Spinal and cortical somatosensory evoked potentials in Japanese patients with multiple sclerosis.

Twenty-seven Japanese patients with multiple sclerosis (MS) were studied by recording the spinal and cortical somatosensory evoked potentials (SEPs) in response to median nerve and/or posterior tibial nerve stimulation. The median nerve SEPs were abnormal in half the cases whereas the tibial nerve SEPs were abnormal in 90% of cases. SEP abnormalities, especially absence or amplitude depression of components, were highly correlated with proprioceptive impairment of hands or legs tested. With regard to the usefulness of SEP in detecting subclinical lesions of the sensory system, the tibial nerve SEP was found more useful than the median nerve SEP. Absence or depressed amplitude of SEP components was seen more commonly with tibial nerve stimulation as compared with median nerve stimulation.