Normal hearing in acoustic neuroma patients: a critical evaluation

A series of 128 acoustic neuromas (ANs) managed in our center in the last 6 years were evaluated. Sixteen cases (12.5%) were found to have normal pure tone audiograms. A comparatively younger age was an important characteristic of these patients. Tinnitus, dysequilibrium, and subjective hearing loss or distortion were their most common complaints. Pure tone audiometry showed a mean pure tone average of 14.5 dB. Speech discrimination score and performance intensity phonetically balanced index were very insensitive and showed very high false-negative results. Auditory brainstem responses proved to be a reliable test, being positive in 93.8% of cases. The mean tumor size did not show any significant difference when compared with acoustic neuroma cases with abnormal hearing. The combination of otologic and neurotologic symptoms in a young patient should prompt the clinician to investigation further even if hearing is within normal limits. A high index of suspicion is a prerequisite for the early diagnosis of such subtle lesions.