[Course of visual evoked potentials in multiple sclerosis. Electro-clinical correlations and pathophysiological...

25 Multiple Sclerosis patients had Visual Evoked Potentials (VEPs) recorded at a one year interval. Abnormal VEPs were observed at least once in 21 patients. They were the only means to assess the lesional dissemination in 9 patients. Their contribution in the diagnostic classification is such that the proportion of "definite" cases rises from 44 to 80 per cent of the 25 cases. The degree of abnormality of the VEPs had no relation to the disability status and the whole severity of the disease. The main feature ws the variability of the VEP latencies at a one year interval: they seem to follow the remittent progressive course of the disease, whether visual pathways are clinically affected or not. These results are interpreted in the light of the pathophysiological data of the disease. In the cases with improvement or normalisation of the second VEPs, "en plaque" edema may be an important mechanism, sometimes free of demyelination so that true restitutio ad integrum may occur.