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 diseases involve damage to nerves (neuropathy), usually from loss of the electrical insulation (myelin ) around nerve fibers. All nerves are affected, but motor nerves (the nerves that stimulate movement) are most severely affected.

The nerves in the legs are affected first and most severely. Symptoms usually begin between mid-childhood and early adulthood. The disorder is inherited, with autosomal dominant, autosomal recessive as well as X-linked recessive inheritance patterns. At least�4 genes have been discovered to be the cause of this group of diseases.

Charcot-Marie-Tooth disease causes destruction of the myelin sheath in some people. In other people, the central (axon) portion of the nerve cell degenerates.

The disorder most commonly affects the nerves to the feet and legs, most significantly the peroneal nerve. The damage is slowly progressive, usually beginning with foot drop and progressing up the legs. There is a loss of muscle control and muscle tone, and eventual loss of muscle mass caused by lack of nervous stimulation to the muscles.

Symptoms:

• Weakness (decreased muscle strength) of the hips, legs, or feet
• "Slapping" gait (the feet hit the floor hard when walking)
• Foot drop (inability to hold foot horizontal)
• Foot deformity (very high arch to feet)
• Progressive leg deformity
• "Stork leg" appearance (loss of lower leg muscle mass leading to skinny calves)
• Numbness in the foot or leg

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

Signs and tests:

An examination by touch may reveal thickened nerve bundles under the skin of the legs in the demyelinating form of Charcot-Marie-Tooth disease. The stretch reflexes in the legs are absent. There is loss of muscle control and atrophy in the foot or leg. There is difficulty with lifting up the foot (dorsiflexion) and with toe-out movements (eversion).

• A muscle biopsy or nerve biopsy may confirm the diagnosis.
• Nerve conduction tests are often performed to distinguish axonal from demyelinating forms of the disorder.
• Genetic testing is available for most forms of the disease.

Treatment:

There is no known cure for Charcot-Marie-Tooth disease. Treatment is aimed at maximizing independence. Orthopedic surgery or equipment (such as braces or orthopedic shoes) may make it easier to walk.

Vocational counseling, occupational therapy, or physical therapy may be appropriate for some people to help maintain muscle strength and maximize independent functioning.

Support Groups:

Expectations (prognosis):

Charcot-Marie-Tooth disease is slowly progressive, eventually causing disability. It is not life-threatening. It is not usually painful, but there may be numbness in the area.

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.