Acoustic neuroma

Introduction

An acoustic neuroma, also called a vestibular schwannoma, is a tumor that develops on a nerve between the inner ear and the brain.

The affected nerve, called the eighth cranial nerve, has three branches: two that send balance information and one that sends hearing information from the inner ear to the brain.

Acoustic neuromas grow on one of the balance branches of the nerve. The tumor is non-cancerous and does not spread to other parts of the body.

The tumor gets the name vestibular schwannoma because it grows from the Schwann cells that wrap around the vestibular, or balance, branch of the nerve.

Inner ear detail showing acoustic neuroma

The causes

A random change in a gene that controls cell growth is the most likely cause of acoustic neuroma.

Most cases involve only one ear, but a very small number of cases have the tumors developing in both ears. That very rare genetic disorder is called neurofibromatosis type 2 (NF 2).

The symptoms

Because the slow-growing tumor presses on the hearing and balance nerves, patients will have changes in their hearing and balance. The symptoms include:

  • Hearing loss that may be sudden or gradual in one ear
  • Ringing or ear noise, called tinnitus, in the affected ear
  • Balance problems, including dizziness
  • Facial numbness and tingling
  • Headaches

Diagnosing an acoustic neuroma

Based on your symptoms, you will likely have an MRI scan with an injected contrast dye. The dye makes it easier to detect a tumor.

Your doctor also will recommend a hearing test to determine if your hearing is affected on the side suspected of having a tumor.

If a tumor is detected, it will be classified as small, medium, or large.

Treatment options

There are three options for managing an acoustic neuroma.

  • Observation
  • Radiation
  • Surgery

With observation, you may have MRIs and hearing tests done on a regular basis to determine the rate of the tumor’s growth. Observation is a good option

  • For patients 65 and older
  • For patients who are not good candidates for surgery
  • For cases where the tumor is casing few or no symptoms

Having no surgery is the main benefit of the observation approach. The risks involved include:

  • The tumor may continue to grow.
  • Hearing loss and balance may worsen.
  • It may be harder to save hearing and facial nerve function if surgery is eventually needed.

The purpose of radiation treatment is to slow or stop the tumor growth. The main benefits for this approach are no surgery and a relatively short recovery time. The risks include:

  • The tumor is still present and may grow.
  • If surgery is needed, it may be more difficult.
  • There is a slight chance of turning a benign tumor into a cancer.

The goal of surgery is to completely remove the tumor and save facial nerve function. This approach is the most effective when the tumor is causing significant dizziness or imbalance. The risks include:

  • Short-term facial nerve weakness or balance problems
  • Hearing may not be saved in the affected ear
  • A four- to six-week recovery period

Details about surgery

The surgery is done with general anesthesia in an operating room and will last from six to eight hours. It usually involves a four- to five-day hospital recovery.

Your surgeon has options for three approaches to the inner ear area and will choose the approach that best suits the size and location of the tumor.

  • Middle fossa is used for smaller tumors when there is a chance to save hearing. Through an incision above the ear, the surgeon removes a piece of bone and approaches the tumor from above.
  • Translabyrinthine is used for larger tumors and when the patient’s hearing is very poor or there is little chance of saving hearing because of the size and location of the tumor. Through an incision behind the ear, the surgeon goes through the inner ear to remove the tumor.
  • Retrosigmoid is used for larger tumors and sometimes allows for hearing to be saved. The incision is far behind the ear and the inner ear is preserved. 

Your care team will review your care during the important four to six weeks of recovery time at home. During that time, patients may experience fatigue, constipation, minor balance issues, minor pain, facial numbness, and ear noise. Patients report that these symptoms fade with time.

During your recovery time, you will not be allowed to lift anything more than 10 pounds, you’ll not be allowed to drive until you’re able to turn your head quickly from side to side without getting dizzy, and you’ll wait about a month before you’re ready to return to work.

Possible complications from surgery

The nerve affected by acoustic neuroma runs alongside the facial nerve, which controls facial movement and expression. The most important goal of surgery is to avoid injury to the facial nerve. In some cases the facial nerve may develop weakness from swelling or stretching the nerve during surgery. Facial nerve weakness or injury can cause incomplete eye closure and drooping in the facial muscles on one side of the face. Though these symptoms are usually temporary, a small percentage of patients may have permanent weakness.

Even when hearing preservation surgery is chosen, there is still a chance of hearing loss in the affected ear. Hearing may be completely lost or greatly decreased. The ability to save hearing is related to tumor size and hearing level before surgery.

Balance issues may be an ongoing problem for several months following surgery. Patients may notice more difficulty with unsteadiness when they are tired or in the dark.

Last reviewed: 
April 2018
Alternative Names: 
Vestibular schwannoma

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