J Korean Neurol Assoc.  1992 Sep;10(3):331-338.

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

• Choi YC
• Sunwoo IN
• Park YK
• Kim KW
• Park KD

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.

MeSH Terms

Adult
Evoked Potentials
Evoked Potentials, Somatosensory*
Extremities
Humans
Sensory Receptor Cells
Spinal Cord Diseases*
Tibial Nerve*