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Acoustic neuroma

An acoustic neuroma, which is also known as a vestibular Schwannoma, is a benign (non-cancerous) brain tumour (growth) on the acoustic nerve.

An acoustic neuroma is a benign non-cancerous growth, or tumour, in the brain. It is also known as a vestibular Schwannoma.

An acoustic neuroma grows on the acoustic nerve (vestibulocochlear nerve), which helps control hearing and balance. The acoustic nerve runs alongside the facial nerve, which carries information from the brain to face muscles.

A small acoustic neuroma generally causes problems with:

  • hearing – causing hearing loss or tinnitus (a perception of noise inside the ear)
  • balance – causing vertigo, the sensation that you are spinning

A large acoustic neuroma can cause multiple symptoms, including:

  • headaches with blurred vision
  • numbness or pain on one side of the face
  • problems with limb coordination on one side of the body
  • less often, muscle weakness on one side of the face 
  • in rare cases, changes to the voice or difficulty swallowing

The symptoms of an acoustic neuroma can vary in severity, and tend to develop gradually. This means the condition can be difficult to diagnose.

If your GP suspects you have an acoustic neuroma, you will be referred to hospital for tests that may include:

Read more information about how an acoustic neuroma is diagnosed.

How common is an acoustic neuroma?

All types of brain tumour are relatively rare. Every year, approximately 20 people out of every million in the population are diagnosed with an acoustic neuroma.

Acoustic neuromas tend to be more common in women than men, although the reasons for this are not yet understood. People aged between 40 and 60 years are most often affected. The condition is rare in children.

The exact causes of acoustic neuroma are not currently known. However, about five out of 100 cases are caused by a rare, inherited condition called neurofibromatosis type 2.

Treating an acoustic neuroma

An acoustic neuroma tends to grow slowly, and will not spread from the original site of the tumour. Sometimes, an acoustic neuroma is so small and grows so slowly it does not cause any symptoms or problems. In this case, the acoustic neuroma may just be monitored to avoid risks associated with surgery.

In rare cases, the tumour can grow large enough to press on the brain. However, most acoustic neuromas can be treated before they get to this stage, using:

  • surgery to remove the tumour
  • radiotherapy to destroy the tumour

Read more information about treating an acoustic neuroma.

An acoustic neuroma is not usually a life-threatening condition, but symptoms can disrupt day-to-day life. For example, loss of hearing may affect a person’s ability to communicate with others.

Read more information about complications of an acoustic neuroma



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Acoustic neuroma

A small acoustic neuroma may not cause any symptoms. As acoustic neuromas tend to grow slowly, your symptoms may develop gradually.

A small acoustic neuroma may not cause any symptoms or your symptoms may develop gradually as acoustic neuromas tend to grow slowly.

The growth rate for acoustic neuromas is around 1-2mm every year. However, they may not grow constantly, and there could be long periods when the tumour does not grow at all.  

Symptoms of an acoustic neuroma include:

  • Hearing loss – this is the most common symptom and usually develops gradually in one ear, though in some cases it can develop suddenly.
  • Tinnitus – the perception of noise in one ear or both ears that comes from inside the body rather than from an outside source; for example, you may hear ringing in one ear.
  • Vertigo – the sensation that you or the environment around you is moving or spinning; you may feel the sensation of movement even when you are standing completely still.
  • Facial numbness, tingling or pain, are relatively rare symptoms which can occur if the tumour begins to press on the nerve that controls feeling and sensation in your face (known as the trigeminal nerve).
  • Headaches – this is also a relatively rare symptom, although it can happen if the tumour blocks the flow of cerebrospinal fluid (fluid that surrounds your brain).
  • Temporary sight problems – this is rare and is also caused by a cerebrospinal fluid blockage.
  • Ataxia – a loss of physical coordination that affects your ability to do activities such as walking or writing. When this is caused by an acoustic neuroma it usually only affects one side of the body (the same side as any hearing loss).

Hearing loss and tinnitus are the most common symptoms of acoustic neuroma and they usually only affect one ear. However, if you have acoustic neuroma caused by neurofibromatosis type 2 (a rare inherited condition), both ears may be affected. 

Read more information about causes of acoustic neuroma.

Hearing loss is not necessarily worse for larger tumours.



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Acoustic neuroma

The cause of most acoustic neuromas is unknown. The only known risk factor is a link to a condition called neurofibromatosis type 2.

The cause of most acoustic neuromas is unknown. The only known risk factor for developing an acoustic neuroma is having a very rare genetic condition called neurofibromatosis type 2.

Acoustic neuromas grow from a type of cell called a Schwann cell. Schwann cells cover nerve cells, helping to keep them insulated. Acoustic neuromas are therefore sometimes called vestibular Schwannomas.

It is thought that a fault in a gene that helps stop tumours growing may be responsible.

It is also not known what causes some acoustic neuromas to start or continue growing while others remain the same size.

Neurofibromatosis type 2

A very small proportion of cases of acoustic neuroma are caused by a rare, inherited condition called neurofibromatosis type 2.

Neurofibromatosis type 2 causes benign (non-cancerous) tumours to grow on the nerve tissue in the body, in particular within the head cavity and spine. Neurofibromatosis type 2 is generally characterised by an acoustic neuroma tumour on each side, that is growing from both the left and right acoustic nerves.

Neurofibromatosis type 2 should not be confused with neurofibromatosis type 1, which is much more common and can also cause benign spinal tumours. Neurofibromatosis type 1 affects the skin and does not cause acoustic neuromas.

Neurofibromatosis type 2 usually affects both acoustic nerves. This means that hearing in both your ears is more likely to be affected. It is important to address issues such as lip reading and sign language early on in case hearing in both ears is lost. 

Read more information about neurofibromatosis type 2.



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Acoustic neuroma

An acoustic neuroma can be difficult to diagnose as the symptoms often develop gradually and can be difficult to spot.

An acoustic neuroma can be difficult to diagnose as symptoms often develop gradually and can be difficult to spot.

Symptoms such as dizziness and hearing loss can also be attributed to a number of other conditions, such as Ménière's disease (a rare disorder that affects the inner ear).

If your GP suspects you may have an acoustic neuroma, you will be referred to a hospital or clinic for further testing.

Neurological testing

You may need to have a series of tests to check whether your nervous system (brain, nerves and spinal cord) is being affected by an acoustic neuroma.

Hearing tests

Part of the neurological testing process involves checking your hearing because an acoustic neuroma often affects hearing. Hearing tests you may have, include:

  • pure tone audiometry test – a machine called an audiometer is used to produce sounds at various volumes and frequencies while you listen through headphones and press a button when you hear a sound
  • speech recognition audiometry test – tests your ability to recognise words spoken at different volumes

Read more about how hearing tests are performed.

Magnetic resonance imaging (MRI) scan

magnetic resonance imaging (MRI) scan is one of the most accurate ways of diagnosing an acoustic neuroma. This type of scan allows your doctor to see the size and position of your tumour (growth).

An MRI scan uses a strong magnetic field and radio waves to take a detailed picture of the inside of your head. It is a painless procedure that takes 15 to 60 minutes to complete. However, it can be noisy and you may feel slightly claustrophobic as you are placed in a tunnel inside the scanner.

MRI scans do not use X-rays (a type of high frequency radiation). However, if you are pregnant and in your first trimester (up to week 13 of the pregnancy) your MRI scan is likely to be delayed. After the first trimester, MRI scans can be used safely.

MRI scans are the most common way of looking for an acoustic neuroma.

Computerised tomography (CT) scan

computerised tomography (CT) scan uses X-rays and a computer to create detailed images of structures inside the body including internal organs, blood vessels, bones and tumours.

During a CT scan, you will usually lie on your back on a flat bed. The CT scanner consists of an X-ray tube that rotates around your body. You will usually be moved continuously through this rotating beam. The rays will be analysed by a detector on the opposite side of your body.

Unlike an MRI scan, where you are placed inside a tunnel, you should not feel claustrophobic.

The scan is painless and will usually take 10 to 30 minutes, depending on the part of your body being scanned.

A CT scan is not able to exclude a small acoustic neuroma but can provide additional information, such as a bone anomaly, to assist the doctor in charge of your care.



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Acoustic neuroma

There are several different treatment options for an acoustic neuroma, depending on a number of factors. Treatment may include surgery or radiotherapy.

There are several different treatment options for an acoustic neuroma depending on your age, overall health, and the size and position of your tumour.

Results of any tests or scans you have had will also help determine the best course of treatment. Your acoustic neuroma will usually be treated by a team of specialists and other health professionals, including:

  • a neurosurgeon – a surgeon who specialises in operating on the nervous system (brain, spinal cord and nerves)
  • an ear, nose and throat (ENT) surgeon – a surgeon who specialises in operating on conditions that affect the ears, nose or throat
  • a radiosurgeon – a doctor who specialises in radiosurgical treatments with a background in either neurosurgery or radiation oncology

Monitoring

If your acoustic neuroma is very small or growing very slowly, you may be advised not to have any immediate treatment. Instead, your condition will be monitored. Some research has suggested that as many as three-quarters of acoustic neuromas do not appear to be growing, so monitoring the tumour is all that is needed.

Although simply monitoring your acoustic neuroma may seem like nothing is being done about your condition, it can be the best option because the risks associated with surgery or radiosurgery (see below) outweigh the risk of an acoustic neuroma affecting your health.

To help monitor your condition you will need to have regular magnetic resonance imaging (MRI) scans (where a magnetic field and radio waves are used to create an image of the inside of your body). The MRI scan will check the size and growth of your acoustic neuroma. Other treatments may be considered if the tumour:

  • shows any signs of growing
  • significantly affects your health

You may need to have an MRI scan every one or two years, although this will depend on your general health and the severity of your tumour.

Microsurgery

Acoustic neuromas can be treated using microsurgery to remove the tumour. The surgery is carried out under general anaesthetic, and the acoustic neuroma is removed through an incision made in your skull.

In most cases if the acoustic neuroma is small it can be completely removed. For large tumours, a small part of the tumour is generally left behind to help preserve the facial nerve. In cases where a small part of the tumour remains, it can either be monitored with MRI scans or effectively treated using radiosurgery (see below).

Hearing loss

After acoustic neuroma surgery, hearing in the ear affected by the tumour is almost always lost. 

After surgery you may discuss with your ENT surgeon the possibility of a 'bone anchored hearing aid', which will help divert sound from your affected ear to your good ear.

Read more information about how hearing loss is treated.

Facial nerve

Occasionally, surgery can damage the facial nerve. This is because the acoustic nerve is very close to the facial nerve and large tumours are often stuck to it. Your surgeon will try very hard not to damage your facial nerve and with large tumours will often leave a small part of the tumour on the facial nerve to try and preserve it.

If your facial nerve is damaged during surgery you may find that:

  • you will have a droop on one side of your face (facial palsy)
  • you may have difficulty closing your eye on the weak side of your face
  • your speech may be less clear 
  • you have problems drooling saliva on the weak side of your face 

These symptoms may improve over 6-12 months following surgery, and be helped with physiotherapy. However, it is important to be aware that some damage to your facial nerve may be permanent.

Damage to your facial nerve can also affect your eyes – for example you may have difficulty blinking or completely closing your eye on the side that was operated on. This may lead to your eyes drying out and you may need artificial tears/eye lubricant.

For people with small tumours, less than one person in every 100 will have their facial nerve badly affected after treatment.

For people with large tumours, around three in 10 people will have permanent, severe facial nerve weakness after surgery if a complete tumour removal is attempted. This falls to around one person in over 100 if a small part of the tumour is left on the facial nerve to preserve it.

Any minor post-surgery facial nerve weakness is likely to be temporary, but may take several months to recover.

Recovery from surgery

Following surgery, you will usually need up to a week in hospital to recuperate.

You should be able to return to work after around two months. The length of time it takes you to recover may depend on the size and position of the tumour that was removed. Healthcare professionals treating you will advise you. 

If your acoustic neuroma was completely removed, you will not usually require further treatment. However, you will continue to be monitored with MRI scans.

Read more information about recovering from an operation.

Stereotactic radiosurgery

Stereotactic radiosurgery delivers a very focused and precise dose of radiation to your acoustic neuroma. Stereotactic means locating a point (in this case the position of the tumour in your brain) using three-dimensional coordinates.

Stereotactic radiosurgery ensures the maximum amount of radiation is aimed at your tumour and that surrounding tissue is not exposed. It may be given as a single dose or delivered over several sessions. It doesn't get rid of your tumour but aims to stop a tumour from growing further. It can only be used for small tumours or for the remains of a small tumour after surgery on large tumours. It is generally not used for large tumours.

Stereotactic radiosurgery is performed under local anaesthetic, which means you will be conscious throughout the procedure but your scalp will be numbed. Usually, a lightweight metal frame is attached to your scalp, and a series of scans accurately pinpoint the position of the tumour. This can then be treated using a precise beam of radiation.

Immediate side effects of stereotactic radiosurgery are rare and you will generally only take a couple of days off work to have the treatment.

Nerve damage

In some cases, stereotactic radiosurgery can cause nerve damage, although this may be delayed for several weeks or months after treatment. 

Symptoms of nerve damage can include:

  • facial numbness (loss of feeling)
  • facial paralysis (not being able to move part of your face)
  • hearing loss

Facial paralysis may affect one person in every 100 who has stereotactic radiosurgery. It is estimated that just under a third of people may have hearing loss after stereotactic radiosurgery.



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Acoustic neuroma

The symptoms of an acoustic neuroma can affect your day-to-life, but more serious complications are rare.

The symptoms of an acoustic neuroma can affect your day-to-day life, however, more serious complications are rare.

Coping with your symptoms

Some symptoms of an acoustic neuroma can be difficult to live with and may affect your quality of life. For example, if your hearing is impaired, you may find your job is affected and communication may be more difficult. Severe dizziness and loss of balance may also affect your job and limit the types of activities you can perform.

Speak to your GP or specialist if your acoustic neuroma is being monitored but you feel the symptoms are significantly affecting your daily life. There may be ways of easing your symptoms, such as hearing aids or painkilling medication, or they may indicate you need treatment to remove the tumour.

You can find more information in the Health A-Z about how to treat some of the problems associated with acoustic neuroma. For example:

Recurrence

It is possible for an acoustic neuroma to return after being removed. The tumour reoccurs in less than five in every 100 people. It is likely you will need to be monitored with magnetic resonance imaging (MRI) scans over a number of years, regardless of which treatment you have.

Hydrocephalus

One of the most serious complications of acoustic neuroma is a condition known as hydrocephalus.

Hydrocephalus occurs when an acoustic neuroma is very large and presses on your brainstem (the lowest part of the brain that connects to the spinal cord). This prevents the cerebrospinal fluid (CSF) from flowing between your brain and spinal cord. This blockage can cause pressure to build up inside your skull, which puts pressure on the delicate tissues in your brain.

Hydrocephalus can be treated by draining away the excess CSF. It is important that this condition is treated quickly because in severe cases it can cause brain damage. In rare instances, it can be fatal.

Read more information about hydrocephalus.



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