[Somatosensory evoked potentials and the spinal cord conduction velocity in multiple sclerosis]

Somatosensory evoked potentials (SSEP) on n. medianus and n. tibialis stimulation were studied in 25 patients with multiple sclerosis (MS) and 30 normals (N). Sensory conduction velocity (SVC) calculated by indirect method using formula of Eisen and Nudelman (1979) in which instead of time parameters of F- and M-responses latencies of the N13 and N21 for hand and leg, respectively, of spinal SSEP was used. Normal spinal cord SCV was 60.8 +/- 1.3 m/s, SCV in MS was 51.9 +/- 10.7 m/s. Extreme dispersion of data in MS is caused by false "normal and paradoxically "increased" SCV values in patients. The causes of false results are analysed. In difference of Eisen and Nudelman methods, the proposed approach allows proper clinical interpretation of the false values and excludes possibility of diagnostic mistakes, as in each case the whole set of the data from cerebral and spinal SSEP is interpreted systematically.