Vestibular (acoustic) schwannomas arise from the inferior vestibular nerve in the internal auditory canal and initially cause hearing loss and tinnitus (ringing in the ear). As they enlarge into the cerebello-pontine angle, they can compress the brainstem and other cranial nerves, resulting in loss of balance and coordination, vertigo, facial numbness, facial weakness and difficulty swallowing.
Trigeminal schwannomas are less common than acoustic schwannomas. They generally arise in Meckel’s cave in the skull base and the pre-pontine space. These tumors typically cause facial pain (trigeminal neuralgia). As they enlarge they can grow further into the cavernous sinus or into the posterior fossa, causing double vision, loss of coordination and other symptoms of brainstem compression.
Schwannomas are typically diagnosed by an MRI with gadolinium or a CT scan of the brain. A focused MRI of the internal auditory canals is typically best for visualizing a vestibular schwannoma. Other tests may also be needed such as angiography (typically now performed as a CT angiogram or an MR angiogram) or an audiogram.