Neurinomas of the trigeminal nerve.

Trigeminal neurinomas account for about 0.2 per cent of all intracranial tumors and for about 2 to 3 per cent of all intracranial neurinomas. Trigeminal neurinomas occur most frequently in persons in the middle decades of life, with the highest incidence between the ages of 38 and 40 years. They show no sex predilection. Although very rare, trigeminal neurinomas are of considerable interest to the neurotologist because of their relation to the temporal bone, skull base, sphenoid and maxillary sinuses, nasopharynx, infratemporal fossa, and, in rare instances, the oral cavity. In addition to producing disturbances of fifth nerve sensory and motor function, these tumors are often associated with other symptoms, such as occlusion of the eustachian tube (sensation of fullness and conductive hearing loss), otalgia, exophthalmos, paralysis of the third, fourth, and sixth cranial nerves, and signs of posterior fossa involvement (sensorineural hearing loss, tinnitus, cerebellar ataxia, and involvement of cranial nerves VII and IX through XI), any of which may be the initial clinical manifestation of the neurinoma. Symptoms depend on the site of origin and course of development. Bilateral trigeminal neurinomas are a manifestation of the central form of neurofibromatosis.