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Charcot-Marie-Tooth (CMT) disease is a hereditary condition affecting the peripheral nervous system which is the network of nerves connecting the spinal cord to the rest of the body. CMT is the most common inherited neuropathy, it affects motor nerves (controlling muscle movement) and sensory nerves (responsible for sensation). CMT is a progressive disorder, typically appearing before the age of 20, and can significantly impact daily life. However, it is non-life-threatening and effective management can greatly enhance quality of life.

There are two main types of CMT:

  • Type 1 (Demyelinating): Affects the myelin sheath, which is the insulating layer surrounding nerve fibres. This type accounts for approximately ⅔ of cases.
  • Type 2 (Axonal): Affects the axon, the central core of the nerve fibre responsible for transmitting electrical signals.

Both the axon and myelin sheath are crucial for effective nerve signalling. Damage to these components slows or weakens signals from the brain and spinal cord to muscles, skin, and other organs. This disruption underpins many symptoms of CMT.

Diagram of nerve cell

Signs & Symptoms

The presentation of CMT can vary depending on the type and severity. Common early signs include:

  • Clumsiness and poor coordination: Difficulty with activities requiring agility or precision.
  • Muscle weakness: Especially in the feet, ankles, and legs, leading to challenges like frequent tripping or ankle sprains.
  • Foot deformities: High arches (pes cavus), hammer toes, or flat feet, which may cause discomfort or difficulty with footwear.

As the disease progresses, additional symptoms may develop. These include:

  • Impaired sensation: Reduced feeling in the hands, feet, or other peripheral areas.
  • Muscle wasting: Visible thinning of the muscles in the lower legs (giving a “stork-leg” appearance) or hands.
  • Pain or discomfort: This can result from joint stress, muscle imbalances, or nerve-related pain (neuropathic pain).
  • Balance difficulties: Weakness and sensory loss can contribute to instability and increased risk of falls.

Causes

As mentioned above CMT is an inherited condition which is caused by genetic mutations affecting the structure and function of peripheral nerves. These mutations can impact different parts of the nerve, depending on the type as mentioned above:

  • Type 1 (Demyelinating): Around 50% of cases are linked to a mutation in the PMP22 (peripheral myelin protein 22) gene, affecting the myelin sheath.
  • Type 2 (Axonal): Caused by mutations in over 10 different genes, with MFN2 (mitofusin 2) being the most common.

The progression and severity of symptoms can vary significantly within each type. There is no universally used severity grading scale, but clinicians typically evaluate symptoms based on functional impairments, such as:

  • Difficulty walking or climbing stairs.
  • Impaired hand function (e.g., difficulty writing or grasping objects).
  • The degree of muscle wasting or foot deformity.

Diagnosis

CMT needs to be formally diagnosed through your medical team and involves a number of tests which help to create a clear clinical picture and hence lead to a diagnosis.

Testing will include:

  • Physical examination of clinical signs including strength and reflexes.
  • Nerve conduction studies which can assist in determining whether Type 1 or 2 CMT is present.
  • Genetic testing which can be utilised to identify abnormal genes which cause the presence of CMT. Testing for type 1 CMT is generally more common as further testing for other types is more complex and would require further discussion with your medical team.

Prognosis and Treatment 

Although CMT is a progressive condition, it is a slow process in most cases. Whilst unfortunately there is no cure, people with CMT often live normal lifespans. With appropriate intervention, many maintain a significant degree of independence and functional mobility throughout their lives. 

Treatment focuses on managing symptoms, improving function, and preventing complications. A multidisciplinary approach is recommended, with physiotherapy playing a key role.

Physiotherapy

Physiotherapy aims to improve strength, mobility, and quality of life. Core interventions include:

  • Strengthening programs: Target unaffected or minimally affected muscles using resistance bands, bodyweight exercises, or weights to maintain strength.
  • Stretching programs: Prevent muscle contractures (tightening of muscles/tendons) and maintain joint flexibility, especially in the ankles, calves, and hands.
  • Balance training: Exercises such as single-leg stands, step-ups, or balance boards improve stability and reduce fall risk.
  • Gait training: Physiotherapists may assist with walking re-education and recommend assistive devices like walking aids or ankle-foot orthoses (AFOs) if necessary.
  • Manual therapy: Techniques to reduce joint stiffness and improve overall comfort.
  • Exercise advice: Low-impact activities like swimming, cycling, or yoga are encouraged to maintain general fitness without placing undue strain on weak joints.

Orthotics and Equipment

  • Ankle-foot orthoses (AFOs): Help stabilise weak ankles, improve walking efficiency, and reduce the risk of falls.
  • Custom footwear: Designed to accommodate foot deformities and improve comfort during walking.
  • Mobility aids: Walking sticks or frames may be prescribed depending on the level of impairment.

Occupational Therapy

An occupational therapist can assist with strategies for improving hand function, managing daily tasks, and recommending adaptive equipment for household or workplace use.

Medical Intervention

  • Pain management: Pain management may involve medication prescription from your doctor, particularly in the case of nerve pain.
  • Surgical intervention: Reserved for severe cases, procedures may include correcting foot deformities or releasing tight tendons to improve mobility and comfort.

Sources

Diseases – CMT – Types of CMT1. (2015, December 23). Muscular Dystrophy Association. https://www.mda.org/disease/charcot-marie-tooth/types/cmt1

Li, J., Parker, B., Martyn, C., Natarajan, C., & Guo, J. (2012). The PMP22 Gene and Its Related Diseases. Molecular Neurobiology, 47(2), 673–698. https://doi.org/10.1007/s12035-012-8370-x

Nagappa, M., Sharma, S., & Taly, A. B. (2024, June 22). Charcot Marie Tooth. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK562163/

National Institute of Neurological Disorders and Stroke. (2023, January 23). Charcot-Marie-Tooth Disease | National Institute of Neurological Disorders and Stroke. Www.ninds.nih.gov. https://www.ninds.nih.gov/health-information/disorders/charcot-marie-tooth-disease

Physical Therapy. (n.d.). Charcot–Marie–Tooth Association. https://www.cmtausa.org/living-with-cmt/managing-cmt/physical-therapy/