Neurofibromatosis

Neurofibromatosis is a genetic disorder of the nervous system. They mostly affect the development and growth of nerve cell tissues. This disorder causes tumors to grow on nerves. It can also cause skin changes and bone deformities. Scientists have classified the disorders as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). Of the two, NF1 is the more common type.

CAUSES

Many affected persons inherit the disorder. But between 30 and 50 percent of new cases arise through change (mutation) in an individual's genes. Once this change has taken place, the mutant gene can be passed on to future generations.

SYMPTOMS

Early symptoms may include:

  • Ringing noise in the ear (tinnitus).

  • Poor balance.

Problems caused by pressure from the tumors include:

  • Headache.

  • Facial pain or numbness.

  • Symptoms of NF1, particularly those on the skin, are often evident at birth or during infancy. They almost always appear by the time a child is about 10 years old.

  • NF2 has bilateral (occurring on both sides of the body) tumors on the eighth cranial nerve. The tumors cause pressure damage to neighboring nerves.

DIAGNOSIS

To diagnose NF1, a caregiver looks for:

  • Changes in skin appearance.

  • Tumors.

  • Bone abnormalities.

  • A parent, sibling, or child with NF1.

To diagnose NF2, a caregiver looks for:

  • Bilateral eighth nerve tumors.

  • Similar signs and symptoms in a parent, sibling, or child. Affected individuals may notice hearing loss as early as the teen years.

TREATMENT

Treatments for both NF1 and NF2 are presently aimed at controlling symptoms.

  • Surgery can help some NF1 bone malformations. It can remove painful or disfiguring tumors. However, there is a chance that the tumors may grow back and in greater numbers. In the rare instances when tumors become malignant (3 to 5 percent of all cases), treatment may include surgery, radiation, or chemotherapy.

  • For NF2, improved diagnostic technologies, such as MRI, can reveal tumors as small as a few millimeters in diameter. This allows for early treatment. Surgery to remove tumors completely is one option. But it may result in hearing loss. Other options include partial removal of tumors or radiation. If the tumors are not progressing rapidly, the conservative approach is watchful waiting.

  • Genetic testing is available for families with documented cases of NF1 and NF2.

  • New (spontaneous) mutations cannot be confirmed genetically.

  • Prenatal diagnosis of familial NF1 or NF2 is also possible. Amniocentesis or chorionic villus sampling procedures would be used.