What Is Acoustic Neuroma?
Acoustic neuromas are benign (non-cancerous) tumors arising from abnormal growth in the cells of the protective sheath (myelin) that surrounds the eighth cranial nerve (or auditory nerve). These tumors tend to grow very slowly, eventually leading to partial or total hearing loss in the affected ear. If left untreated, the tumor may continue to expand and press on several other cranial nerves, causing dizziness and loss of balance, facial pain (neuralgia), or double vision.
In some cases an acoustic neuroma grows large enough to involve the brain stem, leading to loss of muscle coordination (cerebellar ataxia) on the affected side of the body. However, most patients seek treatment before such complications occur. Prognosis depends on the size of the tumor but is generally quite favorable.
While acoustic neuroma is the most common tumor of cranial nerves and represents about 5 percent of primary brain tumors, it is still a rather uncommon disorder. Incidence is highest among those between the ages of 30 and 50.
What Causes Acoustic Neuroma?
- The cause of acoustic neuromas is unknown, although some studies link the problem to a genetic lack of certain proteins that normally prevent tumor growth in the tissue surrounding nerve fibers.
- A small fraction of cases occur in association with a hereditary disorder called neurofibromatosis, characterized by widespread abnormalities in the nervous system, skin, and bones. Neurofibromatosis can be associated with acoustic neuromas that affect both auditory nerves. (In almost all other cases, neuromas develop only in one auditory nerve.)
Symptoms of Acoustic Neuroma
- Partial or complete hearing loss in one ear (or rarely, in both ears). An inability to hear in one ear when using the telephone is often the first sign.
- Feeling of fullness in the ear affected
- Persistent ringing or buzzing in the affected ear (tinnitus)
- Ear pain (in some cases)
- Symptoms that may appear if a tumor affects other nerves or the cerebellum: dizziness and vertigo; numbness or facial pain; double vision; continual headaches with head movement; loss of muscle coordination on the affected side of the body
Acoustic Neuroma Prevention
There is no known way to prevent the development of acoustic neuromas.
Acoustic Neuroma Diagnosis
- Patient history and a hearing test (audiogram) may be strongly suggestive of the diagnosis. Evaluation by an otolaryngologist (ear, nose, and throat specialist) is essential for any signs of hearing loss.
- CT (computed tomography) scans or MRI (magnetic resonance imaging) can confirm the presence of even very small acoustic neuromas.
How to Treat Acoustic Neuroma
- The only effective cure for acoustic neuromas is surgical removal of the tumor. Current microsurgery techniques performed by surgeons experienced in using them often yield favorable results, making it possible to preserve hearing for many patients (especially those who had good hearing preoperatively). Occasionally, however, some degree of permanent hearing loss in the affected ear is inevitable, and sometimes the surgery itself can result in weakness in the facial muscles, numbness, or other neurological symptoms owing to unavoidable damage to surrounding nerves.
- Radiation treatment may be an option to surgery for patients who are elderly or not well enough to undergo surgery. Though not a cure, the treatment slows tumor growth in the majority of cases.
When to Call a Doctor
- Consult a doctor regarding any signs of hearing loss. You will most likely be referred to an audiologist or an otolaryngologist for testing and examination.
Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference
Simeon Margolis, M.D., Ph.D., Medical Editor
Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50
Updated by Remedy Health Media