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.

MR Detection of Dilated Deep Medullary Veins in Intracranial Dural Arteriovenous Fistulas with retrograde Leptomeningeal Venous Drainage.

SUMMARY: Patients with dural arteriovenous fistula (DAVF) are at higher risk of developing neurological deficits when there is retrograde leptomeningeal venous drainage. Our aim is to demonstrate the presence of dilated deep medullary veins in the brain on magnetic resonance imaging (MR) in this group of patients, and to assess their clinical significance. Nine patients with angiographically proven DAVF associated with leptomeningeal venous drainage who had MR before treatment were studied.MR was performed in at least two orthogonal planes before and after gadolinium administration. The dural fistula was located at the cavernous sinus in five patients, at the transverse-sigmoid sinus in three and at the tentorium in one. Dilated deep medullary veins were noted in six patients. Of these, four showed parenchymal abnormalities which included intracerebral haematoma, venous infarction, brain oedema and T2 hyperintensity in brainstem. Venous varix was present in one patient. No neurological complication or parenchymal change was observed in the three patients without dilated deep medullary veins. Therefore, in patients with intracranial DAVF associated with leptomeningeal venous recruitment, the MR finding of dilated deep medullary veins suggests a more severe degree of venous hypertension and congestion in the brain. This subgroup of patients has a much higher chance of neurological complications and warrants urgent intervention.