Effects of conductive hearing loss on auditory brainstem response.

The purpose of this paper is not to propose that auditory brainstem response (ABR) be utilized for the assessment of conductive losses, but to define the effects of conductive hearing loss on the ABR when such a complication occurs. Conductive losses attenuate cochlear stimulation. Since wave V latency is inversely related to stimulus intensity, the magnitude of the conductive loss should be a predictor of the wave V latency delay. In this study, ABR wave V latencies from patients with known conductive losses due to canal occlusion, middle ear effusion, ossicular fixation and chain interruption were compared with latency values calculated from the magnitude of the loss. In those patients with occlusion of the external auditory canal and middle ear effusion, the shift of the wave V latency-intensity function correlated well with the air-bone gap. This correlation was poor for patients with ossicular chain disorders. In mixed hearing losses, the increased wave V latency due to the conductive component may totally mask an increase in latency caused by a retrocochlear component.