Brainstem auditory evoked potentials evoked by clicks of different polarity in multiple sclerosis patients.

Brainstem auditory evoked potentials (BAEP) evoked by condensation, rarefaction clicks and clicks of alternating polarity were examined in 52 controls and in 95 patients with a certain or presumed diagnosis of multiple sclerosis. It was shown that the type of stimulation could influence the shape of the BAEP considerably. In multiple sclerosis patients pathological results were found in 67 ears from 44 patients. Rarefaction as well as condensation clicks independently could elicit BAEPs with increased latencies of one or more peaks, while clicks of alternating polarity failed to detect abnormalities in a great number of cases. These findings make the application of the latter type of stimulation doubtful.