Charcot-Marie-Tooth Disease

Charcot-Marie-Tooth Disease is an inherited condition which affects the peripheral nervous system (the nerves outside of the brain and spinal column). It can affect both the motor nerves (those that supply muscles and cause movement) and the sensory nerves (those that sense pain, temperature and pressure etc).

Symptoms of Charcot-Marie-Tooth Disease

There is a large variation in the symptoms of Charcot-Marie-Tooth Disease, including when the symptoms first appear and how rapidly the symptoms progress.

Common symptoms are listed here, with those which are usually early symptoms listed first:

  • Clumsiness.
  • Accident prone.
  • An awkward gait (walking pattern) - often with a high step.
  • Muscle weakness, especially in the lower legs and feet.
  • Hammer toes.
  • High foot arches (or sometimes flat feet)
  • Decreased sensations in arms and legs.
  • Joint pain.
  • Neuropathic pain.
  • Muscle wasting in the lower leg.
  • Muscle weakness spreads to the arms/hands.
  • Difficulty with fine control tasks such as doing up buttons.
  • Scoliosis.

Charcot-Marie-Tooth (CMT) Disease affects up to one in every 2500 people, with men and women inheriting the disease equally. It is a progressive condition, with the symptoms usually starting in the teens or early twenties and gradually get worse with age.

There are several different types of CMT, which are determined by various mutations of the affected genes. The genes in question produce the proteins which make up the two components of the nerves. These are the Axon (the 'electrical wire' which transmits the nerve impulse) and the myelin sheath (the insulating layer which covers and protects the axon) .

The most common form (CMT 1) causes the myelin sheath to break down, leaving the axon exposed to damage and slowing nerve impulses. CMT 2 is the second most common which affects the axon itself, resulting in a reduced strength impulse.

There is no single gene mutation which causes the disease which explains why there are several different types. The mutated genes can also be inherited in different ways. Sometimes one copy of the mutated gene is enough to cause the condition. In other cases, a mutated gene must be passed on from both the mother and father.

In X-linked inheritance, the affected gene is located on the X chromosome of the mother who shows little or no symptoms because the other healthy X chromosome overrides the mutated one. When a son is born, there is a 50% chance that the mutated gene will be passed on. As males have an X and a Y chromosome, there is no other X chromosome to counteract the effects.

Diagnosis

A doctor will go through your symptoms, medical history and families medical history. They will then examine you for signs of the condition, such as muscle wasting or foot deformities.

If CMT is suspected then you may be referred to a neurologist who may perform tests including EMG (electromyography), Nerve conduction studies, nerve biopsies and genetic testing.

Pre-natal testing is also available for those who have the condition (or know they are a carrier) and are expecting a baby, to determine if the baby is likely to have CMT too.

Treatment

Currently there is no cure of Charcot-Marie-Tooth Disease. Treatment is aimed at slowing the progression of the disease, managing the symptoms and regular monitoring of the patients condition.

Usually a multi-disciplinary test will handle the patients treatment. This team will include the Doctor who oversee's all treatment, as well as possibly a Physiotherapist, Occupational therapist, Podiatrist, Neurologist and Orthopedic surgeon.

Physiotherapy may be used to retain muscular strength and flexibility via a rehabilitation programme involving resistance, stretching and balance exercises. An occupational therapist can assist with making daily living easier by teaching the patient to use adaptive aids such as magnetic tubes to pick items up.

A podiatrist specialises in feet and orthotics and so may be involved to assess the patients feet and make some custom orthotics which can be worn in the shoes to make walking easier.

An orthopedic surgeon is only required as a last resort in the most serious of cases. Foot surgery is by far the most common reason for surgery. Various procedures are used depending on the specific problem, but Osteotomy and Arthrodesis are amongst the most common. These procedures are used to correct severely fallen arches (flat feet).