Charcot Marie Tooth Disease (CMT) is a hereditary nerve disorder that causes muscle weakness and atrophy. Charcot, Marie, and Tooth are the names of the physicians who first identified and described the disease and its symptoms. CMT is a relatively common neurological disorder, affecting approximately 1 in 2,500 people. It is also known as peroneal muscular atrophy and hereditary motor sensory neuropathy.
The cause of CMT has been linked to genetics. The most common cause is due to a duplication of a large section of chromosome 17, which codes for peripheral myelin protein 22. Myelin is integral to healthy nerve function, and mutations that affect the myelin sheath (as well as the neuron itself) can lead to nerve atrophy.
Two forms of CMT have been classified: the hypertrophic form (Type 1) and the neuronal form (Type 2):
Type 1 – Hypertrophic
- Autosomal dominant
- Onset in first or second decade of life
- Most commonly leads to cavovarus foot (high arch)
Type 2 – Neuronal
- Usually less disabled than Type 1
- Onset in second decade of life or later
- Most commonly leads to foot drop
Patients will present with foot pain, sensory deficits, clumsiness, frequent ankle sprains, and difficulty climbing stairs. As the disease progresses, weakness of the hands and feet occurs, as well as a loss-of-touch sensation. Soft tissue deformities develop and many patients lose their ability to walk if the deformity is left untreated. The deformity of CMT is a direct result of weakness of the intrinsic muscles of the foot.