ConditionBrain & nerves
Charcot-Marie-Tooth Disease (CMT)
Charcot-Marie-Tooth disease (CMT) is the most common inherited disorder of the peripheral nerves, affecting about 1 in 2,500 people. It damages the nerves to the feet, legs, hands and arms, causing slowly progressive weakness and muscle wasting, high arches, hammer toes, foot drop and reduced feeling. Symptoms usually start in childhood or early adulthood. There is no cure yet, but braces, physical therapy, foot surgery and avoiding nerve-toxic medicines help people stay active, and life expectancy is normal.
Also called: CMT, hereditary motor and sensory neuropathy (HMSN), peroneal muscular atrophy
At a glance
- What it is
- A group of inherited peripheral nerve disorders affecting motor and sensory nerves.
- Typical signs
- High arches, hammer toes, foot drop, thin lower legs, weak hands, numb feet.
- Onset
- Usually childhood to early adulthood, progressing slowly.
- Diagnosis
- Nerve conduction studies, EMG and genetic testing.
- Management
- Physical and occupational therapy, ankle-foot orthoses, foot surgery and avoiding neurotoxic drugs.
When to get help
See a doctor within a day or two
- Rapidly worsening weakness over days to weeks, which is not typical of CMT and may be another treatable neuropathy
- Severe weakness after a dose of vincristine chemotherapy in someone with CMT or a family history
Book a routine appointment
- Frequent tripping, ankle sprains or difficulty running in a child or teen
- High arches and curled toes, especially with a family history of foot problems
- Gradual numbness, cold feet or weakness of hands
- Foot pain, calluses or ulcers in someone with CMT
How CMT affects the nerves
Peripheral nerves carry signals between the spinal cord and the muscles and skin. They have a central fiber (the axon) and an insulating coat (myelin). CMT is caused by gene changes that damage either the myelin or the axon. The longest nerves, those going to the feet and hands, are affected first, so symptoms start in the feet and lower legs and later involve the hands.
Types of CMT
More than 100 genes are linked to CMT. The main groups:
| Type | Problem | Inheritance | Notes |
|---|---|---|---|
| CMT1 | Myelin damage (demyelinating) | Usually autosomal dominant | CMT1A, from a duplication of the PMP22 gene, is the most common form overall |
| CMT2 | Axon damage | Usually dominant | Nerve speeds near normal; often MFN2 gene |
| CMTX | X-linked (GJB1 gene) | X-linked | Second most common; men more severely affected |
| CMT4 | Demyelinating | Recessive | Often earlier, more severe |
| Intermediate forms | Features of both | Varies |
A related condition, hereditary neuropathy with liability to pressure palsies, is caused by deletion of the same PMP22 gene.
Symptoms
- weakness of the feet and ankles, causing foot drop and a high-stepping gait
- frequent tripping and ankle sprains
- high arches (pes cavus) and hammer toes
- thinning of the lower leg muscles, giving an "inverted champagne bottle" appearance
- reduced feeling, tingling or burning in the feet and later the hands
- cold feet and poor circulation feeling
- later, weak hands with difficulty with buttons, zips and writing
- reduced or absent reflexes
- balance problems, worse in the dark
- fatigue, muscle cramps and sometimes nerve pain
- in some people, scoliosis and hip dysplasia
Severity varies widely, even within one family.
Diagnosis
- Family history and examination of strength, reflexes, sensation and foot shape.
- Nerve conduction studies: slow speeds point to CMT1; reduced signal size with normal speed points to CMT2.
- Electromyography (EMG).
- Genetic testing: usually starts with PMP22 duplication testing, then gene panels. It confirms the type and informs family members.
- Blood tests to exclude acquired neuropathies such as diabetes, B12 deficiency or CIDP.
Management
Rehabilitation
- Physical therapy: stretching (especially calves and Achilles tendons), strengthening and balance training. Low-impact exercise such as swimming and cycling is encouraged.
- Ankle-foot orthoses (AFOs): braces that lift the foot, improving walking and reducing falls.
- Occupational therapy: tools and techniques for hand weakness.
- Supportive footwear and custom insoles.
Surgery
Foot and ankle surgery, such as tendon transfers, releasing tight tissues and bone procedures, can correct severe high arches and toe deformities and improve stability.
Foot care
Reduced sensation raises the risk of unnoticed injuries. Check feet daily, keep skin moisturized and see a podiatrist for calluses.
Medicines to avoid
Some medicines damage nerves and can worsen CMT. Vincristine is the most dangerous and can cause severe, rapid weakness. Others to discuss with your doctor include some chemotherapy drugs (taxanes, platinum drugs), high-dose vitamin B6, nitrofurantoin, metronidazole with long use, and others on the CMT Association's list.
Pain and fatigue
Nerve pain medicines, managing fatigue and good sleep help daily life.
Research
Gene-targeted treatments for CMT1A and other types are in clinical trials.
Outlook
CMT progresses slowly over decades. Most people remain able to walk throughout life, some with braces or aids. Life expectancy is normal. Genetic counseling helps families understand inheritance and testing options.
Frequently asked questions
What are the first signs of Charcot-Marie-Tooth disease?
Early signs often include frequent tripping, ankle sprains, clumsy running, high arches, curled toes and difficulty with heel walking, usually in childhood or the teens. Some people first notice numb feet, cold feet or thin calves.
Is Charcot-Marie-Tooth disease fatal?
No. CMT does not usually shorten life. It causes slowly progressive weakness and sensory loss in the feet, legs and hands. Most people continue to walk, sometimes with braces, and live full lives.
How is CMT inherited?
Most forms are autosomal dominant, meaning a parent with CMT has a 50 percent chance of passing it to each child. Some forms are X-linked or recessive. Genetic testing and counseling can clarify the pattern in a family.
Can exercise help Charcot-Marie-Tooth disease?
Yes. Regular moderate exercise, stretching and balance training help maintain strength, flexibility and mobility. Low-impact activities such as swimming, cycling and walking are good choices. Avoid overworking weak muscles to the point of prolonged fatigue.
Sources
This guide was written from current patient and clinical guidance, including:
- National Institute of Neurological Disorders and Stroke (NINDS): Charcot-Marie-Tooth disease
- Charcot-Marie-Tooth Association: What is CMT
- MedlinePlus Genetics: Charcot-Marie-Tooth disease
- Muscular Dystrophy Association: Charcot-Marie-Tooth disease
- GeneReviews (NCBI): Charcot-Marie-Tooth hereditary neuropathy overview