The sensitivity of auditory brainstem response testing in small acoustic neuromas.

Auditory brainstem response (ABR) testing is a reliable and sensitive test for retrocochlear pathology in neurotologic diagnosis. Several investigators have reported the sensitivity of ABR testing as 95% or greater. Fifty-one consecutive patients with surgically confirmed acoustic neuromas were examined. Forty patients had sufficient hearing preoperatively for assessment with ABR. In addition, all had been evaluated with gadolinium-enhanced magnetic resonance imaging and conventional electronystagmography. Overall, 34 of 40 patients (85%) had abnormal ABRs. One of 25 patients with extracanalicular tumors had a normal ABR for a false-negative rate of 4%; however, 5 of 15 patients with intracanalicular tumors had normal ABRs for a false-negative rate of 33%. Tumor size and nerve of origin were important factors affecting the ABR sensitivity. The ABR was less sensitive in detecting intracanalicular tumors than in detecting extracanalicular tumors.