Auditory brain stem response results from 255 patients with suspected retrocochlear involvement.

Auditory brain stem response (ABR) evaluations were conducted on 255 patients with suspected retrocochlear involvement. Twenty-six patients (10%) had surgically confirmed tumors, and ABRs were abnormal in 25 (96%) of these cases. The remaining 229 patients had nontumor medical diagnoses, but 25% of these were found to have abnormalities in ABR recordings. The most common ABR abnormality in the nontumor patients was large wave V interaural latency difference, followed by no response or poor waveform resolution and delayed absolute wave V latency. Peripheral hearing loss, including decreased sensitivity at 2000 and 4000 Hz, appears to have influenced waveform morphology and component latency.