Charcot-Marie-Tooth Disease (CMT)

Charcot-Marie-Tooth (CMT) disease is an inherited nerve problem. It causes abnormalities in the nerves that supply your feet, legs, hands, and arms. It affects both your motor and sensory nerves. Motor nerves carry signals from your brain to your muscles, telling them to move. Sensory nerves carry sensations, such as heat, cold, and pain back to your brain. CMT is considered a peripheral neuropathy because it affects nerves outside of your brain and spinal cord.

This disease is named after the 3 doctors who first described the disease in 1886. It is one of the most common types of inherited nerve diseases.

CMT is almost always caused by a gene problem inherited from one or both parents. The genetic information that one or both of your parents passes on to you determines the type of gene change (mutation) you have. This gene mutation determines what symptoms you have and how old you are when they start. There are more than 30 known genetic causes of CMT. The exact cause of many more forms has yet to be identified.

Some genetic problems affect the axon. This is the part of the nerve that sends signals to other nerves. Other genetic problems affect the protective lining around the axon (myelin sheath). Either type of problem can lead to long-term damage of the nerve and affect its ability to send signals.

CMT symptoms may vary from person to person, though they usually start in your feet and legs. Over time, the disease may also affect your hands and arms. Symptoms usually first appear in teens and young adults.

Common symptoms include:

• Weakness of your foot and lower leg muscles.
• Foot deformities, including a high arch and bent toes (hammer toes).
• Difficulty lifting your foot while walking (foot drop).
• Loss of muscle around your hands and feet.
• Numbness, tingling, burning, or loss of temperature sensation in your hands and feet.
• Discomfort or pain in your hands and feet.

A specialist called a neurologist may diagnose CMT after doing a complete nervous system exam and asking about your family history. Tests that help make the diagnosis include:

• A blood test to look for genetic problems.
• Nerve conduction studies to measure the strength and speed of electrical signals passing through your nerves.
• Electromyography to measure how well your nerves communicate with your muscles.
• Nerve biopsy. This means taking a small piece of a nerve and looking at it under a microscope. This is often done if blood work can't find the genetic cause of the symptoms.

If you have no family history of this disease, your healthcare provider may consider looking for other causes of your symptoms.

There is no cure for CMT. But these treatments can help:

• Physical therapy to strengthen and stretch your muscles. This may help prevent or delay disability caused by weakness and deformity.
• Occupational therapy to help with your daily activities. This includes using special devices like rubber grips, or changing from buttons and zippers to Velcro.
• Orthopedic devices like ankle braces, high-top boots, and thumb splints.
• Pain medicines if needed.

CMT is not a fatal disease. Most people with it live to a normal age and remain active. In rare cases, it may affect the muscles you need to breathe. Because this can be especially dangerous at night, you may need a nighttime breathing assistive device.

More common complications are:

• Injuries from falls.
• Worsening of the disease that certain medicines can cause.
• Injuries or infections of the feet that go unnoticed because of lack of pain and temperature sensation.

It is very important to learn as much as you can about your disease. Work closely with your neurologist. Genetic counseling may be important for family planning. Other ways to manage your disease include:

• Getting regular low-impact aerobic exercise.
• Not drinking alcohol except in moderation.
• Eating a healthy diet and staying at a healthy weight.
• Checking your feet regularly for any injury or infection.
• Checking with your healthcare provider before taking any new medicines. Certain medicines can make your symptoms worse.

Call your healthcare provider if you have:

• Any new or worsening symptoms.
• Signs of foot injury or infection.
• Trouble breathing.