Somatosensory Evoked Potentials in Ventricular Enlargement of Experimental Hydrocephalus

Huh, Pil Woo; Cho, Byung Il; Lee, Jae Soo; Cho, Kyung Suck; Jung, Chul Ku; Park, Chun Kun; Bail, Min Woo; Kim, Moon Chan; Kim, Dal Soo; Kang, Joon Ki; Choi, Chang Rak

Abstract

We investigated the somatosensory evoked potentials(SEPs) changes and subsequent changes of the ventricular enlargement in different stages of kaolin-induced hydrocephalus. 8 week-old fifty five cats weighing 900g to 1300g, were studied in this experiment. These animals were divided into 2 groups ; a normal control(5 cats), kaolin-induced hydrocephalic groups(50 cats). The kaolin-induced hydrocephalic groups were subdivided into 5 subgroups of 10 cats each ; kaolin induced 1,2,4,6 and 8 weeks hydrocephalic groups after an intracisternal injection of the kaolin. At the each stage of the kaolin-induced hydrocephalic animals, the following parameters were obtained ; somatosensory evoked potentials(SEPs) and the size of enlargement of the ventricles at the each stage of 1,2,4,6 and 8 weeks after intracisternal kaolin injection. The results were as follows: 1) A significant elevation of the intracranial pressure(ICP) was observed in 2 weeks after kaolin injection and peak value(ICP : 10.2+/-0.9mmHg) in 4 weeks after kaolin injection. 2) The mean latencies of these wave components in somatosensory evoked potentials(SEPs) responses were 6.27+/-0.12 msec in Po, 8.41+/-0.25 msec in No, and 12.55+/-0.36 msec in P1 and the mean central conduction time(P1-P0) was 6.10+/-0.16 msec in the normal control animals. 3) Changes of amplitude and latency in SEPs were more prominent in 4 weeks after kaolin injection and progressively prolonged latencies of each wave components and CCT were resulted in 6 and 8 weeks after kaolin injection. 4) In hydrocephalic animals, the size of the ventricle(septum pellucidum (SP)-caudate nucleus(CN) distance) was moderately increased to 5.19+/-0.43mm in 1 week after kaolin injection and continued to increased in maximum size up in the 4th week after injection. However there was no further increase in ventricular size after 4th weeks. 5) A close correlation was found between SEPs and ventricular enlargement at the each stage of kaolin-induced hydrocephalic animals. In conclusion, it is assumed that the detection of SEPs in hydrocephalus is a quite valuable prognostic tool to evaluate the functional integrity of the nerve conduction system near the paraventricular area which might be involved in ventricular enlargement.