DefinitionAn acoustic neuroma is a slow-growing tumor of the nerve that connects the ear to the brain. This nerve is called the vestibular cochlear nerve. It is behind the ear right under the brain.An acoustic neuroma is not cancerous (benign), which means it does not spread to other parts of the body. However, it can damage several important nerves as it grows.
Alternative NamesVestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor
Causes, incidence, and risk factorsAcoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2).Acoustic neuromas are uncommon.
SymptomsThe symptoms vary based on the size and location of the tumor. Because the tumor grows so slowly, symptoms usually start after age 30.Common symptoms include:Abnormal feeling of movement (vertigo)Hearing loss in the affected ear that makes it hard to hear conversationsRinging (tinnitus) in the affected earLess common symptoms include:Difficulty understanding speechDizzinessHeadache
Loss of balanceNumbness in the face or one earPain in the face or one earWeakness of the face
Signs and testsThe health care provider may suspect an acoustic neuroma based on your medical history, an examination of your nervous system, or tests.Often, the physical exam is normal when the tumor is diagnosed. Sometimes, the following signs may be present:
Decreased feeling on one side of the face
Drooping on one side of the faceUnsteady walkThe most useful test to identify an acoustic neuroma is an MRI of the brain. Other tests to diagnose the tumor and tell it apart from other causes of dizziness or vertigo include:
Hearing test (audiology)Test of equilibrium and balance (electronystagmography)Test of hearing and brainstem function (brainstem auditory evoked response)
TreatmentTreatment depends on the size and location of the tumor, your age, and your overall health. You and your health care provider must decide whether to watch the tumor (observation), use radiation to stop it from growing, or try to remove it.Many acoustic neuromas are small and grow very slowly. Small tumors with few or no symptoms may be followed, especially in older patients. Regular MRI scans will be done.If they are not treated, some acoustic neuromas can damage the nerves involved in hearing and balance, as well as the nerves responsible for movement and feeling in the face. Very large tumors can lead to a buildup of fluid (hydrocephalus) in the brain, which can be life-threatening.Removing an acoustic neuroma is more commonly done for:Larger tumorsTumors that are causing symptomsTumors that are growing quicklyTumors that are pressing on the brainSurgery is done to remove the tumor and prevent other nerve damage. Any hearing that is left is often lost with surgery.Stereotactic radiosurgery focuses high-powered x-rays on a small area. It is considered to be a form of radiation therapy, not a surgical procedure. It may be used:To slow down or stop the growth of tumors that are hard to remove with surgeryTo treat patients who are unable to have surgery, such as the elderly or people who are very sickRemoving an acoustic neuroma can damage nerves, causing loss of hearing or weakness in the face muscles. This damage is more likely to occur when the tumor is large.
Expectations (prognosis)An acoustic neuroma is not cancer. The tumor does not spread (metastasize) to other parts of the body. However, it may continue to grow and press on important structures in the skull.People with small, slow-growing tumors may not need treatment.Once hearing loss occurs, it does not return after surgery or radiosurgery.
ComplicationsBrain surgery can completely remove the tumor in most cases.Most people with small tumors will have no permanent paralysis of the face after surgery. However, about two-thirds of patients with large tumors will have some permanent weakness of the face after surgery.About one-half of patients with small tumors may still be able to hear in the affected ear after surgery.There may be delayed radiation effects after radiosurgery, including nerve damage, loss of hearing, and paralysis of the face.
Calling your health care providerCall your health care provider if you have: Hearing loss that is new or getting worseRinging in one earDizziness (vertigo)
ReferencesBaloh RW, Jen J. Hearing and equilibrium. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 430.Brackmann DE, Arriaga MA. Neoplasms of the posterior fossa. In: Cummings CW, Flint PW, Haughey BH, et al, eds. Otolaryngology: Head & Neck Surgery. 5th ed. Philadelphia, Pa: Mosby Elsevier;2010:chap 177.Battista RA. Gamma knife radiosurgery for vestibular schwannoma. Otolaryngol Clin North Am. 2009;42:635-654.Sweeney P, Yajnik S, Hartsell W, Bovis G, Venkatesan J. Stereotactic radiotherapy for vestibular schwannoma. Otolaryngol Clin North Am. 2009;42:655-663.Conley GS, Hirsch BE. Stereotactic radiation treatment of vestibular schwannoma: indications, limitations, and outcomes. Curr Opin Otolaryngol Head Neck Surg. 2010 Oct;18(5):351-6.