Magnetic resonance imaging: a cost-effective first line investigation in the detection of vestibular schwannomas.

Magnetic resonance imaging (MRI) is currently the 'gold-standard' investigation in patients with a unilateral sensorineural hearing loss. The procedure, however, is expensive and of limited availability. Instead, such patients often undergo a series of audiovestibular tests and computed tomography in an attempt to exclude or diagnose a vestibular schwannoma. We describe seven cases of unilateral vestibular schwannoma in which conventional assessment was either equivocal or failed to demonstrate a tumour subsequently diagnosed by magnetic resonance imaging. Two patients with neurofibromatosis type 2 are also reported to show how magnetic resonance imaging confirmed the presence of a second vestibular schwannoma despite CT that showed only a unilateral lesion. We also illustrate how limited protocol MRI of patients is slightly more expensive yet much more cost effective than the usual battery of tests and propose that it should be the first line investigation for patients in whom the clinical picture requires exclusion of a retrocochlear lesion. Not all of these early diagnosed tumours have been immediately removed. In some of the more elderly or infirm patients a 'wait and rescan' policy has been adopted. Nevertheless, the early establishment of the correct diagnosis facilitates the subsequent management of these patients.