Auditory brain-stem response and acoustic reflex test.

Auditory brain-stem response (ABR) and acoustic reflex test (ART) results were reviewed for 30 patients with cerebellopontile angle tumors and for 30 patients without tumor. Patients included in the nontumor group were selected to match the audiometric configurations for individual patients in the tumor group. The ABR waveforms were abnormal for all but one of the patients with tumor and for seven of the patients without tumor. The ART results were abnormal for 25 of the patients with tumor and two of the patients without tumor. Patients without tumor yielding abnormal ABR results usually had more severe hearing losses than the patients without tumor who demonstrated normal ABR waveforms. The ABR and ART merit continued use in the audiologic examination of patients suspected of having retrocochlear lesions, but obviously, degree of hearing loss and other medical information must be considered also when retrocochlear lesions are suspected.