What is Charcot-Marie-Tooth (CMT)?

Charcot-Marie-Tooth

(shar-ko¯’ mä-re´ tooth) or CMT is a group of like diseases caused by inherited genetic mutations. CMT damages the peripheral nerves or the nerves outside of the brain and spinal cord.

What is the Peripheral Nervous System? The nervous system consists of the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of all of the nerves that branch off from the central nervous system and extend to the feet and hands. CMT is often called a neuromuscular condition as it affects the nerves and muscles.

CMT is also commonly called hereditary sensory and motor neuropathy.

Think of your nervous system as an electrical circuitry system. The peripheral nervous system is comprised of both motor and sensory nerve fibers, and since CMT affects the peripheral nerves, it usually results in both motor symptoms (weakness and muscle wasting) and sensory symptoms (numbness). 

What’s in a Name?

CMT is the acronym for Charcot-Marie-Tooth disease, named after the three physicians who first described it: Drs. Jean-Martin Charcot, Pierre Marie (both from France) and Howard Henry Tooth (of the United Kingdom).

Prevalence

1 in 2500 people worldwide are affected by CMT, regardless of gender, race, or ethnicity.

Is CMT progressive?

Yes, all types of CMT are progressive, meaning the symptoms worsen over time.

Is CMT Inherited?

Yes, CMT can be passed on from one generation to the next.

How many genetic mutations have been discovered to date?

Scientists have identified over 100 different gene mutations causing CMT. Most people (90%) have one of four types of CMT: CMT 1A (PMP 22); CMT 1B (MPZ); CMT 2A (MFN2) and CMT 1X (GJB1).

What are the symptoms of CMT?

First signs may include toe-walking, frequent tripping, ankle sprains, clumsiness, and “burning” or pins-and-needles sensations in the feet and/or hands.

Structural foot deformities such as high arches and hammertoes (curled toes) are common, but some people have flat feet and straight toes. Later in the disease process, patients may develop hand contractures.

Foot drop (inability to lift foot at ankle), poor balance, and problems walking can developas muscles atrophy in the feet, legs, hip progresses.

Difficulty with tasks involving manual dexterity, such as writing, grasping or picking up small objects or manipulating zippers and buttons can develop as atrophy in the hands sets in and progresses.

Abnormal sensation, loss of ability to feel light touch, the overall sense of touch, and the ability to perceive temperature change can become diminished, or even lost in CMT. The loss of the ability to sense where one’s body is in space (proprioception) is also common, and many people experience musculoskeletal or neuropathic pain).

Poor tolerance for cool, cold and/or hot temperatures is typical. Many people have chronically cold hands and feet.

Additional symptoms may include flexed fingers, contractures, tremor, knee and/or hip problems, muscle cramps, muscle spasms, thenar muscle atrophy (loss of muscle mass between the thumb and forefinger), loss of overall hand strength, absent or reduced reflexes, chronic fatigue, obstructive sleep apnea, poor circulation, scoliosis, kyphosis, hip dysplasia.

Rare Symptoms include breathing difficulties (caused by respiratory muscle weakness, as CMT does not cause lung tissue disease), swallowing or speaking difficulties, neurogenic bladder, hearing loss, optic neuropathy and vocal cord paralysis.  

Currently, there are no therapies to stop the progression of CMT. Together, we can change that!

Reference

For additional information please visit CMTA USA

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