Definition

Charcot-Marie-Tooth (CMT) disease is a group of inherited disorders. It harms the nerves that control movement and feeling in the arms and legs. The disease gets worse over time.

CMT can be:

• Type 1—This type affects the coating of the nerve called the myelin sheath, causing nerve impulses to travel more slowly. It usually happens to children and teens. It is the most common type of CMT.
• Type 2—This type affects the part of the nerve called the axons. The speed of the nerves is normal, but the size or amount of impulses is less than normal. This type of CMT is less common. It happens after the teen years.
• Type 3—Also called Dejerine-Sottas disease, this is a rare, severe form of CMT. It is sometimes thought to be a subtype of CMT Type 1.
• Type 4—This is like Type 1, but often less severe. A person with it is less likely to pass it on to their children.

Causes

CMT is caused by changes in genes. In most people, the change is inherited. Some forms happen when only one copy of the abnormal gene is inherited. Other forms happen when both copies are inherited. Some other forms are inherited due to an abnormal x-linked chromosome.

Nerve Cell

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Risk Factors

The risk of this problem is higher in people who have family members with this disease.

Symptoms

The symptoms a person has depend on the type of CMT. Problems often start before age 30. The first sign is often a high arched foot or problems walking.

Other problems may be:

• Flexed toes
• A hard time holding the foot up in a horizontal position
• Slapping the feet on the floor when walking
• Muscle cramping and weakness in the legs that can spread to the arms later in life
• Decreased feeling in the feet and legs
• Problems with balance
• Type 3 symptoms:
  • Babies who learn to walk late due to weakness of the leg muscles closest to the trunk
  • Severe sensory problems
  • Problems hearing

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done.

Nerve and muscle function will be tested. This can be done with:

• Nerve conduction study
• Electromyogram (EMG)

Blood tests may be done to look for genetic problems.

Treatment

There is no cure. Treatment may help to reduce symptoms. Options are:

• Physical and occupational therapy
• Braces on the lower legs
• Shoe inserts to correct foot deformity
• Foot care and routine exams with a foot specialist
• Surgery

Prevention

There are no known guidelines to prevent this health problem.