What Is Charcot-Marie-Tooth Disease?

Learn About This Group of Disorders That Progressively Affect Your Nerves

Man with Leg Brace
Man with Leg Brace. Mary Turner / Stringer / Getty Images

Charcot-Marie-Tooth disease (CMT) represents a group of disorders that cause defects in the nerves of your arms and legs. These nerve defects can go on to cause muscle weakness, atrophy, and sensory loss.

Types of Charcot-Marie-Tooth Disease

There are several types of Charcot-Marie-Tooth (CMT) disease. In CMT Type 1 disorders, the disease affects the myelin sheath, the 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.

CMT is found worldwide, affecting people of all ethnic backgrounds. Around 150,000 people in the United States have CMT and 1 in 2,500 worldwide live with the condition. CMT was first described by researchers Jean-Marie Charcot, Pierre Marie, and Howard Henry Tooth in 1886, Charcot-Marie-Tooth is considered rare. CMT has at times been called peroneal muscular atrophy or hereditary motor and sensory neuropathies.

Most cases of Charcot-Marie-Tooth are passed on genetically, as a chromosomal defect. Approximately 15 percent of cases occur without any family history of it. The disease usually becomes apparent between the ages of 15 and 20.

What Are the Symptoms?

First signs of CMT are usually signaled by foot problems, this may include sprained ankles, tripping, or appearing clumsy.

As the disease progresses, the foot arches may become high and the toes curled. It can be difficult for people with CMT to lift up their feet. People with CMT may have to walk very carefully, bending their knee to lift their foot while they walk.

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. For example, one person may hardly notice any symptoms while the other has foot deformities and difficulty walking. People with CMT may be shorter in stature and have close-set eyes.

CMT does not, in most cases, affect other parts of the body like the brain or heart, Mental ability and life expectancy are both normal. The condition is not fatal, but there is no cure.

Approximately 15 percent 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. Severe cases of CMT may cause breathing difficulties as well.

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 can identify some types of CMT.

How Is CMT Treated?

Since there is 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.

Sources:

Muscular Dystrophy Association. Facts About Charcot-Marie-Tooth Disease (CMT).
Kedlaya, D. (2002). Charcot-Marie-Tooth disease. eMedicine.
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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