summary Charcot-Marie-Tooth Disease (CMT), is the most common cause of inherited neuromuscular disease, and encompasses a wide variety of inherited sensorimotor, sensory and/or motor neuropathies. Diagnosis is made with neurophysiologic studies involving the upper and lower extremity (can distinguish between primary or axonal pathology). Clinical exam typically presents with gradual distal extremity weakness and sensory loss in the first two decades of life as well as foot structure deformities (pes cavus, claw toes) due to characteristic muscular imbalances. Treatment involves a multidisciplinary approach to address neuropathy, cavovarus and claw foot deformities, and scoliosis. Epidemiology Incidence 1 in 2500 people login to view 1 more bullet Etiology Pathophysiology CMT is a heterogenous group of inherited peripheral neuropathies that cause damage to the peripheral nervous system login to view 2 more bullets CMT type 1 login to view 7 more bullets CMT Type 2 login to view 6 more bullets CMT type 4 login to view 1 more bullet CMT X login to view 1 more bullet pathoanatomy affected muscles become weak login to view 7 more bullets Genetics inheritance login to view 3 more bullets Orthopedic manifestations foot deformity - pes cavovarus claw toes foot drop hip dysplasia scoliosis hand muscle atrophy and weakness Classification CMT is classified according to the pattern of inheritance and neurophysiologic studies the letter designation denotes the identified genetic pathogenic variant (subtype) there are over 130 identified genes, 160 CMT types which divide into 13 classifications CMT1 CMT2 CMT 4 AR-CMT2 CMTX CMT-DI (dominant intermediate) CMT-RI (recessive intermediate) dHMN (Distal hereditary motor neuropathy) dSMA (Distal spinal muscular atrophy) GAN (Giant axonal neuropathy) HMSN (Hereditary motor and sensory neuropathy) HSAN (Hereditary sensory and autonomic neuropathy) HSN (Hereditary sensory neuropathy) Classification of CMT Type I A demyelinating form that slows nerve conduction velocity Characteristics: 1. autosomal dominant 2. onset in first or second decade of life 3. most commonly leads to cavus foot 4. normal life expectancy 5. motor involvement more profound than sensory Type II Direct axonal death caused by Wallerian degeneration (not demyelination) Characteristics: 1. Usually less disabled than Type I 2. onset in second decade of life or later 3. most commonly leads to flaccid foot Presentation Symptoms motor deficits login to view 5 more bullets lateral foot pain sensory login to view 3 more bullets Physical exam lower extremity login to view 23 more bullets upper extremity login to view 3 more bullets spine login to view 1 more bullet Studies NCS allows for classification of CMT into demyelinating and axonal forms login to view 5 more bullets Genetic Testing key component for diagnosis of CMT DNA analysis login to view 1 more bullet chromosomal analysis login to view 1 more bullet Cavus Foot Deformity Introduction evaluation and treatment follows same principals for cavovarus foot pathophysiology login to view 4 more bullets Treatment nonoperative login to view 16 more bullets operative login to view 29 more bullets Claw Toes Deformity Introduction ankle dorsiflexion weakness may result in the recruitment of toe extensors for assistance login to view 1 more bullet Treatment operative login to view 6 more bullets Hip dysplasias Introduction hip dysplasia is sometimes associated with CMT (typically less than 10%) login to view 1 more bullet Treatment pelvic osteotomy login to view 4 more bullets Scoliosis Introduction often occurs in children with CMT ( ~ 10-20%) characteristic left thoracic and kyphotic curve distinguish from idiopathic scoliosis Treatment nonoperative login to view 3 more bullets operative login to view 3 more bullets