(Hereditary Motor and Sensory Neuropathies [HMSNs])
Charcot-Marie-Tooth (CMT) disease is a group of genetic disorders that affects movement and sensation in the limbs. The disease progresses slowly and causes damage to the peripheral nerves that control muscles and transmit sensation.
CMT is caused by defects in specific genes (genetic mutations) often inherited in an autosomal dominant pattern. This means that for some forms of CMT, if one parent has CMT, each child has a 50% chance of inheriting the gene and the disease.
CMT can be classified in a number of ways:
- Type I (demyelinating)—This type affects the coating of the nerve called the myelin sheath, causing nerve impulses to travel more slowly. It usually occurs in childhood or adolescence and is the most common type of CMT.
- Type II (axonal)—This type affects the part of the nerve called axons. Although the speed is normal, the size or amount of impulses is less than normal. This type of CMT is less common and occurs after adolescence.
Type III—Also called Dejerine-Sottas disease, this is a more rare, severe, early onset form of CMT. It is sometimes considered to be a subtype of CMT Type I. Symptoms may include:
- Delayed ability to walk due to weakness of the leg muscles closest to the trunk
- Severe sensory problems
- Hearing loss
- Type IV (demyelinating autosomal recessive)—This is similar to Type I, but often less severe. The inheritance pattern also makes it less likely to be inherited by an affected individual's children.
Symptom onset and type vary depending on the type of CMT. Usually, symptoms first appear in children and young adults. The first sign of CMT is often a high arched foot or difficulty walking. Other symptoms may include:
- Hammer toes]]>
- High arched heels
- Decreased sensation in the feet and legs
- Muscle cramping in legs and forearms
- Flexed toes
- Difficulty holding the foot up in a horizontal position
- Frequent ]]>sprained ankles]]> and ]]>ankle fractures]]>
- Problems with balance
- Muscle weakness and atrophy in the lower extremities—can spread to the upper extremities later in life
- Foot drop
- Diminished ability to detect hot and cold, vibration, and position
- Difficulty writing, fastening buttons and zippers, and manipulating small objects
- Delay in learning how to walk (Type III)
- Congenital ]]>glaucoma]]> (Type IV only)
The doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include:
Although there is no cure for CMT, treatment may help to improve function, coordination, and mobility. Treatment is also essential to protect against injury due to muscle weakness and diminished sensation. Treatment may include:
- Physical and occupational therapy
- Moderate exercise
- Braces of lower legs
- Shoe inserts to correct foot deformity
- Foot care and routine exams with a specialist (podiatrist)
- Orthopedic surgery
National Institute of Neurological Disorders and Stroke
About Kids Health
Haratai Y, Bosch EP. Disorders of peripheral nerve. In: Bradley WG, ed. Neurology in Clinical Practice. 5th ed. Philadelphia, PA: Butterworth Heinemann Elsevier; 2008.
Muscular Dystrophy Association website. Available at: http://www.mdausa.org .
Nave KA, Sereda MW, Ehrenreich H. Mechanisms of disease: inherited demyelinating neuropathies—from basic to clinical research. Nat Clin Pract Neurol. 2007;3:453-464.
Pareyson D. Differential diagnosis of Charcot-Marie-Tooth disease and related neuropathies. Neurol Sci. 2004;25:72-82.
Peroneal muscular atrophy. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated October 3, 2008. Accessed February 4, 2009.
Last reviewed January 2009 by ]]>J. Thomas Megerian, MD, PhD, FAAP]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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