[Application of correlation factors to the study of visual evoked potentials in multiple sclerosis (author's transl)]

A comparison is made between cerebral evoked potentials through the left and right eye by studying the correlation functions between the two visual responses obtained. Two values were retained: the correlation coefficient CO which shows the degree of similarity between the two curves, and the phase displacement D which indicates the duration for which a curve has to be shifted in relation to the other in order to resemble it as closely as possible. An original representation, in the form of a correlation/phase displacement diagram, is drawn for each subject, and enables easy separation of normal subjects from those with pathological conditions. This technique was applied to 20 normal subjects acting as controls and 40 patients with suspected or confirmed multiple sclerosis. In the latter group, anomalies were found in 67 p. cent whereas retrobulbar optic neuritis had been diagnosed in only 35 p. cent of cases. By reducing the sample to include only known or probable cases of MS, anomalies were found in 88 p. cent with retrobulbar optic neuritis known in only 51 p. cent. These results are comparable with those obtained by using previously described methods, but have the advantage of automatic readings which are completely objective.