Paroxysmal tinnitus due to a meningioma in the cerebellopontine angle

A 44 year old woman presented with frequent paroxysms of unilateral tinnitus and ataxia which were abolished by treatment with carbamazepine. Hearing was normal and initially there were no other symptoms or signs between paroxysms. Brain stem evoked responses from the affected left ear were absent and MRI showed a large tumour in the left cerebellopontine angle. This was completely removed and histologically proved to be a meningioma. There were striking similarities to trigeminal neuralgia and other paroxysmal brain stem symptoms which occasionally occur in multiple sclerosis and diseases of the cerebellopontine angle. Possible mechanisms are discussed.