Charcot-Marie-Tooth disease

Definition

Charcot-Marie-Tooth disease is a group of inherited disorders that affect the peripheral nerves (those outside the brain and spine).

Alternative Names

Progressive neuropathic (peroneal) muscular atrophy; Hereditary peroneal nerve dysfunction; Neuropathy - peroneal (hereditary); Hereditary motor and sensory neuropathy

Causes, incidence, and risk factors

Charcot-Marie-Tooth is one of the most common inherited nerve-related disorders. Defects in at least 14 genes cause different forms of this disease.

The disease involves damage to the covering (myelin sheath) around nerve fibers. In some, the disease causes destruction of the myelin sheath. In others, the central (axon) portion of the nerve cell wears away.

Nerves that stimulate movement (the motor nerves) are most severely affected. The nerves in the legs are affected first and most severely.

Symptoms

Symptoms usually begin between mid-childhood and early adulthood. They may include:

• Foot deformity (very high arch to feet)
• Foot drop (inability to hold foot horizontal)
• Loss of lower leg muscle, which leads to skinny calves
• Numbness in the foot or leg
• "Slapping" gait (feet hit the floor hard when walking)
• Weakness of the hips, legs, or feet

Later, similar symptoms may appear in the arms and hands, which may include a claw-like hand deformity.

Signs and tests

A physical exam may show:

• Difficulty lifting up the foot and making toe-out movements
• Lack of stretch reflexes in the legs
• Loss of muscle control and atrophy (shrinking of the muscles) in the foot or leg
• Thickened nerve bundles under the skin of the legs

A muscle biopsy or nerve biopsy may confirm the diagnosis. Nerve conduction tests are often done to tell the difference between different forms of the disorder.

Genetic testing is available for most forms of the disease.

Treatment

There is no known cure. Orthopedic surgery or equipment (such as braces or orthopedic shoes) may make it easier to walk.

Physical and occupational therapy may help maintain muscle strength and improve independent functioning.

Expectations (prognosis)

Charcot-Marie-Tooth disease slowly gets worse. Some parts of the body may become numb, and pain can range from mild to severe. Eventually the disease may cause disability.

Complications

• Progressive inability to walk
• Progressive weakness
• Injury to areas of the body that have decreased sensation

Calling your health care provider

Call for an appointment with your health care provider if there is persistent weakness or decreased sensation in the feet or legs.

Prevention

Genetic counseling and testing is advised if there is a strong family history of the disorder.

References

Sarnat HB. Hereditary Motor-Sensory Neuropathies. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th Ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 612.