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Charcot-Marie-Tooth Disease

Peripheral nerve disorders

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Updated May 03, 2004

Imagine that it's hard for you to lift up your feet, hold a pen, or keep your balance, and you'll have an idea of what life with Charcot-Marie-Tooth disease (CMT) is like. Although it is found worldwide, in people of all ethnic backgrounds, Charcot-Marie-Tooth is still considered rare. First described by researchers Jean-Marie Charcot, Pierre Marie, and Howard Henry Tooth in 1886, CMT is an inherited defect in the nerves that control the muscles of the hands, feet, and legs. CMT has at times been called peroneal muscular atrophy or hereditary motor and sensory neuropathies.

What is it?
Charcot-Marie-Tooth disease refers to a group of disorders with similar symptoms. In CMT Type 1 disorders, the disease affects the myelin sheath, or insulating covering of the nerves. In CMT Type 2 disorders, the nerves themselves are affected. CMT Type 3 (Dejerine-Sottas disease), CMT Type 4, and CMT X, like Type 1, affect the myelin sheath.

Who gets it?
Charcot-Marie-Tooth disorders are passed on genetically as a chromosome defect in most cases. Sometimes (15% of cases) the disease occurs without any family history of it. The disease usually becomes apparent during ages 10-20.

What are the symptoms?
Usually the first signs of CMT are that the child or teenager has problems with his feet. He may have ankle sprains, tripping, or appear clumsy. As the disease progresses, the foot arches may become high and the toes curled. It can be difficult for him to lift up his feet, so he may have trouble with steps, walk very carefully, and bend his knee to lift his foot while he walks.

Hand weakness may begin with trouble with writing or using zippers or buttons. Pain and muscle cramping may develop.

Even among members of the same family the severity of CMT may vary. Father and daughter may both be affected, for example, but one may hardly notice the effects while the other has foot deformities and difficulty walking.

CMT does not, in most cases, affect other parts of the body, like the brain or heart, so neither mental ability nor life expectancy is changed. It is not fatal, but there is no cure.

However, approximately 15% of individuals with CMT have a form of the disorder linked to the X chromosome (called CMTX). Studies have shown that individuals with CMTX may have transient central nervous system symptoms in addition to the more common symptoms.

How is CMT diagnosed?
If the physician suspects CMT because of hand, leg, and foot weakness, special tests of the nerves (nerve conduction velocity, or NCV) and the muscles (electromyogram, or EMG) can be done to confirm the diagnosis. Special genetic tests are available to identify some types of CMT.

How is it treated?
Since there is at this point no cure or way to slow down the disease process, treatment is focused on relieving the symptoms. Leg braces and special shoes may help with walking, as will physical therapy. Sometimes foot surgery (osteotomy or arthrodesis) may be necessary to correct deformed feet. Medication can be given to relieve muscle pain and cramping.

What is the future for research?
Some of the genes which cause types of CMT have been identified; others remain a mystery. Like other genetic diseases, the hope remains that once the genes are identified researchers will be able to correct the genetic defects. Muscular dystrophy associations around the world are among the many groups supporting research on CMT.

Information for this article was taken from:
- Muscular Dystrophy Association. Facts About Charcot-Marie-Tooth Disease (CMT).
- Kedlaya, D. (2002). Charcot-Marie-Tooth disease. eMedicine, accessed at http://www.emedicine.com/pmr/topic29.htm
- National Institute for Neurological Disorders and Stroke. Charcot-Marie-Tooth Disorder Information Page.
- Zwipp, H., Rammelt, S., Dahlen, C., & Reichmann, H. (1999). The Charcot joint. Orthopade, 28(6), 550-558.

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