Neurofibromatosis

What is Neurofibromatosis?
Neurofibromatosis (NF) is a set of inherited disorders that can affect many tissues in the body. NF causes tumors to grow along some of the nerves in the body and can affect the development of bone. These tumors can grow anywhere on the body. Patients with NF have a higher incidence of learning disabilities than the general population. As with all genetic conditions, there is great variability between patients with NF. Some have severe involvement while others may not be aware that they carry the condition.

What are the types of Neurofibromatosis?
Type 1 or NF1 occurs in 1 of 4,000 births and is characterized by multiple café au lait spots (birth marks) and the presence of neurofibroma (small tumors) under the skin. In some cases, bones may be enlarged or abnormally developed. Spinal deformity is the most common skeletal sign. Tumors may develop in the brain or spinal cord. Learning disability is seen in one half of NF1 patients.

Type 2 or NF2 occurs less frequently in about 1 of 40,000 births and is associated with tumors in the brain and spinal cord. Hearing loss is often the first symptom and occurs in the teens or early twenties.

NF1 is the type most likely to be seen in Orthopaedic offices. Some of the physical signs we will notice are the skin lesions described below. If we suspect NF, we will refer your child to a Geneticist and a Pediatric Neurologist for further evaluation and diagnosis testing.

What are some of the clinical findings in Neurofibromatosis?

1. Café au lait spots are smooth areas of skin that are darker than the surrounding areas of skin. Ten percent of the general population has up to two café au lait spots. However, patients with NF will have six or more such lesions. The size of these spots varies from 5 mm in children to 15mm in adults. These spots are different than freckles in that they are usually very small and increase with sun exposure. Patients with NF do have abnormal freckling under the arms and in the skin creases of the groin.
   
2. Neurofibromas are the most common tumor in NF. These are benign growths, which develop under the skin at the time of puberty. They may increase in size and number throughout life. While a single neurofibroma may occur in the normal population, patients with NF typically have numerous lesions.
   
3. Iris nevi (Lisch nodules) are areas of pigment accumulation on the iris (the colored part of the eye). An Ophthalmologist may be involved for this evaluation.
   
4. The most common skeletal manifestation of NF is scoliosis and kyphosis. Scoliosis is side-to-side curvature of the spine as you look at a person from the front or back. Kyphosis is forward curvature of the spine as the patient is viewed from the side. These types of spine deformities can be quite severe and require close monitoring. There are specific characteristics of spine deformities associated with NF, though patients with NF may have scoliosis like that found in the general population. Special studies such as an MRI are often done in conjunction with plain x-rays to evaluation the spine and spinal cord. If the spinal curve is increasing, surgery may be required. The goal is to prevent the development of a more severe deformity.
   
5. In addition, patients may have an enlarged limb or part of a limb such as a toe. Treatment varies widely with this type of problem and is based on the severity and whether the condition is interfering with normal function.
   
6. Congenital Pseudarthrosis of bones is also associated with NF. The condition may affect the tibia (shin bone) or the bones of the forearm. This is an unsolved problem in Orthopaedic Surgery. The fundamental problem is that the bone does not develop or grow normally. The most difficult aspect of its management is helping these bones to heal, since they don’t grow normally. When this problem is identified in the tibia (leg), a brace is advised to protect the bone from fracture. Unfortunately, even braces do not prevent some patients from breaking their bones. When a fracture occurs, surgery is usally necessary to help the bone to heal.

More information:
The National NF Foundation: http://www.nf.org
Neurofibromatosis Inc: http://www.nfinc.org
Medline Health Information: http://www.nlm.nih.gov/medlineplus/neurofibromatosis.html