To determine the sensitivity of auditory brainstem response (ABR) testing for detecting acoustic neuromas and to determine whether the test is less sensitive for detecting small tumors.
Retrospective review of the medical charts of 58 patients with acoustic neuroma who had all of the data necessary for inclusion in the study.
University-affiliated referral practice of one neurotologist.
Patients with acoustic neuromas who had both ABR tracings and magnetic resonance imaging films available for review.
Main Outcome Measures
Positive ABR and negative ABR results correlated with tumor size.
Tumor size ranged from 0.4 to 7 cm. The overall sensitivity of ABR in diagnosing acoustic neuromas was 90%. However, ABR was progressively less sensitive with decreasing tumor size. Only 7 (58%) of the 12 tumors 1 cm or smaller were detected by ABR.
Auditory brainstem response testing cannot be relied on for detection of small acoustic neuromas and should not be used as a criterion to determine whether magnetic resonance imaging should be performed when an acoustic neuroma is suspected clinically.