Charcot-Marie-Tooth Disease
A 16-year-old boy presents with progressive bilateral foot deformity, difficulty running, and frequent ankle sprains since age 10. His father has similar foot problems. Examination reveals bilateral cavovarus feet with claw toes, wasting of the intrinsic foot muscles and lower leg (inverted champagne bottle appearance), diminished ankle reflexes, and weakness of ankle dorsiflexion and eversion. Nerve conduction studies show significantly reduced motor conduction velocities (less than 38 m/s). Genetic testing confirms a PMP22 gene duplication. Regarding the classification and pathophysiology of Charcot-Marie-Tooth disease:
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CHARCOT-MARIE-TOOTH (CMT) disease is the MOST COMMON hereditary motor and sensory neuropathy (HMSN),...
CMT1 (DEMYELINATING type) shows REDUCED nerve conduction velocity (NCV less than 38 m/s) due to Schw...
CMT is the rarest hereditary neuropathy affecting less than 1 in 100,000 people; CMT1 shows normal n...
The CAVOVARUS foot deformity in CMT results from MUSCLE IMBALANCE: the tibialis posterior and perone...
The clinical pattern follows a LENGTH-DEPENDENT axonopathy affecting the LONGEST nerves first (dista...
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