The Relationship Between Posterior Tibial Nerve Somatosensory Evoked Potentials and Sensory Changes in Patients with Myelopathy

J Korean Neurol Assoc > Volume 10(3); 1992 > Article

Journal of the Korean Neurological Association 1992;10(3): 331-338.

척추질환에서 감각장애와 후경골신경자극 감각유발전위검사의 비고 연구

최영철, 선우일남,박영관,김기환,박기덕

연세대학교 신경과. 이화여자대학교 내과.

The Relationship Between Posterior Tibial Nerve Somatosensory Evoked Potentials and Sensory Changes in Patients with Myelopathy

Young-Chul Choi, M.D., Il-Nam Sunwoo, M.D., Young-Kwan Park, M.D., Ki-Whan Kim, M.D., Kee-Duk Park, M.D.

Department of Neurology, College of Medicine, Yoensei University, Department of Internal Medicine, College of Medicine, Ehwa Womans University

Abstract

Somatosensory evoked potentials(SSEP) study is a simple and quantitative test, and has been used to evaluate the sensory system along the somatosensory pathway from peripheral sensory receptor to the cortex. The ascending pathway of SSEP has been known to be posterior column-lemniscal pathway, but not without controversy. To define the relationship beyween SSEPs and sensort changes, the posterior tibial SSEPs of 226 extremities with variable kinds of myelopathy were analyzed and compared with 123 healthy adults without definite neurological deficit. The lrhs of myelopathy were divided into 4 groups ; A group, 58 extremities showing lateral column dysfunction ; B group 45 extremities showing posterior columhn dysfunction ; C group, 109 estremities showing both lateral and posterior column dysfunction ; D group, 14 extremities showing no definite sensory deficit. Following results are obtained : 1. Spinal T12 evoked potentials are detected in all normal control and patients with myelopathy. Cortical P1 evoked potentials, however, are detectable in 59-100% of patients edpending on sensory deficits, especially low in the groups of posterior column dysfunction (59-86%). 2. There is no significant difference in latencies and amplitudes of spinal T12 between normal controls and patients with myelopathy. 3. The mean latency of cortical P1 and central conduction time (CCT) of the patients with myelopathy are significantly prolonged compared to the group with normal control (p<0.05) and the amplitudes are also significantly diminished (p<0.05). 4. The changes on latencies and amplitudes of cortical P1 are correlated to the integrity of posterior column rather than to that of the lateral column. In conclusion, this stucy shows that the main conduction pathway of SSEP is the posterior column rather than lateral column and, that SSEP is a clinically valuable noninvasive tool for evaluating posterior column function objectively and quantitatively.