An acoustic neuroma is a rare tumour in the brain. The tumour grows on a nerve in the brain near to the ear. Acoustic neuromas tend to grow very slowly and don't usually spread to any distant part of the body.
What causes it?
The cause of most acoustic neuromas is unknown. In less than 1 in 10 people, an acoustic neuroma is caused by neurofibromatosis type 2 (NF2). NF2 is a very rare genetic disorder that causes non-cancerous (benign) tumours of the nervous system. People with NF2 can also develop benign tumours on the spinal cord and the coverings of the brain.
Read more about the causes of acoustic neuroma.
How common is it?
Acoustic neuromas are rare. Between 1 and 20 people in every million worldwide are diagnosed each year with an acoustic neuroma. Acoustic neuromas account for about 6 in 100 brain tumours. They are more common in middle-aged adults and are rare in children. Acoustic neuromas seem to be more common in women than in men.
What are the symptoms?
A small acoustic neuroma may cause no symptoms. If you do have symptoms from an acoustic neuroma, these usually develop very gradually, as the tumour is slow-growing. The most common symptoms of an acoustic neuroma are hearing loss and tinnitus.
Other common symptoms of acoustic neuroma include vertigo and also pain, tingling or numbness in the face. Less common symptoms of acoustic neuroma include headache, earache, and visual problems and also tiredness and lack of energy.
Find out more about the symptoms of acoustic neuroma.
How is it diagnosed?
Acoustic neuromas can be difficult to diagnose. If your GP suspects that you have an acoustic neuroma from your symptoms, you would probably be referred to a hospital ear, nose and throat (ENT) specialist.
Any initial tests will depend on the symptoms caused by the acoustic neuroma. If the tumour causes symptoms such as a headache or balance problems, you may also need to have other tests to check for other causes of these symptoms.
The best test to diagnose an acoustic neuroma is a magnetic resonance imaging (MRI) scan of the brain. An MRI scan uses a strong magnetic field and radio waves to take a detailed picture of your brain, and of the structures inside it. It is painless but it can be noisy and can make you feel anxious about being 'closed in' (claustrophobic).
Hearing tests are also needed if an acoustic neuroma is suspected. This is because one of the most common symptoms of an acoustic neuroma is hearing loss.
What are the treatments?
Acoustic neuromas are usually slow-growing and are rarely life-threatening. The main treatments for acoustic neuroma are surgery or stereotactic radiosurgery. If you have a very small acoustic neuroma, your doctors might decide that the best way to treat you is just to observe and monitor it closely.
Find out more about the treatments for acoustic neuroma.
What are the possible complications?
The possible complications due to the acoustic neuroma include:
- Hearing loss:
- The most common symptom of an acoustic neuroma is hearing loss.
- The extent to which you will be affected by hearing loss varies from person to person.
- 'Water on the brain' (hydrocephalus):
- If your acoustic neuroma grows very large, a complication called hydrocephalus can occur. This happens because the flow of fluid in the brain (cerebrospinal fluid) is obstructed.
- Pressure can build up inside the brain, leading to permanent brain damage if not identified and treated.
- The condition can be treated by inserting a drainage tube (called a shunt) to relieve the pressure and allow the cerebrospinal fluid to flow.
- Hydrocephalus is very unlikely if you have treatment for an acoustic neuroma.
- Damage caused by pressure on other nerves in the brain, or on the brainstem:
- If the acoustic neuroma is growing and untreated, it can cause problems by pressing on nearby structures in the brain. Long-term pressure can cause permanent damage.
- For example, it is possible that the trigeminal nerve (which controls feeling in the face) or the facial nerve (which controls movements of the muscles of the face) can be affected.
- If you have treatment for your acoustic neuroma before it has had the chance to grow very big (remember, it is a slow-growing tumour), this sort of complication is very unlikely.
What is the outlook?
The outlook (prognosis) is generally very good. Acoustic neuromas usually respond well to treatment and complications are uncommon. However, there is often some hearing loss in the affected ear after treatment.
Fewer than 5 in every 100 acoustic neuromas come back. So it is uncommon, but possible. It is more likely if you have NF2. It could cause any of the symptoms mentioned earlier, or any of the complications. After treatment for acoustic neuroma you will generally be followed up in an outpatient clinic to check for any symptoms or signs of it coming back.
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- Van Gompel JJ, Patel J, Danner C, et al; Acoustic neuroma observation associated with an increase in symptomatic tinnitus: results of the 2007-2008 Acoustic Neuroma Association survey. J Neurosurg. 2013 Oct 119(4):864-8. doi: 10.3171/2013.5.JNS122301. Epub 2013 Jun 21.
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