander Baguisi⁵, Mr. David DeWahl⁵, Dr. Hea Jin Park⁴, Dr. Erin Kaiser^1,2,3, Dr. Franklin West^1,2,3

¹Regenerative Bioscience Center, Athens, United States, ²Department of Animal and Dairy Science University of Georgia, Athens, United States, ³Biomedical and Health Sciences Institute Neuroscience Program, Athens, United States, ⁴Department of Nutritional Sciences University of Georgia, Athens, United States, ⁵Ischemix, Inc., Grafton, United States

Traumatic brain injury (TBI) is a leading global cause of long-term disability and death with no Food and Drug Administration-approved treatment. CMX-2043 is a novel therapeutic that has neuroprotective, metabolic, and antioxidative properties that may limit TBI-induced tissue damage and long-term functional deficits. In the present study, we evaluated the effect of CMX-2043 in a translational porcine TBI model. TBI was induced by controlled cortical impact over the left motor cortex. CMX-2043 treatment began 1-hour post-TBI subcutaneously (SQ, n=8) or intravenously (IV, n=8) for a total of 5 days. Control piglets (Placebo, n=11) received saline. Modified Rankin Scores (mRS) were collected pre to 42 days post-TBI. Magnetic resonance imaging (MRI) was performed on days 1, 7, and 42. Brain tissue was collected for immunohistochemistry on day 42. SQ and IV administration of CMX-2043 led to improved neurological function by day 7 as indicated by decreased mRS scores compared to placebo pigs (p<0.05). MRI revealed SQ and IV CMX-2043 treatment decreased lesion volume, hemispheric swelling and atrophy, midline shift, and intracerebral hemorrhage and preserved cerebral blood flow and white matter integrity (p<0.05). Immunohistochemistry analysis indicated SQ and IV CMX-2043 treatment led to increased NeuN+ neuron and Olig2+ oligodendrocyte survival as well as decreased Iba1+ immune cell response and GFAP+ reactive astrocytes (p<0.05). These results in a translation porcine model suggest that CMX-2043 holds significant clinical promise to reduce TBI tissue damage and improve functional recovery in human patients.

Mr. Mark Pavlichenko^1,2, Shreya Patel¹, Radina Lilova^1,2, Amanda Logan-Wesley^1,2, Karen Gorse^1,2, Audrey Lafrenaye^1,2

¹Virginia Commonwealth University, Richmond, United States, ²Richmond Veterans Affairs Medical Center, Richmond, United States

Traumatic brain injury (TBI) is a major healthcare concern affecting millions. Symptoms of TBI include sensory sensitivity and social changes that may persist long-term. Due to similarities in cytoarchitecture, metabolism, and inflammation, higher order minipig models are advantageous for translational TBI research, however, there remains a shortage of information regarding their behavioral sequela following injury. Therefore, in this study, we assessed changes in sociability and somatosensation in adult male and female Yucatan minipigs for up to one-week following a sham or central fluid percussion injury (cFPI). Specifically, the forced human approach task (FHAT) was done to investigate each animal’s approachability/sociability with both known and unknown humans prior to and following cFPI. Von Frey test was also done to determine potential changes in sensitivity to somatosensory stimulus on the ear and tail. We found that while approachability to FHAT was not significantly impacted by previous exposure to the human or cFPI over the first week post-injury, FHAT was highly sensitive to additional external stress in our male cohort (X2(1)=9.16, p=0.002) with a significant interaction between injury and stress. Von Frey assessments showed that the ears, but not tails, in female (n=7) pigs were more sensitive to tactile stimulation than males (n=14) prior to injury (U=17.5, p=0.016). Sensory sensitivity of the ear was decreased in our male cohort following cFPI (χ2(9) = 21.829, p = 0.009), which suggests that TBI has an effect on somatosensation of the ear in this model.

This work was funded by NINDS grants R21NS126611, R56NS128104.

Dr. Marios Georgiadis¹, Mr. Xianghao Zhan¹, Dr. Hossein Moein Taghavi¹, Dr. Jeffrey Nirschl¹, Dr. William Ho¹, Dr. Nicholas J. Cecchi¹, Ms. Jessica A. Towns¹, Ms. Yixin Wang¹, Mr. Yi Yi Du¹, Dr. Kathleen Heng¹, Dr. Cholawat Pacharinsak¹, Dr. Yuzhe Liu¹, Dr. Susan S. Margulies^2,3, Dr. Gerald A. Grant⁴, Dr. Kawin Setsompop¹, Dr. Congyu Liao¹, Dr. Marzieh Memar⁵, Dr. David B. Camarillo¹, Dr. Michael M. Zeineh¹

¹Stanford University, Stanford, United States, ²Emory University, Atlanta, United States, ³Georgia Institute of Technology, Atlanta, United States, ⁴Duke University, Durham, United States, ⁵University of Texas San Antonio, San Antonio, United States

Μild-TBI’s injury mechanisms remain unknown and diagnosis qualitative. Rapid rotation causes tissue stretching, possibly resulting in diffuse axonal injury (DAI) and blood-brain-barrier (BBB) breakdown. Human studies integrating defined impacts, pre/post injury imaging, and pathology are impractical. Rodent models, though comprehensive, lack human brain’s gyriform complexity. Large animal models usually lack multi-timepoint imaging, realistic impacts, and potential human translation. We present a juvenile pig model of rotational closed-head impact via a pneumatic linear impactor (approximating NFL head impact kinematics, scaled to pig) to comprehensively interrogate the biomechanics, injury mechanism, and imaging correlates of mild-TBI.

Anesthetized ∼10Kg Yorkshire pigs experienced impact with impactor velocity 8-10m/s and compliant-foam-padding (LOW, N=2), or 12m/s and hard-foam-padding (HIGH, N=2), producing mostly sagittal-plane rotation. Triaxial bite-bar or skull-affixed gyroscopes measured kinematics (angular velocity/acceleration), used by a validated porcine finite-element model to predict MPS95 strains, exceeding 0.3 for HIGH (DAI threshold 0.286), <0.2 for LOW. We compared one-day pre- and 10-hour post-injury MRI on a human 3T scanner (multi-shell diffusion for microstructure, contrast-enhancement for BBB integrity) and detected DAI in the corona radiata and sometimes overlapping contrast enhancement indicating BBB breakdown in HIGH. Findings were validated with β-APP and fibrinogen extravasation on histology respectively, with no findings for LOW.

Overall, we present a large-animal linear-impact rotational mild-TBI model, incorporating skull measurements, simulations, biomechanics, pre-/post-impact imaging, and pathology. We provide a platform for investigating mild-TBI DAI and BBB disruption dynamics, propelling research in mechanisms, timing, diagnosis, and prevention. The realistic impact and human MRI scanner facilitate direct clinical translation.

Dr. Amelia Maiga¹, Rebecca Irlmeier¹, Dr. Fei Ye¹, Dr. Areg Grigorian², Dr. Mayur Patel¹

¹Vanderbilt University Medical Center, Nashville, United States, ²University of California Irvine, Orange, United States

Background: Treating intracranial hypertension is key for severe traumatic brain injury (TBI). Older adults may be at lower risk of intracranial hypertension due to cerebral atrophy. Studies conflict on whether intercranial pressure (ICP) monitoring benefits older adults. We hypothesized that ICP-guided neuromonitoring does not improve short-term outcomes in older adults with severe TBI.

Methods: This retrospective cohort study included adults with severe TBI (2017-2021 Trauma Quality Improvement Program), excluding withdrawals of life-sustaining treatment (WLST) within 48h. We compared patients with and without ICP monitors, adjusting for age, injury severity score (ISS), TBI severity, preexisting dementia or functional dependency, WLST, and hospital characteristics. Linear regression was used for ICU length of stay. Logistic regression was used for short-term functional status and inpatient mortality.

Results: Of 87,052 patients with a median Glasgow Coma Score 3 [interquartile range 3,7], 25,910 (30%) were monitored. ICP-monitored patients were significantly younger (median 39 [27,56] vs. 46 years [29,64]) with higher ISS (29 [25,38] vs. 26 [22,34]) and more WLST (25% vs. 16%). Of patients ≥65 years, 19% were monitored, with higher WLST rates (47% vs. 30%). ICP monitoring was associated with longer ICU stay (p<0.001), better functional status, and lower inpatient mortality overall (odds ratios 0.52 and 0.16, both p<0.001), but not in ≥65 years.

Conclusion: ICP-guided neuromonitoring occurs in one in five older adults with severe TBI, but is not associated with short-term functional or mortality benefits, and half proceed to WLST. Future studies may better define subsets of older adults benefitting from ICP monitoring.

Dr. Fazle Kibria¹, Dr. Olga Bragina¹, Dr. Alexey Trofimov⁴, Dr. Oxana Semyachkina-Glushkovskaya⁵, Dr. Edwin Nemoto², Dr. Dmitriy Atochin⁶, Dr. Satoshi Kashiwagi⁶, Dr. Patric Stanton³, Dr. Denis Bragin¹

¹Lovelace Biomedical Research Institute, Albuquerque, United States, ²University of New Mexico School of Medicine, Albuquerque, USA, ³New York Medical College, Valhalla, USA, ⁴Privolzhsky Research Medical University, Nizhny Novgorod, Russia, ⁵Saratov State University, Saratov, Russia, ⁶Massachusetts General Hospital, Harvard University, Charlestown

Background: Repeated concussion traumatic brain injury (TBI) results in long-term brain damage and cognitive dysfunctions leading to neurodegenerative diseases. The brain drainage system plays a crucial role in TBI recovery and neurodegenerative disease amelioration by draining waste macromolecules from the brain. Photobiomodulation (PBMT) has gained interest in neuroscience and shown to improve brain drainage. Here, we evaluated the efficiency of PBMT in the treatment of multiple concussions in mice.

Methods: Three close-head concussive TBIs were induced with a 1-h interval to the prefrontal cortex in the left hemisphere in C57BL/6 male mice. PBMT (1270 nm, 10 mW/cm2) was done at 4 hours after the last TBI and the following two days twice a day. In-vivo 2-photon laser scanning microscopy assessed PBMT effects on cerebral microcirculation, hypoxia, blood-brain barrier (BBB) and glymphatic/meningeal lymphatics clearance. Neurological severity scores were obtained 24 hours and 1 and 2 weeks after TBI. Two-way ANOVA for multiple comparisons was used to test intergroup differences with the statistical significance set at p<0.05.

Results: Multiple concussions progressively decreased cortical microcirculation, tissue hypoxia, BBB disruption, and brain drainage dysfunction (p<0.05). PBMT improved microcirculation and tissue oxygenation while protecting BBB and the brain drainage system (p<0.05). Neurological function was better in the PBMT group (p<0.05).

Conclusions: Repetitive PBMT applied after multiple concussion TBI restored cerebral microcirculation and brain drainage system, reducing tissue hypoxia and BBB damage, leading to improvement in neurological outcome. PBMT can be used as an adjunct therapy in TBI. Supported by TU/LBRI Innovative Intramural Research Grant.

Dr. Lindsay Nelson¹, Madeline Kallenbach, Daniel Huber, Dr. Sergey Tarima

¹Medical College Of Wisconsin, Milwaukee, United States

Engaging diverse samples in traumatic brain injury (TBI) research is important to addressing disparities in healthcare and outcomes. As part of a study collecting patient feedback to improve TBI-related healthcare, we investigated the impact of different modes of survey invitation on response rates among persons with TBI. Participants were English-speaking adults treated for TBI between July and October 2023 in 1 of 7 emergency departments and hospitals in a single healthcare system. TBI diagnoses were determined by International Classification of Diseases—10th Edition diagnostic codes. Exclusion criteria were having a legal guardian or activated healthcare power of attorney and having requested no contact for research. Participants (N=460) were randomized to receive a mail, text message, or email survey invitation. Half of individuals assigned to receive an electronic survey were called and left a voicemail before the invitation was delivered alerting them to the forthcoming invitation. Response rates were as follows: 27% mail, 23% email, and 11% text message (p<.001). Providing a phone call before sending an electronic survey more than doubled the response rate (21% vs. 8%, p=.006). Response rates differed by employment status (p<.001) and were higher among individuals who were White (vs. Black; p<.001), partnered (vs. single; p<.001), and who had lower neighborhood-level socioeconomic disadvantage (p<.001). The findings inform future study designs and indicate a need for community-based participatory research to learn strategies for increasing engagement of underrepresented groups in TBI-related survey research.

Ms. Sage Sweeney¹, Ms. Grace Recht¹, Dr. Jiancheng Hou^1,3, Ms. Claire Buddenbaum¹, Dr. Hu Cheng^2,4, Dr. Keisuke Kawata^1,2,5

¹Department of Kinesiology, Indiana University School of Public Health, Bloomington, United States, ²Program in Neuroscience, The College of Arts and Sciences, Indiana University, Bloomington, United States, ³Research Center for Cross-Straits Cultural Development, Fujian Normal University, Fuzhou, China, ⁴Department of Psychological and Brain Sciences, College of Arts and Sciences, Indiana University, Bloomington, United States, ⁵Department of Pediatrics, Indiana University School of Medicine, Indianapolis, United States

This single-site, cohort study aimed to investigate whether there are detectable changes in localized neural activity and neighboring neuronal connectivity in middle age retired contact sport athletes using resting-state fMRI. In total, 37 retired contact sport athletes and 21 age- and sex matched non-contact sport athlete controls participated. During scanning, participants were instructed to passively view a crosshair for 12 minutes. Regional homogeneity (ReHo) and fractional amplitude of low-frequency fluctuation (fALFF) were measured, along with resting-state functional connectivity (rs-FC) with a dorsolateral prefrontal cortex seed region. Both surface-based and volume-based analyses were used to detect differences in neural signals and connectivity. Differences in fALFF, ReHo, and rs-FC between contact and non-contact athletes were assessed using paired t-tests (p < 0.001). Significant increases in fALFF were demonstrated in the contact group for volume- and surface-based analyses (e.g. right inferior temporal gyrus; right middle temporal gyrus, respectively). Significant reductions were also seen in volume- and surface-based analyses (e.g. left lingual gyrus; right Rolandic’s operculum, respectively). Significant increases in ReHo were observed in the contact group for volume- and surface-based analyses (e.g. left middle frontal gyrus; left superior medial frontal gyrus, respectively). Significant decreases in ReHo were also observed for volume- and surface-based analyses (e.g. right superior parietal lobule; left supramarginal gyrus, respectively). Rs-FC analysis revealed both hyperconnectivity and hypoconnectivity in the right superior frontal gyrus via volume- and surface-based analyses respectively. These findings suggest repetitive head impact exposure during previous contact sport participation may influence brain function at a midlife timepoint.

Dr. Cathra Halabi^1,2, Dr. Saef Izzy^3,4,5, Dr. Anthony DiGiorgio^6,7, Hunter Mills⁸, Dr. Farid Radmanesh⁹, Dr. John Yue⁶, Dr. Habi Ashouri Choshali⁸, Dr. Gundolf Schenk⁸, Dr. Sharat Israni⁸, Dr. Ross Zafonte^3,4,5,10,11, Dr. Geoffrey Manley^2,6

¹Department of Neurology, UCSF, San Francisco, United States, ²Weill Institute for Neurosciences, UCSF, San Francisco, United States, ³Department of Neurology, Brigham and Women’s Hospital, Boston, United States, ⁴Harvard Medical School, Boston, United States, ⁵The Football Players Health Study at Harvard University, Boston, United States, ⁶Department of Neurological Surgery, UCSF, San Francisco, United States, ⁷Institute of Health Policy Studies, UCSF, San Francisco, United States, ⁸Bakar Computational Health Sciences Institute, UCSF, San Francisco, United States, ⁹Department of Neurology, University of New Mexico, Albuquerque, United States, ¹⁰Department of Physical Medicine and Rehabilitation, Massachusetts General Hospital, Brigham and Women’s Hospital, Boston, United States, ¹¹Spaulding Rehabilitation Hospital, Charlestown, United States

Background: Patient registry data from a tertiary academic center in Boston, Massachusetts (Harvard) showed emergence of neurological, psychiatric, cardiovascular, and endocrine conditions after TBI. Validation studies across diverse settings will improve care delivery.

Methods: We conducted a retrospective database study across 5 University of California healthcare systems. Pre-specified ICD-9 codes from the Harvard study were used to identify adult patients diagnosed with mild and moderate/severe TBI (mTBI, msTBI) and post-TBI neurological, psychiatric, cardiovascular, and endocrine (including menstruation-related) conditions. Controls (patients without TBI) were frequency-matched by age, race/ethnicity, sex, Area Deprivation Index (ADI), insurance, and duration from date of TBI to most recent encounter. Cox Proportional Hazard Models generated yearly hazard ratios (HRs) 6 months to 10 years post-TBI. Patients with pre-existing comorbidities were excluded. Models were further stratified by ADI.

Results: Overall, 5090 mTBI and 5090 msTBI patients (45% female, 51% White) with 10180 matched controls were included. Increased risks were observed for TBI vs. controls across neurological (HR ranges; mTBI=1.88-4.00, msTBI=2.09-3.41), psychiatric (mTBI=2.00-2.67, msTBI=1.60-3.23), cardiovascular (mTBI= 1.34-1.87, msTBI=1.36-2.18), and endocrine (mTBI=1.30-1.60, msTBI= 1.35-2.94) categories (comparisons p<0.01). These risks remained elevated in lowest and highest ADI quintiles. For example, after mTBI, coronary artery disease HRs were 3.81 [95%CI:2.38-6.09] and 1.74 [1.06-2.87] in lowest and highest quintiles, respectively (p<0.05).

Conclusions: Within a large California healthcare administrative dataset, we confirmed that mTBI and msTBI were associated with increased risks of incident neurological, psychiatric, cardiovascular, and endocrine conditions (including our added code for menstruation changes). Risks remained elevated after adjusting for disadvantaged neighborhood factors.

Dr. Abel Torres Espin¹, J.C. Wong², H E Hinson², Tom Kupiers³, Bart PT Hoekstra³, Sonia Jain⁴, Xiaoying Sun⁴, John Yue², Dana Pisică⁵, Ana Mikolic⁶, Hester F Lingsma⁵, Amy J Markowitz², Adam R Ferguson^2,10, David K Menon⁷, Andrew IR Maas⁸, Ewout W Steyerberg⁵, Geoffrey T Manley², Patrick J Belton⁹

¹University Of Waterloo, Waterloo, Canada, ²University of California San Francisco, ³Leiden University Medical Center, ⁴University of California San Diego, ⁵Erasmus University Rotterdam, ⁶University of British Columbia, ⁷University of Cambridge, ⁸Antwerp University Hospital, ⁹University of Wisconsin-Madison ¹⁰San Francisco VA Health Care System

Early prognosis in TBI is essential to support clinical decision-making, inform patients and relatives, and advance research. The IMPACT prognostic model for 6-month outcomes was originally developed from an international dataset of moderate-severe TBI patients (GCS ≤12; studies conducted 1984-1997). Multiple external validations have been performed but global data privacy regulations have made international sharing of human subject data largely infeasible, preventing validation and updating in combined contemporary datasets. We aimed to present a proof-of-principle method to validate and update the IMPACT model across 2 modern international datasets using a privacy-preserving approach known as federated learning (FL).

We implemented a data infrastructure that enables privacy-preserving analyses across the large-scale US-based TRACK-TBI and European CENTER-TBI observational datasets. Subject data were stored separately on secure servers in San Francisco, US and Leiden, the Netherlands respectively. Using local instances of Opal, an open-source data warehouse software, and DataShield, an R-programming framework for FL, analyses were iteratively performed locally and only the abstracted results were shared with the remote users.

Using this infrastructure, we first created study-specific IMPACT models, fitted locally using logistic regression. A between study joint IMPACT-FL core model was derived by pooling estimates of the study-specific models. In addition, an iterative IMPACT-FL model was trained, where estimates are jointly learned across studies. The across-studies IMPACT-FL model weighted predictors are similar to pooling estimates from study-specific models, demonstrating that privacy-preserving statistical analyses across international studies can be executed without transferring data between study centers.

Dr. Murray Raskind^1,2,3, Dr. Paul Savage³, Ms. Tammy Williams³, Dr. Elaine Peskind^1,2,3, Dr. Cynthia Mayer^1,2,3

¹VA Northwest Mental Illness Research, Education, and Clinical Center, Seattle, United States, ²Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, United States, ³Madigan Army Medical Center, Tacoma, United States

Prazosin is an alpha-1 adrenoreceptor antagonist that reduces noradrenergic signaling. An open-label trial in which prazosin reduced headache frequency in veterans following mild traumatic brain injury (mTBI) provided the rationale for this study.

A 22-week parallel-group randomized controlled trial (RCT) which included 48 military veterans and active-duty service members with mTBI-related headaches was performed. Participants with >8 headache days/4 weeks were randomized 2:1 to prazosin or placebo. After 5-week titration to a maximum dose of 5 mg QAM and 20 mg QHS, achieved dose was maintained for 12 weeks. Outcomes were change in 4-week frequency of headache days, % participants achieving >50% reduction in headache days and change in Headache Impact Test (HIT)-6 scores.

ITT analysis of randomized study participants demonstrated greater benefit over time in the prazosin group (N = 32) compared to placebo group (N=16) for all 3 outcome measures. In prazosin versus placebo, reductions for 4-week headache frequency were -11.9±1.0 (mean ± standard error) versus -6.7±1.5 (p=0.005) and for HIT-6 scores were -6.0±1.3 versus +0.6±1.8 (p=0.004). Percent of participants at 12 weeks with ≥50% reduction in headache days/4 weeks was 70±8% for prazosin (21/30) versus 29±12% for placebo (4/14), odds ratio 5.8 (1.44, 23.6), p=0.013. The trial completion rate of 94% in the prazosin group (30/32) and 88% in the placebo group (14/16) indicated that prazosin was generally well.

In this RCT, prazosin was effective for reducing posttraumatic headaches and was well-tolerated.

Mr. Domenico Lombardi¹, Katherine Kuang¹, Michele Nelson¹, Mikaila Cutone-Dion¹, Yael Rozen², Justin Wong¹, Christine Gotthardt¹, Dr. Ava Puccio³, Dr. David Okonkwo³, Dr. Amber Nolan⁴, Dr. Esther Yuh¹, Dr. Kristine Yaffe¹, Dr. John Boscardin¹, Dr. Geoffrey Manley¹, Dr. Raquel C Gardner²

¹University of California San Francisco, San Francisco, United States of America, ²Sheba Medical Center, Israel, ³University of Pittsburgh Medical Center, Pittsburgh, United States of America, ⁴University of Washington, Seattle, United States of America

Background: Traumatic brain injury (TBI) is associated with increased risk of dementia diagnosis, particularly among older adults within one-year post-injury. Assessment of cognitive endpoints post-TBI is critical to unravelling mechanisms and conducting clinical trials to improve outcomes. However, prior TBI studies have had low rates of completion of 12-month cognitive endpoints among older adult TBI survivors (e.g., 48% completion in TRACK-TBI). Our aim was to develop a feasible cognitive endpoint for use in studies of geriatric TBI.

Methods: TRACK-GERI is an ongoing prospective cohort study of adults age 65y+ presenting to two trauma centers within 72 hours of TBI who received head CT. To date, N=101 TBI survivors have reached the 12-month timepoint. Cognitive endpoints collected at 12 months include the Clinical Dementia Rating Scale (CDR), a 30-minute informant interview considered the gold-standard for assigning cognitive status in dementia research, and the Montreal Cognitive Assessment (MoCA), a brief test of global cognition (score ≥26= normal cognition).

Results: Cohort mean age is 75y, 51% are female, 18% are non-white, 96% presented with GCS 13-15, and 62% were CT+. At 12-months, 65% completed either a CDR or MoCA, 42% completed both, and 35% did not complete a MoCA or CDR due to lost-to-follow-up.

Discussion: A cognitive endpoint comprised of a brief cognitive assessment or informant-reported CDR achieved a 65% 12-month completion rate in this study of acute geriatric TBI. This completion rate exceeds that achieved in prior studies that have employed standard pen-and-paper neuropsychological tests without the option of an informant-reported endpoint.

Dr. Reut Raizman¹, Dr. Tamar Silberg², Dr. Jana Landa¹, Dr. Galia Tsarfaty, Dr. Abigail Livny¹, Prof. Chaim Pick^1,3

¹Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel, Tel Aviv - Yafo, Israel, ²Department of Psychology, Bar Ilan University, Ramat Gan, Israel, ³The Dr. Miriam and Sheldon G. Adelson Chair and Center for the Biology of Addictive Diseases, Tel-Aviv University, Tel-Aviv, Israel

Introduction: Pediatric traumatic brain injury (p-TBI) can have significant and lasting effects on the developing brain, leading to changes in both structural connectivity (SC) and functional connectivity (FC).

Methods: children and adolescents from all injury severities and healthy control subjects underwent structural and functional connectivity scans, clinical and cognitive evaluation in the acute and post-acute phases. Using graph theory to study the brain’s network architecture, we investigated the patterns of structural-functional circuit reorganization after p-TBI, and their joint impact on cognition.

Results: The findings reveal disrupted network topology in both SC and FC brain connectomes in p-TBI patients during acute and post-acute phases, indicating persistent alterations in brain connectivity. Cognitive impairments were observed, particularly in working memory and inhibition during both phases. Coupling SC and FC measures revealed reduced connectivity in p-TBI patients, even during the post-acute phase. Regression analysis showed that coupling variables in the acute phase predicted the inhibition effect of executive function in the post-acute phase.

Conclusion: This study offers valuable insights into the complex relationship between structural and functional brain connectivity in p-TBI, highlighting the potential of multimodal coupling as a tool for understanding the impact of brain connectivity on cognitive outcomes in p-TBI patients.

Ms. Lisa N. Richey^1,2, Dr. Nicholas O. Daneshvari, MD³, Ms. Lisa Young, BA, BS², Dr. Michael J.C Bray, MD, MSc², Dr. Rebecca F. Gottesman, MD, PhD⁴, Dr. Thomas Mosley, PhD⁵, Dr. Keenan A. Walker, PhD⁶, Dr. Andrea L.C. Schneider, MD, PhD⁷, Dr. Matthew E. Peters, MD²

¹Independent, N/A, United States, ²Johns Hopkins University School of Medicine, Department of Psychiatry and Behavioral Sciences, Division of Geriatric Psychiatry and Neuropsychiatry, Baltimore, USA, ³Massachusetts General Hospital, Department of Psychiatry, Boston, USA, ⁴National Institutes of Health, National Institute of Neurological Disorders and Stroke Intramural Research Program, Baltimore, USA, ⁵University of Mississippi Medical Center, USA, ⁶National Institutes of Health, National Institute on Aging Intramural Research Program, Baltimore, USA, ⁷University of Pennsylvania Perelman School of Medicine, Department of Neurology; University of Pennsylvania Perelman School of Medicine, Department of Biostatistics, Epidemiology, and Informatics, Philadelphia, USA

OBJECTIVE: To investigate 1) if cross-sectional associations of cognitive status with mild behavioral impairment (MBI) symptoms differ by head injury status and 2) if prospective associations of MBI domain positivity with incident dementia risk differ by head injury status.

METHODS: We performed cross-sectional (2011-2013) and prospective (2011-2013 through 12/31/2019) analyses of 2,246 participants without dementia (mean age=75.6 years, 59.0% female, 20.7% Black) in the Atherosclerosis Risk in Communities Study. Prior head injury was defined by self-reported and ICD-9/10 code data. MBI domain symptoms were defined via an established algorithm based on the Neuropsychiatric Inventory Questionnaire (NPI-Q). Baseline cognitive status and incident dementia were defined using neuropsychological tests, informant interviews, and hospital and death certificate codes.

RESULTS: In cross-sectional analyses, although MCI status (compared to normal cognition) was associated with greater odds of MBI symptoms, associations did not differ based on head injury history (MCI with prior head injury: OR=2.04, 95%CI=1.44-2.88, MCI without head injury: OR=1.60, 95%CI=1.20-2.14). Specifically, individuals with MCI (with or without head injury) were more likely to have decreased motivation, affective dysregulation, and impulse dyscontrol. In prospective analyses, positivity in 1+ MBI domains was associated with increased risk of incident dementia, but associations did not differ by head injury status (no head injury and MBI domain positivity: HR=2.15, 95%CI=1.55-2.99, head injury and MBI domain positivity: HR=2.62, 95%CI=1.81-3.80).

DISCUSSION: In this community-based cohort, neither cross-sectional associations between cognitive status and MBI domain positivity nor prospective associations of MBI domain positivity with incident dementia risk differed by head injury status.

Dr. Hilaire Thompson¹, Dr. Frederick Rivara, Dr. Ronald Maier, Dr. Kyra Becker, Dr. Nancy Temkin

¹University Of Washington, Seattle, United States

Purpose: To compare trajectory of recovery following mild traumatic brain injury (mTBI) in older adults compared to younger adults with mTBI and non-injured controls. Methods: Prospective cohort design to 6 months post-injury (N=320). Older adults (>55) with mTBI and three comparator groups: younger adults with mTBI and sex/age-matched non-injured controls were enrolled. Physical and behavioral symptoms and function were assessed at 1 week, 1-, 3- and 6-months. Linear mixed models for longitudinal data were used for analyses. Results: At 6 months post-injury, both had similar percentages of good recovery per GOS-E (younger 78%, older 80.3%). No significant differences in the number of symptoms endorsed or severity were seen to 6 months, though symptoms differed among older and younger mTBI. For older mTBI higher total, somatization, and anxiety scores were seen at 7 days post-injury compared to age/gender matched controls, but not at subsequent time points. Persons with mTBI performed worse on the RAVLT and Trails A/B tests at all time points. Aging-related differences in mTBI groups were seen only on the Trails Test A. On the WAIS, scores of both older controls and TBI cases were lower than younger counterparts. Both mTBI groups performed worse than controls, neither returning to control levels by 6 months. Older persons with mTBI had lower scores across all domains and time points compared to younger persons with mTBI.

Conclusion: The trajectory of recovery differs across younger and older adults with mTBI; however, at 6 months there is no difference in those experiencing good recovery.

Mr. Devin Nikjou^1,2,10, Dr. Chani Taggart^2,6,8,9, Dr. Salvatore Lettieri^2,3,4,8,9, Dr. Michael Collins^5,8,9, Dr. Owen McCabe^2,6,8,9, Dr. Layne Rousseau^2,7,8,9, Dr. Iman Feiz-Erfan^1,2,8,9

¹Division of Neurosurgery, Valleywise Health Medical Center, Phoenix, United States, ²Department of Surgery, Valleywise Health Medical Center, Phoenix, United States, ³Division of Plastic Surgery, Valleywise Health Medical Center, Phoenix, United States, ⁴Division of Plastic Surgery, Mayo Clinic, Phoenix, United States, ⁵Department of Radiology, Valleywise Health Medical Center, Phoenix, United States, ⁶Division of Trauma, Valleywise Health Medical Center, Phoenix, United States, ⁷Division of Urology, Valleywise Health Medical Center, Phoenix, United States, ⁸Creighton University, School of Medicine Phoenix, Phoenix, United States, ⁹University of Arizona, College of Medicine Phoenix, Phoenix, United States, ¹⁰Arizona State University, School of Biologic and Health Systems Engineering, Tempe, United States

Introduction: Optimal management of transverse sacral fractures (TSF) remains inconclusive. These injuries may present with neurological deficits including cauda equina syndrome. We present our series of laminectomy for acute TSF with cauda equina compression.

Methods: This was a retrospective chart review of all patients that underwent sacral laminectomy for treatment of cauda equina compression in acute TSF at our institution between 2007 through 2023.

Results: A total of 9 patients (5 male and 4 female) underwent sacral laminectomy to decompress the cauda equina in the setting of acute high impact trauma. Surgeries were done early within a mean time of 5.9 days. All but one patient had symptomatic cauda equina syndrome. In one instance surgery was applied due to significant canal stenosis present on imaging in a patient with diminished mental status not allowing proper neurological examination. Torn sacral nerve roots were repaired directly when possible. All patients regained their neurological function related to the sacral cauda equina on follow up. The rate of surgical site infection (SSI) was 33%.

Conclusion: Acute early sacral laminectomy and nerve root repair as needed was effective in recovering bowel and bladder function in patients after high impact trauma and TSF with cauda equina compression. A high SSI rate may be reduced by delaying surgery past 1 week from trauma, but little data exists at this time for clear recommendations.

Mr. Jared Rifkin¹, Dr. Ahmed Alshareef^2,3, Dr. Taotao Wu⁴, Dr. Matthew Panzer^1,5

¹University Of Virginia Department of Mechanical and Aerospace Engineering, Charlottesville, United States, ²University of South Carolina Department of Mechanical Engineering, Columbia, United States, ³University of South Carolina Department of Biomedical Engineering, Columbia, United States, ⁴University of Georgia School of Chemical, Materials and Biomedical Engineering, Athens, United States, ⁵University of Virginia Department of Biomedical Engineering, Charlottesville, United States

It is crucial that we develop tools to understand cerebrovascular biomechanics during head impact to better prevent bleeding injuries associated with TBIs. State-of-the-art computational models can simulate subject-specific brain mechanical response to impact, but they currently do not predict vascular strain and injury risk. The goal of this study was to refine our automated process of subject-specific brain model generation to include embedded vasculature. First, nonlinear image registration (ANTS) was used to align the brain template image (CAB20MSym) to the subject T1 image and transform the template brain model into the subject-specific model. Then, subject susceptibility weighted imaging (SWI) and time of flight (ToF) imaging were used to generate a computational model of the architecture of veins and arteries, respectively. Finally, the vascular model was embedded into the transformed brain model. In this pilot study, brain models of two subjects were created, each having variants with and without vasculature. Each model was simulated using concussive impact conditions and the resulting strain distributions were compared across the models. Whole brain deformation response based on maximum principal strain (MPS95) did not substantially differ with the presence of vasculature (p << 0.05, Cohen’s d = -0.04–0.08). However, there were notable concentrations of strain identified around vessels when included (p << 0.05, Cohen’s d = 0.22–0.68). Further, the vessel strains were relatively low for this impact case (0.123–0.142) and were considered non-injurious based on vascular literature. Future studies will simulate higher severity impacts to investigate the factors associated TBI bleeding risk.

Ms. Rula Jeries¹, Mrs. Yael Rosen Lang², M.D., Ph.D Esther L. Yuh³, M.D., Ph.D David O. Okonkwo⁴, M.D., Ph.D Geoffrey T. Manley⁵, RN, Ph.D Ava M. Puccio⁴, M.D. Raquel C. Gardner²

¹Department of Epidemiology and Preventive Medicine, School of Public Health, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel ²Joseph Sagol Neuroscience Center, Sheba Medical Center, Ramat Gan, Israel ³Department of Radiology, University of California San Francisco, San Francisco, CA, USA ⁴Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, PA, USA ⁵Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA

Objectives: Older adults have high rates of traumatic brain injury (TBI) and are at a high risk for worse neurological and functional outcomes. There is emerging evidence that statin use may be neuroprotective, however, this has yet to be studied prospectively in older adults. Our aim was to assess whether statin use at the time of acute TBI was associated with a 6-month functional outcome.

Methods: Participants were enrolled under an IRB-approved protocol, Transforming Research and Clinical Knowledge in Geriatric TBI (TRACK-GERI), with inclusion criteria of age≥65 years and presenting to the emergency room of a Level 1 trauma center within 72 hours of TBI. Baseline medication data and 6-month Glasgow Outcome Scale-Extended (GOS-E) scores were collected. Baseline statins use and 6-month GOS-E was analyzed by logistic regression, adjusting for variables that significantly differed between participants by statin use (baseline medication count, emergency department discharge location, and anti-platelet/anti-coagulant use; all p<.05).

Results: 93 participants met inclusion criteria: mean age 77.42 ±7.98y, 53% women, 89% Caucasian, 55% hospital admit, 41% taking a statin at baseline, 51% had good/complete recovery. Compared to those not taking a statin, those taking a statin had 3.7 better odds of good/complete recovery (GOS-E=7-8; adjusted OR 3.70, 95% CI 1.25-12.35, p=.024).

Conclusions: Statins use is associated with better outcomes. Further research and trials are warranted to determine whether statins may be indicated as a neuroprotective treatment following acute TBI in older adults.

Acknowledgments: This study was funded by NIH R01 NS110944 to RCG and GTM.

Ms. Eujung Park¹, Ms. Annie Pico¹, Ms. Haley Kenner¹, Mr. Robert Unger¹, Mr. Kevin Vo¹, Mr. Jacob Saunders¹, Mr. Harrison Feerst¹, Mr. Alex Thompson¹, Ms. Elika Azizi¹, Dr. Peter Nakaji²

¹University Of Arizona, College Of Medicine - Phoenix, Phoenix, United States, ²Department of Neurosurgery, Banner University Medical Center - Phoenix, Phoenix, United States

Objectives: This study aims to characterize relationships between social determinants of health (SDoH) and basilar skull fracture (BSF) outcomes. Previous literature has correlated SDoH and traumatic brain injuries, but this has not been characterized in BSF.

Methods: Patients (>17yrs) diagnosed with BSF at a single institution between 2017-2022 were identified through an IRB-approved internal search. Predictive factors included demographics. Outcomes included intensive care unit (ICU) admission, mechanical ventilation, and complications.

Results: 172 patients were included, 77% male. Average age was 43.4yrs [95%CI: 40.6, 46.3]. 41 identified as Hispanic. Medicare/Medicaid insured 107 patients, private insurance covered 51, and 14 had other payment.

Patients <31yrs had less frequent ICU admissions than older patients (61.0% vs 68.2-72.9%, p<0.05). Hispanics had more frequent ICU admissions than non-Hispanics (75.6% vs 65.6%, p<0.05) as did Medicare/Medicaid patients compared to privately insured patients (76.6% vs 52.9%, p<0.05). Notably, Hispanic and Medicare/Medicaid patients had higher rates of concurrent injuries present with BSF. Ventilation rates were higher in male patients than females (41.8% vs 36.8%), and in patients on Medicare/Medicaid than privately insured (43.9% vs 25.5%) (p<0.05). Incidence of pneumonia and respiratory failure was higher in males compared to females (12.7% vs 7.9%; 12.0% vs 7.9%, respectively), Hispanic compared to non-Hispanic (19.5% vs 9.2%; 17.1% vs 9.2%), and Medicare/Medicaid patients compared to privately insured (12.2% vs 7.8%; 10.3% vs 9.8%) (p<0.05).

Conclusions: These results indicate that certain demographics are at increased risk of adverse BSF outcomes and should be considered for more aggressive care.

Dr. Caitlin Mcnamara¹, Dr. Kelsey Van Noy¹, Dr. Anne Kalinowski¹, Dr. Rachel Berger¹, Dr. Ericka Fink¹, Dr Patrick Kochanek¹, Dr Dennis Simon¹

¹Upmc Children’s Hospital Of Pittsburgh, Pittsburgh, United States

Objective: To examine the rates of ischemia on brain imaging in young pediatric TBI and analyze the association with injury mechanism and outcome.

Methods: All neuroimaging interpretations during admission were inspected for ischemia in a retrospective cohort of children <3yo admitted with TBI to the PICU from 2011-2021. Functional Status Score at pre-injury, 1 year, and 4 years and abusive head trauma (AHT) status were determined from the electronic medical record. Impairment was defined as an increase in FSS>1. Nonparametric tests and multivariable logistic regression were conducted.

Results: 121/772 (16%) had ischemia with 96/121 (79%) diagnosed with AHT. If ischemia was present, it was seen on CT on median day 1 (IQR 0-5) and MRI on day 3 (1-5). While more patients with vs without ischemia presented with severe TBI [54/121 (46%) vs 85/651 (13%), p <0.001], 51/121 (42%) patients presented with mild TBI. Patients with vs without ischemia had higher prevalence of seizures [65/121 (54%) vs 39/651 (6%), p <0.001], higher blood glucose [131 (95, 210) mg/dL vs 97 (87, 116), p <0.001], and impairment at 1 year [65/103 (63%) vs 60/600 (10%), p <0.001] and 4 years [48/87 (55%) vs 46/383 (12%), p <0.001]. Ischemia was associated with impairment at 1 year [OR 4.7 (2.6, 8.6)] and 4 years [3.4 (1.8, 6.4)].

Conclusion: Ischemia was associated with AHT, seizures, and impairment at 1 year and 4 years, suggesting ischemia could play a role in producing unfavorable outcomes in AHT and represent a therapeutic target.

Dr. Katherine Giordano^1,2, Dr. Likith Surendra², Chase Irwin^1,2, Kerri Walker³, Dr. Hirsch Handmaker³, Dr. Jonathan Lifshitz^1,2,3

¹Phoenix VA Health Care System, Phoenix, USA, ²University of Arizona College of Medicine-Phoenix, Phoenix, USA, ³CACTIS Foundation, Scottsdale, USA

The global public health crisis of domestic violence (DV) increases the risk of traumatic brain injury (TBI) as physical assaults often target the head. However, DV-related TBI is grossly underreported or misdiagnosed, therefore going untreated. The HELPS TBI screening tool could inform DV shelter personnel about participant needs for medical evaluation and additional resources. Our objective was to evaluate predictors of DV shelter length of stay (LOS), including individual demographics and the HELPS assessment.

Retrospective analysis of records from an Arizona DV shelter (2008-2020) included an adjusted linear regression model to estimate the impact of demographics and a positive HELPS screen on individual LOS. We report the adjusted beta coefficient, 95% CI, and corresponding p-value for each predictor in our model. Extensive data cleaning was required due to unstandardized and missing data.

The final cohort included 1,088 individuals with an average LOS of 64 days. 47% had a positive HELPS screen, indicating possible TBI. Positive HELPS screen did not predict longer LOS. Rather, older age (β=0.78; 95% CI (0.47–1.08); p<0.001), non-US citizenship (β=15.55; 95% CI (3.95–22.03); p=0.009), and at least one child residing in the shelter (β=15.02; 95% CI (8.00–22.03); p<0.001) were associated with extended LOS.

Understanding trends in TBI screening and disparities among DV shelter participants may inform better care. This study serves as a call to action for more standardized data collection in DV shelters, protocols to improve TBI screening, and more research in DV-related TBI to support survivors.

Funding: NICHD R01-HD110860, Fraternal Order of Eagles.

Mr. Erik Philipson¹, Ms. Emma Lascar²

¹Harborview Injury Prevention & Research Center, Seattle, United States, ²University of Washington School of Medicine, Seattle, United States

Introduction: Initial evidence indicates that traumatic brain injuries (TBIs) have a substantial impact on student’s school experiences, but little is known about potential disparities in these effects. This study investigates disparities in school functioning quality of life following TBI among Hispanic and non-Hispanic white (NHW) middle and high school students.

Methods: One hundred eighty-three eligible participants (32 Hispanic and 151 NHW) who were treated for a TBI and enrolled in school at the time of injury were retrospectively identified from the Child Health After Injury (CHAI) dataset. The PedsQL School Functioning Scale was used to determine the impact of students’ TBIs on their school functioning-related quality of life at 3, 12, 24, and 36 months post-injury.

Results: At baseline, there were no clinically meaningful or statistically significant differences between the PedsQL School scores of Hispanic versus NHW students (74.83 vs. 78.64; P = 0.320). At three months post-injury, Hispanic students reported clinically meaningful and statistically significantly worse PedsQL School scores than NHW students (60.31 vs. 72.74; P = 0.008). Additionally, at twelve (64.16 vs 73.42; P = 0.049), twenty-four (62.65 vs. 76.56; P = 0.005), and thirty-six months (65.36 vs 78.27; P = 0.010) post-injury there continued to be clinically meaningful and statistically significant differences between the PedsQL School scores of Hispanic versus NHW students.

Conclusion: These results indicate that underlying inequalities may impact the effect of TBIs on students’ school-related quality of life. Future work should seek to confirm these observations and elucidate potential solutions.

Ms. Regan M. Shanahan¹, Dr. Shawn R. Eagle¹, Dr. Maxwell Wang¹, Anna L. Slingerland¹, Shovan Bhatia¹, Michael R. Kann¹, Tyler Augi¹, Dr. Ava M. Puccio¹, Dr. David O. Okonkwo¹

¹Department of Neurosurgery, University of Pittsburgh, Pittsburgh, United States

Background: The International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) model leverages patient admission characteristics to predict 6-month mortality. This prognostic model does not account for dynamic changes in a patient’s condition during hospitalization. We evaluated the impact of daily vitals and clinical labs within the first two weeks of hospitalization on mortality prediction.

Methods: Injury characteristics, acute care patient data, and neurological outcomes were documented for severe TBI patients (Glasgow Coma Scale=3-8) presenting to a level 1 trauma center (n=240) under IRB-approved protocol. The IMPACT base model was augmented with daily vitals (heart rate, blood pressure) and laboratory values (sodium, hemoglobin, platelets, blood gas and glucose) for patients alive at two weeks post-injury (n=215) . Area under receiver operating characteristic curve (AUC) analysis using bootstrapping resampling procedures was performed to evaluate accuracy of mortality predictions.

Results: The base IMPACT model demonstrated an AUC of 0.71 (95% CI: 0.6502-0.7435). Daily vitals and clinical laboratory trends alone returned an AUC of 0.75 (95% CI: 0.7096-0.7930). A combined model incorporating IMPACT, daily vitals, and clinical laboratory results yielded an AUC of 0.80 (95% CI: 0.7728-0.8555).

Conclusions: The integration of daily vitals and clinical laboratory values enhances the predictive ability of the IMPACT model to differentiate between severe TBI patients’ 6 month mortality. Incorporation of dynamic changes in patient status during the early phase of hospitalization can improve prognostic capabilities for patients with severe TBI.

Ms. Joye Tracey^1,2, Ms. Leila Etemad^1,2, Ms. Gabriela Satris^1,2, Mr. Justin Wong^1,2, Ms. Christine Gotthardt^1,2, Ms. Bukre Coskun^1,2, Dr. Debbie Madhok³, Dr. Phillip Bonney^1,2, Dr. John Kanter^1,2, Dr. Shawn Eagle⁴, Dr. Esther Yuh^2,5, Dr. Pratik Mukherjee^2,5, Dr. Patrick Belton⁶, Ms. Amy Markowitz^1,2, Dr. Anthony DiGiorgio^1,2,7, Dr. Phiroz Tarapore^1,2, Dr. Michael Huang^1,2, Dr. John Yue^1,2, Dr. Geoffrey Manley^1,2

¹Department of Neurological Surgery, University of California San Francisco, San Francisco, United States, ²Brain and Spinal Injury Center, Zuckerberg San Francisco General Hospital and Trauma Center, San Francisco, United States, ³Department of Emergency Medicine, University of California San Francisco, San Francisco, United States, ⁴Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, United States, ⁵Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, United States, ⁶Department of Neurological Surgery, University of Wisconsin, Madison, United States, ⁷Philip R. Lee Institute for Health Policy Studies, University of California San Francisco, San Francisco, United States

Objectives: The Vestibular Ocular Motor Screening (VOMS) assessment is predominantly used to detect vestibular-ocular impairment after sports-related concussion (SRC). In 2023, the American Congress of Rehabilitation Medicine added vestibulo-ocular impairment to the diagnostic criteria for traumatic brain injury (TBI). We investigated the feasibility of implementing the VOMS to assess TBI patients presenting to the emergency department (ED) with Glasgow Coma Scale score (GCS)=13-15.

Methods: Patients aged ≥18-years presenting to a single United States Level 1 trauma center ED within 24-hours of injury with plausible mechanisms for non-penetrating TBI between 03/2023-12/2023 were prospectively enrolled. VOMS was administered at acute injury (AI; 0-72 hours) and 2-weeks (10-21 days).

Results: In 70 patients, mean age was 41.2±16.4-years, 56% were male, and 49% White/Caucasian; 1% were CT-positive and 7% CT-negative/MRI-positive. Fifty-two completed 2-week follow-up. VOMS full/partial/no completion rates were 29%/61%/10% at AI and 77%/21%/2% at 2-weeks (p<0.001). Completion varied between VOMS domains: smooth pursuits (AI=90%; 2-week=98%), saccades (AI=87%; 2-week=96%), convergence (AI=73%; 2-week=98%), vestibular-ocular reflex (AI=69%; 2-week=98%), and visual motion sensitivity (AI=33%; 2-week=77%). Reasons for partial/no completion of assessments included peripheral injuries (AI=44%; 2-weeks=83%), poor effort (AI=30%; 2-week=0%), logistics (AI=16%; 2-week=8.3%), and cervical spine immobilization requirement (AI=8%; 2-week=0%).

Conclusion: In a single-institution GCS=13-15 TBI cohort, the VOMS showed a low completion rate of 29% in the ED, primarily limited by peripheral injuries, patient effort, and logistics. Increased 2-week completion is encouraging, likely attributable to similarities to SRC settings. Given high partial completion rates, strategies for VOMS integration by clinicians in the ED require further evaluation.

Martina Anto-Ocrah^1,2, Dr. Hemika Vempalli¹, Nabeeha Affan², Yu-Fu Michael Chen³, Erin Skotzke Fishman⁴, Stefanie Hollenbach⁵, Leon Ruiter-Lopez⁶, Michele D. Levine⁷, Celestin Niyomugabo⁸, Katherine Snedaker⁹

¹Department of Medicine, Division of General Internal Medicine, University of Pittsburgh School of Medicine, Pittsburgh, United States, ²Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, United States, ³JSI Research & Training Institute, United States, ⁴Department of Occupational Therapy, Galaxy Brain and Therapy Center, United States, ⁵Department of Obstetrics and Gynecology, University of Rochester Medical Center, United States, ⁶Department of Neuroscience, Dietrich School of Arts & Science, University of Pittsburgh, Pittsburgh, United States, ⁷Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, United States, ⁸VONSUNG, Rwanda, ⁹PINK Concussions, Norwalk, United States

Introduction: Sexuality is an important aspect of health and should be considered in the recovery paradigm of patients with brain injury secondary to concussion. Though emerging research shows that yoga improves concussion outcomes, its impact on the sexual health and wellbeing of female concussion patients, particularly those with sexual dysfunction, is unknown. In this study, we explored if a brain-injury tailored yoga program would improve female sexual functioning, depression and other mood correlates in female concussion patients.

Methods: We enrolled 12 female concussion participants in a 6-week yoga program and an additional 15 were assigned to a wait-list control. Participants received a self-report survey at week 7.

All participants were yoga novices, with little to no prior yoga experience. Sessions were held over Zoom and led by a certified Yoga trainer with over 10 years of experience delivering brain-injury tailored yoga.

The Female Sexual Functioning Index-6 (FSFI-6) was used to assess sexual dysfunction. We also examined depression (PHQ-9), a known correlate of sexual dysfunction, anxiety (GAD-7) and PTSD (PCL-5).

Results: Out of the 12 enrolled in the program, 6 completed at least 3 sessions and were sent the follow-up survey. Intervention participants reported substantial improvements in their sexual functioning (Glass’ delta=0.58 vs 0.16 controls), depression (Glass’ delta=0.45 vs 0.35 controls), anxiety (Glass’ delta=0.80 vs 0.66 controls) and PTSD symptoms (Glass’ delta=0.40 vs 0.26 controls).

Conclusion: Yoga has the potential to improve women’s sexual functioning after concussion, and also offers a non-pharmacological alternative for treating mood and other important correlates.

Mx. Madeline Kallenbach¹, Mr. Daniel Huber¹, Dr. Courtney Barry¹, Dr. Terri deRoon-Cassini¹, Michelle Wesline¹, Dr. Staci Young¹, Dr. Lindsay Nelson¹

¹Medical College Of Wisconsin, Milwaukee, United States

Despite patient outcomes being a focus of clinicians’ priorities, there can be a disconnect between care delivered and patient preference. We sent a survey to English-speaking patients (n=125 responded/460 sent) treated across 7 hospitals or emergency departments in a single healthcare system between July and October 2023 for a traumatic brain injury (TBI), defined by International Classification of Diseases—10th Edition diagnostic codes. Survey questions included satisfaction with care, how information was received versus preference, understanding of the TBI diagnosis, and social determinants (e.g., housing, transportation, and food security). Survey respondents scored more advantageously on the area deprivation index (ADI) and were more likely to be White (83.2%). We found 64% of patients (n=80) recalled being told they had a TBI by their provider and 76.6% (n=95) believed they had a TBI. Participants recalled receiving discharge information via handout (46.6%, n=41), MyChart (5.7%, n=5), or both (29.5%, n=26), while 18.2% (n=16) received none. They expressed it would be helpful to receive information via handout (92.3%), MyChart (78.9%), a conversation with them at the hospital (93.2%), a phone call once home (85.4%), and a conversation with a loved one present (86.1%). Most felt well-informed in the hospital (84.3%, n=75) and understood discharge instructions when they got home (82.0%, n=73). The findings reveal opportunities to improve the provision of in-hospital patient education for TBI, such as including those who support patients after discharge and providing information about TBI through multiple modalities.

Mr. Sean Inzerillo¹, Dr. Salazar Jones²

¹SUNY Downstate College Of Medicine, Brooklyn, United States, ²Icahn School of Medicine at Mount Sinai, New York, United States

Traumatic Brain Injury (TBI) represents a significant public health challenge among Medicare beneficiaries. Despite recent policy reform, many specialties, including neurosurgery, have reported consistent annual decreases in utilization and reimbursement rates. This study investigated trends in Medicare utilization and reimbursement rates for neurosurgical procedures related to TBI from 2003-2021, aiming to provide insights into the economic aspects of TBI care.

Utilizing Medicare Part B National Summary Data, we analyzed 14 neurosurgical procedures commonly used in TBI over the 18-year period. We assessed total percent changes from 2003-2021 in procedural volume and mean reimbursement per procedure, adjusting all financial figures for inflation to 2021 USD using the Consumer Price Index. Trends over time were identified through simple linear regression.

From 2003-2021, TBI-related neurosurgical interventions showed a total percent change of -15.39% for overall procedural volume and -3.11% for inflation-adjusted mean reimbursement per procedure. Linear regression analyses indicated a significant downward trend in overall procedural volume (p < 0.001) but no significant trend in inflation-adjusted mean reimbursement rates (p = 0.585). Subgroup analyses did not reveal significant changes in reimbursement rates for the specific categories of decompressive craniotomy/craniectomy, cranioplasty, intracranial pressure management, and traumatic fracture/penetration procedures.

Our study indicates a significant decrease in neurosurgical TBI procedural volumes. However, Medicare reimbursement rates were stable when adjusted for inflation, an atypical trend compared to declines in other neurosurgery areas. These findings prompt further exploration into TBI-care economics, particularly in comparison to spinal trauma, and healthcare policies to ensure resource adequacy for affected Medicare beneficiaries.

¹University of CO School of Medicine, Fort Collins, United States

Post-morbid traumatic brain injury (TBI) symptomatology can be easily overlooked, misinterpreted, and trivialized by others. Impairments emerge across multiple functional domains, enduring for months and even years following the original injury. These symptoms are often perplexing to etiologically link to TBI. Since TBI recovery trajectory varies widely, contingent on individualized, predisposing factors and injury dynamics, lingering post-morbid symptoms frequently appear to others as disproportionate to the actual neural insult. These dismissive impressions expose the already sensitive TBI patient to unsupportive social feedback, which is discouraging, humiliating and potentially re-traumatizing.

A systematic review of a sample of confirmed TBI cases gathered from a private outpatient clinic revealed that all patients self-reported and/or demonstrated prolonged, delayed onset and/or atypical TBI symptom sequelae. These symptoms persisted for between one and greater than three years following the brain injury incident. Owing to this unraveling symptom constellation, patients reported the added burden of coping with social perceptions that their symptoms seem exaggerated, and inauthentic.

Psychological treatments should include clinical observation, records reviews, and standardized assessments. Therapeutic priority should focus on validating patient experiences, along with interrogation of TBI-linked symptom genesis. Didactic CBT coping skills, and evidence-based psychoeducation are a first-line approach within the psychological setting. Beneficial clinical techniques may include reframing, EMDR, exposure therapy, compensatory strategies, and integration of spiritual principles, along with referral to multidisciplinary specialists, as warranted. Affirmation of patient TBI-induced symptom credibility is essential. Significant others may participate in treatment to better inform, educate and enhance social support systems for patient recovery.

Ms. Amanda Filicky¹, Dr Natalie Sherry, Dr Shawn Eagle, Dr Luke Henry, Ms Hannah Appleton, Dr David Okonkwo, Dr Pascal Zinn

¹University Of Pittsburgh, Pittsburgh, United States

Introduction: Neurosurgical patients have high risk of experiencing cognitive deficits that can reduce quality-of-life. The purpose of this study was to associate demographics, medical history, objective neurocognitive testing, and mental health symptoms with subjective cognitive complaints (SCC) in pre- and post-operative cohorts.

Methods: The standardized test was administered, Hopkins Verbal Learning Test – Revised (HVLT-R), for verbal list learning and memory evaluation. A backwards linear regression was built for pre- and post-operative patients including demographics/medical history variables (age, sex, years of education, working [vs. in school]), and history of neurological disease, substance abuse, psychiatric condition), anxiety symptoms (Generalized Anxiety Disorder-7), depression symptoms (Personal Health Questionnaire-9) and objective neurocognitive testing domains (processing speed, executive functioning, language, learning memory, attention) as SCC predictors.

Results: The most common reason for referral was brain cancer/mass (29.0%; n=47) and Chiari malformation (21.6%; n=35). There was no difference between pre- and post-operative patients in age (p=0.57), years of education (p=0.06), sex (p=0.66), race (p=1.00), psychiatric history (p=0.07), developmental history (p=0.31), or work status (p=0.40). The model predicting SCC in pre-operative patients (adj. R2=0.72; p<0.001; n=108) included depression symptoms (&cenveo_unknown_entity_calibri(body)_F0E2;=-0.82; p<0.001), age (&cenveo_unknown_entity_calibri(body)_F0E2;=0.02; p=0.004), years of education (&cenveo_unknown_entity_calibri(body)_F0E2;=-0.24; p=0.03), working (&cenveo_unknown_entity_calibri(body)_F0E2;=0.82; p<0.001), executive function (&cenveo_unknown_entity_calibri(body)_F0E2;=0.73; p<0.001), and processing speed (&cenveo_unknown_entity_calibri(body)_F0E2;=-0.37; p=0.02). The model predicting SCC in post-operative patients (adj.R2=0.58; p<0.001; n=54) included depression symptoms (&cenveo_unknown_entity_calibri(body)_F0E2;=-0.42; p=0.01), years of education (&cenveo_unknown_entity_calibri(body)_F0E2;=0.33; p=0.03), and visual spatial function (&cenveo_unknown_entity_calibri(body)_F0E2;=0.26; p=0.04).

Discussion: Both cohorts revealed that perceived neurocognitive function is influenced by other factors tested in comparison to objective neurocognitive testing.

Mr. Richard Cook¹, Kathleen Ran², Dr. John Willaims¹, Dr. Tej Azad²

¹McGovern Medical School, Department of Neurosurgery, Houston, United States, ²Johns Hopkins University School of Medicine, Department of Neurosurgery, Baltimore, United States

Background. Health literacy enables patients to effectively navigate the healthcare system and be an active participant in their own care. Low health literacy is associated with poor clinical outcomes and higher costs across a host of conditions. Despite the vulnerability of traumatic brain injury (TBI) patients, who have higher care complexity and potential cognitive challenges, little is known about the health literacy in this population, particularly how these measures vary among socioeconomic and demographic groups.

Methods. Using of the NIH’s All of Us Research Program, we analyzed survey responses among matched TBI (N = 6,036) and non-TBI patients (N = 259,930). Chi-squared tests compared responses between different racial, ethnic, and income groups among unmatched TBI patients (N = 6,112). Binary and logistic regression compared responses between the matched TBI and non-TBI patients.

Results. Patients with TBI consistently reported lower health literacy (3/3 questions, P < 0.01) and limited access to care (4/15 questions, P < 0.05). Multivariable analyses revealed increased difficulty understanding medical forms (OR 2.00, 95% CI 1.73-2.30, P < 0.01) and affording emergency care (OR 1.69, 95% CI 1.12-2.55, P = 0.01). Black, Hispanic, and low-income patients reported more difficulty navigating medical forms. The lowest and second-lowest income groups reported more difficulty navigating medical forms and accessing care.

Conclusion. Health literacy and access to care are limited in patients with a self-reported history of TBI. These disparities are magnified in historically underserved populations and in lower socioeconomic groups. Multidisciplinary efforts to address these limitations are necessary.

Ms. Vivian Xiao^1,4, Dr Yesul Kim^1,4, Associate Professor Gerard O’Reilly^1,8,9, Ms Madeline Green^1,4, Mr Ron Jithoo^1,3,4, Associate Professor Jin Tee^1,3,4, Ms Noel Sceriha³, Professor Andrew Udy^5,6, Ms Lara Kimmel^7,8, Dr Christopher Buntting³, Associate Professor Joseph Mathew^1,2,4, Professor Mark Fitzgerald^1,2,4

¹National Trauma Research Institute, Melbourne, Australia, ²Trauma Service, The Alfred Hospital, Melbourne, Australia, ³Department of Neurosurgery, The Alfred Hospital, Melbourne, Australia, ⁴Central Clinical School, Monash University, Melbourne, Australia, ⁵Department of Intensive Care & Hyperbaric Medicine, The Alfred Hospital, Melbourne, Australia, ⁶Australian and New Zealand Intensive Care - Research Centre, Monash University, Melbourne, Australia, ⁷Allied Health Executive, The Alfred Hospital, Melbourne, Australia, ⁸School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia, ⁹Emergency and Trauma Centre, The Alfred Hospital, Melbourne, Australia

Objectives: Although recognised as a leading cause of death and disability, it is unclear whether current treatment strategies have improved outcomes from blunt moderate to severe traumatic brain injuries (msTBI) due to a lack of available epidemiological data. This study sought to determine if in-hospital mortality and early functional outcomes of msTBI patients have changed over 20 years. Early functional outcomes were determined through the surrogate measure of the proportion of patients discharged directly to home.

Methods: A longitudinal cohort study with analyses of The Alfred Health Trauma Registry data. Subjects were adults aged 16-70 years with blunt msTBI (Head Abbreviated Injury Scale 3-5) admitted to The Alfred Hospital Trauma Service between 1 January 2002 to 31 December 2021.

Results: A total of 8,222 patients presented with msTBI over the 20 years, with 692 total deaths. The crude in-hospital mortality rate declined significantly, from 12% in 2002 to 4% in 2021 (OR 0.96, 95% CI 0.95-0.97, p<0.001). Odds of death per annum remained the same after adjusting for changes to the injury severity of presentations (OR 0.96, 95% CI 0.93-0.99, p<0.001). The crude proportion of patients discharged to home increased from 31% to 61% over the period (OR 1.05, 95% CI 1.04-1.06, p<0.001).

Conclusions: It is likely that changes in management within the Victorian State Trauma System and The Alfred Hospital have been effective in improving blunt msTBI outcomes. These results support ongoing research into neurotrauma management and future studies should investigate which changes and interventions were particularly efficacious.

Dr. Alicia Swan^1,2, Dr. Mary Jo Pugh^3,4, Eric Strom⁴, Alan Johnson⁴, Dr. Annika Lenz⁴, Dr. Shana Godfred-Cato

¹South Texas Veterans Health Care System, San Antonio, United States, ²University of Texas at San Antonio, San Antonio, United States, ³VA Salt Lake City Health Care System, Salt Lake City, United States, ⁴University of Utah, Salt Lake City, United States

Objective: Characterize self-reported blast exposure and neurobehavioral symptom sequela among military service members affected by the 2020 Al Asad missile attack.

Methods: Approximately 4-6 weeks after the attack, personnel present were surveyed on blast exposure, neurobehavioral symptoms, and sleep habits before and since the event. ANOVA was used to examine differences in self-reported sleep duration by the location of the individual relative to the blast.

Results: In total, 627 service members and contractors completed the survey, of which 85% were 40 years of age or younger. At the time of the missile attack, 80% were present on the Forward Operating Base (FOB); of the remainder, 67% were in a bunker. Among those on the FOB, 27% reported that they were within 100m, 21% 100-200m away, 17% 200-300m away, and 35% more than 300m away from the closest blast. Sleep Difficulty (41%) was the most reported problem. Following the blast, service members who reported being within 200m of the blast, regardless of whether they were in a bunker, reported significantly less sleep than those not on the FOB (p<0.01).

Discussion: Over 80% of the participants reported some level of blast exposure attributable to the missile attack on Al Asad Air Base in 2020. Individuals closer to the blast reported significantly less sleep and more persistent sleep problems relative to those not on the FOB. Given the impact sleep quality has on functioning and wellbeing (e.g., psychological and physical health consequences), understanding and mitigating the impact of blast on sleep is critical.

Ms. Christine Gotthardt¹, Mr. Jason K. Barber², Dr. Lindsay D. Nelson³, Dr. Thomas A. Van Essen⁴, Dr. Shawn R. Eagle⁵, Mrs. Gabriela G. Satris¹, Ms. Leila L. Etemad¹, Ms. Joye X. Tracey¹, Ms. Bukre C. Coskun¹, Mr. Justin C. Wong¹, Dr. Mahmoud M. Elguindy⁶, Dr. Patrick J. Belton³, Dr. Debbie Y. Madhok¹, Dr. Frederick K. Korley⁷, Dr. Adam R. Ferguson¹, Dr. Abel Torres-Espin⁸, Dr. Cathra Halabi¹, Dr. Michael C. Huang¹, Dr. Phiroz E. Tarapore¹, Dr. Anthony M. DiGiorgio¹, Dr. Alex B. Valadka⁶, Dr. Claudia S. Robertson⁹, Dr. Pratik Mukherjee¹, Dr. Esther L. Yuh¹, Mrs. Amy J. Markowitz¹, Dr. Ava M. Puccio⁵, Dr. David O. Okonkwo⁵, Dr. Joseph T. Giacino¹⁰, Dr. Michael A. McCrea³, Dr. Nancy R. Temkin², Dr. Geoffrey T. Manley¹, Dr. John K. Yue¹

¹University of California, San Francisco, San Francisco, United States, ²University of Washington, Seattle, United States, ³Medical College of Wisconsin, Milwaukee, United States, ⁴Leiden University, Leiden, Netherlands, ⁵University of Pittsburg, Pittsburg, United States, ⁶University of Texas Southwestern Medical Center, Dallas, United States, ⁷University of Michigan, Ann Arbor, United States, ⁸University of Waterloo, Waterloo, Canada, ⁹Baylor College of Medicine, Houston, United States, ¹⁰Harvard University, Cambridge, United States

An estimated 50-75% of mild traumatic brain injury (mTBI) patients report chronic pain symptoms. Symptomatology evolution, subtypes, risk factors are poorly understood. We evaluated pain intensity and interference with daily function in a prospective longitudinal United States mTBI cohort.

The TRACK-TBI Study (2014-2018) enrolled patients presenting to 18 trauma centers who received head computed tomography (CT) within 24-hours of TBI. Subjects aged≥17-years with arrival Glasgow Coma Scale=13-15, Marshall CT Score=1-2, completion of PROMIS-Pain Intensity/Interference assessments across 2-weeks/3-/6-/12-months, without cranial surgery, major extracranial injury, or significant baseline musculoskeletal pain were included. Healthy controls (HCs) completed assessments at all timepoints. Pain Intensity/Interference T-scores were compared using mixed-effect linear regressions. Adjusted mean differences (aMD) and [95%CIs] were reported.

In 906 subjects (mTBI=710, HC=196), mean age was 39.6±16.7-years, 64% were male, and 75%-White/Caucasian. Thirty-five-percent with mTBI were head CT-positive and 31% received no TBI care post-discharge. Compared with HCs, CT-negative subjects had elevated pain intensity across time (2-week/3-/6-/12-months: aMD=14.6 [11.0-14.4]; 5.1 [2.7-6.1]; 3.5 [1.4-4.9]; 2.7 [0.7-4.1]) and CT-positive had elevated scores within 6-months (2-week/3-/6-months: aMD=12.4 [10.3-14.1]; 3.5 [1.5-5.3]; 2.4 [0.5-4.3]; 12-months: 1.9 [0.0-3.8]). Similarly, higher longitudinal pain interference scores were present in CT-negative (2-week/3-/6-/12-months: aMD=12.3 [10.9-13.7]; 4.5 [3.1-5.9]; 2.9 [1.5-4.4]; 1.9 [0.5-3.4]) and CT-positive subjects (aMD=11.5 [9.9-13.2]; 3.8 [2.2-5.4]; 2.7 [1.1-4.3]; 1.9 [0.3-3.5]).

Pain intensity and daily interference symptoms remained longitudinally elevated in mTBI vs. controls. Symptoms improved over time, most substantially at the subacute-to-chronic transition (2-weeks/3-months). The majority received no post-discharge follow-up, underscoring gaps in care and opportunities for preventative and therapeutic interventions.

Dr. Juliet Haarbauer-Krupa¹, Dr. Miriam Beauchamp², Dr. Vicki Anderson³, Dr. Stacy Suskauer⁴, Dr. Shari Wade⁵, Dr. Audrey McKinlay⁶, Dr. Linda Ewing-Cobbs⁷

¹Emory University School Of Medicine, Marietta, United States, ²Department of Psychology, University of Montreal and CHU Sainte-Justine Azrieli research center, Montreal, Canada, ³Murdoch Children’s Research Institute, Victoria, Austrailia, ⁴Kennedy Krieger Institute and Departments of Physical Medicine & Rehabilitation and Pediatrics, Johns Hopkins University School of Medicine, Baltimoe, USA, ⁵Cincinnati Children’s Hospital and University of Cincinnati, Cincinnati, USA, ⁶University of Canterbury, School of Psychological Sciences, University of Melbourne, Murdoch Children’s Research Institute, Queens University, Belfast, United Kingdom, Melborne, Austrailia, ⁷University of Texas, Houston, Houston, USA

Objectives: Children younger than 5 years have the highest incidence of emergency department visits for traumatic brain injury (TBI) and are at risk for long term effects. Children in this age group return to a variety of childcare settings and schools that may not understand the effects of the injury.

Methods: This presentation will describe TBI symptoms in young children, mechanisms of injury, outcomes, and pathways for return to childcare and school after the injury.

Results: Studies report preschool children may demonstrate different symptoms than older children and are also most at risk for abusive head trauma. Critical components for assessing younger children are parent report of injury circumstances, behavioral observations, past medical history, developmental history, dietary status, family and social history. Children who experience a TBI during the preschool years are at risk for disruption in their development and school readiness for entering kindergarten. Following medical care, preschool children are typically enrolled in early childhood settings where developmental screenings are part of the routine but the effects of TBI in young children are not always recognized and there is not a direct pathway for services.

Conclusions: Young children are vulnerable to the effects of TBI that can impact their behavior and learning. Recognition of TBI when the child presents for medical care as well as monitoring and follow-up after the injury is much needed for this young age group. Parents need education to understand the effects of the TBI and to continue to monitor their children after the injury.

Prof. Wilco Peul¹, MSc Ranjit Singh, Dr. Thomas van Essen, Dr. Jeroen van Dijck, MSc Rick Vreeburg, Prof. Fiona Lecky, Prof Andrew Maas, Prof Virendra Sinha, Prof Deepak Gupta

¹Leiden University Neurosurgical Center Holland, Leiden, Netherlands

Introduction: Traumatic Brain Injury (TBI) constitutes a global health problem that disproportionally affects LMIC. We aimed to describe epidemiological differences in acute TBI care provision between India and Europe.

Methodology: CENTER-TBI&CINTER-TBI included patients with indication for CT-scan presenting to 65 centres across Europe, Israel and two trauma centres in India. Descriptive analyses of demographics, injury and treatment characteristics were performed. Random-effects logistic regression with covariate adjustment was used to examine the likelihood of in-hospital mortality and acute neurosurgical interventions.

Results: Of 22849 and 3904 patients included, median age was 55 [IQR 32-76] in Europe compared to 27 years [IQR 18-40] in India. Falls were the most common cause in Europe [53%] while in India traffic incidents predominated [55%]. Proportion with s-TBI was higher in India [22%]) than in Europe [7%]). Professional pre-hospital care was available in 75% of European cases and in 6% of Indian cases. Indian patients had higher odds of undergoing intracranial pressure monitor placement (OR 2.3 [2.0-2.7]), but lower odds of receiving an external ventricular drain compared to European patients (OR 0.13 [0.06-0.30]). s-TBI patients were more likely to undergo emergency intracranial surgery (OR 2·0 [1·7-2·5]), which more often included decompressive craniectomy (OR 5.1 [3.5-7.5]) in India compared to Europe. Discharge destinations in Europe included rehabilitation centres [6%]) or nursing homes [5%]) while in India these were rarely reported [0%] and [0%], respectively).

Conclusions: Disparities between India and Europe exist along the entire neurotrauma care chain. Both systems have unique features and corresponding challenges for the future.

Ms. Claire Buddenbaum¹, Ms. Grace Recht¹, Ms. Adriana Rodriguez¹, Dr. Sharlene Newman², Dr. Keisuke Kawata^1,3

¹Department of Kinesiology, Indiana University School of Public Health, Bloomington, United States, ²Alabama Life Research Institute, University of Alabama, Tuscaloosa, United States, ³Program in Neuroscience, The College of Arts and Sciences, Indiana University, Bloomington, United States

This study aimed to investigate the differences in mental health outcomes among middle-aged, retired amateur contact and non-contact sport athletes. This study included former amateur athletes aged between 30 and 60 (39 contact athletes, 21 age- and sex-matched non-contact athletes) with at least 10 years of organized contact or non-contact sport participation. All participants completed demographic and mental health questionnaires. Mental health outcomes included depression, anxiety, post-traumatic stress disorder (PTSD), attention deficit hyperactive disorder (ADHD), and aggression. The contact group exhibited a 2.25-fold higher likelihood of being diagnosed with mental health disorders and a 1.29-fold higher likelihood of using associated medications compared to the control group. The contact group reported significantly higher PTSD-related symptoms [4.61 (0.03,9.2), p=0.05] compared to the control group. While not statistically significant, the contact group showed increased depressive [2.37 (0.05, 4.79), p=0.07] and ADHD symptoms [4.53 (0.51, 9.57), p=0.08]. In a secondary analysis, a distinct trend emerged within the contact group, revealing pronounced elevations in mental health symptoms among individuals with lower socioeconomic status (<$50,000/year) compared to higher income subgroups, and these symptoms decreased as income levels rose. This trend was absent in the non-contact control group. Our data suggests that individuals at the amateur level of contact sports have an increased likelihood of being diagnosed with mental health disorders or experiencing mental health symptoms compared to non-contact athletes. Our findings indicate that socioeconomic status may have an interactive effect on individuals’ mental health, particularly among those with a long history of repetitive head impact exposure.

Dr. Wesley Shoap¹, Dr. Berje Shammassian

¹LSU Health Sciences Center, New Orleans, United States

Craniocerebral gunshot injuries constitute a devastating subset of traumatic brain injury and knowledge is limited regarding optimal treatment algorithms. The aim of this study was to determine the association of mortality, ICU length of stay (icuLOS), and the Glasgow Outcome Scale Extended (GOSE) based on timing and type of intervention.

The institutional trauma database was queried for all gunshot wound head patients ages 14 and older who received neurosurgical intervention from January 2016 to June 2023. Patients were divided into three groups; ICP monitor only with medical treatment (ICP), primary decompressive craniectomy (pDC), or secondary decompressive craniectomy (sDC). The Surviving Penetrating Injury to the Brain (SPIN) score was calculated to compare baseline survivability of injury. Outcomes included mortality, icuLOS, and GOSE.

72 patients were identified who underwent either decompressive craniectomy or ICP monitoring. Mean SPIN scores were similar: ICP, pDC, and sDC (30.5, 32.67, 31.55 (p=0.4252)). The overall mortality rates were not statistically different among the three groups as a whole (40.91%, 17.95%, 36.36% p=0.1241). However, when comparing two groups, the odds of death was higher in the ICP group compared to the pDC group (OR = 3.71, 95% CI =1.06, 14.35). With regard to hospital trajectory, icuLOS was different among the groups: ICP, pDC, and sDC (16.7, 17.4, 23.4 p=0.0002).

Primary decompression is associated with improved mortality when compared to ICP monitoring with medical management alone and shorter ICU stay than secondary DC. These findings suggest early and aggressive management individualized to specific injury phenotype.

Madison Webster¹, Amber Schifano¹, Dr. Amanda Glueck¹

¹University of Kentucky, Lexington, United States

Stroke is a leading cause of long-term disability in the United States. Engaging in moderate-intensity exercise can improve overall health outcomes and recovery post-stroke, while also reducing the likelihood of a second stroke occurring. However, despite the myriad health benefits of exercise, it is difficult to get patients to participate in physical activity. Exercise gaming, or exergaming, with virtual reality, incorporates technology-driven activities, such as video game play, with exercise, which can be beneficial for patient rehabilitation. Several studies have demonstrated that exergaming using traditional gaming platforms for rehabilitation leads to improvements in compliance, motivation, mobility, balance, overall functional outcomes, and reduces inflammatory markers. This study is open to patients (aged 18-65) who have suffered a stroke at least 4 months before being enrolled and who have been cleared to participate in moderate-intensity exercise. Patients will be randomly assigned to one of three conditions: exercise, virtual reality (VR) gaming, or VR exergaming, and complete 20, one-hour intervention sessions over 7-weeks. Before beginning their assigned intervention, participants will undergo baseline neuropsychological, motor function, and balance assessments, and complete a symptom inventory. Additionally, participants will provide a blood sample to measure inflammatory levels before the intervention. These assessments will be repeated 12-36 hours following their final training session to track changes following the intervention. We hypothesize that participants assigned to the exergaming condition will demonstrate significantly greater benefits in the neuropsychological measures, motor function, and balance, as well as significantly lowered inflammation compared to the exercise and VR conditions.

Dr. Rebekah Mannix^1,2, Erin Borglund¹, Alexandra Monashefsky¹, Dr. Christina Master³, Dr. Daniel Corwin⁴, Dr Mohamed Badawy⁵, Dr Danny Thomas⁶, Dr Andrew Reisner⁷

¹Boston Children’s Hospital, Boston, United States, ²Harvard Medical School, Boston, United States, ³Division of Orthopaedics, Children’s Hospital of Philadelphia, Philadelphia, United States, ⁴Division of Emergency Medicine, Children’s Hospital of Philadelphia, Philadelphia, United States, ⁵Division of Emergency Medicine, Dept of Pediatrics, UT Southwestern Medical Center, Dallas, United States, ⁶Section of Emergency Medicine, Dept of Pediatrics, Medical College of Wisconsin, Milwaukee, Unted States, ⁷Departments of Neurosurgery and Pediatrics, Emory University School of Medicine, Children’s Healthcare of Atlanta, Atlanta, United States

Background: The Food and Drug Administration recently approved the use of two blood biomarkers, ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) and glial fibrillary acidic protein (GFAP), for identifying adult traumatic brain injury (TBI) patients likely to have negative findings on computed tomography (CT). Despite the growing evidence of the utility of blood brain biomarkers in the management of TBI in adults, less is known about the performance of these biomarkers in children.

Methods: Plasma specimens from healthy children and adolescents aged 0-<19 years were obtained from a hospital-based biobank. UCH-L1 and GFAP levels were quantified with the Alinity platform. The relationship between age and biomarker expression was determined using linear regression. Biomarker levels were compared to established thresholds for ruling out the need for a head CT in adults with a mild TBI (mTBI) within 12 hours from injury (UCH-L1 400 pg/ml, GFAP 35 pg/ml).

Results: The age range of the 366 healthy control patients was 3 months to 18 years (median 13 years, interquartile range 9 years to 16 years). There was a significant (P<0.0001) negative association between age and both plasma UCH-L1 (p<0.001) and GFAP (p<0.001). Only 1.4% of samples exceeded the UCH-L1 cutoff, however 20% of samples exceeded the GFAP cutoff and 92% of these were in children < 12 years of age.

Interpretation: Age appears to modify physiological plasma UCH-L1 and GFAP levels. Diagnostic cutoffs for CT-positive TBI may need to be adjusted in children < 12 years of age presenting within 12 hrs of TBI.

Mr. David Ellis¹, Dr. Madeleine Nowak⁴, Mr. Osamudiamen Ogbeide¹, Dr. Stephen Barnes³, Dr. Patrick Quinn¹, Dr. Sharlene Newman², Dr. Keisuke Kawata¹

¹Indiana University, Bloomington, United States, ²University of Alabama, Tuscaloosa, United States, ³University of Alabama at Birmingham, Birmingham, United States, ⁴Boston University, Boston, United States

We conducted a targeted metabolite panel for plasma samples from athletes with ADHD (n = 25) and age and sex-matched controls without an ADHD diagnosis (n = 25). To replicate subconcussive head impacts (SHI) we used a soccer heading paradigm, which induces 10 controlled SHI in humans, and excludes extraneous variables that occur such as fatigue and exercise. ADHD diagnoses were verified by AISRS interviewing. For analysis, 4mL of venous blood was collected into an EDTA vacutainer, which was then centrifuged into plasma. These samples were taken from participants at three time-points: pre-SHI, 2 hours post-SHI, and 24 hours post-SHI. The metabolite panel included eight TCA-cycle metabolites. Significant group baseline differences were observed for citrate and isocitrate, where the ADHD group exhibited higher baseline levels for the respective metabolites compared to controls. Both groups experienced significant decreases for citrate and isocitrate at the 2 hour and 24 hour timepoints and an increase in fumarate at the 24 hour timepoint. A significant increase for alpha ketoglutarate at the 24 hour timepoint was observed in the non-ADHD group. ANOVA tests revealed significant group by time interactions for citrate, isocitrate, and alpha ketoglutarate. The ADHD cohort experienced a significant decrease from baseline to the 24-hour timepoint in malate and oxaloacetate. These results suggest mitochondrial dysfunction may occur after SHI regardless of the status of an ADHD diagnosis.

Ms. Paula Bernander, Dr. Ksenia Musaelyan, Dr. Raj Chandran, Dr. Jaime Marino, Dr. Saul Datwyler, Dr Swati Pradhan-Bhatt, Dr. Hongwei Zhang, Dr. Beth McQuiston

¹Abbott Laboratories, Chicago, United States

Background: Blood biomarkers glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) were introduced in emergency departments (EDs) for intracranial lesions rule out in adult mild traumatic brain injury (TBI) patients. Yet their post-injury kinetics and relationship with CT status across trauma conditions are not well described.

Methods: Trauma patients were recruited in the ED at a US level 1 trauma center. Head CT scan was deemed positive if intracranial lesions were found. Blood was drawn at admission and over the proceeding 24 hours. Biomarkers were tested using plasma with prototype i-STAT™ GFAP and UCH-L1 assays (Abbott Laboratories, Abbott Park, IL).

Results: 191 patients with isolated body trauma (N=22), combined body and TBI trauma (N=110), or isolated TBI (N=59) were included (median age 52, 32% female). 88 cases were CT-positive. LOESS regression showed UCH-L1 peak within 10 minutes after injury and decreased over the next 5 hours, while GFAP steadily increased for 12 hours. Both biomarkers were significantly higher in CT-positive compared to CT-negative cases within 3 hours from injury and 3-to-6 hours later.

Conclusions: This study confirms early response of blood GFAP and UCH-L1 levels to injury and demonstrates their sensitivity to CT status. Hyperacute kinetic profiles highlight the opportunity to include novel blood biomarkers for diagnostic aid in suspected TBI cases in the ED.

Funding: The study was funded by Abbott Laboratories and in collaboration with the US Army Research and Materiel Command under Collaborative Research and Development Agreement No. 20-1266-CRA and Contract No. W81XWH-17-C-0079.

Dr. Elaine Peskind^1,2, Dr. Jeffrey Iliff^1,2, Ms. Jane Shofer¹, Dr. Cynthia Mayer^1,2, Dr. James Meabon^1,2, Dr. David Cook^1,3, Dr. Kathleen Pagulayan¹, Dr. Murray Raskind^1,2, Dr. Henrik Zetterberg⁴, Dr. Kaj Blennow⁴, Dr. Ge Li^1,2

¹University Of Washington, Seattle, United States, ²Veterans Affairs Northwest Mental Illness Research, Education, and Clinical Center (MIRECC), Seattle, United States, ³VA Puget Sound Geriatric Research, Education Center (GRECC), Seattle, United States, ⁴University of Gothenburg, Mölndal, Sweden

Moderate-severe TBI increases risk of Alzheimer’s disease (AD); it is not well established whether mild TBI (mTBI) in Veterans confers similarly increased risk. We investigated changes in early cerebrospinal fluid (CSF) AD biomarkers in blast mTBI Veterans.

This cross-sectional observational study included Veterans with mTBI and non-mTBI Veterans and civilians from 2 sources. Blast-mTBI Veterans had >1 war zone blast mTBI meeting VA/DoD criteria for mTBI. Control participants had no lifetime history of TBI. All underwent clinical/neuropsychological assessments and CSF collection. CSF Aβ40 and Aβ42 were measured on MesoScale Discovery platform and CSF p-tau18 and total tau (t-tau) via INNOTEST ELISA.

Participants were 51 mTBI Veterans (aged 34.0 ± 10.1[SD]) and 85 controls (33.5 ± 8.9). Group differences in CSF AD biomarkers were age-dependent: at age 50, the mTBI group had significantly lower mean CSF Aβ42 and Aβ40. In contrast, CSF p-tau181 and t-tau remained constant with age in participants with mTBI, while tending to be higher at older ages for the non-mTBI group. The mTBI group had poorer cognitive performance at older ages (omnibus p<0.08): at age 50, mean TMT-B time was higher by 34 seconds and mean CVLT-II short-delay recall was lower by 4.2 points. Poorer verbal memory and verbal fluency performance were associated with lower CSF Aβ42 (p≤0.05) in older participants.

CSF Aβ was lower in middle-aged mTBI Veterans, suggesting neuropathologic processes in blast mTBI share properties with pathogenic processes that portend AD onset, raising concern that blast-related mTBI Veterans may be at increased risk for AD.

Dr. Amelia Hicks¹, Ms. Holly Carrington¹, Ms Lisa Bura¹, Ms Alicia Yang¹, Mr Rico Pesce¹, Dr Belinda Yew¹, Dr Kristen Dams-O’Connor¹

¹Icahn School of Medicine at Mount Sinai, New York, United States

Our objective was to conduct a systematic review of studies examining blood-based protein biomarkers of traumatic brain injury (TBI) in adults (≥16yrs) at least 12 months post-injury.

Following independent and duplicate screening of 12,523 articles, only 30 met inclusion criteria. Thirty-six proteins were examined, mostly in serum, with NfL, GFAP, UCHL-1, and tau most studied. Time since injury ranged from 12-months to 48 years.

The most robust group comparison (TBI vs control) findings were reported for GFAP, with significant differences noted across all TBI severities at 12-months post-injury. For studies examining beyond 12-months (n=6), group differences generally did not remain. TBI-control comparisons of NfL (12mths – 32yrs), UCHL-1 (12mths – 7yrs) and tau (12mths – 8yrs) were non-significant, with the exception of two studies (rated as intermediate risk of bias) examining NfL and tau up to five years post-injury. NfL was the only protein to show replicated and significant change over time; decreasing over periods: 30d-5yrs; 3mths-12mths; 8mths-8yrs. Across these four proteins, the only other replicated findings were association of greater injury severity with higher GFAP at 12mths and 8yrs, and association of higher NfL with lower GOSE at 12mths and GOSE decline from 8mths-8yrs. This systematic review reveals a dearth of studies, and fewer replicated findings, for blood-based biomarkers in chronic TBI (i.e., >12mths post-injury). The most consistent evidence to date suggests GFAP elevations in TBI versus control groups at 12mths post-injury. There is an urgent need to accelerate study of biomarkers of chronic TBI and post-traumatic neurodegeneration risk.

Dr. David Barton¹, Mr. John Maczuzak², Ms. Natalee Gallo¹, Ms. Marisa Hirsh³, Dr. Maria Pacella-LaBarbara¹, Dr. Jenna Carlson^4,5, Dr. Anthony Kontos³, Dr. Amy Wagner^2,6,7

¹Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, USA, ²Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, USA, ³Department of Orthopaedic Surgery, UPMC Sports Medicine Concussion Program, University of Pittsburgh, Pittsburgh, USA, ⁴Department of Human Genetics, University of Pittsburgh, Pittsburgh, USA, ⁵Department of Biostatistics, University of Pittsburgh, Pittsburgh, USA, ⁶Department of Neuroscience, University of Pittsburgh, Pittsburgh, USA, ⁷Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA

Mild traumatic brain injury (mTBI) is a stressor that requires adaptation of all body systems to support recovery. Inflammatory signaling includes stress-sensitive molecules that may be sensitive to allostatic load and affect mTBI symptoms. Our goal is to characterize baseline cortisol-associated inflammatory cytokine levels among mTBI and control groups, and evaluate biomarker associations with mTBI symptoms and psychological health (PH) metrics. We report preliminary data from a prospective, observational cohort study of adults with acute mTBI (n=44) and orthopedic injury [OI] controls (n=22) enrolled <72 h post-injury. We measured enrollment serum inflammatory biomarkers via Luminex 34-marker immunoassay and serum cortisol via ELISA. We measured baseline mTBI symptoms (Neurobehavioral Symptoms Index [NSI]) and PH (Patient Health Questionnaire-9 [PHQ-9], Generalized Anxiety Disorder-7 [GAD-7], Post-Traumatic Stress Disorder Checklist [PCL-5]). Mann-Whitney and Spearman tests were used to test group associations. In 44 mTBI subjects [mean±SD age 33±13yrs, 62% female] vs. 22 OI controls [mean±SD age 31±13yrs, 66% female], mTBI had higher median cortisol (122.7 vs. 84.5 ng/mL; p=0.01) and sgp130 levels (171030 vs. 150372 pg/mL; p=0.01), and lower ITAC (53 vs. 92 pg/mL; p<0.01) and RANTES levels (41724 vs. 65399 pg/mL; p<0.01). GAD-7 scores were associated with MIP-1b (r=0.42, p<0.04) and NCAM (r=-0.63, p<0.01). Biomarker associations with NSI, PHQ-9, and PCL-5 did not reach significance. In conclusion, acute serum cortisol and inflammatory cytokines are altered after mTBI, potentially reflecting differences in cortisol-related signaling. Select markers correlated with baseline anxiety scores. Future work will evaluate biomarker relationships with 10- and 30-day outcomes.

Support: DoD W81XWH-22-2-0056.

Mr. Tyler Henry², Dr. Harkirat Sohi³, Dr. Jason Mcdermott³, Dr. Jon Jacobs³, Dr. Karin Rodland², Dr. H.e. Hinson¹

¹UCSF, San Francisco, United States, ²OHSU, Portland, United States, ³PNNL, Richland, United States

Progression of Intracranial hemorrhage (PICH) is associated with poor outcomes after severe traumatic brain injury (TBI). This study’s purpose was to identify molecular pathways associated with PICH after TBI using overrepresentation analysis (ORA) of proteomic data.

We analyzed subjects (n=30) from a prospective observational study of adults with acute TBI and hemorrhage on the initial head CT. Proteomic data was generated using depletion of high abundant proteins followed by TMT labeling and high mass accuracy LC MS/MS. Previous analysis of this dataset identified significant up/downregulation of THSD7A, SALL2, APOA/APOA2, and GOLGA6L2. We performed ORA in leapR to determine if molecular pathways related to these proteins (identified using STRING and from literature) were overrepresented in proteins of interest (POI), proteins with p-value < 0.05 and |Log2 (fold change)| > 1 in PICH vs. no-PICH differential abundance analysis.

ORA revealed that the chosen proteins involved in hemostasis and inflammation were not significantly over-represented in POI, though this analysis may be limited by the dataset’s proteomics panel. Reviewing STRING interactions showed that THSD7A upregulation may be linked to Notch and the B-catenin/WNT pathway and VEGFR expression. APOA/APOA2 downregulation may be related to baseline blood vessel integrity and increased risk for bleeding. SALL2 was linked to highly conserved brain-specific transcription factors, POU3F2 and PODXL, important for maintaining endothelial integrity and reducing leukocyte margination under acute stress.

Future directions include expanding the proteomics panel and pathways for improved ORA and immunoassay screening for chosen proteins from pathways of interest.

Mr. Alireza Abbasi Ghiri¹, Mr. Bahram Jafari¹, Dr. Morteza Seidi¹, Dr. Marzieh Memar¹

¹University of Texas at San Antonio, San Antonio, United States

Recent shift in traumatic brain injury (TBI) research focuses on understanding non/sub-concussive repeated head impacts (RHI), which although asymptomatic, can lead to neurodegenerative outcomes over time. This study examines the effect of sex, head kinematic severity, and hormonal levels on elevation of well-established TBI biomarkers including GFAP, TAU, NFL, and UCH-L1 post-RHI. Participants, equipped with sensor-embedded mouthguards for measuring head kinematics, followed a standardized soccer heading protocol (10 headings, one-minute apart, using a soccer machine) and blood samples were collected pre-RHI and at 1-hour, 1-day, and 1-week post-RHI. The absolute and elevation levels of biomarkers were compared across and within groups of males (n=13), females in follicular-phase (FP, n=7) and luteal-phase (LP, n=7), separately and combined, with and without considering head kinematic parameters or progesterone level as covariates. Progesterone was measured pre-RHI and at 1-week post-RHI. When kinematic parameters were considered as covariates, biomarkers elevation become more similar across groups and majority of significant differences initially observed between groups disappeared, evidenced by increased p-values compared to analysis without covariates. Although differences between groups diminished, p-values for the biomarkers elevation within each group over time remained consistent to analysis without covariate. Considering progesterone as a covariate did not significantly alter the biomarkers elevation across and within groups, although UCH-L1 experienced more changes than other biomarkers. In summary, RHI led to significant biomarker elevations at several time-points regardless of covariates. Furthermore, kinematics severity emerged as a more critical factor than progesterone, influencing the level of biomarkers elevation. Funded by UTSA-SwRI CONNECT program.

Dr. Megan Huibregtse¹, Ms. Tianyi Li², Dr. Nathaniel Harnett^2,3, Dr. Tanja Jovanovic⁴, Dr. Karestan Koenen⁵, Dr. Ronald Kessler⁶, Dr. Kerry Ressler^2,3, Dr. Samuel McLean^7,8, Dr. Jennifer Stevens¹

¹Department of Psychiatry and Behavioral Sciences, Emory University School Of Medicine, Atlanta, United States, ²Division of Depression and Anxiety, McLean Hospital, Belmont, United States, ³Department of Psychiatry, Harvard Medical School, Boston, United States, ⁴Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, United States, ⁵Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, United States, ⁶Department of Health Care Policy, Harvard Medical School, Boston, United States, ⁷Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, United States, ⁸Department of Emergency Medicine, University of North Carolina School of Medicine, Chapel Hill, United States

Female patients with mild traumatic brain injury (TBI) tend to report worse symptoms relative to male patients. An underlying neurobiological mechanism remains unclear, despite preclinical evidence that female white matter microstructure may be more vulnerable to traumatic injuries. Here, we investigated if there were sex-specific white matter disruptions among trauma survivors with elevated acute levels of glial fibrillary acidic protein (GFAP), an astrocyte-derived intermediate filament associated with TBI. Individuals aged 18–75 who presented to emergency departments (ED) within 72h of a traumatic event provided plasma samples and returned for diffusion-weighted imaging at 2-weeks post-trauma. Twenty participants (11F/9M) with elevated GFAP levels in the ED were matched 1:3 with low-GFAP controls on race/ethnicity, sex, and age (±5y; final sample N=77). We conducted a sex-stratified whole-brain connectometry analysis in DSI Studio (FDR<0.05, T-threshold=2.5, minimum length=30 voxels). Among females, the high-GFAP group had reduced quantitative anisotropy (a metric of axonal density estimated with Q-space imaging) relative to low-GFAP controls in many tracts, including the forceps minor, forceps major, bilateral inferior fronto-occipital fasciculi, body of the corpus callosum, left corticospinal and corticopontine tracts, left medial lemniscus, and left extreme capsule. Among males, no significant differences were observed between the high-GFAP and low-GFAP groups. These results suggest that elevated GFAP in female trauma survivors may be associated with extensive white matter disruption. Future work should examine sex differences in the relationship between integrity of white matter and post-traumatic symptom burden.

Funding: F32MH134528, W81XWH-22-C-0122, U01MH110925, US Army MRMC, One Mind, and The Mayday Fund.

Mr. Mojibola Fowowe¹, Dr. Cristian Gutierrez-Reyes¹, Mr. Moyinoluwa Adeniyi¹, Mr. Sherifdeen Onigbinde¹, Dr. Firas Kobeissy², Dr. Stefania Mondello³, Dr. Ava Puccio⁴, Dr. Yehia Mechref¹

¹Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, United States, ²Center for Neurotrauma, MultiOmics & Biomarkers (CNMB) Morehouse School of Medicine, Atlanta, United States, ³Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy, ⁴Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, United States

Effective therapies for traumatic brain injury (TBI) depend on identifying reliable diagnostic markers of injury development and progression. Small extracellular vesicles (sEVs), secreted by most cells, can traverse the blood-brain barrier (BBB) and carry essential biomolecular cargos, including proteins. Therefore, sEVs offer a promising source for unraveling TBI pathophysiology. In this study, we employed an LC-MS/MS approach to investigate proteome alterations in serum and cerebrospinal fluid (CSF)-derived sEVs from severe TBI patients, aiming to identify biomarkers of injury development and progression. A total of 164 and 114 differentially expressed proteins (DEPs) were quantified in serum- and CSF-derived sEVs, respectively. Notably, we observed a significant elevation of astrocytes-expressed glial fibrillary acidic protein (GFAP), and neuronal ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) in both serum and CSF sEVs at 24 h, 72 h, and 120 h post-injury (p < 0.05). In healthy subjects, levels of GFAP in serum sEVs were higher than those in CSF; however, at 72 h to 120 h post-injury, CSF sEVs showed a significant increase compared to serum (p < 0.05). Additionally, we observed elevated levels of C-reactive protein (CRP) in CSF sEVs, a sensitive biomarker predicting poor clinical outcomes of TBI and reflecting responses from trauma and chronic inflammatory conditions. These DEPs could potentially highlight the changes between injured and healthy individuals. Further examination of these proteins will elucidate the biological mechanisms and molecular pathways associated with TBI over time.

This work was supported by grants from NIH (1R01GM130091-02) and Welch Foundation D-0005 and The CH Foundation.

Mr. Moyinoluwa Adeniyi¹, Joy Solomon¹, Mojibola Fowowe¹, Sherifdeen Onigbinde¹, Daramola Oluwatosin¹, Judith Nwaiwu¹, Andrew I. Bennett¹, Federico Moro², Teresa Ravizza², Firas Kobeissy³, Pavel Klein⁴, Elisa R. Zanier², Kevin K. Wang³, Yehia Mechref¹

¹Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, United States, ²Department of Neuroscience, Mario Negri Institute for Pharmacological Research IRCCS, Italy, ³Department of Neurobiology, Center for Neurotrauma, Multiomics and Biomarkers (CNMB), Neuroscience Institute, Morehouse School of Medicine (MSM), Atlanta, United States, ⁴Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Bethesda, MD, USA

Traumatic brain injury (TBI) poses a significant global health challenge, particularly impacting the younger adult population, with millions of cases reported annually worldwide. TBI severity varies, often leading to post-traumatic syndromes such as epileptogenesis, characterized by unprovoked seizures. The risk of developing post-traumatic epilepsy (PTE) correlates with injury severity, yet therapeutic strategies remain limited due to the lack of non-invasive biomarkers for identifying at-risk patients and predicting disease severity. Protein glycosylation is pivotal in the development, structure, and function of the nervous system. Alterations in glycosylation have been associated with various neurological disorders, suggesting a potential link to the pathophysiology of PTE. In this study, an LC-MS/MS approach was utilized in the analysis of N-glycoproteomic differences in serum samples collected from healthy individuals, TBI patients (PTE-), and TBI patients who later developed PTE (PTE+). Specifically, pairwise comparison of the PTE- vs PTE+ revealed differential expression (p-value < 0.05) of N-glycopeptides RESVTDHVNLITPLEKPLQNFTLCFR_HexNAc(4)Hex(5)NeuAc(2) from Serum amyloid protein, FNLTETSEAEIHQSFQHLLR_HexNAc(5)Hex(6)Fuc(1)NeuAc(3) from Alpha-1-antichymotrypsin, NISDGFDGIPDNVDAALALPAHSYSGR_HexNAc(4)Hex(5)NeuAc(2) from Vitronectin, IPCSQPPQIEHGTINSSR_HexNAc(4)Hex(5)NeuAc(1) from Complement factor H, EHEGAIYPDNTTDFQR_HexNAc(5)Hex(6)NeuAc(3) from Ceruloplasmin and LPTQNITFQTESSVAEQ EAEFQSPK_HexNAc(4)Hex(5)NeuAc(2) from Inter-alpha-trypsin inhibitor heavy chain, among others. These proteins play crucial roles in a complex network of inflammation and neuroregulation. Our findings demonstrate that N-glycopeptides levels can provide critical insights into the prediction of PTE development and early assessment of disease severity in TBI patients.

This work was supported by grants from the National Institutes of Health, NIH (1R01GM130091), the Robert A. Welch Foundation under grant Number D-0005, and The CH Foundation.

Dr. John Yue¹, Dr. Sonia Jain², Dr. Ava Puccio³, Ms. Xiaoying Sun², Dr. Thomas van Essen⁴, Dr. Romit Samanta⁵, Dr. Patrick Belton⁶, Dr. Esther Yuh⁷, Dr. Lindsay Nelson⁸, Dr. Mahmoud Elguindy¹, Ms. Joye Tracey¹, Dr. Shawn Eagle³, Dr. Frederick Korley⁹, Dr. Andrea Schneider¹⁰, Dr. Pratik Mukherjee⁷, Dr. Raquel Gardner¹¹, Dr. Amy Markowitz¹, Dr. Firas Kobeissy¹², Dr. David Okonkwo³, Dr. Ramon Diaz-Arrastia¹⁰, Dr. Geoffrey Manley¹, Dr. Kevin Wang¹²

¹Department of Neurological Surgery, University Of California, San Francisco, San Francisco, United States, ²Department of Biostatistics, University of California, San Diego, San Diego, United States, ³Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, United States, ⁴Department of Neurological Surgery, Leiden University Medical Center, Leiden, The Netherlands, ⁵Department of Anesthesia and Critical Care, University of Cambridge, Cambridge, United Kingdom, ⁶Department of Neurological Surgery, University of Wisconsin-Madison, Madison, United States, ⁷Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, United States, ⁸Department of Neurological Surgery, Medical College of Wisconsin, Milwaukee, United States, ⁹Department of Emergency Medicine, University of Michigan, Ann Arbor, United States, ¹⁰Department of Neurology, University of Pennsylvania, Philadelphia, United States, ¹¹Department of Neurology, University of California, San Francisco, San Francisco, United States, ¹²Department of Neurobiology, Morehouse School of Medicine, Atlanta, United States

Objectives: Systemic and neuroinflammatory responses mediate secondary injuries after traumatic brain injury (TBI), which lead to adverse outcomes. Diagnostic and prognostic properties of 26 inflammatory biomarkers were examined.

Methods: The 18-center prospective TRACK-TBI Study (2014-2018) enrolled patients receiving head computed tomography (CT) within 24-hours of TBI. We evaluated 394 TBI patients, 100 orthopedic trauma controls (OCs), and 67 healthy controls (HCs) with plasma biomarkers (MesoScale Diagnostics) and outcomes. Comparisons included CT-positive/negative TBI, Glasgow Coma Scale (GCS)=3-12/13-15, and 6-month unfavorable/favorable outcome (GOSE=1-4/5-8). Medians/quartiles were evaluated; differences between medians (fold-change) and discrimination (area under the curve (AUC)) were reported. Significance threshold p<0.002 (0.05÷26 biomarkers). Comparisons reported at p<0.0001(*) unless denoted.

Results: Eleven biomarkers differentiated TBI/HC, TBI/OC, severity, and outcome. Fold-changes and AUCs were consistent across TBI severity comparisons (CT+/CT-, GCS=3-12/13-15, respectively): interleukin-10 (IL-10; 6.4-fold*/7.6-fold*; AUC=0.81/0.89), IL-6 (4.6*/3.7*; AUC=0.82/0.87), IL-2 (3.3*/4.1*; AUC=0.82/0.85), tumor necrosis factor-alpha (TNFa; 2.3*/3.0*; AUC=0.81/0.85), IL-15 (1.4*/1.5*; AUC=0.77/0.85), c-reactive protein (CRP; 8.8*/10.2*; AUC=0.79/0.81), serum amyloid A (SAA; 19.8*/18.6*; AUC=0.78/0.0.80), IL-1b (3.4*/4.3*; AUC=0.76/0.83), IL-4 (3.4*/3.9*; AUC=0.74/0.79), IL-17a (1.7*/2.0*; AUC=0.69/0.74), IL-12p70 (1.4*/1.6*; AUC=0.65/0.70). Notably, biomarker metrics for TBI severity were generally consistent for unfavorable outcome: IL-10 (5.6-fold*/AUC=0.83), IL-6 (1.5*/AUC=0.75), IL-2 (3.9*/AUC=0.81), TNFa (2.8*/AUC=0.77), IL-15 (1.6*/AUC=0.79), CRP (4.9*/AUC=0.71), SAA (4.1*/AUC=0.67), IL-1b (2.7*/AUC=0.74), IL-4 (2.5*/AUC=0.73), IL-17a (2.1*/AUC=0.73), IL-12p70 (1.7*/AUC=0.70), Bivariate correlations (Spearman’s ρ>0.7) emerged amongst IL-1b, IL-2, IL-4, TNFa (with several other markers), and between CRP/SAA.

Conclusions: We identified 11 blood-based inflammatory proteins with diagnostic and prognostic relevance to TBI. These biomarkers distinguished TBI severity and 6-month unfavorable outcome with consistent magnitudes of association.

Ms. Lauren Evans¹, Mr William O’Brien¹, Ms Becca Xie¹, Mr Gershon Spitz¹, Ms Lauren Giesler¹, Mr Brendan Major¹, Mr Steven Mutimer¹, Prof. Biswadev Mitra^1,2, Dr Terence O’Brien^1,2,3, Prof. Sandy Shultz^1,2,3,4, Dr Stuart McDonald^1,2

¹Monash University, Melbourne, Australia, ²Alfred Health, Melbourne, Australia, ³Royal Melbourne Hospital, Melbourne, Australia, ⁴Vancouver Island University, Nanaimo, Canada

AIM: To quantify non-concussive head impact exposure and their association with post-match blood biomarkers of astroglial and axonal injury blood biomarkers in male amateur Australian footballers.

METHODS: Thirty-two athletes underwent in-season (24h post-match) and post-season (>5w) blood collections and/or wore HITIQ Nexus A9 Instrumented Mouthguards (iMGs) measuring peak linear (PLA) and rotational (PRA) acceleration. Match footage was used to verify and code impacts. Simoa® quantified blood NfL, GFAP and p-tau-181 levels.

RESULTS: In-season elevations were found for GFAP (mean dif.=8.07pg/mL, 95%CI=0.28-15.86), NfL (mean dif.=1.43pg/mL, 95%CI=0.58-2.28) and p-tau-181 (mean dif.=10.44pg/mL, 95%CI=6.81-14.08) compared to post-season levels.

Post-match GFAP was associated with maximum single impact PLA (β=0.18pg/mL/g, 95%CI=0.02-0.33) and PRA (β=1.85pg/mL/krad/s2, 95%CI=0.04-3.66), and cumulative PLA (β=0.07pg/mL/g, 95%CI=0.02-0.12) and PRA (β=0.70pg/mL/krad/s2, 95%CI=0.20-1.20), and impact number (β=1.9pg/mL per impact, 95%CI=0.34-3.47) within a single match.

Change in NfL between two matches correlated with cumulative PLA (r=0.73, 95%CI=0.23-0.92) and PRA (r=0.66, 95%CI=0.10-0.90), and impact number (r=0.67, 95%CI=0.12-0.91).

CONCLUSION: Maximum and cumulative head accelerations measured by iMGs were associated with elevated biomarkers of brain cell injury, highlighting the potential of both technologies for enhanced head impact management in collision sports.

Ms. Ruby Taylor^1,2, Dr. Robert Keane³, Dr. W. Dalton Dietrich², Dr. Jon Perez-Barcena⁴, Dr. Juan Pablo de Rivero Vaccari²

¹Medical Scientist Training Program, University Of Miami Miller School Of Medicine, Miami, United States, ²Department of Neurological Surgery and the Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, United States, ³Department of Cellular Physiology and Molecular Biophysics, University of Miami Miller School of Medicine, Miami, USA, ⁴Hospital Universitari Son Spases, Palma de Mallorca, Spain

Aneurysmal subarachnoid hemorrhage (aSAH) is a neurological emergency caused by intracranial aneurysm rupture, resulting in blood extravasation into the subarachnoid space. We have previously shown that inflammasome proteins are reliable biomarkers of the inflammatory response in TBI. However, whether these proteins are reliable biomarkers of the inflammatory response in aSAH is yet to be determined. In this study, we provide receiver operator characteristic (ROC) curves and pertinent biomarker statistics following analyses of serum and CSF samples from patients with aSAH and from non-injured controls to examine the potential of inflammasome signaling proteins as biomarkers of aSAH. Serum and CSF samples from 15 patients with aSAH and from non-injured controls were analyzed in this study for samples ranging from the day of injury to 4 days after aSAH. Analysis of inflammasome protein concentration in serum and CSF samples were performed using the Ella System (Protein System) and Simoa HD-X analyzer. Data obtained were analyzed with Prism 10 software. Protein levels of ASC, Caspase-1, IL-18, IL-6, and IL-1β are significantly elevated within 24 hours of aSAH when compared with control values. ROC curves, confidence intervals, sensitivity and specificity for each biomarker examined revealed that caspase-1 (0.98 area under the curve (AUC)), ASC (0.93 AUC), and IL-6 (0.98 AUC) in serum and ASC (0.91 AUC), IL-18 (0.93 AUC), IL-1β (AUC 1.00), and IL-6 (AUC 1.00) in CSF are promising biomarkers of aSAH pathology. These findings indicate that inflammasome proteins are excellent diagnostic biomarkers of the inflammatory response in aSAH.

Ms. Courtney McCabe^1,2, Dr. Emily L Dennis^1,2, Dr. Talin Babikian^3,6, Dr. Christopher C Giza^6,7,8, Dr. Robert F Asarnow^3,4,5

¹Department of Neurology, University Of Utah School of Medicine, Salt Lake City, United States, ²George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, United States, ³Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, United States, ⁴Brain Research Institute, UCLA, Los Angeles, United States, ⁵Department of Psychology, UCLA, Los Angeles, United States, ⁶UCLA Steve Tisch BrainSPORT Program, Los Angeles, United States, ⁷Department of Pediatrics, Division of Neurology, UCLA Mattel Children’s Hospital, Los Angeles, United States, ⁸Department of Neurosurgery, David Geffen School of Medicine at UCLA, Los Angeles, United States

Traumatic brain injury (TBI) presents a public health concern as a leading cause of death and disability in children. Pediatric populations are particularly vulnerable to TBI due to periods of rapid growth, synaptic pruning, and myelination. Pediatric patients with moderate-severe TBI (msTBI) (n=57 ) and healthy controls (n=72) were evaluated from the post-acute (mean=13.74 weeks; SD=5.78) to chronic phase (mean=62.92 weeks; SD=11.11) post-TBI using diffusion magnetic resonance imaging (dMRI) and an event-related potential measure of interhemispheric transfer time (IHTT) which measured the speed of information transfer across the corpus callosum. We previously identified two subgroups of patients based on IHTT, with one group showing a significantly slower IHTT (IHTT-slow), poorer cognitive performance, and progressive microstructural disruption, while the other group did not differ from controls on IHTT (IHTT-normal) or cognitive performance, and showed relative microstructural recovery over time. Here we examined group differences in restricted diffusion imaging (RDI), which is a dMRI metric sensitive to inflammation. Comparing IHTT-slow, IHTT-normal, and controls on RDI at both timepoints, connectometry analysis found tracts showing lower RDI in the IHTT-slow group compared to the IHTT-normal group across the white matter. Longitudinal analyses indicate that while both groups exhibit a decrease in RDI over time, suggesting resolution of neuroinflammation and recovery, the decreases in the IHTT-slow group were smaller. The differences in RDI between IHTT-slow and IHTT-normal suggests that neuroinflammation may play a key role in poor cognitive/functional outcomes of some pediatric patients with msTBI.

Ms. Karinn Sytsma¹, Dr. Rhonda Mittenzwei¹, Dr. Heather Maioli³, Dr. C. Dirk Keene¹, Dr. Christine Mac Donald¹, Dr. Brian Edlow², Dr. Chiara Maffei², Dr. Amber Nolan¹

¹University Of Washington, Seattle, United States, ²Massachusetts General Hospital, Boston, United States, ³New York City Office of the Medical Examiner, New York City, United States

Diffuse axonal injury (DAI) is caused by accelerative-decelerative forces during head injury that induce shearing within white matter tracts. Susceptibility-weighted imaging (SWI) identifies microhemorrhages that are considered the radiographic hallmark of DAI and often used in clinical prognostication. However, this assumption is limited by a lack of systematic radiographic-pathologic correlation studies. Thus, three brain donors with TBI and microhemorrhages (survival interval: 7-13 days) were selected to further evaluate this relationship by comparing ex-vivo MRI and pathological data. Coronal brain slices were co-registered against ex-vivo SWI to guide sampling. All regions with white matter microhemorrhages on SWI were sampled (n = 34 slides). Slides stained with H&E and amyloid precursor protein (APP) underwent scanning and analysis using the Halo® platform (Indica Labs). Axonal injury was assessed as a function of distance from a microbleed by 200-micron concentric outlines up to 1mm. 61% of microhemorrhages demonstrated axonal injury (>3 APP+ axonal swellings >4 μm in diameter within an outline), and this injury exhibited a positive correlation with spatial proximity to the microbleed. However, 39% of microbleeds showed no axonal injury. This relationship was correlated with estimates of apparent fiber density as measured by ex-vivo diffusion-weighted imaging. Analysis of location by lobe, deep versus superficial white matter, and proximity to contusion were not correlated with axonal injury. Further studies are needed to understand the relationship between microbleed and axonal injury. Our results suggest caution when making a diagnosis of DAI based purely on the presence of microhemorrhage and support incorporation of diffusion MRI.

Dr. Azeezat Azeez¹, Ms. Malvika Sridhar¹, Mr. Andrew Geoly¹, Dr. Afik Faerman¹, Dr. Kirsten Cherian¹, Dr. John Coetzee^1,2, Ms. Saron Hunegnaw¹, Dr. Derrick Buchanan¹, Dr. Nimrod Keynan¹, Dr. Ian Kratter¹, Dr. Cammie Rolle¹, Dr. Manish Saggar¹, Dr. Maheen Adamson^2,3,4, Dr. Nolan Williams¹

¹Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, United States, ²Department of Rehabilitation, VAPAHCS, Palo Alto, United States, ³WRIISC-WomenCOE, VAPAHCS, Palo Alto, United States, ⁴Department of Neurosurgery, Stanford University, Stanford, United States

Objective: This analysis sought to identify the neural mechanisms underlying the strong therapeutic results from a recent study that evaluated the safety and clinical impact of ibogaine in treating military veterans with traumatic brain injury (TBI). TBI is a leading cause of disability with sequelae of psychiatric symptoms such as post-traumatic stress disorder (PTSD), major depressive disorder (MDD), and generalized anxiety disorder (GAD).

Methods: We collected arterial spin labeling (ASL) and blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) data at three-time points pre and post-treatment on 30 Special Operations Veterans (SOV) who had voluntarily enrolled in tabernanthe iboga exposure at a clinic in Mexico. We used a multimodal whole-brain resting-state exploratory approach of examining changes to regional Cerebral Blood Flow, Functional Connectivity, and Network communication to characterize neural features that were altered post-ibogaine treatment.

Results: Significant changes were identified in blood flow (p<0.001, PFDR<0.05), functional connectivity (p<0.005), and networks of the limbic and sensory-motor system, regions associated with TBI and PTSD. We found associations between neuroimaging findings in the left hemisphere insula, anterior cingulate cortex, and hippocampus-dorsal attention network with clinical measures of disability index and PTSD symptomology.

Conclusions and Relevance: Our novel multimodal neuroimaging approach revealed potential mechanisms underlying the therapeutic benefits of ibogaine for SOV suffering from TBI with comorbid disability and psychiatric symptoms. Further research with larger and diverse populations would be beneficial to establish clinical and neuroimaging alterations from ibogaine on subjects without lifetime TBIs or combat-induced PTSD.

Dr. Alex Trofimov², Kseniia Trofimova², Dr. Oxana Semyachkina-Glushkovskaya³, Dr. Edwin Nemoto⁴, Dr. Denis Bragin¹

¹Lovelace Biomedical Research Institute, Albuquerque, United States, ²Department of Neurological Diseases, Privolzhsky Research Medical University, Nizhny Novgorod, Russia, ³Department of Physiology, Saratov State University, Saratov, Russia, ⁴Department of Neurology, University of New Mexico School of Medicine, Albuqueruque, USA

Introduction Although net water uptake (NWU) assessment by perfusion computed tomography (PCT) allows more accurate evaluation of brain edema in foci of cerebral ischemia, such studies are rare, even in cerebrovascular diseases and strokes, and have never been used for the analysis of posttraumatic ischemia (PTI).

The research question was to study brain NWU in foci of PTI foci in moderate-to-severe traumatic brain injury (TBI) and its effects on cerebral microcirculation.

Materials and Methods 128 moderate-to-severe TBI patients (women 44; men 84, age 37±12 years) were stratified into three groups: Marshall 2-3 – 48 patients, Marshall 4 – 44 patients, Marshall 5 – 36 patients. The groups were matched by sex and age. Patients received multiphase PCT 2-7 days after admission. NWU was calculated from non-contrast computed tomography. Data are shown as a median [interquartile range]. P<0.05 was considered statistically significant.

Results Cerebral blood flow in posttraumatic ischemia foci in the Marshall 4 group was significantly higher than in the Marshall 5 group (P =0.027). Net water uptake in posttraumatic ischemia zones was substantially higher than in zones without posttraumatic ischemia (8.1% versus 4.2%; p <0.001). Mean transit time in posttraumatic ischemia zones was inversely and significantly correlated with higher net water uptake (R2 = 0,089, p<0.01).

Discussion and Conclusion: Cerebral blood flow slowdown through the cerebral microvascular bed was significantly correlated with the increase in NWU in PTI foci. Marshall’s classification did not predict the progression of posttraumatic ischemia. The study was funded by RSF 24-45-00010

Dr. Li Jiang¹, Dr. Ze Wang¹, Mr. Steven Roys¹, Ms. Rosy Linda Njonkou Tchoquessi¹, Dr. Andrew Furman¹, Dr. Prashant Raghavan¹, Dr. Rao Gullapalli¹, Dr. Neeraj Badjatia¹, Dr. Jiachen Zhuo¹

¹University of Maryland School of Medicine, Baltimore, United States

Introduction: Mild traumatic brain injury (mTBI) is a prevalent neurological condition associated with short- or long-term cognitive impairments. Since these consequences are often not accompanied by structural damages, studying brain activity is critical to understanding their underlying mechanisms. Functional brain entropy (BEN), which captures both the information processing capacity and the irregularity of brain activity, may shed light on mTBI mechanism. This study aims to elucidate BEN in mTBI and its correlation with cognitive impairment using resting-state fMRI.

Methods: Fifty patients with mTBI and 23 non-TBI control patients, matched for age and sex, underwent MRI scans and cognitive tests using the NIH Toolbox Cognition Battery within one month of their injuries. Resting-state fMRI preprocessing utilized the CONN Toolbox, with BEN maps generated using the BEN Mapping Toolbox (BENtbx). Group comparisons employed general linear model, and association analysis used Pearson correlation.

Results and Discussion: While mTBI showed no significant difference in cognitive scores, elevated entropy levels were observed in the para-hippocampal gyrus and hippocampus compared to non-TBI controls. Furthermore, elevated entropy negatively correlated with Pattern Comparison Processing Speed test scores, suggesting higher entropy in memory-related brain regions may act as a compensatory mechanism for sustaining cognitive function. This study underscores the potential of brain entropy analysis as a valuable tool in mTBI research, shedding light on underlying mechanisms. The study is supported by NIH grant 5R01NS105503.

Dr. Andrew Furman¹, Dr. Li Jiang¹, Mr. Steven Roys¹, Ms. Rosy Linda Njonkou Tchoquessi¹, Dr. Rao Gullapalli¹, Dr. Prashant Raghavan¹, Dr. Neeraj Badjatia¹, Dr. Jiachen Zhuo¹

¹University of Maryland School of Medicine, Baltimore, United States

Headache is a common outcome following mild to moderate TBI. Damage to the trigeminal nerves, a trio of nerves responsible for conveying sensory information from the face, has been suggested to be a mechanism involved in the development of headaches. The thalamus has been hypothesized to be a core region in TBI pathophysiology, and its ventral posteromedial (VPM) and mediodorsal (MD) nuclei receive dense innervation from the trigeminal nerves4. At present, little is known about how changes in the functional connectivity of these two regions relate to the development and persistence of TBI headaches. In the current study, resting-state functional MRI (rs-fMRI) was used to investigate the functional connectivity of VPM and MD in acute TBI patients (imaging within 14 days of injury). Individual nuclei of the thalamus were segmented with the Morel Atlas and the connectivity of TBI patients (n=57) was compared against healthy controls (n=27). We found that VPM of TBI patients showed hyper-connectivity with the primary somatosensory cortex (S1), one of its immediate upstream targets and that this hyper-connectivity was positively correlated to headache symptoms. Interestingly, the identified S1 cluster occupies areas traditionally associated with torso rather than face somatotopy. TBI patients also demonstrated hyperconnectivity between MD and one of its primary upstream targets, the anterior cingulate cortex (ACC)6, which was positively correlated to headache symptoms. Together, these results provide initial evidence that changes to thalamic nuclei receiving facial sensory information play an important role in the pathophysiology of TBI-induced headaches.

Ms. Alana Wickham^1,2, Nicholas Kim², Holly Carrington², Dr. Katherine Breedlove³, Leonard Jung^1,2,4, Tim Wiegand^2,4, Omar John¹, Fatima Tuz-Zahra⁵, Dr. Yorghos Tripodis⁵, Dr. Daniel Daneshvar^6,7,8, Michael Coleman², Dr. Charles Adler⁹, Dr. Charles Bernick^10,11, Dr. Laura Balcer^12,13,14, Dr. Michael L. Alosco¹⁵, Dr. Jefferey L. Cummings¹⁶, Dr. Eric Reiman^17,18,19,20, Dr. Robert Stern^15,21,22, Dr. Alexander Lin^3,23, Dr. Inga Koerte^2,4,24,25, Dr. Martha Shenton^2,23,25, Dr. Sylvain Bouix²⁶, Dr. Hector Arciniega¹

¹Arciniega Lab, Department of Rehabilitation Medicine, NYU Grossman School of Medicine, New York, United States, ²Psychiatry Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women’s Hospital, Harvard Medical School, Boston, United States, ³Center for Clinical Spectroscopy, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, United States, ⁴cBRAIN, Department of Child and Adolescent Psychiatry, Psychosomatics, and Psychotherapy, LMU University Hospital, Ludwig-Maximilians-Universität, Munich, Munich, Germany, ⁵Department of Biostatistics, Boston University School of Public Health, Boston, Boston, United States, ⁶Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, United States, ⁷Department of Physical Medicine and Rehabilitation, Massachusetts General Hospital, Boston, United States, ⁸Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Boston, United States, ⁹Department of Neurology, Mayo Clinic College of Medicine, Mayo Clinic Arizona, Scottsdale, United States, ¹⁰Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, United States, ¹¹Department of Neurology, University of Washington, Seattle, United States, ¹²Department of Neurology, NYU Grossman School of Medicine, New York, United States, ¹³Department of Population Health, NYU Grossman School of Medicine, New York, United States, ¹⁴Department of Ophthalmology, NYU Grossman School of Medicine, New York, United States, ¹⁵Department of Neurology, Boston University Alzheimer’s Disease Research Center and CTE Center, Boston University Chobanian & Avedisian School of Medicine, Boston, United States, ¹⁶Chambers-Grundy Center for Transformative Neuroscience, Pam Quirk Brain Health and Biomarker Laboratory, Department of Brain Health, School of Integrated Health Sciences, University of Nevada Las Vegas, Las Vegas, United States, ¹⁷Banner Alzheimer’s Institute and Arizona Alzheimer’s Consortium, Phoenix, United States, ¹⁸Department of Psychiatry, University of Arizona, Phoenix, United States, ¹⁹Department of Psychiatry, Arizona State University, Phoenix, United States, ²⁰Neurogenomics Division, Translational Genomics Research Institute and Alzheimer’s Consortium, Phoenix, United States, ²¹Department of Anatomy and Neurobiology Boston University Chobanian & Avedisian School of Medicine, Phoenix, United States, ²²Department of Neurosurgery, Boston University Chobanian & Avedisian School of Medicine, Boston, United States, ²³Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, United States, ²⁴Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität, Munich, Germany, ²⁵Department of Psychiatry, Massachusetts General Hospital, Boston, United States, ²⁶Department of Software Engineering and Information Technology, École de Technologie Supérieure, Université du Québec, Montréal, Canada

Background: Repetitive head impacts (RHI) may be linked to Chronic Traumatic Encephalopathy (CTE) or other neuropathological changes such as white matter shear injuries. Here, we leverage diffusion-tensor imaging (DTI) to investigate in vivo alterations of white matter in former American football players, taking into consideration age and factors related to RHI exposure.

Methods: We analyzed data from the DIAGNOSE CTE Research Project, focusing on former American football players (n = 166). The measures included whole-brain Fractional Anisotropy (FA), reflecting water diffusion directionality in white matter, and FreeWater-corrected FA (FAt) accounting for extracellular free water, using FSL Tract-Based Spatial Statistics (TBSS). We performed linear regressions on FA and FAt with age, age of first exposure to football, and estimates of cumulative head impact index (CHII) scores of frequency, linear acceleration, and rotational force controlling for age, body mass index, race, education, and APOE e4 allele presence as covariates.

Results: Both FA (p < 0.00001) and FAt (p < 0.00001) decreased as age increased. Additionally, FA (p < 0.01) and FAt (p < 0.01) were significantly lower with an earlier age of first exposure to football. We observed an FAt decrease as CHII linear acceleration (p < 0.04) and rotational forces (p < 0.02) increase.

Conclusion: Our study reveals age-related declines in both FA and FAt and highlights that the duration and intensity of exposure to RHI have an impact on white matter microstructure later in life. Overall, these results underscore the impact of prolonged exposure to RHI on white matter microstructure.

Dr. David Barton¹, Dr. Tae Kim², Dr. Joseph Mettenburg², Dr. Ashok Panigrahy², Dr. Amy Wagner^3,4,5, Dr. Clifton Callaway^1,5

¹Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, USA, ²Department of Radiology, University of Pittsburgh, Pittsburgh, USA, ³Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, USA, ⁴Department of Neuroscience, University of Pittsburgh, Pittsburgh, USA, ⁵Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, USA

BBB dysfunction has been reported after severe or complex traumatic brain injury (TBI) and repetitive head trauma, but it remains unclear if BBB dysfunction occurs acutely after a single mild TBI, or concussion. Detecting BBB dysfunction after concussion could inform pathophysiology, improve prognostication, and help elucidate novel treatment targets. We sought to quantify and localize BBB permeability in patients with a single, acute concussion. We enrolled 10 patients in the emergency department diagnosed with concussion (mean age 34yrs, 70% female) and compared findings to 8 healthy controls (mean age 28yrs, 50% female). Within 14 days post-injury (median 4.5, range 0-14 days), we performed brain dynamic contrast-enhanced magnetic resonance imaging (3T Siemens Prisma system). To measure BBB permeability, we calculated Ktrans (transfer constant) – the contrast agent delivery rate to the brain per tissue volume and per contrast agent concentration in arterial blood. Threshold-free cluster enhancement was used to identify contiguous high-signal voxel clusters. We compared Ktrans voxel-wise between concussion vs. control groups, with age and sex as covariates, via permutation testing (n=2000) controlling family-wise error rate. The highest difference cluster was located in the left temporal lobe (Ktrans median difference: 3.1 x10-3 arbitrary units, 95% CI 1.2-13.8 x10-3; p=0.009 by Mann-Whitney test). Five concussion subjects had cluster Ktrans levels higher than all controls. Our data suggest BBB dysfunction occurs in a substantial proportion (50%) of subjects with acute concussion. Future work will investigate relationships between BBB permeability, symptom and cognitive measures, and blood biomarkers.

Acknowledgements: NIH T32HL134615, Emergency Medicine Foundation.

Mr. Bluye DeMessie¹, Dr. Roman Fleysher², Dr. Kenny Ye^3,4, Dr. Walter Stewart⁵, Dr. Richard Lipton⁶, Dr. Mimi Kim³, Dr. Molly Zimmerman⁷, Dr. Thomas Kaminski⁸, Dr. Michael Lipton^2,9

¹Department of Neuroscience, Albert Einstein College Of Medicine, Bronx, United States, ²Department of Radiology, Columbia University Irving Medical Center, New York, USA, ³Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, USA, ⁴Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, USA, ⁵Medurio Inc., USA, ⁶Department of Neurology, Albert Einstein College of Medicine, Bronx, USA, ⁷Department of Psychology, Fordham University, Bronx, USA, ⁸Department of Kinesiology and Applied Physiology, University of Delaware, Newark, USA, ⁹Department of Biomedical Engineering, Columbia University, New York, USA

Computational models of head impacts and postmortem studies of chronic traumatic encephalopathy (CTE) suggest the cortical sulci are vulnerable to repetitive head impacts (RHI). We assessed the relationship of RHI and diffusion MRI (dMRI) measures in the juxtacortical white matter (jWM) adjacent to the depths of sulci.

Adult amateur soccer players (n=380) and non-collision athletes (n=82) completed multiple assessments over 24-months: 12-month heading (HeadCount-12m), dMRI (3T, 2mm3, 109 directions, b=300, 800, 2000) and cognitive performance (Cogstate). dMRI metrics were extracted from jWM and deep WM and compared for soccer subgroups (heading quartile) against non-collision athletes, using generalized estimating equations adjusted for age, sex, and concussion.

jWM from soccer players in the highest RHI quartile differed from non-collision athletes: lower orbitofrontal (OFC), parietal (PL), and temporal (TL) fractional anisotropy (FA); lower occipital lobe (OL), OFC, and PL axial diffusivity; lower OFC mean diffusivity; higher frontal, OL, OFC, PL, and TL orientation dispersion; and lower OFC neurite density. Effect sizes were larger in jWM than in the corticospinal tract, corpus collosum (genu, body, and splenium), fornix, and uncinate fasciculus. Only OFC jWM FA partially mediated the association of more heading with worse verbal learning (P=0.016) and memory (P=0.024); other white matter regions had no mediation effect.

These findings indicate that clinically significant changes in jWM microstructure related to RHI, consistent with axonal injury, demyelination, and inflammation, may occur in young, otherwise healthy athletes. Our mediation result provides preliminary support for a causal role of RHI.

Support: Dana Foundation, R01NS123374, R01NS082432, T32GM149364-01, 3R01NS123374-02S1.

Ms. Grace Recht¹, Dr. Jiancheng Hou^1,2, Ms. Claire Buddenbaum¹, Dr. Hu Cheng^3,4, Dr. Keisuke Kawata^1,3,4

¹Department of Kinesiology, Indiana University School of Public Health, Bloomington, United States, ²Research Center for Cross-Straits Cultural Development, Fujian Normal University, Fuzhou, China, ³Department of Psychological and Brain Sciences, College of Arts and Sciences, Indiana University, Bloomington, United States, ⁴Program in Neuroscience, College of Arts and Sciences, Indiana University, Bloomington, United States

This single-site cohort study investigated the effects of lifetime exposure to sports-related head impacts on brain morphology in retired, middle-aged amateur athletes. This study included 37 retired contact sport athletes and 21 age- and sex-matched non-contact sport athletes. High resolution anatomical, T1 scans through a 3T MRI were collected and analyzed for the following morphometrics: cortical thickness, sulcal depth, and gyrification. Morphological brain differences between groups were observed in all volumetric and geometric morphometrics. Specifically, the contact athletes exhibited significant cortical thinning in widespread areas of the cortex (e.g., the precuneus and the rostral middle frontal gyrus) compared to the non-contact athletes. Consistent group differences were also noted with contact athletes displaying significantly deeper sulcal depths, particularly in the postcentral gyrus and pars opercularis, as compared to non-contact athletes. There were region-specific group differences for gyrification, where the contact athletes showed decreased gyrification in areas such as the postcentral gyrus but increased gyrification in areas such as the precuneus and the precentral gyrus as compared to non-contact athletes. These data indicate that brain morphology of retired, amateur athletes was significantly different compared to non-contact athletes and that lifetime exposure to repetitive concussive and non-concussive head impacts may be associated with neuroanatomical changes.

Miss. Florencia Ontiveros^1,2, Dr. William Cunningham³, Dr. Elisabeth Wilde⁴, Dr. Kathryn Vannatta^2,5, Dr. Warren Lo^5,6, Dr. Keith Yeates^7,8, Dr. Kristen Hoskinson^2,5

¹The Ohio State University, Columbus, United States, ²Abigail Wexner Research Institute at Nationwide Children’s Hospital, Columbus, United States, ³Department of Psychology, University of Toronto, Toronto, Canada, ⁴Department of Neurology, University of Utah, Salt Lake City, United States, ⁵Section of Pediatrics, The Ohio State University, College of Medicine, Columbus, United States, ⁶Nationwide Children’s Hospital, Columbus, United States, ⁷Department of Psychology and Hotchkiss Brain Institute, University of Calgary, Calgary, Canada, ⁸Alberta Children’s Hospital Research Institute, Alberta Children’s Hospital, Calgary, Canada

Traumatic brain injury (TBI) can cause widespread cortical and subcortical damage, including to regions linked with cognitive and social outcomes. This damage may contribute to morbidities faced by youth after TBI, including reductions in adaptive functioning and social and academic competence. This project explored subcortical area volumes and their associations with adaptive and behavioral function following complicated-mild TBI (cmTBI; n=11, Mage= 12.63yr, Male=8), moderate-to-severe TBI (msTBI; n=13, Mage= 11.30yr, Male=9), and orthopedic injury (OI; n=22, Mage=11.72yr, Male=14). Participants completed MRI in a 3T Siemens scanner including a T1-weighted structural scan. Parents completed the Adaptive Behavior Assessment System (ABAS-3) and Child Behavior Checklist (CBCL), measuring adaptive and behavioral function. Freesurfer was used to calculate thalamic nuclei, hippocampal, basal ganglia, and amygdala volumes. We focused on medium-to-large (ηp2>.06) effect sizes for group differences. General linear models controlling for age and sex showed differences in ABAS-3 Conceptual (ηp2>.41), Social (ηp2>.29), and Practical Skills (ηp2>.28), and CBCL Social (ηp2>.28) and Academic (ηp2>.11) Competence, all msTBI<cmTBI=OI, indicating poorer functioning in msTBI. Groups also differed in right-hemisphere thalamic, basal ganglia, hippocampal, and amygdala volume (ηp2s=.07-.17) and left-hemisphere basal ganglia and amygdala volume (ηp2s=.06-.12). Partial correlations, controlling for age and sex, showed that larger subcortical volumes, particularly among basal ganglia and thalamic structures, were associated with better adaptive function and competence (ps<.05). The findings indicate links between subcortical structures and behavioral sequelae of TBI, particularly moderate-to-severe injury. This suggests a potential brain-behavior mechanism underlying long-term consequences of childhood TBI, diverging from healthy neurodevelopment, increasing our understanding of these deficits.

Mrs. Yael Rosen Lang¹, Dr. Esther Yuh², Dr. Raquel Gardner¹

¹Joseph Sagol Neuroscience Center, Sheba Medical Center, Ramat-gan, Israel, ²Department of Radiology, University of California San Francisco, San Francisco, USA

Objectives: Existing traumatic brain injury (TBI) mortality prediction models were developed in young cohorts (mean age 30-40 years). We tested validity in older adults with CT-positive TBI and explored predictors of 6-month mortality.

Methods: TRACK-Geriatric TBI is a two-center prospective study of adults 65+ yo., presenting to emergency departments (ED) within 72h of TBI. This analysis included N=115 CT-positive participants, after excluding non-TBI-related deaths (n=3). Multivariate Imputation Chain Equations were applied to impute outcome in 18 cases. Outcome prediction models Marshall, Rotterdam, and IMPACT were evaluated using Receiver Operating Characteristic (ROC) curves. Baseline injury/CT TBI Common Data Elements (CDEs) were tested for univariable association with the outcome.

Results: Existing model sensitivity (area under the ROC curve,[95%CI]): Marshall 42% (0.69,[0.58-0.79]), Rotterdam 38% (0.62,[0.47-0.77]), IMPACT Lab 46% (0.62,[0.47-0.77]), IMPACT Extended 75% (0.62,[0.49-0.76]), IMPACT Core 58% (0.48,[0.34-0.62]). Variables significantly associated with outcome included most CT CDEs used in existing models, as well as contusion, edema, and shear, and ED hyperglycemia (not in existing models; all p<0.04). Notably, age, epidural hematoma, subarachnoid hemorrhage, Glasgow Coma Scale motor, pupil reactivity, hypoxia, hypotension, and hemoglobin were not significantly associated with outcome in univariable models (all p>0.05).

Conclusions: Existing 6-month TBI mortality models miss over half of deaths in older adults (except for IMPACT Extended). Major components of existing models (Rotterdam, IMPACT) such as age, epidural and subarachnoid hematoma were not significantly associated with mortality in this cohort of older adults. Non-hemorrhagic CT pathologies and ED hyperglycemia may be used to improve outcome prediction in older adults.

Dr. Deborah Huang¹, Dr. Jason Talbott^1,2, Dr. Michael Huang^1,2, Dr. Vineeta Singh^1,2

¹University Of California San Francisco, San Francisco, United States, ²Zuckerberg San Francisco General Hospital, San Francisco, United States

Background & Purpose: Traumatic brain injury (TBI) can lead to venous sinus injury and thrombosis, which are associated with elevated intracranial pressure (ICP) and poor outcomes. We seek to examine risk factors, management, and clinical outcomes of VST.

Methods: We queried radiology databases from 2013 to 2022 for reports of, “venous sinus thrombosis,” “sinus thrombosis,” and “venous occlusion.” TVST on computed tomography was confirmed by a neuroradiologist.

Results: We identified 135 patients on initial screening and entered 112 into final analysis. Patients were predominantly male (76.8%), with mean age 44. Initial Glasgow Coma Scale of 13-15, 9-12, and 3-8 comprised 60.7%, 12.5%, and 26.8% of our cohort, and 89 patients (79.5%) were alive at hospital discharge. Most patients sustained skull fractures (97.3%), including skull base (33%). 50 patients (44.6%) developed VST at two or more sites. 17 patients required interventions for refractory ICP elevations, of which 16 (94.1%) had multiple VST. Patients received antithrombotic (anticoagulation 13.4%, antiplatelet 34.8%), or conservative treatment for tVST (51.8%). More bleeding complications were observed with anticoagulation (21.4%) and antiplatelet (17.9%) versus conservative management (3.4%), even after adjusting for lower survival in the conservative group. Follow-up imaging was available for 52 patients, showing recanalization in 26 patients by six months post-injury.

Conclusion: We discovered significant heterogeneity in tVST monitoring and treatment practices, with antiplatelet surpassing anticoagulation. We additionally note high recanalization rates in all groups but more antithrombotic bleeding complications, emphasizing the quandary of tVST management.

Ms. Jaclyn Xiao¹, Dr. Lanya Cai¹, Dr. Esther Yuh¹, Dr. Xiaoying Sun², Mr. Amir Sadikov¹, Dr. Christine Mac Donald³, Dr. Ramon Diaz-Arrastia⁴, Dr. Joseph Giacino⁵, Dr. Sonia Jain², Dr. Michael McCrea⁶, Dr. David Okonkwo⁷, Dr. Claudia Robertson⁸, Dr. Murray Stein², Dr. Nancy Temkin³, Dr. Geoffrey Manley¹, Dr. Pratik Mukherjee¹, TRACK-TBI Investigators

¹University of California San Francisco, San Francisco, United States, ²University of California San Diego, San Diego, United States, ³University of Washington, Seattle, United States, ⁴University of Pennsylvania, Philadelphia, United States, ⁵Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, United States, ⁶Medical College of Wisconsin, Milwaukee, United States, ⁷University of Pittsburgh Medical Center, Pittsburgh, United States, ⁸Baylor College of Medicine, Houston, United States

Objective: To determine how cortical volume changes after TBI affect global cognition and function.

Methods: Freesurfer/SynthSeg deep learning volumetrics was performed on 3T T1-weighted MRI 2-weeks and 6-months after TBI in patients age 17-90 years from 13 U.S. Level 1 trauma centers participating in TRACK-TBI. Associations of changes in cortical volumes with changes in processing speed (WAIS-PSI and TMT-A) and global function (GOSE-TBI) were assessed using linear regression models adjusting for age, sex, years of education, and 2-week cognition or GOSE-TBI.

Results: In 835 patients from 2-weeks to 6-months post-injury, specific regions increased in volume, including left rostral middle frontal cortex (+0.6%, p=0.017) and left caudal middle frontal cortex (lcMFC: +0.6%, p=0.018), while hippocampi showed the greatest decrease (left: -0.5%, p=0.0004; right: -0.5%, p=0.0002). Total cortical volume increased at trend level (+0.14%, p=0.29). In 723 patients with cognitive scores (64% male; 96% GCS 13-15), improved processing speed was linked to increased total cortex volume (WAIS-PSI: β=+0.74, p=0.04) and increased lcMFC volume (TMT-A: β=-0.76, p=0.007). In 739 patients with GOSE-TBI (66% male; 96% GCS 13-15), increased volumes of bilateral posterior default mode network (DMN) hubs (precuneus, posterior & isthmus cingulate) were associated with improved functional outcome (β=+0.114, p=0.001).

Conclusions: We confirm prior reports of hippocampal atrophy. In patients whose processing speed improved over time, total cerebral cortex volume increased, particularly the left middle frontal gyrus. Furthermore, volume increases in posterior DMN hubs are linked to recovery from disability.

This study was funded by NIH U01 NS086090 and DoD W81XWH-14-2-0176.

Ms. Joan Song¹, Dr. Roman Fleysher², Dr. Mimi Kim¹, Dr. Walter Stewart¹, Dr. Kenny Ye¹, Dr. Molly Zimmerman³, Dr. Richard Lipton¹, Dr. Michael Lipton²

¹Albert Einstein College Of Medicine, Bronx, United States, ²Columbia University Irving Medical Center, Manhattan, United States, ³Fordham University, Bronx, United States

Soccer-related repetitive head impacts (RHI) are associated with poorer cognitive performance and risk of neurodegenerative disease. These adverse outcomes are consistent with evidence of RHI associations with white matter diffusion tensor imaging (DTI) metrics from regions of interest. This study investigated the relationship of RHI with structural connectivity derived from DTI.

361 soccer players (age 18-53; 27% women) underwent assessment of DTI and completed a validated 12-month RHI exposure questionnaire. Tractography (probtrackx) was performed, seeding from all white matter voxels to a gray matter termination mask comprising 84 regions based on the JHU atlas. Structural connectivity between two regions was taken as the number of fibers calculated for each tract. Linear regression was used to test the association of RHI with number of fibers within a tract, with sex and age as covariates. A Bonferroni adjusted p-value (0.05/10458=4.78e-06) was considered significant. Greater RHI was associated with more fibers within tracts connecting right amygdala to right caudate (p= 1.09e-12), right caudate to right parahippocampal cortex (2.26e-07), left lingual cortex to right posterior cingulate cortex (7.46e-09), and right caudal middle-frontal cortex to right rostral anterior-cingulate cortex (1.07e-06). Areas where RHI was associated with structural connectivity are distinct from those previously reported on the magnitude of DTI parameters from white matter regions of interest, suggesting that structural connectivity approaches may reveal distinct information relevant to understanding the nature and potential neurological impact of RHI.

Enna Selmanovic¹, Ariel Pruyser², Dr. Etty Cortes³, Emma Thorn⁴, Dr. Adam Goldstein⁴, Dr. John Crary⁴, Dr. Rebecca Folkerth¹, Dr. Kristen Dams-O’Connor^1,2

¹Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, United States, ²Department of Rehabilitation And Human Performance, Icahn School of Medicine at Mount Sinai, New York, United States, ³Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, United States, ⁴Department of Pathology, Icahn School of Medicine at Mount Sinai, New York, United States

Chronic traumatic encephalopathy (CTE) is a neurogenerative disorder associated with head trauma (HT), primarily studied to date in contact sport athletes with extensive repetitive head impacts (RHI) exposure. The objective of this study was to determine the prevalence and severity of CTE neuropathology in the Late Effects of TBI (LETBI) brain donor cohort of decedents with HT ranging from RHI to isolated severe TBI. A consecutive series of 35 cases underwent comprehensive neuropathologic evaluation per consensus CTE protocols. Five cases had any evidence of CTE: 3 played football ≥15 years, and 1 had ≥6 years non-blast RHI in military service. One case had no known exposure to RHI: this case (death: 6th decade) had 2 isolated severe TBIs (sustained 30y and 3y prior to death). CTE was described as Stage 1 (mild) by 1 of 3 study neuropathologists, and was accompanied by low Alzheimer’s disease neuropathologic change (Thal-1, Braak stage-0/VI, CERAD-0), as well as hydrocephalus, diffuse aging-related tau astrogliopathy, remote contusion, and cerebellar atrophy, consistent with late effects of severe TBI. CTE was not found in any of the remaining 30 cases (11 isolated mod-sevTBI, 6 TBI+RHI<5years, 10 with varied HT). These findings converge with a growing body of evidence indicating that CTE is largely unique to RHI, and commonly co-exists with other pathologies. Given the substantial overlap of clinical symptoms associated with CTE and those of chronic TBI, clarifying exposure thresholds for CTE risk will facilitate development of disease-modifying interventions that target the pathologic process underlying in-vivo symptom expression.

Dr. John Arena¹, Dr. John Wolf¹, Dr. Alexandra Ulyanova¹, Dr. Douglas Smith¹, Dr. H. Isaac Chen¹, Dr. D. Kacy Cullen¹, Dr. Victoria Johnson¹

¹University Of Pennsylvania, Philadelphia, United States

Traumatic brain injury (TBI) is associated with the development of chronic traumatic encephalopathy (CTE), defined by perivascular tau pathologies at the sulcal depths. However, mechanisms of CTE pathogenesis and the reasons why sulci are preferentially affected are unknown. Interestingly, it has been hypothesized that cortical sulci are biomechanically-vulnerable to forces experienced during TBI. However, there has been limited exploration of the nature of acute TBI pathologies that preferentially affect the sulcus. Using a novel porcine model of cortical impact with focal and diffuse pathologies, we performed detailed histological examination of sulci at 30min and 72hr post-injury versus shams.

Marked accentuation of blood brain barrier (BBB) permeability (fibrinogen extravasation) was frequently observed at the sulcal depths post-TBI at 72hr (n=3)(p<0.001 vs. sham (n=2)), but not 30min (n=2)(p=0.819 vs. sham). This was observed throughout the brain, including regions remote from the impact/contusion. Interestingly, at 72hr, foci of neurons and astrocytes demonstrated fibrinogen immunoreactivity, often in a patchy distribution around vessels with BBB permeability, and frequently at sulcal depths. Notably, detailed mapping failed to reveal sulcal-predominance of axonal/neuronal degeneration (H&E, APP, SNTF, Fluorojade-C) or microglial reactivity (IBA-1) in any group.

We demonstrate that sulci may be an important site of vascular dysfunction post-TBI, with associated cellular-uptake of serum proteins. The absence of other mechanically-induced pathologies preferentially at the sulcal depths suggests BBB permeability in this region is a delayed secondary event. Understanding how early sulcal vascular pathologies might contribute to later degenerative processes will be important to explore.

Support: R01-NS123034, W81XWH2010838, W81XWH-20-1-0901, T32-NS043126.

Ms. Vanesa Hyde¹, Chaoming Zhou¹, Juan Fernandez¹, Gina Boito¹, Jeffrey Cheng², Anthony St. Leger³, Corina Bondi², Anthony Kline², Or Shemesh¹

¹Department of Neurobiology, University of Pittsburgh, Pittsburgh, United States, ²Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, United States, ³Department of Ophthalmology, University of Pittsburgh, Pittsburgh, United States

Chronic Traumatic Encephalopathy (CTE) is diagnosed via postmortem detection of hyperphosphorylated tau deposits, clusters of astrocytic tangles surrounding small blood vessels, and abnormalities in phosphorylated 43 kDA TAR DNA-binding protein (TDP43). Paired with personality changes, reduced inhibition, and cognitive impairments, CTE provides a unique opportunity to study the relationship between traumatic brain injury and neurological effects (manifesting as both pathological and neuropsychiatric symptoms) in an effort to comprehend mechanism. For our study, we are working with a cohort of human brain samples containing both control and clinically confirmed CTE cases. We utilized expansion microscopy (ExM), a tissue manipulation method which enables the imaging of biological samples at 40nm resolution. For our specific purposes, we selected a novel version of ExM, decrowding expansion pathology (dExPath), which exposes inaccessible protein epitopes to antibody staining while enabling super resolution imaging. This technique permits traditionally unattainable insight into the best model to understand brain disease—the human brain itself. Using dExPath, we visualized the relationship between integral cell types for both brain structure and immune function, markers of brain injury, canonical CTE neurological pathologies, and potential environmental triggers. Our results suggest that (1) dExPath is a key technology to understanding CTE disease development and (2) known CTE pathologies might be a biological response mechanism to environmental factors exacerbated in the presence of traumatic brain injury. Our continued research focuses on isolating the mechanism from which CTE neurological pathologies and neuropsychiatric symptoms develop with specific interest in future disease prevention.

Dr. Jiepei Zhu¹, Ms. Zo-Yu Wu¹, Dr. Marcelo Febo², Dr. Firas Kobeissy¹, Dr. Kevin Wang¹

¹Morehouse School Of Medicine, Atlanta, United States, ²University of Florida, Gainesville, United States

Biofluid biomarkers, magnetic resonance imaging (MRI), and behavioral assessments are key predictors for diagnosing and prognosticating traumatic brain injury (TBI). Employing the lateral fluid percussion injury (LFPI) model at 2.0 or 2.5 atm (the standard atmosphere) in Sprague-Dawley rats (n=48), including male and female subjects and sham controls (n=16/group), the study examines motor and cognitive impairments post-TBI. Motor deficits were assessed using the rotarod test and neurological scores 24 hours post-injury, while cognitive function was evaluated via Y maze performance on days 8, 15, and 22. LFPI at 2.5 atm in male rats showed significantly shorter durations and lower speeds on the rotarod performance compared to the controls. The average neurological score, specifically at the hindlimb flexion test, was significantly reduced in the 2.0 and 2.5 atm LFPI groups compared to the control group. The results of the rotarod and neurological scoring indicated acute damage to motor coordination function after LFPI. There was no significant difference between LFPI groups nor within LFPI gender groups. In Y-maze performance, the number of entries into the novel arm (spatial memory) was significantly reduced in female 2.0 atm LFPI groups at 8 days post-TBI compared with controls. There was no significant difference in the time spent in the novel arm among the groups, nor in the average number of visits to the novel arm in LFPI groups on day 22 after the injury. These results correlate with changes in biofluid biomarkers and MRI in understanding TBI outcomes (Funded by NIH-NINDS UH3 NS106938).

Dr. Kate Karelina¹, Taylor Payne¹, Debbie Corbin¹, Jayden Barr¹, Emma Reger¹, Dr. Zachary Weil¹

¹West Virginia University, Morgantown, United States

Aerobic exercise is an effective rehabilitative strategy for promoting traumatic brain injury (TBI) recovery; however, the benefits of exercise in this patient population depend on numerous factors including injury severity, as well as exercise timing and intensity. Moreover, exercise intolerance, defined as an inability or decreased ability to exercise for an extended duration, remains a critical barrier to physical rehabilitation. Although aerobic exercise increases exercise tolerance in otherwise healthy individuals, less is known about the capacity to improve exercise tolerance following a TBI. Here, we investigated exercise tolerance and energy metabolism in a mouse model of TBI. Male and female mice underwent a controlled cortical impact (CCI), and exercise tolerance was assessed with and without treadmill training. Energy metabolism was assessed in a separate cohort that was housed in metabolic cages following CCI or sham injury. Exercise significantly increased average time- and distance run to exhaustion in brain injured female, but not male, mice. Metabolic rates, measured via indirect calorimetry, revealed decreased heat production following CCI, as well as significant sex differences in respiratory exchange ratio and wheel rotations. Overall, these data are consistent with our previous report of sex differences in CCI outcomes and recovery following treadmill exercise. A greater understanding of sex differences in metabolism and exercise tolerance following brain injury will bring us closer to developing a method for optimizing exercise as a recovery strategy for TBI.

Ms. Carmel Al-Sheikh^1,2,3, Ms. Michelle Zhong^1,2,3, Mr. Jackson Alga-Sheriff^1,2,3, Dr. Afshin Paydar^1,2,3, Dr. Neil Harris^1,2,3, Dr. Janel Le Belle^1,2,3

¹UCLA Brain Injury Research Center, Los Angeles, United States, ²UCLA Department of Neurosurgery, Los Angeles, United States, ³UCLA David Geffen School of Medicine, Los Angeles, United States

Sensory sensitivity following mild traumatic brain injury (mTBI) is a prevalent symptom experienced by a majority of patients. The number of sensory modalities involved, the changes to sensory processing, and their contribution to cognitive function is still not fully understood, and we postulate that they are especially relevant for understanding chronic post-concussion syndrome. Sensory over-responsivity to incoming stimuli is a common autism phenotype, where sensory processing abnormalities have been shown to strongly affect cognitive function. Although altered cognition is also common symptomology following mTBI, an underlying mechanistic link to multi-modal sensory dysregulation has not been studied. Multiple lines of evidence show that sensory processing and associated brain networks are conserved across species so that rodent models can be used to study dysregulation and mechanisms relevant to humans.

We acquired behavioral datasets using multiple behavioral tasks at 2months following repeat closed head injury (rCHI) to the frontal lobes in male and female, CD-1 and C57BL/6 adult mice (5X,24hrs-apart) and in age matched shams (n=8/group). We found significant chronic sensory dysregulation and cognitive deficits characterized by: reduced withdrawal threshold in the Von Frey Sensitivity Test, tactile avoidance in a new sensory version of the classic light/dark box test, abnormal sensory gating and lack of habituation in the pre-pulse inhibition test of sensory processing. In the same mice we found reduced cognitive flexibility in the delayed-match-to-place task using sensory distractors (P<.05) but not without, indicating a possible link between sensory sensitivity and cognitive deficits after brain injury.

Work supported by UCLA BIRC.

Ms. Eleni Moschonas^1,2,3,6, Ms. Ellen Annas^1,2,3,6, Ms. Haley Capeci^1,2,6, Ms. Veronica Domyslawski^1,2,6, Ms. Hailey Donald^1,2,6, Mr. Jeffrey Cheng^1,2,6, Dr. Anthony Kline^1,2,3,4,6, Dr. Corina Bondi^1,2,3,5,6

¹Physical Medicine and Rehabilition, Pittsburgh, United States, ²Safar Center for Resuscitation Research, Pittsburgh, United States, ³Center for Neuroscience, Pittsburgh, United States, ⁴Critical Care Medicine, Pittsburgh, United States, ⁵Neurobiology, Pittsburgh, United States, ⁶The University of Pittsburgh, Pittsburgh, United States

Attention relies on an intact cholinergic network originating in the nucleus basalis of Meynert (NBM) and projecting to the medial prefrontal cortex (mPFC). We utilized in vivo microdialysis to test the hypothesis that TBI-induced decreases in task-evoked acetylcholine (ACh) release in the mPFC will correlate with impairment on the 3-Choice serial reaction time test (3-CSRT). Adult male rats trained in the 3-CSRT were randomized to cortical impact or sham injury. 14 days later a guide cannula was implanted in the right mPFC. Sustained attention and distractibility were assessed on days 21-27. Dialysate collected before and during 3-CSRT onset on day 21 was analyzed with HPLC (ACh detection limit:100 fmol/10μl). On day-28, cholinergic neuron ultrastructure in the NBM and mPFC were reconstructed and analyzed (IMARIS). TBI produced deficits in attention and distractibility compared to baseline and Shams (p<0.05). A significant increase in ACh release during the 3-CSRT was seen in Shams compared to their baseline before task onset (p<0.05), but not in TBI rats, which remained unaltered (p>0.05). Preliminary findings suggest that TBI reduced NBM soma and projection volume and branching, indicative of degenerative morphology. Injury-induced disruptions to attention may be due to disturbances in cholinergic neuronal integrity and reductions in behaviorally-evoked ACh efflux in the mPFC. These findings support our hypothesis and represent the first application of in vivo microdialysis in TBI rats performing a cognitive task. Integrating in vivo microdialysis with real-time behaviors offers high temporal resolution and can elucidate the correlative relationship between TBI and behaviorally-driven chemical dynamics.

Ms. Suzanne Pinar¹, Dr. Michelle Theus

¹Virginia Tech, Blacksburg, United States

Traumatic brain injury (TBI) is a significant public health concern, often resulting in long-lasting cognitive and motor deficits. The diverse nature of TBIs, which can range from diffuse impacts to focal injuries, contributes to the complexity of understanding their distinct effects on neural function and recovery. Moreover, the chronic neuroinflammatory responses are implicated in the aftermath of TBI and play a pivotal role in the development of neurocognitive aging. However, a comprehensive investigation into the specific chronic behavioral outcomes associated with different forms of injury is lacking. The current study compared behavioral and neuroinflammatory outcomes using a diffuse and moderate focal CCI injury model. To quantify behavioral changes, we used T-maze, Rotarod, and open field tests over a chronic period of 90 days post-injury and evaluated regional microglial and astrocyte activation using immunohistochemistry, IMARIS for morphological analysis and assessments of cellular senescence. To better understand whether chronic activation of glial cells may correlate with blood-brain barrier (BBB) permeability, we utilized a triple labeling strategy using IgG, sodium fluorescein, and Evans blue dye extravasation to assess regional changes in BBB stability as it relates to glial changes. Findings from this work will improve our understanding of the neuroinflammatory basis of behavior across different forms of TBI.

Ms. Ashley Ruhland^1,3, Mr. Connor Leighty^1,3, Mr. Daniel Griffiths^1,3, Mr. Alberto Fuentes², Dr. Maurizio Bergamino², Nina Karamanova³, L. Matthew Law^1,3, Ashley Stokes², Raymond Migrino^1,3, Jonathan Lifshitz^1,3

¹University of Arizona College of Medicine, Phoenix, United States, ²Barrow Neurological Institute, Phoenix, United States, ³Phoenix VA Health Care System, Phoenix, United States

Traumatic brain injury (TBI) is associated with persistent neurological and physiological dysfunction across demographics, resulting in cognitive decline. Among TBI pathophysiology, cerebrovascular dysfunction has its own distinct relationship to neurodegenerative disorders and associated changes in cognition. Therefore, we hypothesize that mild traumatic brain injury (mTBI) will induce vascular perturbations that contribute to cognitive decline. Male and female Sprague-Dawley rats (8-10 weeks old) underwent midline fluid percussion injury (N=16) or sham surgery (N=16). Tasks which utilize different types of functional memory (novel object recognition [NOR], novel object location [NOL], and temporal order object recognition [TOR]) assessed cognitive function through discrimination ratios (DR). Cerebral blood volume (CBV) and cerebrovascular reactivity (CVR) were measured with magnetic resonance imaging (MRI). Cognitive assays, imaging, and tissue harvest took place 9 weeks post-mTBI. Cognitive function results, with sex as a variable, find no difference between groups (NOR: F(1,11)=0.095,p=0.764,N=7-8; NOL: F(1,12)= 1.490,p=0.246,N=8; TOR: F(1,12)=3.152,p=0.101,N=8). CBV within hippocampal CA1 and left corpus callosum (CC) was increased (Left CA1: F(1,26)=7.392,p=0.012; Right CA1: F(1,26)=4.353,p=0.047; Left CC: F(1,26)=6.465,p=0.017; Right CC: F(1,26)=3.771,p=0.063), while CVR found no regional difference. Overall, post-TBI regional change in CBV was noted, but no cognitive performance differences were seen 9-weeks post-injury. This lack of change in cognitive function within the subacute period differs from our previous report of impaired vascular function and cognition 6 months post-injury. The biologic significance of CBV requires exploration and may represent increased effort to achieve measured performance levels. Age-related cognitive and vascular decline may arise more chronically post-TBI.

Funding: U.S.V.A. Merit I01 RX002691.