Charcot Marie Tooth Disease

What are other Names for this Condition? (Also known as/Symptoms)

• Charcot-Marie Atrophy
• CMT (Charcot-Marie-Tooth Disease)
• Hereditary Motor and Sensory Neuropathy (HMSN)

What is Charcot Marie Tooth Disease? (Definition/Background Information)

• Charcot Marie Tooth Disease (CMT) is a group of hereditary disorders that target the peripheral nerves; the nerves that communicate signals from the brain and spinal cord to the muscles and sensory organs in the arms and legs
• The characteristic signs and symptoms of CMT include muscle weakness, decreased muscle bulk in the legs and feet, decreased sensation, and frequent tripping or falling down
• Mutations in the genes responsible for the structure and function of the peripheral nerves can lead to Charcot Marie Tooth Disease, which has many forms of the disease. Each type of CMT results from different abnormal proteins being produced
• Even though CMT is a progressively degenerating condition, with suitable treatment measures including physical and occupational therapy, and even surgery, individuals are able to cope with the muscular weaknesses that affect their limbs

Who gets Charcot Marie Tooth Disease? (Age and Sex Distribution)

• Charcot Marie Tooth Disease is a hereditary disorder; but, the symptoms of this disorder typically arise in adolescence or early adulthood
• In some individuals, the onset of the disease may occur during mid-adulthood
• Both males and females are affected; no gender preference is observed
• All races and ethnic groups are at risk

What are the Risk Factors for Charcot Marie Tooth Disease? (Predisposing Factors)

• The risk factor for Charcot Marie Tooth Disease is a positive family history. Since, CMT is a hereditary disorder, an individual has a higher chance of developing the condition, if any individual in their immediate family has the condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Charcot Marie Tooth Disease? (Etiology)

• Charcot Marie Tooth Disease (CMT) is caused by mutations
  • In genes that produce proteins involved with the structure and function of the peripheral nerve axon - fibers that carry electrical signals between the brain and spinal cord and the rest of the body
  • Or, in genes for proteins that form the myelin sheath, which is the protective membrane covering the nerve axon
• Over 30 defective genes have been found to cause Charcot Marie Tooth Disease; each one linked to a particular type of CMT
• Some genetic defects cause damage to the nerve itself; others affect the myelin sheath - in both cases, the peripheral nerves do not function normally, and signals transmitted by the nerves are weakened or are slow in movement
• As a result, these nerves degenerate, losing their ability to activate their target muscles. Some muscles in the legs and feet may not receive the brain’s messages, leading to weakened muscles

What are the Signs and Symptoms of Charcot Marie Tooth Disease?

The signs and symptoms of Charcot Marie Tooth Disease may include:

• Weakness in the legs, ankles, and feet
• Decreased muscle bulk in legs and feet
• Foot deformities, including high foot arches
• Curled toes (hammertoes)
• Foot drop, or inability to lift foot at the ankle
• “Slapping” gait or higher than normal step (feet hitting the floor hard)
• Numbness or decreased sensation in legs or feet
• Frequent tripping or falling

How is Charcot Marie Tooth Disease Diagnosed?

The following tests and exams may be conducted to diagnose Charcot Marie Tooth Disease:

• Physical examination with complete medical history evaluation
• Nerve conduction studies are used to examine the speed and strength of electrical signals carried by nerves in the arms and legs. Electrodes are placed on the skin to send small electric shocks, stimulating the nerves within the arms and legs. Delayed or weak responses may indicate some type of neurological disorder
• Electromyography (EMG) involves inserting a thin needle electrode through the skin and into the muscle. The electrical activity is then measured as the muscle is relaxed and tightened
• In a nerve biopsy, a small part of peripheral nerve in the calf of the leg is removed and examined to distinguish cases of CMT with other nerve-related disorders
• Genetic testing involves blood tests, which can help determine whether or not an individual has Charcot Marie Tooth Disease

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Charcot Marie Tooth Disease?

The complications may vary from one individual to another, but the most common complication of Charcot Marie Tooth Disease includes:

• Gradual difficulty in walking and progressive muscle weakness
• Injury to areas of the body that have decreased sensation may also take place

How is Charcot Marie Tooth Disease Treated?

Although, there is currently no cure for Charcot Marie Tooth Disease, physical therapy, occupational therapy, surgery, and orthopedic devices, may be used to help manage the symptoms associated with the disorder:

• Physical therapy for Charcot Marie Tooth Disease aims to strengthen and stretch the muscles not only to deter any muscle tightening or loss, but to also increase stamina. Most physical therapy programs are specialized and approved by the physician to accommodate the patient’s abilities and needs. If started early, these programs can help delay nerve degeneration and muscle weakness before disability occurs
• Occupational therapy is useful for individuals with Charcot Marie Tooth Disease that has affected their hands and arms, leading to weakness in these areas. Such therapy can help with daily activities, such as writing, fastening buttons or tying shoe laces
• Surgery can be beneficial for patients with severe foot deformities to reverse the defects, help alleviate pain, or improve their ability to walk
• Orthopedic devices, including leg and ankle braces or splints, can help patients with CMT retain their mobility, as well as provide stability while walking or climbing stairs. High-top shoes may be used to support weak ankles or custom-made shoes can help with patients’ ‘higher than normal gait’
• Pain medications may be administered to individuals experiencing severe pain

How can Charcot Marie Tooth Disease be Prevented?

• Currently, there are no specific methods or guidelines to prevent Charcot Marie Tooth Disease, since it is a genetic condition
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Charcot Marie Tooth Disease? (Outcomes/Resolutions)

• Charcot Marie Tooth Disease is an inherited disorder that progressively and slowly worsens over time. Generally, most people with CMT adapt and adjust to their disabilities and are able to manage their symptoms
• Charcot Marie Tooth Disease is generally not life-threatening and almost never affects the brain. Though, some regions of the body may become numb, and the associated pain may range from mild to severe

Additional and Relevant Useful Information for Charcot Marie Tooth Disease:

CMT is one of the most common hereditary nerve-related disorders, affecting approximately 1 in 2,500 people in the U.S.