What is Neurofibromatosis type 2?
Neurofibromatosis 2 (NF2) is a genetic disorder in which tumors called schwannomas are found on nerves in the inner ear. These tumours can also develop on nerves in other areas of the brain or spinal cord. Persons with NF2 are at high risk for developing brain tumors and most of all affected individuals develop tumors on both nerves to the ears (also called the eighth cranial nerve). This nerve has two portions: the acoustic (hearing) which carries information about sound to the brain and the vestibular nerve which carries balance information to the brain.
Signs and symptoms usually appear during adolescence or in the early 20s. The most common early symptoms are hearing loss, ringing in the ears (tinnitus), and loss of balance caused by tumors growing on the nerve from the ear to the brain. If tumors are growing in other parts of the brain, signs and symptoms vary according to location and can include seizures, changes in vision or sensation, and fluid build up in the brain. Some people with neurofibromatosis 2 also develop cataracts (clouding of the lens in the eye) at an early age.
Although tumors on the eighth cranial nerve are most common, persons with NF2 can develop tumors on other nerves also. These tumors are called schwannomas because they arise from the Schwann cells. Schwann cells support and protect nerve cells and provide nerves with the insulation they require to conduct information. The symptoms of a schwannoma will depend on its location in the body.
In addition to schwannomas, persons with NF2 occasionally develop other sorts of tumors which grown on the coverings of the brain and spinal cord. These tumors (called ependymomas and meningiomas) may cause many different kinds of neurological symptoms depending on their location. As with schwannomas, a physician may detect signs of a tumor on a detailed neurological examination before a patient can detect symptoms in everyday life.
NF2 individuals can develop a special sort of cataract, know as a juvenile posterior sublenticular opacity or have other problems with the eyes. Since cataracts are likely to impair vision if not removed, it is important for all persons with NF2 to have a detailed eye exam by a specialist familiar with NF2.
Onset is unique to each individual with NF2. Some get their first symptoms during late teenage years or in their early 20's. A few people develop symptoms in childhood and some do not have problems until their 40's. Neurofibromatosis type 2 is far less common than neurofibromatosis1 affecting about 1 in 40,000 births.
Mutations in the NF2 gene cause neurofibromatosis 2. Normally, the NF2 gene produces a protein that inhibits cell division particularly in the specialized cells that insulate the nerve cells of the brain and spinal cord (Schwann cells). The mutated gene produces an abnormal protein that cannot properly control cell division, leading to tumor development.
How do people inherit Neurofibromatosis 2?
NF2 is inherited in an autosomal dominant pattern which means only one copy of the altered gene is necessary to cause the disorder. In about half of all cases, an affected person has one affected parent. The other half result from new mutations which means that neither parent is affected. All individuals have a 50% chance of passing the disorder on to their children. NF2 affects both genders equally and is located on the 22 chromosome.
What other names do people use for neurofibromatosis 2? - BANF- Bilateral Acoustic Neurofibromatosis
- Bilateral Acoustic Neurofibromatosis
- Central NF2 Neurofibromatosis
- Familial Acoustic Neuromas
- Neurofibromatosis Type 2
- Neurofibromatosis Type II
- Schwannoma, Acoustic, Bilateral
- NF2
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What treatments are available for NF2?
Presently, the only treatments available for the tumors of NF2 are surgery and radiation therapy. Most individuals with NF2 require at least one operation during their lifetime. Since these tumors lie on nerves and or near the brain and spinal cord, their surgical removal is not without risk. Surgery in small and delicate places may cause further injury to nerves and further neurological problems. For these reasons an attempt should be made to postpone surgery until the risk of further damage by the tumor itself out weights the risk of the surgical damage. When surgery is no longer an option for a particular person because of their medical problems or the size or location of a tumor, radiation therapy may be considered. As with any surgery, radiation therapy has both risks and benefits which must be carefully considered.
There are two very common tests that may be helpful in defining its nature and progression. An MRI (magnetic resonance imaging) scan and audiometry (a hearing test). MRI scans are used to visualize the anatomy of the body. They are most commonly taken of the brain, but may also be used to "see" the spine or nerves in the arms and legs.
MRI (magnetic resonance Imaging)
To scan the patient has to lie very still on a small bed which slides into a donut-shaped machine. Magnets are activated around the patient. At some point the patient may be injected with a dye that enhances the appearance of some parts of the brain. No x-irradiation is used. Although MRI scans can show a very detailed structural information (what your body looks like), they cannot show functional information (how well your body is working). Audiometry test how well the hearing portion of the eighth cranial nerve is working. To undergo audiometry a person puts on earphones in a soundproof room.
Sounds of different intensity and frequency are given to each ear and the ability to detect them is monitored. Information from the audiometry augments the structural information form an MRI.
What is NF2? 
