Charcot-Marie-Tooth disease (hereditary)

Charcot-Marie-Tooth disease (hereditary)

Definition:

Charcot-Marie-Tooth disease defines a group of slowly progressive, inherited disorders that result from progressive damage to nerves. In addition to loss of sensation, there is wasting of muscle tissue in the feet and legs, then hands and arms.

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 demyelination or loss of the electrical insulation around nerve fibers. All nerves are affected, but motor nerves are disproportionately so.

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 and recessive as well as X-linked recessive inheritance patterns. At least four genes have been discovered to be the cause of this group of diseases.

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

The disorder most commonly affects the nerve cells 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, loss of muscle tone, and eventual loss of muscle mass caused by lack of nervous stimulation to the muscles.

Symptoms:

Weakness (decreased muscle strength, independent of exercise) of the hips, legs, or feet
"Slapping" gait (walking pattern -- when walking the feet hit the floor hard)
Foot drop (unable to hold foot horizontal)
Foot deformity (exagerated arch to feet)
Progressive leg deformity
"Stork leg" appearance (loss of lower leg muscle mass leading to skinny ankles)
Decreased sensation or numbness in the foot or leg

Note: Later, similar symptoms may appear in the arms and hands. This includes hand deformities (the hand develops a claw-like shape).

Signs and tests:

An examination of the skin by touch (palpation) may reveal thickened nerve bundles under the skin in the demyelinating form of the disorder. The stretch reflexes in the legs are absent. There is loss of muscle control and atrophy (loss of muscle mass) 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 maximize the ability to walk.

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

Expectations (prognosis):

Charcot-Marie-Tooth disease is slowly progressive, causing eventual disability. It does not shorten the expected life span. It is not usually painful, but sensation may decrease in the area.

Complications:

Progressive decrease in the ability to walk
Progressive weakness
Injury to areas of the body that have decreased sensation (insensate regions)

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.

Review Date: 8/6/2001
Reviewed By: David G. Brooks, M.D., Ph.D., Division of Medical Genetics, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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