Brain Stem Auditory Evoked Response

Abstract

This paper studies the effect of otologic disease on the brain stem auditory evoked response (BAER). Both conductive and neurosensory hearing losses are analyzed by plotting wave V latencies and amplitudes as a function of sound intensity. It was found that the BAER is elicited primarily by frequencies greater than 2000 Hz. Conductive hearing losses produce a latency intensity function which approaches the norm with high decibel stimulation. Neurosensory losses produce a variety of latency intensity functions. In determining the degree of hearing loss, wave threshold is found to be the best index. Wave latency at high decibels is found to have little correspondence to degree of neurosensory loss; wave amplitude is highly variable among subjects but still a useful indicator for detecting pathology. Between-ear comparisons of wave latencies elicited by high decibel sound stimulation suggest that unilateral nonrecruiting or partially recruiting hearing losses will result in a latency difference. This method can be used to detect unilateral acoustic neuromas, and the false positives found by this technique are probably caused by other unilateral nonrecruiting hearing losses. In evaluating neurological disease, and especially when testing for a second occult lesion in multiple sclerosis (MS) an audiogram should be obtained because the criterion of a normal wave latency with decreased amplitude for the diagnosis of MS can be mimicked by peripheral hearing loss.