Pattern visual evoked potentials in Japanese patients with multiple sclerosis without history of visual pathway involvement

A delay of the peak latency of the pattern visual evoked cortical potentials (pVEP) is accepted as one of the paraclinical evidence for a diagnosis of multiple sclerosis (MS). The purpose of this study was to evaluate the pVEPs in Japanese patients with MS without a history of visual pathway involvement. We studied the medical records of 29 MS patients without any history of visual pathway involvement, and with visual acuity correctable to ≥20/20. The Goldmann visual fields, pupillary light reflexes, and optic disks were normal in all. pVEPs elicited by 3 rev/s (transient) and 12 rev/s (steady-state) were recorded from the MS patients and compared with those recorded from normal subjects. The latency of the P100 component of the transient pVEPs was significantly prolonged in 9/29 (31%) MS patients. A phase lag in the steady-state pVEPs was found in 6/29 (21%) MS patients, and the mean amplitude was significantly smaller. The incidence of cases with abnormal pVEPs is lower than that reported from Europe and United State. This difference is possibly due to racial differences, and the use of different criteria for diagnosing optic neuritis.