Charcot-Marie-Tooth Disease (Hereditary Motor and Sensor Neuropathy Peroneal Muscular Atrophy)

Overview

Charcot-Marie-Tooth Disease (CMT) also known as Hereditary Motor and Sensory Neuropathy or Peroneal Muscular Atrophy comprises a group of disorders caused by mutations in genes that affect the normal function of the peripheral nerves. The peripheral nerves lie outside the brain and spinal cord and supply the muscles and sensory organs in the limbs.

Charcot-Marie-Tooth Disease has nothing to do with the teeth. The disease is named for the three physicians who first identified it in 1886 - Jean-Martin Charcot Pierre Marie and Howard Henry Tooth. Today it is one of the most common inherited neurological disorders affecting approximately 1 in 2500 people in North America. CMT is not fatal and people with most forms of the disease have a normal life expectancy.

The condition is characterized by weakness of the foot and lower leg muscles which may result in foot drop and a high-stepped gait with frequent tripping or falls. Foot deformities such as high arches and hammertoes (a condition in which the middle joint of a toe bends upwards) are also characteristic due to weakness of the small muscles in the feet. In addition the lower legs may take on an "inverted champagne bottle" appearance due to the loss of muscle bulk. Later in the disease weakness and muscle atrophy may occur in the hands resulting in difficulty with fine motor skills. Some patients experience pain which can range from mild to severe.

Symptoms

Symptoms usually begin in late childhood or early adulthood and can vary:

  • Usually the initial symptom is foot drop due to involvement of the nerve that is responsible for raising the feet. This can also cause hammer toe where the toes are always curled
  • Wasting of muscle tissue of the lower parts of the legs may give rise to "stork leg" appearance
  • Weakness in the hands and forearms occurs in many people later in life as the disease progresses
  • Breathing can be affected in some; so can hearing vision and the neck and shoulder muscles
  • Scoliosis is common
  • Hip sockets can be malformed
  • Gastrointestinal problems can be part of CMT as can chewing swallowing and speaking (as vocal cords atrophy)
  • A tremor can develop as muscles waste
  • Pregnancy and emotional stress have been known to exacerbate CMT

Causes

CMT is caused by mutations in genes that produce proteins that are involved in the structure and function of either a peripheral nerve cell or the myelin sheath which insulates it. The gene mutations are usually inherited.

Treatment

There is no cure for CMT but physical therapy occupational therapy braces and other orthopedic devices as well as orthopedic surgery can help patients cope with the disabling symptoms of the disease. In addition pain-killing drugs can be prescribed for patients who have severe pain.