Visual evoked potentials in normal subjects and patients with multiple sclerosis

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Abstract
Visual evoked potentials (VEP) by checkerboard pattern-reversal stimulation were recorded in 70 subjects aged 10-69 yr and in 100 patients with definite, probable or possible multiple sclerosis (MS). Longer latencies and smaller amplitudes of the major positive component were found in male subjects, in old subjects and when the amplifier''s band-pass was narrowed. Subjects 10-14 yr old had longer latencies and higher amplitudes than mature adults. Based on findings in the normal material, the following 3 criteria were used in evaluating the recordings from patients: the latency, the side difference in latencies and the ratio of amplitudes between the 2 sides of the major positive component, with various limits for the 2 sexes and different age groups. The incidence of abnormal recordings was 85% for all the patients, 100% in 50 patients with definite MS, 70% in 50 patients with probable or possible MS, 73% in patients who had a history of spinal symptoms only, 98% if they had experienced optic neuritis and 74% if they had not. The incidence of abnormal findings increased with increasing duration of symptoms. All patients with visual acuity below 0.67 had abnormal VEP. The high incidence of abnormal recordings confirmed the value of the test in establishing MS diagnosis, and suggested that the use of different normative values for sex and age many increase the diagnostic yield, without increasing the number of false positive findings.