Acoustic Neuroma

An acoustic neuroma is a benign, usually slow-growing tumor that develops from certain nerves in the inner ear. No one knows the exact cause or causes of acoustic neuroma. As an acoustic neuroma grows, it presses against the nerves associated with hearing and balance, resulting in early symptoms such as: one-sided or high-tone hearing loss, ringing in the ear, dizziness, and loss of balance. Once an accurate diagnosis is made, the doctor can describe the options available for treating an acoustic neuroma.

 

Acoustic Neuroma: An Introduction

An acoustic neuroma is a benign (meaning non-cancerous), usually slow-growing tumor that develops from the nerves associated with balance and hearing that supply the inner ear. An acoustic neuroma comes from an overproduction of Schwann cells -- the cells that normally wrap around nerve fibers like the skin of an onion to help support and insulate the nerves.
 
Other names for an acoustic neuroma include:
 

Acoustic Neuroma: Unilateral Versus Bilateral

An acoustic neuroma can affect one ear or both ears. When one ear is affected, it's known as unilateral acoustic neuroma. When both ears are affected, it's known as bilateral acoustic neuroma.
 
Unilateral Acoustic Neuroma
Unilateral acoustic neuroma affects only one ear. Unilateral acoustic neuroma accounts for approximately 8% of all tumors inside the skull. One out of every 100,000 individuals per year develops an acoustic neuroma. Symptoms may develop at any age, but usually appear between the ages of 30 and 60. Unilateral acoustic neuroma is not a hereditary condition.
 
Bilateral Acoustic Neuroma
Bilateral acoustic neuromas affect both hearing nerves and are usually associated with a genetic disorder called neurofibromatosis type 2 (NF 2). Half of affected individuals have inherited the disorder from an affected parent and half seem to have a mutation for the first time in their family. Each child of an affected parent has a 50% chance of inheriting the disorder.
 
Unlike those with a unilateral acoustic neuroma, individuals with NF2 usually develop acoustic neuroma symptoms in their teens or early adulthood. In addition, patients with NF2 usually develop multiple brain- and spinal cord-related tumors. They can also develop tumors of the nerves associated with:
 
  • Swallowing
  • Speech
  • Eye and facial movement
  • Facial sensation.
     
Determining the best way to manage bilateral acoustic neuromas as well as the additional nerve, brain, and spinal cord tumors is more complicated than deciding how to treat a unilateral acoustic neuroma. Further research is needed to determine the best treatment for individuals with neurofibromatosis type 2.
 
(Click Acoustic Neuroma Gene for more information on the gene responsible for neurofibromatosis type 2.)
 

Causes of Acoustic Neuroma

No one knows the exact cause or causes of acoustic neuroma. Doctors cannot always explain why one person gets acoustic neuroma and another does not. However, acoustic neuroma research has shown that people with certain risk factors for this condition are more likely than others to develop acoustic neuroma. A risk factor is anything that increases a person's chance of developing a disease.
 
Specific acoustic neuroma risk factors include:
 
  • Age
  • Family history of neurofibromatosis type 2.
     

Symptoms of Acoustic Neuroma

Because of its location, an acoustic neuroma can produce serious acoustic neuroma symptoms or even death by compression of important structures, including the cranial nerves and the brainstem.
 
As the acoustic neuroma grows, it presses against the nerves associated with hearing and balance. This results in early acoustic neuroma symptoms, such as:
 
  • One-sided or high-tone hearing loss
  • Ringing in the ear (tinnitus)
  • Dizziness
  • Loss of balance.
     
As the acoustic neuroma grows, later symptoms of acoustic neuroma may include:
 
  • Headaches
  • Facial numbness
  • Weakness of facial muscles
  • Paralysis of facial muscles.
     

Diagnosing Acoustic Neuroma

In order to make an acoustic neuroma diagnosis, the doctor must ask a series of questions (medical history), perform a physical exam, and recommend a number of acoustic neuroma tests.
 
The tests your doctor may recommend to help in diagnosing acoustic neuroma include:
 
  • A hearing test (audiogram)
  • Computerized tomography (CT) scans, enhanced with intravenous dye (contrast)
  • Magnetic resonance imaging (MRI), enhanced with intravenous dye (contrast).
     
These tests for acoustic neuroma are critical in the early detection of an acoustic neuroma, and are helpful in determining the location and size of a tumor and in planning its removal.
 

Acoustic Neuroma: Treatment

Making an early diagnosis of acoustic neuroma is key to preventing its serious consequences. Once a diagnosis is made, acoustic neuroma treatment options include:
 
The doctor can describe the options available for treating your acoustic neuroma and the expected results of each. You and your doctor can work together to develop a treatment plan that meets your medical needs and personal values. Choosing the most appropriate form of acoustic neuroma treatment is a decision that ideally involves both the patient and the healthcare team.
 
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Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD