Acoustic Neuroma

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Introduction

The inner ear is responsible for hearing and balance.  Acoustic neuroma is a tumor that develops on the nerve in the inner ear.  Acoustic neuroma is also called vestibular schwannoma.  The vast majority of acoustic neuromas are not cancerous and are slow growing.  Symptoms of hearing loss, false sensations of movement, and hearing unusual sounds develop as the tumor presses on the nerve.  A doctor may simply monitor some acoustic neuromas.  Acoustic neuromas can be treated with monitoring, radiation or microsurgery.
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Anatomy

The ear is divided into three areas: the outer, middle, and inner ear.  Your ears not only enable you to hear, but play a role in balance as well.  Structures in the inner ear work with the eighth cranial nerve (auditory nerve) to send nerve signals to your brain.  Your brain processes the nerve signals as sounds and messages about body positioning to allow you to maintain an upright position.
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Causes

Acoustic neuroma is a tumor that develops on the eighth cranial nerve, usually at the point where the nerve leaves the skull and crosses into the inner ear.  It appears that acoustic neuroma is a genetic problem.  In some cases, it is associated with a genetic disorder called neurofibromatosis type 2 (NF2).  In almost all cases, acoustic neuroma is benign (not cancerous).  The extremely rare cancerous form of this tumor is called malignant peripheral nerve sheath tumor.
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Symptoms

Symptoms develop when the tumor grows large enough to press on the eighth cranial nerve.  You may experience tinnitus, which is ringing or buzzing in the ear.  Your hearing may also decrease.  You may experience vertigo, the false sensation that the room is spinning. 

If the facial nerve is also involved you may experience facial pain, paralysis, tingling or numbness.  Drooling may occur because of poor mouth closure.  Less common symptoms include headache, dizziness, balance problems, vision problems, impaired eye movement, and taste changes. 
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Diagnosis

Contact your doctor if you experience the symptoms of acoustic neuroma.  Your doctor can diagnose acoustic neuroma by reviewing your medical history and conducting examinations.  You may be referred to a neurologist, audiologist, or ear, nose, and throat specialist.
 
Magnetic resonance imaging (MRI) scans and computed tomography (CT) scans are used to diagnose this tumor.  Hearing tests (audiometry) are used to determine your degree of hearing loss.  Brainstem auditory evoked response (BAER) is used to evaluate hearing and neurological functions.  The test involves listening to sounds while a device records your brain’s activity.
 
Electronystagmography (ENG) is used to identify nerve damage in the ear.  ENG testing uses receptors to measure involuntary eye movements during certain procedures, such as caloric testing.  Caloric testing checks involuntary eye movements when hot or cold water is placed in the ear. 
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Treatment

Acoustic neuromas may be monitored, treated with radiation and/or surgery.  Tumors that are small, growing slowly, and not causing symptoms may be monitored with regular imaging tests.  Radiation is used to treat small tumors or parts of a tumor that cannot be removed with surgery.  Gamma-knife radiosurgery or stereotactic radiosurgery allows the doctor to deliver radiation precisely to the tumor.  Radiosurgery is most frequently used for older adults and people that cannot tolerate open surgery.

Microsurgery is used to preserve the facial and auditory nerve.  Microsurgery is used to remove all or part of a tumor.  A partial tumor removal is used to preserve nerve tissue, while eliminating enough of the tumor to make it non-life threatening.
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Am I at Risk

Symptoms from acoustic neuroma most frequently develop between the ages of 30 and 60.  The tumor develops very slowly and may be present well before symptoms are experienced.  Children rarely develop the condition. 
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Complications

Large tumors can cause hydrocephalus.  Hydrocephalus results from fluid buildup and increased pressure inside of the skull.  This condition can be life threatening and requires immediate treatment.
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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on February 16, 2022. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.