Sensitivity of Auditory Brainstem Response in Acoustic Neuroma Screening

Abstract

Auditory brainstem response (ABR) is the reference screening technique for acoustic neuromas, but because of a few false negatives and the increasing performance of magnetic resonance imaging (MRI), its role as the standard method has been questioned. We assessed sensitivity of screening tests in 89 patients with surgically proven acoustic neuromas. Sensitivity of ABR was 92%; 94% for extracanalicular neuromas and 77% for intracanalicular neuromas. For stapedius reflex (SR), sensitivity was 84% and for caloric vestibular response (CVR) 86%. The combined sensitivity of ABR+SR was 97% and of ABR+RS+CVR 98%. For false negatives, the greatest diameter including the intracanalicular portion was always less than 18 mm, with a mean of 15 mm, and none of these tumours reached the brainstem. For patients with unilateral cochleo-vestibular deficit, we propose ABR and SR as first-line screening tests. These tests are repeated at 6 months and at 1 year in the case of normal results. MRI is ordered for patients whose auditory threshold is too low and for those whose ABR or SR results favour retrocochlear disease.