Auditory electrophysiology: findings in multiple sclerosis.

15 patients suffering from definite multiple sclerosis were studied by electrocochleography (ECochG) and brain stem electric responses (BSER), including objective analysis of the electrophysiological data. In 7 patients, both ECochG and BSER were performed, in 2 only ECochG and in 6 only BSER. Systematic deviations from normative values were found in all 9 patients tested by ECochG, but the deviations occurred only at 75 dB pe SPL or below. Despite normal or near-normal audiometric thresholds, the cochleae seemed to be involved. At click intensities of 95 dB pe SPL or higher, the BSER revealed a normal AP-V (Jewett) interval in all 13 patients tested. However, a deviant configuration of the BSER following the wave V complex was found in 6 of the 13 patients. The deviation is described as a dominant, relatively low-frequency component of the response. The discrepancies between these results and those reported in the literature indicate a strong need for applying methods that compensate for peripheral hearing dysfunctions and objective methods of analysis to identify and evaluate the various components of the evoked potentials.