Neurofibromatoses are genetic disorders of the nervous system. Mainly, these disorders affect the growth and development of nerve cell tissue. The disorders are known as neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). NF1 is the more common type of neurofibromatosis. Schwannomatosis has recently been identified as a third and more rare type of neurofibromatosis, but little is known about it.
NF1, also called von Recklinghausen NF or peripheral NF, is characterized by multiple café au lait spots (patches of tan or light brown skin) and neurofibromas (soft, fleshy growths) on or under the skin. Enlargement and deformation of bones and curvature of the spine (scoliosis) may also occur. Occasionally, tumors may develop in the brain, on cranial nerves, or on the spinal cord. About 50% to 75% of people with NF1 also have learning disabilities.
NF2, also called bilateral acoustic NF (BAN), is much less common than NF1 and is characterized by multiple tumors on the cranial and spinal nerves. Tumors that affect both of the auditory nerves and hearing loss beginning in the teens or early twenties are generally the first symptom of NF2.
What Causes Neurofibromatosis?
Neurofibromatosis is often inherited (passed on by family members through our genes), but about 50% of people newly diagnosed with the disorder have no family history of the condition, which can arise spontaneously through a mutation (change) in the genes. Once this change has taken place, the mutant gene can be passed on to future generations.
What Are the Symptoms of Neurofibromatosis?
The following symptoms appear in people with NF1:
- Several (usually 6 or more) café au lait spots
- Multiple freckles in the armpit or groin area
- Tiny growths in the iris (colored area) of the eye; these are called Lisch nodules and usually do not affect eyesight.
- Neurofibromas that occur on or under the skin, sometimes even deep within the body; these are benign (harmless) tumors; however, in rare cases, they can turn malignant or cancerous.
- Bone deformities, including a twisted spine (scoliosis) or bowed legs
- Tumors along the optic nerve, which may cause eyesight problems
- Nerve-related pain
- High blood pressure
People with NF2 often display the following symptoms:
- Loss of hearing
- Weakness of the muscles of the face
- Poor balance
- Uncoordinated walking
- Cataracts (cloudy areas on the lens of the eye) that develop at an unusually early age
People with schwannomatosis may have the following symptoms:
- Pain from the enlarging tumors
- Numbness and tingling of the fingers or toes
- Weakness in the fingers and toes
How Is Neurofibromatosis Diagnosed?
Neurofibromatosis is diagnosed using a number of tests, including:
- Physical examination
- Medical history
- Family history
- Computerized tomography (CT) scans
- Magnetic resonance imaging (MRI)
- Biopsy of neurofibromas
- Eye tests
- Tests for particular symptoms, such as hearing or balance tests
- Genetic testing
To receive a diagnosis of NF1, you must have 2 of the following features:
- Six or more café au lait spots that are 1.5 cm or larger in post-pubertal individuals or 0.5 cm or larger in pre-pubertal individuals
- Two or more neurofibromas (tumor that develops from the cells and tissues that cover nerves) of any type or one or more plexiform neurofibroma (nerve that has become thick and misshapen due to the abnormal growth of cells and tissues that cover the nerve)
- Freckling in the armpit or groin
- Optic glioma (tumor of the optic pathway)
- Two or more Lisch nodules
- A distinctive bony lesion, dysplasia of the sphenoid bone or dysplasia or thinning of long bone cortex
- A first-degree relative with NF1
To be diagnosed with NF2, you must have:
- Bilateral (on both sides) vestibular schwannomas, also known as acoustic neuromas; these are benign tumors that develop from the balance and hearing nerves supplying the inner ear.
- Family history of NF2 (first-degree family relative) plus unilateral (on one side) vestibular schwannomas (bilateral or unilateral) or any two of the following health conditions:
- Multiple meningiomas (tumors that occur in the meninges, the membrances that cover and protect the brain and spinal cord)
- Glioma (cancer of the brain that begins in glial cells, which are those that surround and support nerve cells)
- Any neurofibromas
- Juvenile cataracts
How Is Neurofibromatosis Treated?
There is no cure for neurofibromatosis. Treatments for neurofibromatosis focus on controlling symptoms. There is no standard treatment for NF, and many symptoms, such as café au lait spots, do not need treatment. When treatment is necessary, options may include:
- Surgery to remove problematic growths or tumors
- Treatment that includes chemotherapy or radiation if a tumor has turned malignant or cancerous
- Surgery for bone problems, like scoliosis
- Therapy (including physical therapy, counseling or support groups)
- Cataract removal surgery
- Aggressive treatment of associated pain
What Is the Outlook for a Person With NF?
The outlook for a person with neurofibromatosis depends on the type of NF they have. Often, the symptoms of NF1 are mild and people who have it are able to lead full and productive lives. Sometimes, however, pain and deformity can result leading to significant disability. The outlook for people with NF2 depends of the person's age at onset of the disease and on the number and location of tumors. Some can be life-threatening. Often, those with schwannomatosis have severe pain, and this can be very debilitating.