Acoustic Neuroma Tumor

Acoustic neuroma (also called acoustic neurinoma, vestibular schwannoma and acoustic neurilemoma) is a noncancerous tumor that slowly grows inside the head. There are 12 cranial nerves that emerge from the brain. The eighth cranial nerve (called the vestibulocochlear or acoustic nerve) runs into the inner ear and is responsible for hearing and equilibrium. Acoustic neuroma occurs from an overproduction of the cells (Schwann cells) that cover the acoustic nerve.

Significance

• According to the American Hearing Research Foundation (AHRF), only 2,000 to 3,000 people are diagnosed with acoustic neuroma each year in the United States. Acoustic neuroma accounts for 6 percent of intracranial brain tumors. According to the National Institutes of Health, only 1 in 1,000 people with asymmetrical hearing loss suffer from acoustic neuroma.

Symptoms

• Acoustic neuroma causes signs and symptoms when it becomes large enough to push down on the acoustic nerve. The most common symptom is hearing loss. Hearing loss usually occurs gradually, but it may be sudden in some cases. It typically occurs in one ear, but may affect both ears. Other symptoms include: vertigo, tinnitus (ringing of ears), difficulty keeping balance and numbness of the face. If a tumor becomes too large, it can put pressure on the brainstem and can be potentially fatal.

Causes

• The acoustic nerve is divided into three branches: cochlear, superior vestibular and inferior vestibular. Acoustic neuroma typically occurs on one of the vestibular branches. The exact cause of acoustic neuroma is not known. In rare cases, a hereditary disorder (called neurofibromatosis 2) can cause the formation of tumors on the acoustic nerves in both ears. According to Mayo Clinic, some studies suggest that persistent cell phone use and exposure to loud noises may cause acoustic neuroma, but these studies do not provide conclusive evidence.

Diagnosis

• Typically, the signs and symptoms of acoustic neuroma don't appear in the initial stages, so it can be hard to get a timely diagnosis. The tests used to diagnose acoustic neuroma include: audiometry (conventional hearing test), electronystagmography (ENG), brainstem auditory evoked response (BAER), magnetic resonance imaging (MRI) and computerized tomography (CT).

Treatment

• There is no drug that can slow or stop the growth of the acoustic neuroma tumor. Treatment of acoustic neuroma involves constant monitoring of the growth of the tumor and use of hearing aids. Surgical removal of the tumor is the best option for people with significantly sized tumors. Some complications associated with surgery include: persistent headaches, partial or total hearing loss, and dizziness. In case the tumor is inoperable, stereotactic radiosurgery is used to prevent the tumor from growing.