The Mayo Clinic defines acoustic neuroma, also known as a vestibular schwannoma, as a slow growing, non cancerous tumor that develops adjacent to the brain on a portion of the eighth cranial nerve that runs from the brain to the inner ear. Acoustic neuroma is a rare condition, though one of the most common forms of brain tumors. The Acoustic Neuroma Association states that acoustic neuroma occurs in roughly two out of every 100,000 people.
Causes
According to the Mayo Clinic, the eighth cranial nerve can be separated into three sections: the cochlear section, which carries sound, and the superior and inferior vestibular branches, which carry information regarding balance. The tumors almost always occur on the vestibular branch. While nobody knows exactly why the tumors form, in some cases it can be a symptom of a rare genetic disorder known as neurofibromatosis 2. Tumors that are associated with this genetic disorder usually occur in both ears rather than just one.
Symptoms
Medline Plus, a publication of the National Institutes of Health, explains that symptoms of acoustic neuroma vary based on the size of the tumor. Due to slow tumor growth, most symptoms don't show up until after the age of 30. The most common symptoms include vertigo, or the abnormal sensation of movement, hearing loss in the affected ear and ringing in the effected ear. Other less common symptoms can include difficulty understanding speech, dizziness, headache, loss of balance, numbness in the face or ear, sleepiness, vision problems, and weakness of the facial muscles.
Diagnosis
It is often difficult to diagnose acoustic neuroma because the symptoms of tinnitus, or ringing in the ears, vertigo and hearing loss can be attributed to many other causes. A physician will do an MRI or CT scan of the brain to get a visual image. A physician may perform a test called an electronystagmography, or ENG. This test evaluates balance, controlled by the vestibular branch, by detecting abnormal eye movement often associated with inner ear problems.Brainstem auditory evoked response, or BAER, may also be used for a diagnosis. The test involves using electrodes placed on the scalp and earlobes to evaluate hearing and neurological functioning by capturing the brains response to noises heard through earphones. It then records these findings on a graph.
Treatment
According to the Mayo Clinic, if the tumor is small and causing no symptoms of discomfort, a health care team may choose watchful waiting as a treatment. They will continue to monitor the tumor until a time when they feel that they may need to intervene to make a patient comfortable. If the tumor is causing symptoms, a physician may choose stereostatic radiosurgery to stop the growth of the tumor. Stereostatic radiosurgery enables doctors to deliver radiation precisely to a tumor without having to make an incision. If a patient is experiencing facial paralysis or the tumor is causing disfigurement, they may decide to excise the tumor surgically.
Prognosis
The National Institutes of Health reports that most people who have surgery will have no permanent paralysis of the face after surgery. Approximately 50 percent of all patients with small tumors regain hearing function following surgical intervention. There is a small chance that a tumor will reoccur, so it is important to follow up with your physician and report any suspected recurrence.
