[Retrochiasmatic lesions in multiple sclerosis. Demonstration by visual evoked potentials. Correlation with magnetic resonance imaging].

Monocular stimulation of each visual hemifield can show an interhemispheric asymmetry of VEP. Validity of this test needs a reproducibility of responses and exclusion of stimulation induced by eye movements. In a prospective study of 22 MS cases, it appeared that interhemispheric asymmetry was a criterion of dissemination is space and had a good diagnostic value: MS became clinically definite in 10/12 cases; in 10 other cases in which a correlative MRI-VEP study was possible, there were disseminated high signal areas in T2 weighted sequences on hemispheric MRI.