Diseases & Conditions

Bilateral Acoustic Neurofibromatosis - Neurofibromatosis


Overview, Causes, & Risk Factors

This condition is a genetic disorder of the nervous system. It affects growth and development of nerve cells and tissues and causes tumors on the nerves. There are 2 types:

  • NF1, which is the more common type
  • NF2, which is a less common, but often more severe form
  • Contrary to common belief, NF is not the same as Elephant Man Disease.

    What is going on in the body?

    This disease is caused by a mutation in one of the genes of the body. About half the time, this mutation is inherited from a parent. But the other half of the cases arise spontaneously. NF1 and NF2 are caused by mutations of 2 different genes. This mutation causes tumors to grow along the nerves of the body. It can also affect how tissues such as bones and skin develop. NF2, though more rare, tends to be more severe. Its tumors form along the cranial and spinal nerves, especially the auditory nerves. It also causes other lesions of the brain and spinal cord.

    What are the causes and risks of the disease?

    A parent who has this disorder has a 50-50 chance of passing the same form of NF on to each of his or her children. But another 50% of cases develop on their own. It is not known why. People of all sexes and races have an equal chance of having NF. NF1 affects about 1 out of every 4000 births worldwide. NF2 is more rare, affecting only about 1 in 40,000 births worldwide. NF1 and NF2 together affect more than 100,000 people in the US.


    Symptoms & Signs

    What are the signs and symptoms of the disease?

    NF1

    Symptoms of NF1 are often noticed at birth or during infancy. Almost all affected children will have symptoms by the age of 10. Symptoms include:

  • changes in skin appearance, such as cafe-au-lait spots
  • pea-sized bumps on or under the skin
  • enlarged freckle-type spots under the arms or in the groin area
  • spots on the iris of the eye called Lisch nodules
  • skeletal abnormalities, such as bowed legs or scoliosis
  • NF2

    This form results in tumors on both sides of the body. Symptoms include:

  • multiple tumors on the head and spinal nerves
  • hearing loss that begins in the teens or early twentie
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  • ringing in the ears, called tinnitus
  • poor balance
  • headache
  • facial pain or numbness

  • Diagnosis & Tests

    How is the disease diagnosed?

    The doctor will start with a thorough medical history and physical exam. He or she will look for changes in skin, tumors, and bone abnormalities. A parent or sibling with NF will also lead the doctor to suspect NF in the child. When a doctor suspects NF2, x-rays and MRI /CAT scans of the brain and spine may be ordered. Blood tests for both NF1 and NF2 are also available.


    Prevention & Expectations

    What can be done to prevent the disease?

    At present, there is no known way to prevent NF once a child is born with the mutant gene, but much research is being done. Genetic testing and counseling for affected families may be needed to help parents make decisions about having children.

    What are the long-term effects of the disease?

    The effects of NF1 are mild to moderate in most people, but lead to learning disabilities in about half of the people who have it. Other problems that may occur with NF1 and/or NF2 include:

  • high blood pressure
  • curvature of the spine, called scoliosis
  • poor formation of the long bones, such as the femur in the legs
  • speech problems
  • seizure disorders
  • cataracts
  • poor body image due to skin discolorations and tumors
  • blindness
  • deafness
  • cancer, though this is rare
  • What are the risks to others?

    NF is not catching, but it can be passed on from a parent to a child genetically.


    Treatment & Monitoring

    What are the treatments for the disease?

    Treatment for NF is focused on controlling symptoms for the most part. Surgery may be used to help some NF1 bone malformations or to remove tumors that are painful or bothersome. But there is a chance that tumors will grow back and in greater numbers. NF1 tumors become malignant or cancerous in only about 3 to 5 percent of cases. When they do, surgery, chemotherapy, or radiation may be used.

    For NF2, surgery is sometimes used, but the doctor and patient will need to weigh the risks, such as hearing loss against the benefits. Radiation may be used in some cases.

    What are the side effects of the treatments?

    Side effects of treatments depend on the treatment used. Radiation and chemotherapy always carry some risks.

    What happens after treatment for the disease?

    Treatment of NF lasts a lifetime. Although NF cannot be cured, it can often be controlled with careful management and treatment. Any complications that do occur must be treated promptly.

    How is the disease monitored?

    All people with NF should be followed by a doctor at least once a year. Referral to a specialist for any vision or hearing problems should also be made. Children with NF should always have a yearly exam by an ophthalmologist. Blood pressure should also be monitored for any elevation above a healthy range. Any new or worsening symptoms should always be reported to the doctor.


    Attribution

    Author:Kathleen A. MacNaughton, RN, BSN
    Date Written:
    Editor:Crist, Gayle P., MS, BA
    Edit Date:01/20/03
    Reviewer:Melinda Murray Ratini, DO
    Date Reviewed:01/17/03