Electrophysiolgical diagnosis for multiple sclerosis

Evoked potentials(EPs) in daily practice contain brainstem auditory evoked potentials (BAEPs), short-latency somatosensory evoked potentials(SSEPs), pattern-reversal visual evoked potentials(PVEPs) and motor evoked potentials(MEPs) with transcranial magnetic stimulation(TMS). In this review, we summarize the EP findings in Caucasian and Japanese MS. EPs can confirm the presence of lesions in patients with suspected involvement, and document the presence of clinically unsuspected lesions. In addition, the combined use of these EPs in each patients, so-called multimodality EPs, enables us to evaluate multiple aspects of sensory and motor systems. In 73 Japanese MS, the abnormality rates were 10.3% in median nerve SSEP, 37.1% in posterior tibial nerve SSEP, 35.6% in upper limb MEP, 56.1% in lower limb MEP, 39.3% in PVEP and 34.3% in BAEP. The frequency of clinically unsuspected lesions was about 30% in each EP. These findings are in good agreement with the recent fact that conventional MS have been increased in Japan. Other electrophysiological methods such as multimodality VEPs, pain-related SEPs, paired TMS and event related potentials(P300) may be useful for the diagnosis or evaluation of MS.