Charcot-Marie-Tooth disease (CMT) is a group of inherited disorders of the peripheral nervous system, the network of nerves that supply movement and sensation to the arms and legs. First described in 1886 by three physicians—Jean-Martin Charcot, Pierre Marie, and Howard Henry Tooth—CMT is one of the most common inherited neuropathies (diseases that affect nerve function). It is also known as hereditary motor and sensory neuropathy (HMSN)
What are peripheral nerves?
Peripheral nerves transmit messages about movement and sensation back and forth between the limbs (arms and legs) and the brain. When you want to move a muscle, your brain sends messages through motor nerves, which interact with muscle cells to stimulate muscles to contract. Sensory nerves relay messages to the brain when they detect sensations such as heat, cold, or pain. Peripheral nerves themselves lie outside the brain and spinal cord—messages reach the brain via nerves inside the spinal cord.
How does CMT affect peripheral nerves?
Charcot-Marie-Tooth disease occurs when a child inherits faulty genes that cause defects in peripheral nerves. The genetic mutation may directly damage the nerve cell (neuron) or may interfere with the formation of myelin, an insulating material that prevents the loss of electrical signals as they travel down long nerve fibers through the arms and legs. Damage to the neuron or myelin slows down the transmission of nerve signals— the signals prompting muscles to contract are weaker, and messages about pain or heat may be slower to reach the brain. Many different types of genetic mutations can cause CMT.
What are the main symptoms of CMT?
Abnormal transmission of nerve signals causes muscle weakness, loss of muscle tissue, and, if sensory nerves are affected, diminished sensation of heat, cold, or pain. Symptoms usually begin in the feet and legs—small, weak muscles make walking difficult– then may spread to hands and arms. Although the inherited defects of CMT are present from birth, symptoms may not appear until late adolescence or early adulthood. Symptoms gradually get worse with age, but life expectancy is normal.
Is there a cure for CMT?
Physical therapy can help strengthen and stretch muscles, occupational therapy can help people adapt to perform activities of daily living, and orthopedic devices, such as braces or special shoes, can help with walking. Surgery is sometimes needed to correct foot deformities, which often occur in CMT.
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