Charcot-Marie-Tooth disease

• Charcot-Marie-Tooth disease is a term for a number of conditions that affect the nerves
• Charcot-Marie-Tooth disease symptoms can include muscle weakness and a reduced sensation of touch, pain, or changes in temperature
• There is no cure for Charcot-Marie-Tooth, but treatment can help relieve the symptoms

Charcot-Marie-Tooth disease refers to a number of conditions caused by faulty genes. These faulty genes cause damage to the nerves, which leads to a number of symptoms. There are different types of Charcot-Marie-Tooth, each with their own characteristics and their own outlook. In this article by Ada’s medical team, you’ll find more information on Charcot-Marie-Tooth, the different types, symptoms, and treatment options. 

Charcot-Marie-Tooth disease (CMT disease) is an umbrella term for a group of genetic conditions that affect the nerves. These conditions are due to inherited genetic mutations which cause the genes to malfunction. Different mutations can lead to different types of Charcot-Marie-Tooth. Charcot-Marie-Tooth disease can affect both the sensory and motoric nerves. The sensory nerves send information about touch, temperature, pain, and pressure to the brain. The motoric nerves send information from the brain to the muscles, resulting in muscle movement. 1

Charcot-Marie-Tooth disease can be divided into many different subtypes, depending on the specific genetic mutation you are affected by, the moment the first symptoms appear and whether the myelin sheath or the axon is affected by the condition. Some of the more common subtypes are:  1 2

• Charcot-Marie-Tooth disease type 1a develops due to problems with the layer around the nerves called the myelin sheath. The symptoms often start during childhood and mostly include muscle weakness. 
• Charcot-Marie-Tooth disease type 1b also develops due to problems with the myelin sheath. The symptoms can appear at any age, and both muscle weakness and numbness can be present. 
• Charcot-Marie-Tooth disease type 2 affects another part of the nerves called the axon. This can cause muscle weakness, numbness, and issues with speech or breathing.
• Charcot-Marie-Tooth disease type 4 is a rare, but severe form of CMT nerve disease. The symptoms often develop early on, with most people losing the ability to walk in their teen years. 
• Charcot-Marie-Tooth disease X affects the myelin sheath and often causes more severe symptoms in boys.  

Charcot-Marie-Tooth disease symptoms appear when the nerves conducting information from and to the brain start to break down due to the condition. The condition usually affects the distal leg and feet first. Later, thighs and arms can be affected as well. You may notice:  3 1

• Muscle weakness in the arms, legs, hands or feet
• Numbness, tingling sensations, or pain 
• Atrophy, meaning that the affected muscles break down and reduce in size 
• A drop foot caused by weakness in the lower leg and foot
• Frequent falls 
• Difficulty walking
• Balance issues
• Difficulty with small movements such as writing due to muscle weakness
• An abnormal curvature in the spine called scoliosis
• Muscle cramps
• Nerve pain 
• Foot deformities such as very high arched feet, called pes cavus.  

The severity of Charcot-Marie-Tooth disease symptoms can vary from person to person, depending on which exact genetic mutations you’re affected by. The symptoms of Charcot-Marie-Tooth often develop around the age of 5 to 20 and get worse over time as the nerve damage continues. 4

Charcot-Marie-Tooth disease is a condition which can lead to a decrease in quality of life. It is important to visit your doctor if you notice any of the signs of Charcot-Marie-Tooth disease. If your parents or grandparents suffer from CMT disease, then it is also a good idea to visit your doctor. Through genetic testing, you can know whether or not you have inherited the faulty gene responsible for the development of the condition.

Charcot-Marie-Tooth disease is caused by genetic mutations that you have inherited from your parents. Most subtypes are passed down in an autosomal dominant pattern, affecting both sexes equally. But there are also subtypes passed down related to the x chromosome, the female sex chromosome, or in an autosomal recessive pattern. These mutations affect the nerves connecting your brain to the rest of your body. The nerves consist of several parts. With Charcot-Marie-Tooth disease, the axon or the myelin sheath will be affected. The axon is the part of the nerve through which electrical signals pass, while the myelin sheath is wrapped around the axon to protect it and to help guide the electrical signal through the nerve. When the axon or the myelin sheath gets damaged, it causes the electrical signal to get weaker. In severe cases, it can even stop the transmission of the electrical signal. When the signal does not travel through the nerves properly anymore, Charcot-Marie-Tooth disease symptoms will appear. 1 3

There is no cure for Charcot-Marie-Tooth disease. The condition gradually gets worse due to the ongoing nerve damage. Although there is no cure, Charcot-Marie-Tooth disease is also not life-threatening. With the right treatment and support, you can maintain a good quality of life. 3

The diagnosis of Charcot-Marie-Tooth disease can be made by your healthcare provider. They will first ask you questions about your medical history and symptoms, followed by a physical examination. If your healthcare provider suspects that you may suffer from Charcot-Marie-Tooth disease, then there are certain tests to be done in order to confirm the diagnosis and to rule out other conditions which may cause your symptoms. Some possible tests are: 1

• Nerve conduction studies
• Electromyography (EMG)
• Genetic testing confirming the diagnosis
• Nerve biopsy 

Charcot-Marie-Tooth disease treatment focuses on relieving your symptoms and supporting you in your daily activities. Your healthcare provider may recommend: 1 3

• Physical therapy in order to improve your balance and strength 
• Occupational therapy to help you with your daily activities
• Certain medical devices such as walking aids to increase your quality of life

Psychological support to help you cope with the diagnosis

• Hereditary motor and sensory neuropathy (HMSN)
• Peroneal muscular atrophy (PMA)

Charcot-Marie-Tooth (CMT) disease refers to a group of hereditary conditions that cause damage to the nerves. This damage makes it harder for you to feel things and for your muscles to work. Although Charcot-Marie-Tooth disease is not life-threatening, it can have a big impact on your life. Through treatment, you can reduce this impact and improve your quality of life.

Q: Why is it called Charcot-Marie-Tooth disease? 
A: This group of conditions is named after the surnames of the scientists who discovered and described the condition in 1886. 

Q: What is the life expectancy of someone with Charcot-Marie-Tooth? 
A: Charcot-Marie-Tooth is not life-threatening. Most people have a similar life expectancy as people without this condition. 

Q: Is there any treatment for Charcot-Marie-Tooth disease? 
A: There is no cure for Charcot-Marie-Tooth disease, but there are several treatment options that can help you relieve your symptoms and improve your quality of life. Your healthcare provider may recommend physical therapy, occupational therapy, or walking aids. 

Q: What does CMT pain feel like? 
A: The pain that occurs with Charcot-Marie-Tooth disease may feel like nerve pain, which can feel like a lightning bolt. Some people also experience numbness or a sensation of pins and needles.

Q: At what age do Charcot-Marie-Tooth disease symptoms appear? 
A: The symptoms of CMT often appear around the age of 5 to 20. It is however also possible to develop symptoms of this condition later in life.