Prolonged follow-up of abnormal visual evoked potentials in multiple sclerosis: evidence for delayed recovery.

A case is described in which the latency of the P100 component of the pattern evoked visual response (VEP) was shown in serial recordings to have remained greatly prolonged for three years after an attack of optic neuritis, but had returned to normal after a further three and a half years. A similar pattern was found in one of a group of 21 patients re-examined between 6 and 8 years after abnormal VEP had been recorded. The pathophysiological implications are briefly discussed.