Charcot-Marie-Tooth (CMT): Symptoms, causes, types, treatment, and outlook

Charcot-Marie-Tooth disease is a genetic condition of the nerves that affects 1 in 2,500 people in the United States. People with this condition experience muscle weakness, particularly in the arms and legs.

Charcot-Marie-Tooth (CMT) affects the peripheral nerves. These are the nerves outside the main central nervous system (CNS). They control the muscles and relay data from the arms and legs to the brain, allowing a person to sense touch. It is a progressive condition, which means that symptoms get worse over time.

CMT is also known as Charcot-Marie-Tooth hereditary neuropathy, peroneal muscular atrophy, or hereditary motor and sensory neuropathy. Its name comes from the three physicians who first described it: Jean Charcot, Pierre Marie, and Howard Henry Tooth.

Most people with CMT will have a normal lifespan.

Fast facts about Charcot-Marie-Tooth

The impact it will have depends on the type and how severe it is.

Charcot-Marie-Tooth (CMT) is a neurological condition.

It leads to muscle wasting, especially in the lower legs.

It tends to run in families.

The impact it will have depends on the type and how severe it is.

Symptoms

Hand weakness
Hand weakness can be a symptom of CMT.

Symptoms often appear in adolescence or early adulthood.

Key symptoms include:

Weakness and eventual wasting of muscles in the foot, lower leg, hand, and forearm

Loss of sensation in the fingers, toes, and limbs

Other symptoms may include:

abormalities in the muscles of the feet, leading to high arches and hammer toes

difficulty using the hands

unstable ankles and problems with balance

cramping in the lower legs and forearms

some vision and hearing loss

scoliosis

reduced reflexes

Symptoms and their severity may vary considerably between individuals, even among close relatives who have inherited the condition.

In the early stages, people might not know that they have CMT, because the symptoms are so mild.

Symptoms in children

If symptoms appear during childhood the child may:

be clumsier than their peers and more prone to accidents

have an unusual gait, as it is hard to lift their feet off the ground with each step

have feet that drop forward as they lift their feet

Other symptoms often appear as the child finishes puberty and enters adulthood, but they can emerge at any age, from very young to the late 70s.

In time, the leg may change shape, becoming very thin below the knee, while the thighs retain their normal muscle volume and shape.

Symptoms tend to worsen over time, and there may be:

growing weakness in the hands and arms

increased difficulty in using the hands, for example, to do up buttons or open jars and bottle tops

muscle and joint pain, as problems with walking and posture place a strain on the body

neuropathic pain due to damaged nerves

walking and mobility problems, especially in older people

Assistive devices may include a wheelchair, a leg brace, special shoes, or other orthopedic devices.

Causes

CMT is hereditary, so people who have close family members with CMT have a higher risk of developing it.

It affects the peripheral nerves. A peripheral nerve consists of two main parts, the axon, which is the inside of the nerve, and the myelin sheath, which is the protective layer around the axon.

CMT can affect the axon, the myelin sheath, or both, depending on the type of CMT.

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Types

There are many types of CMT. Here are the main forms.

CMT 1 accounts for about 1 in 3 cases. Symptoms often appear between the ages of 5 and 25 years. Faulty, genes cause the myelin sheath to disintegrate. As the sheath wastes away, eventually the axon becomes damaged and the patient’s muscles no longer receive clear messages from the brain. This results in muscle weakness and loss of sensation, or numbness. Fewer than 1 in 20 people will need a wheelchair.

Subtypes of CMT1 include CMT1A and CMT1B. They are caused by different genetic changes, and symptoms can vary.

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