Threshold Electric Skin Sensitivity Fluctuations in Pregnancy, Labor and Puerperium

The Threshold Electric Skin Sensitivity (TESS) was intensively investigated by many researchers during the past 100 years and a good survey of the previous literature is discussed in the work of Notermans, 1966 [[8][1]]. He used square wave constant current stimulus and tried to determine how many


Introduction.
The Threshold Electric Skin Sensitivity (TESS) was intensively investigated by many researchers during the past 100 years and a good survey of the previous literature is discussed in the work of Notermans, 1966 [8]. He used square wave constant current stimulus and tried to determine how many variables could have an influence on the skin sensitivity to electric stimulation. He found nearly constant pain threshold when measured in the same individual over a course of time. Schumacher et al, 1940 [12] measuring threshold sensitivity to heat stimulation in an earlier study came to the same conclusion. On the contrary, Lanier, 1943 [6] found that the threshold sensitivity to electric skin stimulation could vary considerably.
Most authors measured the skin sensitivity in m a n y d i f f e r e n t s k i n a r e a s , b u t n o t r e p e a t e d l y i n s h o r t intervals over the same area of the same subject.
Uher et al, 1963 [13] found decreased electric skin sensitivity above the pubic symph ys is in early labor and after the administration of oxytocin. He found inc re ased se nsiti vity afte r a dmin ist rati on of strychnine. In our previous study Cernoch et al, 1969 [2], was used the same stimulator with constant voltage square waves on pregnant and puerperal women and we found long term changes of skin sensitivity. Later, we also found interesting short-term changes of sensitivity when w e u s e d a s t i mu la t o r w i t h c o n s t a n t c u r r e n t s q u a r e w a v e s o n puerperal women after administration of oxytocin and neostigmine. Cernoch et al, 1970 [1]. In pregnant women we found significant skin sensitivity changes after intravenous administration of oxytocin already b e f o r e t h e b e g i n n i n g o f t h e u t e r i n e contraction. We tried to find, under the same conditions, changes in other biophysical parameters of the skin; however, measurement of the skin temperature and electric conductivity did not reveal any similar changes. Cupr et al. 1972 [3] was using the same constant current square wave stimulator constructed by Valosek et al, 1969 [14]. They found different skin sensitivity during and between the u t e r i n e c o n t r a c t i o n s i n l a b o r i n g w o m e n w i t h a h i s t o r y o f dysmenorrhea and no change in women with no dysmenorrhea.
As we found in the previous investigation Cernoch et al, 1969Cernoch et al, , 1970, there are long term and short-term changes of the Threshold Electric Skin Sensitivity TESS in specific areas of the abdomen during pregnancy, labor, and puerperium. During the labor, the average TESS above the p ub ic s ymp h ys is a nd i n th e lat e ra l a r ea s of th e l owe r abdomen is increased but around the navel is decreased. Afte r administration of ox ytoc in to p u e r p e r a l wo m e n , t h e u s u a ll y s t e a d y T ES S i n th e lateral abdomen suddenly starts fluctuating up and down. After a dm in ist ra ti on of ne os tigmin e, the re is no ch a nge o f s te a dy TESS in lateral areas; but there is a prominent increase of TESS fluctuations around the navel and above the pubis. These TESS fluctuations may be related to the functional state of the internal organs like uterus and bowel. The projection referred pain skin area for the uterus is on both sides of the lowe r abdomen, fus ing together above the pubic symphysis as a referred pain skin area for the uterine cervix Rubin, 1947 [11]. The referred pain skin area for the bowel is in the midline of the abdomen. Jones, 1938 [5].

Methods.
Th e Th reshold Ele c tr ic Skin Sensitivit y (TESS) wa s m e a s u r e d r e p e a t e d l y i n s h o r t i n t e r v a l s o n a b d o m e n a n d r i g h t fo r ea rm o f 7 0 p r e g n a n t a n d n o t p r e g n a n t w o m e n . The subjects were informed of the measurement procedure and they gave informed consent to participate in the study. The m ean age was 23 ye ars (r ange 1 5 to 43 yea r s) . They ha ve been randomly selected from available patients that came in the clinic and hospital for treatment. Rossmann et al, 1991 [10].
We also used in this study different stimulator, then that was u s e d i n p r e v i o u s r e s e a r c h .
It w a s a n NS -3 P e r i p h e r a l n e r v e stimulator from Professional Instruments Co. Ea c h s u bj e ct w ou ld lie re la x ed on t he b e d or on th e examination table. Before starting the measurement, the patient was instructed to immediately say "yes" when she started to feel the first mild sensation below the electrode. After that, a few orientation stimulations were done to make the patient familiar with the procedure and to exclude the effect of learning on the results. The sequence of measurements was right side of lower abdomen, left side of lower abdomen, middle above umbilicus, middle above pubic symphysis, and on the right forearm. We have done in 5 to 10 second intervals 30,300 single TESS   Table 1. Analysis of the variance performed on this data indicated that there were statistically significant differences (p < 0.05) among the means for the factors presented in Table 2. The null hypothesis must therefore be rejected,      (B) Same patient four days after the obstruction was relieved by ureteric stent. Tables   Table 1. Changes of Threshold electric skin sensitivity (TESS) fluctuations during pregnancy, labor and post partum.       (B) Same patient four days after the obstruction was relieved by ureteric stent.