Charcot-Marie-Tooth disease (CMT)

About Charcot-Marie-Tooth disease (CMT)

Charcot-Marie-Tooth disease is also known as hereditary motor and sensory neuropathy (HMSN).

The peripheral nerves are found outside the main central nervous system (brain and spinal cord). They control the muscles and pass on sensory information, such as the sense of touch, from the limbs to the brain.

Symptoms of CMT

The symptoms of Charcot-Marie-Tooth disease (CMT) can differ from person to person, even among relatives with the condition.

Symptoms can vary depending on the type of CMT and even people with the same type can experience it differently.

For example, it's not possible to say at what age symptoms will first appear, how quickly the disease will progress, or how severe it will be.

Early symptoms of CMT

CMT is a progressive condition. This means the symptoms gradually get worse over time. Therefore, it may be difficult to spot any symptoms in young children who have CMT.

Signs that a young child may have CMT include:

• appearing unusually clumsy and accident-prone for their age
• finding it difficult to walk because they may have problems lifting their feet from the ground
• their toes dropping forward as they lift their feet (known as 'foot drop')

Main symptoms of CMT

The main symptoms of CMT usually appear between the ages of five and 15. Although the main symptoms sometimes don't develop until well into middle age or later.

Some of the main symptoms of CMT include:

• muscle weakness in the feet, ankles and legs at first
• having feet that are very highly arched, which can make the ankle unstable, or having very flat feet
• curled toes ('hammer toes')
• an awkward or high step and difficulty using the ankle muscles to lift the foot, which makes walking more difficult
• a lack of sensation in the arms and feet
• very cold hands and feet, caused by poor circulation
• wasting of the muscles in the lower legs, causing legs to have a distinctive 'upside-down champagne bottle' shape
• feeling tired a lot of the time, as a result of the extra effort it takes to move around

Some people also develop other problems such as:

• tremor (uncontrollable shaking)
• scoliosis (abnormal curvature of the spine)
• problems speaking, breathing or swallowing (dysphagia) – but these symptoms are rare in CMT

Later symptoms of CMT

As CMT progresses, the muscle weakness and lack of sensation worsens. It starts to affect your hands and arms more. This can lead to problems with both using your hands and hand strength, making tasks such as doing up the buttons of a shirt very difficult.

Problems with walking and posture can put extra strain on your body, which often leads to muscle and joint pain. Less commonly, damaged nerves may also cause pain, known as neuropathic pain.

Problems with mobility and walking tend to get worse with age. It's uncommon to lose the ability to walk completely. But older people with CMT often need a walking aid to get around.

Causes of CMT

CMT is caused by an inherited fault in one of the many genes responsible for the development of the peripheral nerves. This fault means the nerves become damaged over time.

A child with CMT may have inherited the genetic fault responsible for the disease from one or both of their parents.

There's no single faulty gene that causes CMT. There are many varieties of CMT that are caused by different genetic faults and these can be inherited in several different ways.

Testing for CMT

See your GP if you think you may be developing symptoms of CMT. If your GP thinks you may have CMT, they'll refer you to a neurologist for further tests to confirm the diagnosis. A neurologist is a doctor who specialises in treating conditions of the nervous system.

You should also see your GP if you or your partner have a family history of CMT and are considering having a baby. Your GP can refer you to a specialist for advice.

How CMT is treated

There's currently no cure for CMT. Treatments can help relieve symptoms, aid mobility and increase the independence and quality of life for people with the condition.

These treatments may include:

• physiotherapy and certain types of exercise
• occupational therapy
• walking aids

In some cases, surgery may be needed to treat problems such as flat feet and muscle contractures (where muscles shorten and lose their normal range of movement).

Living with CMT

CMT isn't life-threatening and most people with the condition have the same life expectancy as a person without the condition.

However, it can make everyday activities difficult. Living with a long-term, progressive condition can also have an emotional impact.

Some people find it helpful to speak to others with the condition through support groups. You may also benefit from a talking therapy, such as cognitive behavioural therapy (CBT).

More useful links

• How to use your health services
• Charcot-Marie-Tooth UK