Definition

Neurofibromatosis is a genetic problem that causes tumors in the nervous system. Tumors develop in the nerves or the tissue that surrounds the nerves, called the myelin sheath. Neurofibromatosis is divided into 3 types, neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis. The type is determined by the specific genes that are affected.

This articles discusses NF1, the most common neurofibromatosis. It affects the nerves outside the brain and spinal cord, called peripheral nerves.

The Nervous System Copyright © Nucleus Medical Media, Inc.

Causes

NF is caused by a change in a specific gene. The gene normally makes proteins that help control growth in the nerves. Since the gene is defective, these proteins are not able to control growth, and tumors develop.

In many cases, the abnormal gene is inherited from a parent. A person with the inherited form of NF has a 50% chance of passing the abnormal gene to each child. Any parents, children, and siblings of an affected individual should be considered at risk for NF. However, the gene change can occur in a person with no family history of NF.

Risk Factors

The main risk factor for NF is having a family member with the disease.

Symptoms

Most symptoms begin between birth and age 10. NF1 may cause:

• Light brown spots (called café-au-lait spots) on the skin
• Freckles in the armpits or groin
• Larger than normal head circumference in children
• Shorter than normal stature in children
• Problems with growth of the spine, bones of the skull, or the shin bones

Other medical conditions that are associated with NF1 include:

• Mild impairment of intellectual function, learning disabilities such as attention deficit hyperactivity disorder (ADHD)
• Seizures
• Headaches
• Congenital heart defects or damaged blood vessels
• High blood pressure

Diagnosis

You will be asked about your medical and family medical history. A physical exam will be done. It may take a few years before NF1 is diagnosed. NF1 may be suspected if there is a history of:

• Neurofibromas (tumors that grow on a nerve or nerve tissue)— rarely occur before puberty
  • These tumors can progress to become aggressive malignant tumors.
• Growths on the iris of the eye (called Lisch nodules or hamartomas)
• Tumor on the optic nerve that may affect vision (optic nerve gliomas)

Images may be taken of your nerves and brain. This can be done with an MRI scan. Samples of tumors may also be removed and sent for a biopsy.

Genetic testing may be recommended for families with a history of neurofibromatosis. Prenatal diagnosis may also be possible with amniocentesis or chorionic villus sampling.

You may be referred to specialists to look for signs of tumors of the nervous system.

Treatment

There are no current treatments to stop these tumors from growing. Treatment may not be needed since these tumors are rarely cancerous, grow slowly, and may not cause problems. Regular exams are recommended to check for new tumors or symptoms.

Treatment may be needed to control symptoms. Surgery may be done to remove painful or disfiguring tumors. Medications and therapies may also be needed to manage other symptoms such as seizures and learning disabilities.

Rarely, some tumors can become cancerous. These tumors may need to be treated with surgery, chemotherapy, or radiation therapy.

Prevention

There are no current guidelines to prevent neurofibromatosis.