Screening for vestibular schwannoma by magnetic resonance imaging: analysis of 1821 patients.

OBJECTIVES To study the spectrum of diseases that can be detected by magnetic resonance imaging in patients suspected to have vestibular schwannoma (acoustic neuroma) presenting with sensorineural or mixed hearing loss, and to assess the extent of the problem of hearing loss in a screened population. DESIGN Retrospective study. SETTING Diagnostic radiology and imaging department of a regional hospital, Hong Kong. PATIENTS A total of 1821 consecutive patients from September 1999 to February 2001 with sensorineural or mixed hearing loss were referred by otolaryngologists for magnetic resonance imaging of the internal auditory canal. MAIN OUTCOME MEASURES Vestibular schwannoma; other cerebellopontine angle masses and other diseases that could account for the patients' hearing loss. RESULTS In all, 132 (7%) patients had positive findings that could explain their hearing loss. Fifty-four (41%) of the 132 patients had vestibular schwannoma; 39 (30%) had inflammation of the middle ear and mastoids; 17 (13%) had ischaemic foci in the brainstem; 10 (8%) had other cerebellopontine angle masses or tumours; four (3%) had inner ear dysplasia; seven (5%) had vascular loop compression; and one (1%) had chronic cryptococcal meningitis. The overall incidence of vestibular schwannoma detected in this screened population was about 3%. CONCLUSIONS This study indicates that magnetic resonance imaging is an effective tool to screen for vestibular schwannoma in patients with sensorineural or mixed hearing loss. It can also be used to assess a considerable number of different pathological conditions in patients with audiovestibular disorders.