Otologist and Skull Base Surgeon Mr Lloyd answers your questions about Acoustic Neuromas:
What is an acoustic neuroma?
An acoustic neuroma is a benign tumour (not a cancer) that grows on the balance nerve within the inner ear. This nerve runs from the brain through a narrow channel in the bone of the skull to the inner ear. These tumours originate inside the bony channel and grow out of the channel into the space where the brain is situated. Once the tumour reaches a certain size, it can compress the brain. Within the channel where these tumours originate there are 2 other nerves, the hearing nerve (or cochlear nerve) and the facial nerve. These nerves can also be compressed by the tumour.
What causes acoustic neuromas?
These tumours are caused by damage to the genetic material inside the lining of the balance nerve. The reason why the genetic material gets damaged is not known. It is not caused by anything you have done and it cannot be caught from someone else. It is not passed on to your children.
How common are acoustic neuromas?
Acoustic neuromas are very rare. There is one new acoustic neuroma diagnosed each year for every 100,000 of the population. They can affect all ages but are most commonly identified in people in their sixth decade.
How fast do acoustic neuromas grow?
Only around 40% of acoustic neuromas grow after the time they have been identified. If they grow they generally slowly increase in size by an average of 1-2mm/year. They can occasionally grow faster than this. The pattern of growth is variable.
What symptoms do acoustic neuromas cause?
The most common symptom that people with acoustic neuromas experience is hearing loss. Some people may loose their hearing altogether but most notice a gradual deterioration over time. Some patients may experience noises in the ear, called tinnitus. This can be quite troublesome for some people but there are a number of effective therapies that can help. Many patients are troubled by occasional or persistent imbalance. Other symptoms include numbness of the face, aching of the bone behind the ear, headache and facial twitch. Weakness of the muscles of the face is unusual.
Are acoustic neuromas dangerous?
Acoustic neuromas are not cancers and do not spread to other areas of the body. If they are allowed to grow, they enlarge into the space where the brain is situated and compress the brain. If they grow very large, they can become life threatening because they can compress areas that controls breathing.
How can acoustic neuromas be treated?
There are three main ways of treating acoustic neuromas. If the tumour is small then many patients prefer to undergo a period of observation. This has no potential side effects unlike the other treatment options but you require periodic scans to make sure that the tumour is not growing. If the tumour grows or symptoms become disabling then active treatment may be recommended.
The other treatments are surgery and radiotherapy. If you have the tumour removed it is usually possible to remove it completely. However, the operation is a major procedure with the possibility of damaging the facial nerve. This results in weakness of the side of the face on the side of the tumour. The risk varies from 5-20% depending on the size of the tumour. There are other less common complications that can occur after surgery. These include leakage of fluid from around the brain, infection of the lining of the brain (meningitis) and stroke.
Radiotherapy is very successful at stopping the tumour from growing but 5-10% can still grow despite this treatment. If the tumour still grows then the tumour will need to be removed and surgery after radiotherapy is difficult and has a much higher chance of facial weakness. However, the chances of complications are otherwise less than for surgery although in the long term there is a very small chance that the tumour could become cancerous. The risk of this is less than 1% for each decade after treatment.