Charcot-Marie-Tooth disease
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Charcot-Marie-Tooth disease (CMT) is one of the most common inherited neurological disorders; it affect the peripheral nerves, which are the nerves outside the brain and spinal cord.
This disease is named after the three physicians who first described it in 1886 ; Jean-Martin Charcot and Pierre Marie of France, and Howard Henry Tooth in England.
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symptoms of Charcot-Marie-Tooth disease
- Weakness in your legs, ankles and feet
- Loss of muscle bulk in legs and feet
- High foot arches
- Curled toes (hammertoes)
- Decreased ability to run
- Difficulty lifting your foot at the ankle (footdrop)
- Awkward or higher than normal step (gait)
- Frequent tripping or falling
- Decreased sensation or a loss of feeling in your legs and feet
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Causes of CMT
CMT is caused by defects in the genes for proteins that affect axons — fibers that carry electrical signals between the brain and spinal cord and the rest of the body — or in the genes for proteins that affect myelin, a coating on axons that insulates and nourishes them. It is not contagious, nor is it caused by anything in the environment.
types of Charcot-Marie-Tooth disease (CMT)
CMT 1
CMT type 1 is caused by abnormalities in the myelin sheath. It is a disorder of peripheral myelination resulting from a mutation in the peripheral myelin protein-22 (PMP-22).Patients experience weakness and atrophy of the muscles of the lower legs beginning in adolescence; later they experience hand weakness and sensory loss.
Pain and temperature sensations usually are not affected because they are carried by unmyelinated (type C) nerve fibers. In response to demyelination, Schwann cells proliferate and form concentric arrays of remyelination.
CMT 2
CMT type 2 primarily is a neuronal (ie, axonal) disorder, not a demyelinating disorder. It results from abnormalities in the axon of the peripheral nerve cell rather than the myelin sheath. It results in peripheral neuropathy through direct axonal death and Wallerian degeneration and mutations in Mitofusin 2, a protein associated with mitochondrial fusion.
CMT 3
CMT type 3 (also known as Dejerine-Sottas disease) is a severe demyelinating neuropathy that begins in infancy. It results in severe demyelination with delayed motor skills; it is much more severe than CMT type 1. This rare disorder can be caused by a specific point mutation in the P0 gene or a point mutation in the PMP-22 gene.
CMT4
CMT type 4 comprises several different subtypes of autosomal recessive demyelinating motor and sensory neuropathies. Each neuropathy subtype is caused by a different genetic mutation, may affect a particular ethnic population, and produces distinct physiologic or clinical characteristics which includes leg weakness in childhood and by adolescence they may not be able to walk.
CMT X
CMT type X is caused by a point mutation in the connexin-32 gene on the X chromosome. The connexin-32 protein is expressed in Schwann cells-cells that wrap around nerve axons, making up a single segment of the myelin sheath.
CMT X (X-linked CMT) and CMT 4 also are demyelinating neuropathies.
Diagnosis
physical examinations may show:
- Difficulty lifting up the foot while walking;
- Difficulty with dorsiflexion of the toes and ankles
- Reduced or absent deep tendon reflexes (knee-jerk reflex);
- Loss of muscle control and atrophy (shrinking of the muscles) in the feet and lower legs (and later the hands).
- Sensory loss in your feet and hands
Treament for CMT
There is no cure for CMT, but physical therapy, occupational therapy, braces and other orthopedic devices, and even orthopedic surgery can help individuals cope with the disabling symptoms of the disease.
Charcot-Marie-Tooth disease may cause pain due to muscle cramps or nerve damage. If pain is an issue for you, prescription pain medication may help control your pain.
If foot deformities are severe, corrective foot surgery may help alleviate pain and improve your ability to walk. Surgery can't improve weakness or loss of sensation.
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