Acoustic Neuroma

This information is about a specific type of brain tumour called an acoustic neuroma, sometimes referred to as a vestibular schwannoma or neurilemoma. It should ideally be read with CancerBACUP’s general information about brain tumours.

Brain tumours

Cells within the brain normally grow in an orderly and controlled way, but if for some reason this order is disrupted, the cells continue to divide and form a lump or tumour.

The tumour may be benign, where the cells do not spread from the original site, or malignant (cancerous), where the cells invade and destroy surrounding tissue and may spread to other parts of the brain.

Tumours affecting the whole central nervous system (CNS), which is made up of the brain, spinal cord and a network of nerves throughout the body, are fairly rare. Just over 5000 new tumours are diagnosed each year in the UK. Many of these are malignant.

Acoustic neuromas

Most brain tumours are named after the type of cells from which they develop. An acoustic neuroma is a benign tumour that develops in the acoustic or auditory nerve. The auditory nerve is responsible for hearing. The acoustic neuroma starts from schwann cells which cover the nerve and is sometimes therefore called a schwannoma. It is usually a slow-growing tumour and does not spread from its original site within the brain.

Acoustic neuromas account for about 8% of all primary brain tumours. They are most likely to be found in middle-aged adults. For unknown reasons they are more common in women than men. Acoustic neuroma may be found in people with the disease neurofibromatosis.

Causes of acoustic neuromas

Apart from the link with neurofibromatosis the cause is unknown. Research is being carried out into possible causes.

Signs and symptoms

Acoustic neuroma is a slow-growing benign tumour and symptoms often develop gradually over several years. The most common symptom is loss of hearing in the affected ear. This may be accompanied by a buzzing or ringing noise in the ear (tinnitus) and a feeling of fullness and sometimes pain in the ear. Dizziness and poor balance are also fairly common.

People who develop acoustic neuroma as part of the disease neurofibromatosis may have bilateral tumours (affecting both sides of the brain).

If the tumour is pressing on the nearby nerve that controls feeling and sensation of the face, it can cause numbness of half of the face. Rarely the facial muscles can become weak on one side. There may be general signs of a brain tumour, such as headaches (particularly on waking), lethargy (tiredness and lack of energy) and changes in personality.

Larger tumours may lead to headaches, sight changes and problems with walking. People may walk awkwardly or stumble and have problems keeping their balance. Sometimes, speech may also be affected.

Tests and investigations

In order for the doctors to plan your treatment they need to find out as much as possible about the type, position and size of the tumour, by doing a number of tests and investigations.

Neurological examination (nerve tests) 

You will usually have a neurological examination to assess any effect of the tumour on your nervous system. Your hearing will be tested and sometimes a test is done to check your sense of balance.

CT (computerised tomography) scan 

A CT scan takes a series of x-rays, which are fed into a computer to build up a detailed picture of your brain. The test itself is completely painless, but it will mean that you have to lie still for about 10 minutes.

MRI (magnetic resonance imaging) scan 

This test is similar to a CT scan, but uses magnetism instead of x-rays to build up cross-sectional pictures of your brain. During the test you will be asked to lie very still on a couch inside a large metal cylinder that is open at both ends. The whole test may take up to an hour. It can be slightly uncomfortable and some people feel a bit claustrophobic during the scan, which is also very noisy. You will be given earplugs or headphones to wear and you can usually take someone with you into the room to keep you company.

Biopsy 

To give an exact diagnosis, a sample of cells from the tumour (biopsy) is sometimes taken, then looked at under a microscope. The biopsy involves an operation. Your doctor will discuss with you whether this is necessary in your case, and exactly what the operation involves.

Treatment

The treatment for an acoustic neuroma depends on a number of factors, including your general health and the size and position of the tumour. The results of your tests will enable your doctor to decide on the best type of treatment for you. Sometimes if the tumour is small or if it is not causing any symptoms, no treatment may be needed. Because acoustic neuromas tend to be very slow-growing it may be a long time before any problems develop, if they develop at all. In this situation regular scans will be done to check for any growth of the tumour.

Surgery

For most people, surgery is the best form of treatment for acoustic neuroma. In many cases the tumour can be completely removed and no further treatment is necessary. Before you have surgery your doctor will discuss the possible risks associated with this type of operation.

Unfortunately, hearing loss in the affected ear cannot be avoided for many people. Often, a hearing aid which diverts sounds from the affected ear to the good ear can be fitted. Your doctor will be able to give you more information about this. Hearing therapists (contactable through your GP) can help with special equipment for people with hearing problems and they also provide counselling and help with communication.

For people with bilateral tumours and the risk of total hearing loss, surgery may be delayed if at all possible and the tumours will be monitored for any growth. Occasionally one side will be operated on first, usually the side with worse hearing loss. If hearing is maintained in this ear, the other side can then be operated on. If hearing is lost during the first operation it may be possible to delay surgery on the second tumour, or to use radiotherapy, which is less likely than surgery to cause hearing loss.

Occasionally, during surgery the facial nerve may be slightly damaged. This can cause temporary or permanent numbness or palsy (drooping) of one side of the face. Facial palsy can cause problems with facial movements, such as chewing and blinking. Often, exercises and massage can help to stimulate facial movement but these should be done under medical supervision. The British Acoustic Neuroma Association produces information about practical ways to cope with facial palsy.

Damage to the facial nerve, which controls blinking, may lead to eye problems, such as dry eyes or difficulty in closing the eye properly. Your doctor can refer you to an eye specialist if necessary.

Occasionally the surgeon will have to leave a tiny part of the tumour, to avoid causing nerve damage. In this situation you will need to have occasional MRI scans to check the tumour every couple of years. It is very uncommon for these tiny parts of the tumour to regrow.

Radiotherapy

Radiotherapy treatment (the use of high-energy rays to destroy the cancer cells) is occasionally used to treat acoustic neuroma. It can be used if surgery is not possible. Radiotherapy may be given as a short course of treatment over a number of days or as a single session. A technique known as stereotactic radio-surgery may be used. This involves hundreds of beams of radiotherapy aimed at the tumour from different angles, given in a single session. Giving radiotherapy in this way helps to reduce side effects.

Stereotactic radio-surgery may also be used as an alternative to surgery for small acoustic neuromas, but the pros and cons need to be discussed fully with your specialist. Stereotactic radio-surgery does not remove the tumour, but usually prevents further growth. After this treatment you will need to have MRI scans every couple of years to monitor the tumour.

Your feelings

You may find the idea of a tumour affecting your brain extremely frightening. The brain controls the body, and not being in control is something that can be very worrying. You may experience many different emotions, including anxiety and fear. These are all normal reactions and are part of the process that many people go through in trying to come to terms with their condition. Many people find it helpful to talk things over with their doctor or nurse. Close friends and family members can also offer support.

CancerBACUP has a section on the emotional effects of cancer and how to deal with them.

References

This section has been compiled using information from a number of reliable sources including:

• Oxford Textbook of Oncology (2nd edition). Souhami et al. Oxford University Press, 2002.
• Cancer and Its Management (4th edition). Souhami and Tobias. Oxford Blackwell Scietific Publications, 2003.
• Cancer in the Nervous System (2nd edition). Levin. Oxford University Press, 2002.

For further references, please see the general bibliography.