Neurofibromatosis (NF) is a neurocutaneous syndrome that can affect many parts of the body, including the brain, spinal cord, nerves, skin, and other body systems. NF can cause growth of non-cancerous (benign) tumors involving the nerves and brain.
NF can range from mild to severe. Some children live almost unaffected by their NF, while others can be severely disabled.
Types of NF
Of the three types of neurofibromatosis — NF1, NF2, and schwannomatosis — NF1 is most common. NF1, also known as von Recklinghausen disease, occurs in 1 of every 2,500 births and affects about 100,000 Americans.
NF2 is much rarer, found in about 1 in 25,000 births. A person with NF2 almost always has bilateral vestibular schwannomas, which are non-cancerous tumors affecting the nerves that carry hearing and balance information to the brain.
Schwannomatosis is the third and rarest type of NF. People with schwannomatosis have many noncancerous tumors (schwannomas) affecting the nerves throughout the body. In contrast to NF2, they don’t develop tumors on the vestibular nerves of the ear and lose their hearing. This disorder isn't usually identified until people reach their mid-20s and begin to get symptoms of chronic pain.
Even in a family in which more than one person has NF, the disease may cause slightly different problems in each person who has it.
Causes of NF
Both neurofibromatosis 1 and 2 are kind of inherited disorder. People with NF have 1 in 2 chance of passing it on to each of their babies. About half of cases of NF are inherited in this way. In the other half of cases, the mutation that causes neurofibromatosis happens spontaneously. In these families where nobody has had NF before, the genetic material gets changed when the sperm meets the egg.
Blood testing helps confirm whether a person has NF, and helps check for mutations.
Signs and Symptoms
In younger kids or in those with mild cases, NF1 can be found early when café-au-lait spots (birthmarks) appear on the skin.
Many people without NF1 have one café-au-lait spot. But if a young child has more than five of these birthmarks, at least ½ inch in diameter (roughly the size of a dime), a doctor will look for other clues that may indicate NF1. Other signs of NF1 include freckling in the armpits and groin areas, as well as neurofibromas — tumors on, under, or hanging off the skin — and Lisch nodules, tiny, noncancerous bumps on the iris (the colored part of the eye). Although Lisch nodules help identify a person with NF1, they don’t cause any vision problems.
Neurofibromas can be on various parts of the body, often right before puberty starts.
People with NF1 may also have bone problems, such as the thinning or overgrowth of the bones in the arms or lower leg, or scoliosis, an abnormal curving of the spine.
NF2 isn't usually diagnosed until a child is older. Hearing loss in the late teens and early 20s, is often the first symptom of the disorder, and is caused by tumors growing on the vestibular nerves. The vestibular nerves carry electrical impulses from the ear to the brain, allowing us to hear, and these tumors can occur on one or both sides.
Other symptoms of NF2 include continuous ringing in the ears, headache, facial pain, or weakness, and feeling unsteady or off-balance.
Other tumors may involved the lining of the brain (meningiomas) and spinal cord (ependymomas). Young children also may have problems with the retina in the back of the eye.
Neurofibromatosis is usually diagnosed based a child having at least two of these seven signs:
- café-au-lait spots of a certain number, size, and location
- the appearance of two or more neurofibromas (often resembling pea-sized bumps on the skin)
- two or more Lisch nodules
- an optic glioma (tumor along the main nerve from the eye responsible for sight)
- certain skeletal defects
- a close family member with NF1
- freckling under the arms or in the groin
This list helps diagnose patients with NF1 in all but the youngest children, and by age 8, most children with NF1 will meet the criteria. By the age of 20, all patients meet the criteria. If the diagnosis isn't certain based on these factors, genetic testing is available, but the result can't help a person tell which signs of NF they will develop.
If a doctor suspects your child has NF1, he or she may refer you to NF1 specialists.
Other tests help identify medical problems associated with the NF. Tests like magnetic resonance imaging (MRI) help screen for changes in the brain called "bright spots," brain enlargement, and tumors. X-rays may help identify skeletal problems.
To diagnose NF2, doctors will check for any evidence of hearing loss or balance problems. They'll order audiometry (hearing tests) as well as brain and spine imaging studies to look for tumors in the nerves of the ears, spinal cord, or brain. They'll also ask about family members who may have NF2. Individuals will also be sent to an eye doctor to check for cataracts and retinal problems.
Genetic testing is now available for NF2. For women with NF2 who are pregnant, amniocentesis or chorionic villus sampling can also sometimes determine if an unborn child has the condition.
Treatment for NF requires multi-disciplinary team management.
Research over the past decade has resulted in the discovery of new treatments for people with NF. These new therapies are currently being offered as part of ongoing clinical trials to provide better options for affected individuals.
Caring for Your Child
The first noticeable sign of neurofibromatosis usually is the presence of multiple café-au-lait spots. If your child has several of these birthmarks, ask your doctor to refer you to a clinical program with expertise in NF.