A neuroma is a noncancerous tumor that forms along a nerve, causing nerve irritation as well as pain or other symptoms anywhere along the nerve pathway. An acoustic neuroma develops on one of the nerves in the head (the cranial nerves) called the acoustic nerve or the vestibulocochlear nerve. This nerve connects the inner ear to the brain, helping people hear and understand sound and also aiding in balance. Acoustic neuromas are also called vestibular schwannomas or neurilemmomas, and they typically grow very slowly. Most acoustic neuromas have no known cause (although radiation exposure to the head (is considered to be a risk factor); a few rare neuromas can be caused by an inherited disorder called neurofibromatosis type 2. This latter type accounts for only about 1 in 20 cases and typically causes symptoms in both ears developing by the age of 30.
Most acoustic neuromas cause few if any symptoms in their early stages and symptoms that do occur tend to be very subtle. The most common initial symptoms is a gradual loss of hearing in one ear, often accompanied by persistent ringing or buzzing noises in the same ear (a condition called tinnitus). Some people may feel pressure or “fullness” in the affected ear. Less commonly, symptoms can develop very suddenly. Over time, additional symptoms can occur, including:
Symptoms become worse as the tumors grow and press on other areas of the brain; very large tumors that press on the brain stem or other portions of the brain can be deadly.
In many cases, acoustic neuromas that cause no or few symptoms will be observed to monitor their growth over time, with surgery reserved for tumors that begin to grow rapidly or large or that cause serious symptoms. Surgery can be performed using traditional techniques and incisions around the ear or the back of the skull or using radiosurgery, which uses very precise, targeted streams of radiation to shrink the growth without the need for any incisions.