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(Hereditary Motor and Sensory Neuropathies; HMSNs)
- 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 the teen years. It is the most common type of CMT.
- Type II (axonal)—This type affects the part of the nerve called the 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 the teen years.
Type III—Also called Dejerine-Sottas disease, this is a 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. It is less likely to be inherited by an affected individual's children.
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- 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 in the lower extremities—can spread to the upper extremities later in life
- Reduced ability to detect hot and cold, vibration, and position
- Difficulty writing, fastening buttons and zippers, and handling small objects
- Delay in learning how to walk—Type III
- Physical and occupational therapy
- Moderate exercise
- Braces on the lower legs
- Shoe inserts to correct foot deformity
- Foot care and routine exams with a foot specialist
- Orthopedic surgery
Charcot-Marie-Tooth Association http://www.charcot-marie-tooth.org
National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov
About Kids Health http://www.aboutkidshealth.ca
Health Canada http://www.hc-sc.gc.ca
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 Updated November 7, 2012. Accessed July 24, 2013.
Reilly MM, Murphy SM, Laura M. Charcot-Marie-Tooth disease. J Periph Nerv Syst . 2011;16(1):1-14.
- Reviewer: Kari Kassir, MD; Michael Woods, MD
- Review Date: 07/2013
- Update Date: 05/11/2013