Acoustic neuroma is a rare condition in which a noncancerous tumor grows on a nerve that runs from the brain to the inner ear. This nerve regulates hearing and a person’s sense of balance. These tumors grow slowly and may not cause symptoms for years. However, larger tumors can cause significant hearing damage and may even be life-threatening.

Experts do not completely understand the cause of acoustic neuromas. However, they are known to arise from an overproduction of the insulating cells of the balance nerve in the inner ear. Acoustic neuromas are rare in children and are most likely to develop in people between the ages of 30 and 60.

Symptoms of acoustic neuroma generally begin with gradual hearing loss, although in some cases the loss of hearing may be sudden. A sense of fullness in the affected ear may occur. Patients also may experience ringing in the ear, dizziness, loss of balance, and facial numbness and tingling.

If tumors become especially large, they may press on the brain stem and cause a potentially life-threatening buildup of cerebrospinal fluid (CSF) in the skull. Symptoms of this condition include abnormal gait, confusion and headaches. 

Early diagnosis of an acoustic neuroma is crucial to a successful treatment outcome. If a physician suspects an acoustic neuroma, certain tests likely will be planned, including imaging tests, hearing test, and specialized tests of the patient's balance and brain responses to certain sounds.