Neurofibromatosis (continued)

Signs and Symptoms

NF1 is sometimes diagnosed in younger children, especially those with more severe forms of the disorder. One key to early diagnosis of mild NF is the appearance of café-au-lait spots on the skin.

Many people who do not have NF have a few café-au-lait spots. But if a young child has five or more, at least 1/2 inch in size (roughly the size of a dime), a doctor will look for other clues that may indicate NF, including neurofibromas — tumors on, under, or hanging off the skin — and Lisch nodules, tiny, noncancerous tumors on the iris (the colored part of the eye). Lisch nodules are of no clinical significance except that they help confirm a diagnosis of NF.

Neurofibromas often become evident on various parts of the body, beginning at the arms, around 10 years of age. A child may also develop freckling in the folds of the skin of the armpit or groin or on other parts of the body where the skin creases.

Abnormalities of the skeleton, such as the thinning or overgrowth of the bones in the arms or lower leg, curvature of the spine (scoliosis), and other bone deformities also may be features of NF1.

NF2 is usually not diagnosed until a child is older. Hearing loss in the late teens and early twenties is often among the first symptoms of the disorder, and is caused by tumors growing on the auditory nerves (which carry electrical impulses from the inner ear to the brain, allowing us to hear) 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.

Diagnosis and Treatment

Neurofibromatosis is usually diagnosed based on a combination of findings. A child must have at least two of the following signs to be diagnosed with NF1:

• 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)
• Lisch nodules on the irises
• an optic glioma (tumor along the main nerve of the eye that is responsible for sight)
• certain skeletal abnormalities
• a family member with NF1
• freckling under the arms or in the groin

Tests like magnetic resonance imaging (MRI) and X-rays may be used to screen for tumors or evidence of skeletal problems. A child's head circumference will be measured, as kids with symptoms of NF can have a circumference that's larger than normal for their age. Blood pressure will be monitored. Doctors also take a detailed personal history, looking for signs of learning difficulties.

To diagnose NF2, doctors will check for any evidence of hearing loss. They'll order audiometry (hearing tests) as well as imaging tests to look for tumors in the nerves of the ears, spinal cord, or brain. They'll also determine if there's a family history of NF2.

Genetic testing is now available for people with a family history of either NF1 or NF2, though such testing is still not 100% sensitive. Amniocentesis or chorionic villus sampling can sometimes determine if an unborn child has the condition.