|Based on clinical, electrophysiologic, and morphologic criteria· HMSN I/CMT 1 “hypertrophic form” demyelinating CMT;· Usually autosomal dominant; recessive form more severe· Pathology-nerve biopsy: segmental demyelination, onion-bulb formation, increase endoneural space, extensive loss of myelinated fibers.· Slowly progressive distal weakness and wasting more prominent than sensory loss; areflexia distal or more generalized· Foot deformity (pes cavus), gait disturbance, late childhood/early adulthood. Scoliosis in more severe cases.· Marked NCV reduction.
· EMG: positive sharp wave, fibrillation activity frequently; loss of motor unit recruitment pattern with sign of increased amplitude/duration MUPs with re-innervation.
· HMSNII/CMT 2 “neuronal form” neuroaxonal CMT;
· Usually autosomal dominant, less severe than CMT1.
· Pathology- biopsy: loss of larger axons, onion bulb formation absent. Demyelination rare, little loss of endoneural space.
· NCV slowing not as marked. May be in normal range.
· EMG fasciculation, complex repetitive discharge activity more frequent.
· EMG partial denervation
· HMSN III Dejerine-Sottas disease-early onset demyelinating;
· Autosomal recessive
· Motor/sensory peripheral neuropathy
· Weakness, gait disturbance, sensory loss, decreased/absent DTR.
· May be sensory ataxia.
· NCV-marked slowing; sensory responses may be absent.
· HMSN IV Refsum Disease
· HMSN V familial spastic paraplegia
· HMSN VI optic atrophy
· HMSN VII retinitus pigmentosa