What is an acoustic neuroma?

Feeling unsteady on your feet? Have you noticed a loss of hearing in one ear but not the other? Should you consider these symptoms simply a sign of getting older? Maybe, but what if there is something more going on than just the effects of old age?

Understanding an acoustic neuroma

One possibility to consider when certain odd symptoms appear is an acoustic neuroma.  Acoustic neuroma is a benign (noncancerous) tumor that arises from the cranial nerves for hearing and balance. The word “acoustic” refers to sound or hearing. However, acoustic neuromas do not grown along the hearing nerve but instead develop on the vestibular nerve, which controls balance. There are four nerves that are affected in acoustic neuromas – two vestibular (balance) nerves, the hearing nerve and the nerve that controls movement in the face.  Each of these nerves is tightly bundled together in that part of the skull.

Acoustic neuromas are rare. The Acoustic Neuroma Association estimates that approximately 3.5 people out of 100,000 are affected. Each year in the United States around 5,000 people are diagnosed with an acoustic neuroma.

Symptoms

One of the first symptoms people will notice with an acoustic neuroma is a loss of hearing in one ear. That’s because neuromas typically press against the hearing nerve, causing problems with hearing. Other early symptoms can include trouble with balance, ringing in the ear, feeling dizzy or being unsteady on your feet or difficulty with walking. Other unusual symptoms might include facial numbness or facial paralysis or a burning sensation of the tongue.

While acoustic neuromas are benign, grow slowly, and do not metastasize or spread, they can become dangerous if they grow large and begin to press against the brainstem or brain.

What causes acoustic neuromas?

This is difficult to answer as the cause is not well understood. What is known is most acoustic neuromas are sporadic or nonhereditary with only 5% of cases associated with a genetic disorder called neurofibromatosis type 2.

For most acoustic neuromas, it begins at the cellular level of a ‘governor’ gene that exert their effects by suppressing the growth of Schwann cells which are cells responsible for coating nerve fibers with insulation. The result is a wart-like growth of these cells to produce the neuroma.

Another possible cause is if a person has been exposed to high-dose, therapeutic radiation to the head. Cell phone use has not been found to cause acoustic neuromas.

How are acoustic neuromas diagnosed?

Usually diagnosis begins with a visit to an Ear, Nose, and Throat doctor for an audiogram. An audiogram tests for hearing loss or ringing in the ear.  If this test shows either, then an MRI scan will be done to help identify any tumors.

How are acoustic neuromas treated?

The treatment options vary depending on the patient’s age, hearing, overall health and the tumor size and location. The options may include observation with serial imaging since the tumors grow very slowly, or surgery or stereotactic radiosurgery may be necessary for larger tumors or tumors causing severe symptoms. The doctor will discuss with a patient about their options, as well as the risks, benefits and expected outcomes.

For patients who have mild or moderate degrees of hearing loss, conventional hearing aids can help. For those with dizziness or balance problems, physical therapists can help patients rehabilitate their balance over time.

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