Symptoms:

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

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.

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.