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Acoustic Neuroma

An acoustic neuroma is a low-grade tumor. It is on the eighth cranial nerve leading from the brainstem to the ear. This nerve is involved in hearing and ...



An acoustic neuroma is a tumor that grows on the nerve leading from the brainstem to the ear. This nerve plays a role in hearing and in maintaining your balance. An acoustic neuroma grows slowly. It is a benign tumor, which means it is not cancerous. However, this condition can still cause serious problems.

The Ear

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The exact cause of acoustic neuroma is unknown.


Factors that may increase your chance of an acoustic neuroma include:


The first symptoms of an acoustic neuroma include:

  • Gradual hearing loss in one ear with near normal hearing in the other ear
  • Decrease in sound discrimination, especially when talking on the telephone
  • Ringing in the affected ear, called tinnitus

As the neuroma gradually grows larger, symptoms may include:

  • Balance problems
  • Facial numbness and tingling
  • Weakness of the facial muscles on the side of the tumor

If headaches or mental confusion occurs, the tumor may be life threatening. Call your doctor right away.



The doctor will ask about your symptoms and medical history. Your ears will be examined. Your doctor will also do tests of your nervous system.

Images may be taken of your head. This can be done with:

  • MRI scan
  • CT scan

Tests may be done on your ears. These may include:

  • Audiogram
  • Auditory brainstem response test
  • Electronystagmography


The exact type of operation done depends on the size of the tumor and the level of hearing in the affected ear. If the tumor is very small, hearing may be saved. As the tumor grows larger, surgical removal is more difficult because the tumor may have thinned out the nerves that control facial movement, hearing, and balance and may also have affected other nerves and structures of the brain.

Surgery offers immediate treatment but with higher up-front risk. The risks of surgery include: cerebrospinal fluid leak (5% to 17% risk), meningitis, hydrocephalus and/or a wound infection. Other common effects include a period of headaches or balance difficulties or facial weakness. These risks increase with size of the tumor and the type of surgical procedure performed.

Gamma Knife Radiosurgery
The goal of Gamma Knife on acoustic neuromas is tumor volume control rather than tumor removal. Gamma Knife's tumor control rate is about 95%. The risks of radiosurgery are less than those for regular surgery.

As acoustic neuroma may be slow growing, observation may be acceptable for some patients. This is especially the case for elderly or frail patients with mild symptoms where the risks of therapy may be greater and where the tumor may not grow during their lifespan.

Those with smaller tumors may also decide upon "watchful waiting," getting frequent MRIs and audiograms. In this situation it is highly likely that treatment may be needed, but there is potential to postpone therapy for many years. Treatment may proceed when tumor growth is confirmed or symptoms worsen.



There are no guidelines for preventing acoustic neuroma because the cause is not usually known.

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