Definition

Neurofibromatosis is a genetic disorder 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 article discusses NF2. These tumors tend to arise in the central nervous system. The eighth cranial nerve, which affects hearing and balance, is the most commonly involved nerve.

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

Symptoms will depend on the exact location and size of the tumor. Smaller tumors may not cause symptoms.

Symptoms that may occur include:

• Hearing loss
• Tinnitus (ringing in the ears)
• Poor balance
• Headaches
• Pain or numbness in the face
• Visual problems such as double or blurry vision
• Weakness or tingling in the arms or legs
• Bumps under the skin (tumor) or small flesh colored skin flaps—in adults may also have dark, rough, hairy patches over the tumors

Diagnosis

You will be asked about your medical and family medical history. A physical exam will also be done. It may take a few years before NF2 is diagnosed. NF2 may be suspected if there is a presence or history of:

• Tumors such as:
  • Vestibular schwannomas —tumor that grows from tissue around the eighth cranial nerve
  • Glioma —tumor of the brain or spine
  • Meningioma —tumor of tissue that surrounds the brain and spine
  • Schwannoma—tumor from tissue that covers all nerves
• Juvenile cataracts

The diagnosis is generally made based on your history, symptoms, and the physical exam.

An MRI scan may be done to create images of the nerves and brain to look for tumors. Samples of tumors may also be removed and sent for microscopic evaluation.

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. You will be referred to a specialist for regular check-ups. Regular exams are recommended to check for new tumors or symptoms.

Surgery may be needed to remove tumors that are causing symptoms such as hearing loss. Other surgeries may be needed, such as cochlear implants or cataract repairs.

Some tumors may also shrink in response to radiation or certain medication. These treatments can have some side effects and complications. You and your doctor will weigh the risks and benefits of each treatment option.

Prevention

There are no guidelines for preventing neurofibromatosis.

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