What is Charcot-Marie-Tooth disease?
Charcot-Marie-Tooth disease (CMT disease) is an inherited peripheral nerve disorder. With CMT, problems with the peripheral nerves cause symptoms such as muscle weakness, wasting, and loss of sensation in your arms and legs. CMT is progressive, meaning the symptoms worsen over time.
There’s currently no cure, but treatments are available to help you manage your symptoms.
Your peripheral nerves connect your brain and spinal cord, or central nervous system, to the rest of your body. The peripheral nerves carry messages from your brain and spinal cord to your muscles and other areas, and send information from these areas back to your brain. Problems with these nerves, like those in CMT, are known as peripheral neuropathy.
CMT was named after the physicians who discovered it in 1886: Jean-Martin Charcot, Pierre Marie, and Henry Tooth. This condition is sometimes called hereditary motor and sensory neuropathy (HMSN).
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Symptoms of CMT often occur in adolescence, but they can appear as late as mid-adulthood.
Early signs include:
- clumsiness, stumbling, or tripping
- difficulty walking or running
As symptoms progress, they can include:
- weakness in your leg or arm muscles
- reduced or missing reflexes (areflexia)
- high stepping when walking, or foot drop
- weakness in your hands, which can cause problems with handwriting or fastening clothes
- muscle atrophy
- stiff joints (joint contracture)
- muscle pain
- balance problems
- loss of sensation, such as decreased ability to feel pain, heat, or cold
- nerve pain
- hearing loss
Physical signs of CMT can include:
- foot issues, such as hammer toes or high arches
- muscle loss in your lower leg, causing a distinct curved shape to the calf
Symptoms commonly occur on both sides of the body.
As CMT progresses, you may experience difficulty with a range of voluntary movements. This can affect your fine motor skills, your mobility, and in some cases, your speaking, swallowing, or breathing.
Many CMT symptoms can differ from person to person, but everyone with CMT will eventually
Treatments, therapies, and supportive devices can help you to manage most symptoms.
CMT is a congenital disease. This means it’s present at birth, even though the symptoms of CMT often don’t appear until you’re in your teenage years or older.
The condition is caused by problems with one or more of your genes. In most cases, you inherit the problem genes, known as mutated genes, from one or both of your parents. And if you later have children, you can pass these CMT-causing genes to your own children.
In some rare cases, people are born with the genes that cause CMT spontaneously, without inheriting them from their parents. These people will develop CMT, and they can also pass down the CMT-causing genes to their children.
The CMT-causing genes can cause problems with different parts of the peripheral nerves. Most commonly, CMT affects the protective sheath that coats your nerves, called myelin. In other cases, the condition affects one of the parts that make up your nerve cells, the axon. Some types of CMT affect both the axon and the myelin sheath. All of these changes make it harder for your peripheral nerves to carry signals between your central nervous system and the rest of your body.
Because there are many types of CMT, each with a different genetic cause, talking with a genetic counselor may be helpful if you or someone in your family is diagnosed with CMT. A genetic counselor can help you to understand who in your family could be at risk of CMT.
Because CMT can be caused by many different genes, and the symptoms can vary widely between different types, classifying CMT is complex. Some research has
Here are the basic facts about the five main types of CMT:
- CMT1 is caused by problems with your nerves’ protective myelin sheath.
- With CMT1, symptoms typically start before age 20. Life expectancy is not usually affected.
- A CMT1 subtype known as CMT1A is the
most commontype of CMT. It’s caused by problems with a protein called PMP22. It typically has a slow progression, and usually affects the lower legs first.
- There are six other subtypes of CMT1, caused by other genes.
- CMT2 is caused by problems with the axons in your peripheral nerve cells. People with CMT2 may have less sensory loss than those with CMT1.
- Age of onset varies for CMT2, but it’s often diagnosed by age 25.
- There are more than a dozen subtypes, each caused by different genes. Some subtypes can result in problems with breathing or speaking.
- CMT3, also called Dejerine-Sottas disease, causes severe muscle and sensory symptoms in infants. This type of CMT is rare, and it can have several different genetic causes.
- A severe form of CMT known as congenital hypomyelinating neuropathy is usually diagnosed in young infants.
- CMT4 is inherited recessively, which means that you must inherit a gene from both of your parents to develop it.
- There are several different subtypes caused by different genes. This type is not commonly diagnosed in the United States.
- CMTX1 is caused by a problem with a gene on the X chromosome. This affects the cells that produce your nerve cells’ myelin sheath. People with XY chromosomes (male sex) usually have more severe symptoms than people with XX chromosomes (female sex).
There are additional rare types of CMT that have different causes and symptom patterns.
To diagnose CMT, your doctor will begin by asking you about your symptoms, your medical history, and any medical conditions that run in your family. They’ll conduct a physical exam to look for signs of CMT. They’ll also conduct a neurological exam to examine your reflexes, coordination, and muscle strength.
Your doctor will likely request other tests to help diagnose potential nerve damage. These tests may include:
- Nerve conduction study. Also known as an NCV test, this procedure measures the speed of electrical signals in your peripheral nerves. To do this, a neurologist will place two small discs called electrodes on your skin, one at each end of a nerve. Then, they’ll measure how quickly electricity moves between the electrodes.
- Electromyography test (EMG). This test is often performed at the same time as NCV. Small needles are used to place electrodes into one of your muscles. Electrical activity is then measured along your muscle. Your doctor will ask you to contract and then relax your muscle, so that electrical activity can be measured in both positions.
- Nerve biopsy. This procedure involves removing a small sample of your nerve, often from your calf. Your nerve sample is then taken to a laboratory for testing. A doctor or lab technician may be able to see signs of CMT by looking at your nerve under a microscope.
- Genetic testing. This involves a blood test. Your blood sample will be tested in a laboratory to look for changes (mutations) to the genes that can cause CMT.
There is currently no cure for CMT. It usually progresses slowly, but no treatment has been proven to stop the progression. Treatment is focused on making symptoms more manageable, to improve quality of life.
Physical therapy is a typical treatment for people with CMT. A physical therapist, or a specialist doctor known as a physiatrist, can develop a physical therapy plan for you.
Physical therapy can help reduce pain and fatigue. It may also help you to maintain your:
- range of motion and flexibility
- muscle strength
- fine motor skills
Your physical therapist or doctor may recommend stretching, strength training, and aerobic exercise. If you have CMT, it’s important to check with your doctor before adding new exercises or making a big change in your physical activity level.
Many different assistive devices may be useful for people with CMT:
- Splints or braces can help you carry out daily tasks with more comfort and stability.
- Walkers or wheelchairs can help you improve your mobility.
- If you have hearing loss, your doctor may recommend hearing aids.
- If your feet have physical changes due to CMT, orthotic shoes may help.
An occupational therapist can help you learn to use assistive devices, and share other strategies to assist with daily living.
If needed, your doctor can prescribe medications to help with symptoms such as pain and cramping.
In some cases, people with CMT may be treated with orthopedic surgery. A doctor can use surgery to correct problems with your feet or joints.
CMT is not usually a life threatening condition. It will progress over time, but it often progresses slowly. A doctor can diagnose which type of CMT you have, and help you understand what to expect.
The severity of CMT symptoms varies from one person to another. Many symptoms can be managed well with physical therapy, medication, and assistive devices.
To lower your risk of injury and loss of function, it’s important to take good care of your muscles and joints. This can include following your physical therapy plan, and using splints, walkers, or other devices as recommended by your healthcare team.
Is Charcot-Marie-Tooth an autoimmune disease?
No, CMT is not an autoimmune disease. People with CMT have problem genes (mutations) that cause degeneration of their peripheral nerves.
Is Charcot-Marie-Tooth a form of MS?
No, CMT is not a form of MS. Multiple sclerosis is an autoimmune condition that affects the central nervous system, and it isn’t inherited. CMT is an inherited disease that affects the peripheral nervous system.
Is Charcot-Marie-Tooth the same as muscular dystrophy?
No. Although the two conditions share symptoms such as muscle weakness, CMT affects the peripheral nerves, while muscular dystrophy affects the muscles directly.