Neurofibromatosis (NF) is the name given to two different conditions. Neurofibromatosis type 1 (also called von Recklinghaus disease) is a condition that affects the skin, eyes, kidneys, and many other parts of the body. Neurofibromatosis type 2 (also called bilateral acoustic neurofibromatosis) mainly affects hearing and the central nervous system. Neurofibromatosis Type 1 is ten times more common than Type 2, and it affects about 1 out of 4,000 live births. Boys and girls are equally likely to have either of these conditions.
What is Neurofibromatosis Type 1?
Neurofibromatosis I is a hereditary condition usually passed from parent to child (autosomal dominant), but in about half the people with Neurofibromatosis 1, there is no history of the disease in the family. If the parents of a child with Neurofibromatosis Type 1 do not have the disease, then any other children they have are not at increased risk of the disease. But the children of a person with Neurofibromatosis I stands a 50-50 chance of getting the disease from that parent.
The most common feature of Neurofibromatosis I are skin lesions called a cafe au lait spots. These are flat, smooth, medium to light brown irregularly shaped spots than can occur anywhere on the skin. Many people have one or two cafe au lait spots, and these are often called birth marks. If a child has six or more cafe au lait spots measuring at least half a centimeter (about a 1/4 of an inch), then he should be carefully followed to see if he develops any more signs of Neurofibromatosis I. A second skin finding is axillary freckling. What makes these axillary freckles different in Neurofibromatosis Type 1 is that they occur in places not usually exposed to the sun like the armpit (axilla) and groin.
After the age of three years, many children will develop Lisch nodules in their irises (the colored part of the eye). These can be detected by an ophthalmologist using a special piece of equipment called a slit lamp. These growths do not affect vision.
Another finding is called a neurofibroma, a soft fleshy growth (or tumor) just under the skin, but a neurofibroma can be deeper in the body. A neurofibroma can be large and have many finger like projections in which case it is called a plexiform neurofibroma. Most people with Neurofibromatosis do not develop neurofibromas until puberty. Because a neurofibroma can occur anywhere in the body, there are many possible complications from them. Sometimes these tumors can become malignant (cancerous) or they can affect vital organs. One complication is the development of a tumor along the nerve going to the eye. This is called an optic glioma and can lead to blindness, unlike the Lisch nodule. Although many people without NF may have a neurofibroma, they usually do not have many.
Another sign of Neurofibromatosis I can be certain deformities of the bone. For example, there can curvature of the spine (scoliosis) or an enlargement of a bone in the arms or legs leading to a leg length discrepancy. Other bony defects can be bowed legs and thinning or absence of the bones forming the eye socket. A large head is also sometimes associated with Neurofibromatosis I.
Finally, about half the people with Neurofibromatosis I have learning disabilities that can range from mild to severe. Learning disabilities are about five times more common in people with Neurofibromatosis I than in those without the disease.
How is Neurofibromatosis Type 1 Diagnosed?
Doctors look for the features mentioned above like café au lait spots, neurofibromas, Lisch nodules, and bony deformities. If there is a parent with Neurofibromatosis Type I and the child has at least one of the findings above that suggest Neurofibromatosis I, then the diagnosis can be made. If the parent does not have Neurofibromatosis I, then the doctor will look for a least two of the above findings. Because the various features do not develop at the same time, the doctor must periodically reexamine the child for new findings. If the child reaches adulthood without meeting the criteria for Neurofibromatosis Type I, then she probably does not have the disease. If there is a family history of Neurofibromatosis I, genetics testing can be performed.
What treatments are available?
For most of the features, like café au lait spots and Lisch nodules, no treatments may be needed. Because some people with Neurofibromatosis Type I can have a disfigurement from a neurofibroma if it is particularly large or numerous, surgery can be performed to remove these tumors. The tumors have a tendency to come back, however. Sometimes the tumors are in such a place that they cannot be removed. Currently there are several research projects about treatments using drugs to stop or slow the growth of a neurofibroma. Doctors will also want to keep track of the patient's growth, physical and mental development, blood pressure, vision and hearing.
What is Neurofibromatosis Type 2?
Neurofibromatosis Type 2 is a rare, hereditary disorder that is similar to Neurofibromatosis I in that it involves tumors along the nerves. Neurofibromatosis Type 2 is also an autosomal dominant disorder meaning it is passed from parent to child, but the gene that causes Neurofibromatosis II is different than the one that causes Neurofibromatosis I. Also, just like Neurofibromatosis I, about half the people with Neurofibromatosis II do not have a history of the disease in either parent.
In Neurofibromatosis II, there are not as many physical signs of the disease. Therefore, people with Neurofibromatosis II do not have multiple café au lait spots, Lisch nodules or bony deformities. They may have a few café au lait spots, however. What people with Neurofibromatosis II do have is a kind of tumor called a neuroma or schwannoma. These tumors affect the nerves that are responsible for hearing and balance. The first sign of the disease is often ringing in the ears (tinnitus), hearing loss, or difficulty with balance when a person is in her teens or twenties. Although only one ear may be affected initally, eventually both ears will be affected in most people. About 90% of people with Neurofibromatosis II will develop these tumors in their lifetimes.
In Neurofibromatosis II, these tumors can occur anywhere in the body. In addition to schwannomas, patients with Neurofibromatosis II are at risk for other types of tumors called gliomas and meningiomas that are found in the brain. These tumors are usually not cancerous in that they are not likely to spread to other parts of the body, but they can cause significant problems depending on where they are located. People with NF II are also at risk for a particular kind of cataract that make one's vision cloudy or dim.
How is Neurofibromatosis II Diagnosed?
Just like in Neurofibromatosis I, the diagnosis is easier to make if there is a family history of Neurofibromatosis II. If a person has just one schwannoma affecting the nerves to the ear and he has a parent with Neurofibromatosis II, then the diagnosis can be made. For someone who does not have a family history of Neurofibromatosis II, then the diagnosis requires at least two tumors associated with the disease or one kind of tumor and the certain kind of cataract. If doctors suspect Neurofibromatosis II, there is a direct genetic test than can be done. Recently researchers interested in both types of Neurofibromatosis have suggested updating the criteria doctors used to diagnosed these two diseases, but these updated methods have not gained widespread use yet.
What are treatments for Neurofibromatosis II?
Treatments involve surgery, radiation therapy or both for the tumors. The type of treatments depend on the nature and location of the tumor. Cataract surgery is also available. For a child with a parent with Neurofibromatosis II, periodic hearing tests even into adolescence and young adulthood are recommended.
Neurofibromatosis Reading List:
In association with amazon.com, these books can help you to learn more and become better educated about your child's condition, its treatment and preventing complications.
Neurofibromatosis Web Resources:
- National Neurofibromatosis Foundation: a nonprofit medical foundation, dedicated to improving the health and well being of individuals and families affected by the Neurofibromatosis.
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