The use of the auditory evoked potential in the diagnosis of multiple sclerosis.

Auditory evoked potentials, both early and middle components, were recorded from 227 patients with a variety of conditions including multiple sclerosis, brain stem vascular disease, intracranial tumours and Arnold-Chiari malformation. Abnormalities were found in a substantial proportion of patients with definite multiple sclerosis and a smaller proportion of those in the less definite clinical categories of this condition. There was a high correlation between clinical evidence of brain stem involvement and an abnormal auditory evoked potential in multiple sclerosis. Abnormalities were also found in a few patients presenting with an isolated episode of central nervous system dysfunction involving the brain stem. The auditory evoked potential was abnormal in other patients with known diagnoses including half of those with Arnold-Chiari malformation. Tumours involving the brain stem caused abnormalities of the brain stem evoked potentials in some cases and more frequently distortion of the middle components. The specificity of these auditory evoked potential abnormalities to multiple slcerosis is discussed.