Charcot-Marie-Tooth Disease (CMT)

What Is Charcot-Marie-Tooth Disease (CMT)?

Charcot-Marie-Tooth disease (CMT) is an inherited neurological disorder. It is called a peripheral because it affects peripheral nerves, which are nerves outside the brain and spinal cord. The nerve types affected in CMT are:

• motor nerves, which carry signals from the brain to the muscles to tell the muscles what to do. Problems with motor nerves can cause muscles to become weaker and smaller.
• sensory nerves, which carry signals from the body to the brain to let us feel pain, pressure, touch, temperature, body position, and other sensations. Problems with sensory nerves can affect how a person feels things.

Often, CMT symptoms are not severe, and many treatments can help. 

What Are the Signs & Symptoms of Charcot-Marie-Tooth Disease (CMT)?

There are many different types of CMT. The symptoms someone has and at what age they start varies depending on the type. In some kinds of CMT, babies and toddlers have weakness and muscle loss. They may:

• hold their head up, sit, crawl, stand, and walk later than most kids do
• fall more than brothers, sisters, or playmates of the same age
• have trouble grasping or holding items

In the most common forms of Charcot (shahr-KOE)-Marie-Tooth disease, symptoms first appear in teens or young adults. Symptoms all relate to muscle weakness or changes in sensation in the hands, forearms, lower legs, and feet, and include:

• trouble buttoning clothing and holding small items such as coins
  
• stumbling or unsteady steps, which may look like clumsiness
• dragging the feet or toes while walking (foot drop)
• trouble going up or down steps
• shuffling or marching steps
• feet with high arches and toes that stay curled (hammertoes)
• trouble with balance
  
• muscle cramps
• numbness, tingling, burning, or pain in the hands and feet 
• problems with feeling changes in temperature

Kids with CMT can develop scoliosis (a curved spine) or stiff and deformed joints (contractures) as the disease progresses.

What Causes Charcot-Marie-Tooth Disease (CMT)?

CMT happens because of gene mutations (changes). The changes can damage the nerves or their protective coating, called myelin. If a nerve or its myelin is damaged, the nerve can't send signals.

Changes to many different genes can cause CMT. The type of CMT someone has depends on which gene is affected.

Usually, a child with CMT inherited the changed gene from one parent. Sometimes the changed gene doesn't come from a parent, but happens as the child's genes form before birth.

How Is Charcot-Marie-Tooth Disease (CMT) Diagnosed?

Doctors will do an exam, ask about symptoms, and find out whether family members have CMT or similar symptoms.

Tests can help make sure the problem is CMT and not something that could go away with treatment. These tests include:

• Genetic testing: This blood test checks for mutations that can cause CMT. Knowing the kind of mutation helps doctors tell the patient and family what to expect. Family members also can be tested to see if they have the mutation.
• Nerve conduction velocity (NCV) testing and electromyography (EMG): These check how the nerves and muscles are working to find what's causing the weakness.

How Is Charcot-Marie-Tooth Disease (CMT) Treated?

There is no cure for CMT yet. The treatment goal is to help the person stay as active as possible. Because of the loss of feeling, avoiding injury from impact and burns requires extra care.

Treatments to help kids stay as active as possible include:

• braces, such as ankle-foot orthoses (AFOs), and other devices to support the feet for easier walking
  
• medicines for pain relief
• physical therapy (PT) exercises and stretching to help maintain strength and flexibility
• occupational therapy (OT) to help with managing tasks at home, school, and work
• surgery to loosen tight tendons and joints

Doctors will also check for other problems that are rare in CMT disease, like trouble with breathing during sleep.

What Else Should I Know?

People with CMT have a normal life expectancy, and most can walk their entire lives.

Finding support can help you and your child. Ask the care team about ways to connect with other families who are managing CMT and how to stay up to date on treatment research. You also can find more information and support online at:

• CMT Association