What is Charcot-Marie-Tooth Disease?

Charcot-Marie-Tooth Disease or CMT is one of the most common inherited neurological disorders. It is caused by an inherited genetic mutation. In rare cases a mutation occurs spontaneously within an egg or sperm. Charcot, Marie and Tooth are the names of the physicians who identified the disease and described its symptoms. CMT is also known as Hereditary Motor and Sensory neuropathy or HMSN and peroneal muscular atrophy. There are about 125,000 CMT patients in the United States. CMT is not the same as Charcot Foot Disease, which is a complication of diabetes mellitus.

CMT is a group of disorders that are caused by mutations in genes that affect the normal function of the peripheral nerves. The peripheral nerves are located outside the brain and the spinal cord. They supply the muscles and the sensory organs in the limbs. Onset is usually in the first two decades of life.

CMT has wide variety of symptoms that include a high arched foot, gait disturbances, foot bone abnormalities, hammer toes, problems with hand function, balance problems, occasional lower leg cramping, occasional forearm muscle cramping, loss of reflexes, muscle degeneration in foot, lower leg, hand and forearm, mild loss of sensation in limbs, fingers and toes, occasional partial sight loss, hearing loss, scoliosis, weak feet muscles, difficulty holding foot up, difficulty walking on heels and reduced temperature sensitivity in the lower legs and feet. Occasionally sensorineural hearing loss occurs. Autonomic symptoms are usually absent, but a few men have reported impotence.

There are several methods used to diagnose CMT. These methods include a neurological examination, nerve conductions studies, electromyography, a nerve biopsy and genetic tests.

A neurological examination is performed to look for signs of muscle weakness in the arms, legs, hands and feet, decreased muscle bulk, reduced reflexes and sensory loss. During the neurological examination the doctor also looks for signs of foot deformities such as high arches and flat feet.

Nerve conduction studies are done to measure the strength and speed of electrical signals that are transmitted through the nerves. Electrodes are place on the skin over the peripheral or the sensory nerve. The electrodes produce a small electric shock and it stimulates the nerve. A delayed or weak response is an indication of a nerve disorder like CMT.

Electromyography (EMG) is done by inserting a thin-needle electrode through the skin into the muscle. The electrical activity is measured during relaxation and while tightening the muscle. Changes in the pattern of electrical activity can confirm CMT.

A nerve biopsy is performed by taking a small piece of the peripheral nerve from the calf of the leg. The lab tests will confirm CMT.

Genetic tests are done by blood samples and this will produce a definite diagnosis. Patients usually have a significant family history of CMT.

The treatment of CMT depends on the severity of symptoms. Making the patient comfortable and increasing their ability to perform daily activities is the goal. Treatment options include orthotics, custom-made shoes, physical therapy and surgery. Orthotics will improve mobility and gait. They also provide support and decrease the risk of injury. Custom-made shoes improve gait and they also redistribute the weight of the body on the foot. Physical therapy maintains muscle strength in the affected limbs. Surgery provides stability and support by fusing the bones.

Deformities and walking problems can create lifelong disabilities. Longevity and mental function are not often affected and most people with CMT lead productive lives.