A vestibular schwannoma(acoustic neuroma),is a benign primary intracranial tumor of the myelin-forming cells of the vestibulocochlear nerve (CN VIII).It arises from Schwann cells, which are responsible for the myelin sheath in the peripheral nervous system.
The earliest symptoms of acoustic neuromas include ipsilateral sensorineural hearing loss/deafness, disturbed sense of balance and altered gait, vertigo with associated nausea and vomiting, and pressure in the ear, all of which can be attributed to the disruption of normal vestibulocochlear nerve function. Additionally more than 80% of patients have reported tinnitus.Large tumors that compress the adjacent brainstem may affect other local cranial nerves. Paradoxically, the 7th cranial nerves are rarely involved pre-operatively; involvement of the trigeminal nerve (CN V) may lead to loss of sensation in the involved side’s face and mouth. The glossopharyngeal and vagus nerves are uncommonly involved, but their involvement may lead to altered gag or swallowing reflexes.
Larger tumors may lead to increased intracranial pressure, with its associated symptoms such as headache, vomiting, and altered consciousness.
Acoustic neuromas may occur sporadically, or in some cases occur as part of von Recklinhausen neurofibromatosis.
Contrast-enhanced CT will detect almost all acoustic neuromas that are greater than 2.0 cm in diameter and project further than 1.5 cm into the cerebellopontine angle. Those tumors that are smaller may be detected by MRI with gadolinium enhancement.Indicated treatments for acoustic neuroma include surgical removal and radiotherapy.
