Auditory event-related potentials in multiple sclerosis.

The present study examined the effects of multiple sclerosis (MS) on the N1, P2, and P300 components of the late auditory evoked potential (LAEP). A group of 30 subjects with confirmed MS were compared with 30 control subjects who were pair-matched to the MS subjects with respect to age and gender. A standard stimulus oddball procedure was used to elicit the LAEP, in which subjects had to selectively attend to rare tones randomly interspersed among more frequently occurring tones of a different frequency. LAEPs were recorded with and without the presence of simultaneous speech competition in the nontest ear. Although the presence of speech competition produced significant latency and amplitude changes with the different components of the LAEP, the magnitude of the changes were similar for both subject groups. However, in comparison to the control group, a significantly higher proportion of MS subjects exhibited absent P300 responses on all test runs.