Follow-up of patients with suspected multiple sclerosis: a clinical and electrophysiological study.

We re-examined 21 patients with suspected multiple sclerosis, seven classified as probable and 14 as possible cases. At the first investigation all patients but two had abnormal visual evoked potentials and somatosensory evoked potentials, or both. All but three had an increased intracerebral production of immunoglobulin G expressed by the cerebrospinal fluid IgG index. At follow-up two to four years later, 13 of 16 patients (81%) in whom both evoked potentials and IgG index were abnormal initially had entered into a higher multiple sclerosis diagnostic class. In the five patients in whom either evoked potentials or IgG index were normal the original diagnosis was unchanged.