HealthyCanada.com

Overview

An acoustic neuroma or vestibular schwannoma is a benign brain tumour that develops in the middle ear. It is one of the most common of non-cancerous brain tumours, affecting an estimated 200 to 300 Canadians each year. While it can cause hearing loss, effective treatment is available.

Causes

Vestibular schwannomas are a result of an overproduction of cells that normally wrap around nerve fibers to help support and insulate nerves. Scientists believe the problem is linked with the loss of function of a gene on chromosome 22 which normally produces a protein that controls the growth of these cells. In about half of all those affected, the disorder is inherited, in which case it affects both ears and is known as bilateral vestibular schwannoma. Unilateral vestibular schwannomas affect only one ear and are not hereditary. Scientists don't know exactly why the gene stops functioning in these people.

Regardless of the cause, as the tumour grows, it presses against the nerves that affect hearing and balance, usually causing ringing in the ears, dizziness or loss of balance and typically hearing loss. The tumour is usually slow growing but, eventually it can interfere with other nerves causing numbness or paralysis on the side of the face where the tumour is located. If it becomes large enough, the tumour may eventually press against the brainstem or the cerebellum which can be life-threatening.

Symptoms

Among the early signs are a loss of hearing in one or both ears, tinnitus (ringing in the ears), and dizziness or problems with balance. Initially, the problems may be mild or vague and, perhaps even be confused with other middle and inner ear problems. In order to make an accurate diagnosis, your doctor will want to send you for an ear exam and hearing test and, depending on the outcome, an MRI or CT scan.

Treatment

There are three ways to go about treating this problem:

1. monitoring or watching the tumour for growth

2. radiation therapy to shrink the tumour

3. surgical removal of the tumour

Typically the latter is the treatment of choice but it depends on the location and size of your neuroma. The outcome will depend on the size of the tumour and the level of hearing in the affected ear. If the problem is caught early when the tumour is small, hearing may be saved. However, if the tumour has already grown significantly it may have damaged the nerves that control hearing, balance and even facial movement. If this is the case, some of the damaged nerves may also have to be removed.