What is neurofibromatosis type 2?
Neurofibromatosis is the name for a number of genetic conditions that cause tumours to grow along your nerves.
Tumours are abnormal tissue growths. In neurofibromatosis, the tumours are usually non-cancerous (benign).
Types of neurofibromatosis
There are two main types of neurofibromatosis:
- Neurofibromatosis type 1 (NF1) is the most common type of neurofibromatosis, affecting about one in 3,000 people.
- Neurofibromatosis type 2 (NF2) is less common, affecting about one in 35,000 people.
Despite sharing the same name, the two types of neurofibromatosis are separate conditions that have different causes and symptoms.
This information is about neurofibromatosis type 2 (NF2).
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How it affects you
Almost everyone with NF2 will develop tumours on the nerves responsible for hearing and balance. These typically cause symptoms such as:
- gradual , that usually gets worse over time
- ringing or buzzing in the ears
- balance problems, particularly when moving in the dark or walking on uneven ground
Tumours can also develop inside the brain or spinal cord, or the nerves to the arms and legs. This can cause symptoms such as weakness in the arms and legs and persistent headaches.
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Why it happens
NF2 is caused by a genetic mutation. This is where the instructions that are carried in all living cells become scrambled in some way. As a result, the growth of nerve tissue is not controlled properly.
In half of all cases of NF2, the genetic mutation is passed from a parent to their child. In other cases, the genetic mutation appears to develop on its own. This is known as a sporadic mutation.
Although there are genetic tests that can be carried out during pregnancy to check if your child will have NF2, most cases are diagnosed using tests after birth.
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How it's treated
There is currently no cure for NF2. Treatment involves regular monitoring and treating any problems that occur.
Surgery can be used to remove most tumours, although there is a risk this will cause problems such as complete deafness or facial weakness. Therefore, the risks and potential benefits will need to be carefully considered before treatment.
Most people with NF2 eventually develop significant hearing loss and often benefit from learning to lip read or using a hearing aid. Sometimes, special implants can be inserted to aid hearing.
NF2 tends to get worse over time, although the speed at which this happens can vary considerably. However, most people with NF2 will eventually lose their hearing and some people will require a wheelchair or other type of mobility device.
Tumours that develop inside the brain and spinal cord can place a strain on the body and shorten life expectancy. The average life expectancy for someone with NF2 is 65 years of age.
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Neurofibromatosis type 2 symptoms
The symptoms of neurofibromatosis type 2 (NF2) typically start when a person is in their late teens or early twenties, but they can develop at any age.
As NF2 causes non-cancerous (benign) tumours to grow in various part of the body, most of the problems caused by the condition are related to where these tumours develop.
Most people with NF2 develop benign tumours in the nerves used by the brain to help with hearing and sense of balance. These are known as vestibular schwannomas.
Vestibular schwannomas can cause ear problems such as:
- gradual that usually gets worse over time
- a constant ringing or buzzing sound
- balance problems, such as feeling dizzy – this is usually made worse when walking on uneven ground or moving around in the dark
These tumours tend to only cause problems in one ear initially, but both ears are often affected eventually.
Less common symptoms of vestibular schwannomas can include a feeling that your environment is spinning around you, nausea and vomiting.
It's likely these tumours will grow larger over time, eventually causing additional symptoms such as:
- numbness in parts of your face
- weakness of your tongue, which can cause slurred or unusual-sounding speech and difficulty swallowing
- facial pain, although this is less common
About two-thirds of people with NF2 develop cataracts. These are cloudy patches in the lens, the transparent structure at the front of the eye.
Cataracts can make a person’s vision blurred or misty. However, they are usually mild in NF2 and rarely disrupt vision significantly.
Cataracts are normally associated with old age, but they can develop in children and young adults with NF2.
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Just over half of people with NF2 develop benign tumours on or underneath the surface of their skin. These are called schwannomas.
These often take the form of skin plaques. These are small, coloured, raised patches of skin that are usually less than 2cm across.
Tumours that develop under the skin can grow to around the size of a golf ball and they can be painful if they develop along a section of nerves.
Some people with NF2 also develop one or two coffee-coloured patches on their skin, called café au lait spots. However, having lots of café au lait spots is usually a sign of.
Many people with NF2 will develop a condition called peripheral neuropathy. Peripheral neuropathy is where a section of the nervous system, known as the peripheral nervous system, becomes damaged.
Peripheral neuropathy can cause a wide range of symptoms, depending on which sections of the peripheral nervous system are damaged. Possible symptoms include:
- in the affected body part
- numbness and a reduced ability to feel pain or temperature changes, particularly in your feet
- a burning pain, usually in the feet and legs followed by the hands and arms as the neuropathy progresses
- muscle weakness
Read more about peripheral neuropathy.
Around half of people with NF2 develop one or more benign tumours inside their brain. These types of tumours are called meningiomas.
Meningiomas may cause no noticeable problems. However, they can sometimes lead to an increase in pressure in and around the brain, causing symptoms such as:
- seizures (fits)
- disturbances in vision, such as
The tumours can also disrupt certain brain functions. Depending on where in the brain they are located, this may cause:
- personality changes
- weakness or numbness in one side of the body
- difficulty speaking, understanding words, writing and reading
- vision problems
- fits or blackouts
- memory problems
- loss of smell or a sensation of strange smells
- unsteadiness, loss of co-ordination and difficulty walking
- difficulty speaking and swallowing
Spinal cord problems
Around half of people with NF2 will develop one or more benign tumours inside their spinal cord. These are known as ependymomas.
The spinal cord is a long band of nerves that runs from your brain down the centre of the spine.
Around half of people who develop ependymomas will not have any noticeable symptoms. The remaining half may have the following symptoms:
- muscle weakness
- unpleasant physical sensations in certain parts of the body, such as numbness, tingling, or a "crawling" sensation on the skin
Causes of neurofibromatosis type 2
Neurofibromatosis type 2 (NF2) is caused by a genetic mutation in a gene called the NF2.
Genes are the instructions that are used to produce all human characteristics.
The NF2 gene produces a protein called merlin (also called schwannomin). This protein plays an important role in regulating the growth of nerve tissue.
However, the mutation causes some of the instructions inside the body’s cells to become scrambled. This results in the cells producing an incomplete protein, or no protein at all. Without an effective merlin protein, multiple areas of uncontrolled growth (tumours) can develop in the nervous system.
The faulty gene that causes NF2 is found on chromosome number 17.
How it's inherited
In around half of all cases of NF2, the mutated gene is passed down from a parent to their child.
The NF2 mutation is known as an autosomal dominant mutation. This means only one parent has to have the faulty gene for a child to be at risk of developing the condition.
If either the mother or father has the faulty gene, there is a one in two chance each child they have will develop NF2.
Males and females have the same chance of developing the condition.
In around half of NF2 cases, the mutation appears to occur in either the sperm or egg just before conception. This is known as a sporadic mutation. It is unclear what causes it or whether anything increases the risk of it happening.
If you have a child who develops NF2 as a result of a sporadic mutation, it is highly unlikely any further children you have will also develop the condition.
A person who develops NF2 sporadically can pass the condition to their children. The chances of this happening are usually the same as those for someone who inherited the condition (see above), unless they develop a form of NF2 called mosaic NF2 (see below).
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In about one third of cases, NF2 takes a mild form called mosaic NF2.
Mosaic NF2 develops when the mutation occurs after an embryo has been conceived. This is different from "normal" NF2, where the mutation is already present in the sperm or the egg before conception takes place.
As the mutation takes place later in the development of the embryo, not all the cells of the body are affected in mosaic NF2. Therefore, the symptoms of mosaic NF2 are milder and are often restricted to a certain area or side of the body.
As the genetic mutation is not present in all the cells of someone with mosaic NF2, the risk of someone with this form of the condition having a child with NF2 is less than the usual 50%. However, if the child of someone with mosaic NF2 is affected, the child will have the normal – and more severe – form of the condition.
Diagnosing neurofibromatosis type 2
If you or your child develops symptoms of neurofibromatosis type 2 (NF2), a number of tests can be used to look for signs of the condition.
If you have a family history of NF2, this will also be taken into account when diagnosing the condition.
Some of the tests commonly used to check for signs of NF2 are described below.
Auses strong magnetic fields and radio waves to produce detailed scans of the body’s soft tissue. It can be used to check for the presence of non-cancerous (benign) tumours inside the nerve tissue next to your ears, as well as your brain and spinal cord.
Hearing and eye tests
A number of differentcan be used to find out whether your hearing has become impaired.
Eyes tests are often used to check for(cloudy patches at the front of the eye), which are common in NF2.
Acan be used to check your DNA for the NF2 mutation. However, this test only correctly identifies the mutation in about two-thirds of cases, so a negative result does not necessarily mean you don't have NF2.
If you or your partner has NF2, there is a chance you could pass it on to any children you have.
Therefore, you may choose to have treatment to ensure your children don't develop the condition, or you may wish to have tests during pregnancy to check if your child is affected.
Pre-implantation genetic diagnosis (PGD)
A type oftreatment called pre-implantation genetic diagnosis (PGD) can be used to help ensure a pregnancy is unaffected by NF2.
In this procedure, several of the woman’s eggs are fertilised by the man’s sperm outside the body to produce embryos. The embryos can then be tested for the NF2 mutation, and one or two healthy embryos will be transferred into the womb.
However, it's likely you will have to pay for PGD privately. A course of PGD can cost between £6,000 and £10,000, and there is no guarantee that one course of treatment will lead to a successful pregnancy.
Tests during pregnancy
The most commonly used tests to check an embryo for the genetic mutation that causes NF2 include:
- – where a sample of cells from the placenta are removed and tested, usually between weeks 10 and 13 of pregnancy
- – where a sample of amniotic fluid is removed and tested, usually during weeks 15 to 20 of pregnancy
If you wish to have these tests during pregnancy you will be referred to a genetic counsellor. They can discuss with you the implications of the test result. If tests show that your child will develop NF2, the genetic counsellor will support you through the testing process and help you decide how you want to proceed with the pregnancy.
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Treatment for neurofibromatosis type 2
There is currently no cure for NF2, so management focuses on regular monitoring and, if possible, treating problems as and when they arise.
Your specialist care team
If you are diagnosed with NF2, it is likely you will be referred to a specialist centre so that a treatment plan can be drawn up.
Everyone with NF2 will require regular monitoring. This is needed to check for signs of any problems developing and arrange treatment if necessary.
Monitoring NF2 usually involves:
- annual to check whether any new tumours have developed and whether any existing tumours have grown larger
- annual eye tests to check for the presence of (cloudy patches at the front of the eye)
- annual to check the extent of any
Depending on the extent and severity of your symptoms, more frequent tests may sometimes be required.
Contact your specialist centre if any new symptoms develop in between these examinations, or if any existing symptoms get worse.
The growth of tumours is one of the main problems associated with NF2 and it's not always obvious what the best treatment is.
Many tumours are small and may not grow large enough to causes any problems, but others can be large and have a significant impact on your life.
You should discuss the best option for you with your care team before deciding on a particular treatment.
It's possible to surgically remove some tumours, but the risks involved can often outweigh the benefits.
For example, removing tumours from the nerve tissue next to your ears could further damage your hearing and causeof your facial muscles.
Removing tumours from the spinal cord carries a small risk of damaging the spinal cord, which could cause some degree of paralysis.
However, in some cases, surgery may be required to prevent potentially serious complications. These could include a tumour that grows so large that there is a risk of it damaging your brain.
For smaller tumours, a type of, known as the gamma knife, may be an option. This treatment does not involve the use of an actual knife, it uses a tightly focused beam of gamma radiation to shrink a tumour.
As with surgical removal, this treatment is not without risks. There is a possibility the gamma radiation could cause biological changes to occur in tissue, which could result in any new tumours becoming cancerous. Although the chances of this happening are thought to be quite small, it will need to be considered when weighing up your treatment options.
Treating hearing problems
If you have NF2, your hearing will probably become impaired to such an extent that you will require treatment.
One option may be to consider a hearing implant. These are surgically implanted electrical devices used to bypass problems in the hearing mechanism. There are two types of hearing implants used in NF2, called cochlear implants and auditory brainstem implants (ABIs).
Cochlea implants and ABIs have an external microphone that receives and processes sounds. These signals are then passed into an internal receiver before being carried through wires to electrodes either in the cochlea (the coiled, spiral tube inside the inner ear) or the brainstem.
If you have an ABI fitted, the surgeon will first remove any tumours from the hearing nerves. These implants will not fully restore your hearing, they will only restore some degree of hearing. However, they can make lip reading easier (see below).
As with all types of surgery, there is a risk of complications. Some of these can be serious, such as infection on the outer layer of the brain, which can occur in around one in every 60 cases. These risks will need to be taken into consideration when deciding on the best way to manage your hearing problems.
Another option is learning to lip read. Your treatment centre should be able to recommend a hearing therapist or another healthcare professional who is qualified to teach lip reading.
Treating other problems
NF2 can also cause several other health problems, which require different treatments. For example, NF2 can cause:
- – which is usually treated with surgery to remove the cloudy lens and replace it with a clear artificial lens
- – which is usually treated with medication
- – which may be treated with a number of different therapies, such as tinnitus retraining therapy to help you tune out the constant buzzing or ringing noise