Sudden hearing loss as a presenting symptom of acoustic neuroma

Purpose: Retrocochlear pathological findings may be suggested by findings on the brainstem response and acoustic sensorineural reflex (AR) tests. We describe the incidence of acoustic neuroma presenting as sudden hearing loss (SHL) and the effectiveness of the discrimination (DISC) test, the brainstem-evoked response, and AR test in predicting acoustic neuroma in patients with SHL. Methods: We retrospectively reviewed the charts of all adult patients who presented to our center with sensorineural SHL between 1989 and 1995. Two groups were defined: those with cerebellopontine angle (CPA) tumor and those with negative imaging findings. Results of the brainstem-evoked response, AR, and DISC tests were compared. Results: Forty patients were admitted with sensorineural SHL, of whom 19 (47.5%) had a CPA tumor. The latter group showed a significantly lower mean age and better results for the low frequencies on pure tone audiometry, as well as better brainstem-evoked response test results than the patients with negative imaging findings. There was also a significant difference between the groups for both the affected and unaffected ears on the discrimination test. Conclusion: Acoustic tumors may be a more common cause of sudden sensorineural hearing loss than previously suspected. The DISC test is a useful screening tool for acoustic tumor, whereas the brainstem-evoked response test shows poorer results in affected patients with sensorineural hearing loss than in other subgroups with different signs of acoustic neuroma. We recommend that young patients presenting with mild SHL who have normal results on the AR and brainstem-evoked response tests undergo magnetic resonance imaging to rule out CPA tumor.