Charcot-Marie-Tooth disease (CMT) is a group of conditions also known as hereditary motor and sensory neuropathy. CMT develops because of a defective gene that causes abnormalities in the nerves that supply your feet, legs, hands, and arms. CMT, which is named after the three doctors who first described the disease in 1886, affects about one of every 2,500 Americans. It is one of the most common types of inherited nerve diseases. CMT is considered a peripheral neuropathy because it affects nerves outside of your brain and spinal cord.
CMT 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 symptoms can include both weakness and numbness.
Because CMT consists of more than one disorder, symptoms may vary from person to person, though they usually start in your feet and legs. Over time, CMT may also affect your hands and arms.
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
Depending on the specific type of genetic defect you have, CMT may affect the part of the nerve, called the axon, that sends signals to other nerves. CMT may also affect the protective lining around a nerve, called the myelin sheath. CMT can affect both men and women.
Who's at risk
Many types of gene mutations can cause CMT. The genetic information that one or both of your parents passes on to you determines the type of gene mutation you have. This genetic inheritance and resulting gene mutation determine what symptoms you have and how old you are when they start.
The combination of a foot deformity and lower leg weakness is often the first sign of CMT. A specialist called a neurologist may diagnose CMT after doing a complete neurological exam and asking about your family history. Tests that help make the diagnosis include:
A blood test to look for genetic defects
Nerve conduction studies to measure the strength and speed of electrical signals passing through your nerves
Electromyography to measure how well your muscles respond to electrical stimulation
Nerve biopsy, which involves taking a small piece of a nerve and examining it under a microscope
There's no cure for CMT, but these treatment options 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 medications if needed
CMT is not a fatal disease, and most people live to a normal age and remain active. In rare cases, CMT 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 include:
Injuries from falls
Worsening of the disease that certain prescription drugs can cause
Injuries or infections of the feet that go unnoticed because of lack of pain and temperature sensation
There is no way to prevent CMT.
How to manage or live with CMT
Learn as much as you can about your disease, and 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
Avoiding alcohol except in moderation
Eating a healthy diet and maintaining a healthy weight
Checking your feet regularly for any injury or infection
Telling your doctor about any new prescription drugs
Calling your doctor if you have any new symptoms, signs of foot injury or infection, or difficulty breathing