What is Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy)

Charcot-Marie-Tooth (CMT) disease is a disease affecting the peripheral nerves.
The nervous system in the body can be divided into 2 categories: the central nervous system and the peripheral nervous system.
The peripheral nerves make up a vast network that transmits impulses from the brain and spinal cord (the central nervous system) to every other part of the body. Peripheral nerves also send sensory information back to the brain and spinal cord.
Peripheral neuropathies refer to a diverse group of diseases affecting the motor, sensory and autonomic nerves lying outside the central nervous system (i.e. the spinal cord and the brain). This can cause a wide variety of symptoms, such as weakness, numbness or sensitivity to touch.

Statistics on Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy)

CMT disease is not uncommon. In fact, it affects 1 in 2500 of the population in the US, making it the commonest inherited nerve disease.
Below is the cases in different countries:

  • In Japan, prevalence is reported at 10.8 per 100,000 population
  • In Italy, prevalence is reported at 17.5 per 100,000 population
  • In Spain, prevalence is reported at 28.2 per 100,000 population
  • Some report as high as 40 cases in 100,000 population.

    Risk Factors for Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy)

    CMT disease is a genetic disease, with the pattern of inheritance mainly autosomal dominant. This means that if a parent is affected, the children have 50% chance of developing the disease. It may also be autosomal recessive or X-linked recessive, both of which are rarer.
    It affects all races and ethnic groups, and it has no gender predilection.

    Progression of Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy)

    CMT disease comprises of a spectrum of disorders all caused by a specific mutation in one of several myelin genes. This eventually results in disturbances in myelin structure, maintenance, and formation.
    Depending on the genetic defects, CMT can be divided into 7 types, classified as type 1 to type 7. CMT type 1 and type 2 are considered the most common of hereditary peripheral neuropathies.
    Malfunctioning nerves can soon lead to disuse atrophy of the muscles gradually.

    How is Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy) Diagnosed?

    If a patient comes in and presents with peripheral neuropathy, it is important to rule out other treatable diseases. Hence a full physical examination will be done on the patient. These include looking at the blood function, kidney function, liver function, thyroid function, and the body’s iron, vitamins and electrolytes level.

    Prognosis of Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy)

    CMT disease is not a fatal disease as it does not affect normal life expectancy. However, significant inconvenience can occur as ‘normal’ lifestyles will be affected. Most patients suffering from CMT disease continue to work. Wheelchair confinement is rare.
    Very rarely, CMT disease might affect the nerve supplying the diaphragm (needed for breathing) causing failure to breathe and eventually death.

    How is Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy) Treated?

    There is no cure for CMT disease. The treatment aims at symptomatic control and rehabilitation to optimize the outcome of disease.
    Foot care:
    Proper foot care reduces potential complications such as ulcer and secondary infection. These include wearing custom-made shoes and leg braces. These are also important to reduce discomfort and optimize residual function.
    Physiotherapy and exercises are important to prevent wasting of the muscles. Moderate exercise is recommended to promote muscle strength and muscle endurance.
    Maintain function:
    Splinting, specially-made household devices and/or surgery may be needed to maintain the function of the affected limbs, especially when the hands are affected.
    Psychosocial support:
    Many of the patients feel depressed and may need psychological support. Although many of the patients are employed, it is important to establish the fact that the patients might not be able to perform many tasks required in many jobs.
    Genetic testing and counseling:
    If the patient is married, it is important to provide the opportunity of genetic counseling concerning the future generations as there is possibility of the children having the disease as well.

    Charcot-Marie-Tooth disease (hereditary motor sensory neuropathy) References

    [1] Gabreels-Festen, AA, Gabreels, FJ, Jennekens, FG, et al. Autosomal recessive form of hereditary motor and sensory neuropathy type I. Neurology 1992; 42:1755.
    [2] Hoff JM, Gilhus NE, Daltveit AK. Pregnancies and deliveries in patients with Charcot-Marie-Tooth disease. Neurology. 2005;64(3):459-62.
    [3] Kasper D et al, editors. Harrison’s Principles of Internal Medicine. 16th ed. New York: McGraw-Hill; 2005.
    [4] Kedlaya D. Charcot-Marie-Tooth Disease [online]. 2005 [Cited 2005 October 22th]. Available from: URL: http://www.emedicine.com/orthoped/topic43.htm
    [5] Kumar V, et al. Robbins and Cotran Pathologic Basis of Disease. 7th ed. New York: WB Saunders Company; 2004.
    [6] Mersiyanova IV, Ismailov SM, Polyakov AV, et al. Screening for mutations in the peripheral myelin genes PMP22, MPZ and Cx32 (GJB1) in Russian Charcot-Marie-Tooth neuropathy patients. Hum Mutat 2000; 15:340.
    [7] Up to Date: Hereditary primary motor sensory neuropathies, including Charcot-Marie-Tooth disease [online]. 2005. [Cited 2005 October 22th]. Available from: URL: http://www.utdol.com/application/topic.asp?file=ped_neur/5537&type=A&selectedTitle=1~9


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