G.P.294: Charcot-Marie-Tooth disease type 1A presenting as muscle hypertrophy and muscle cramps

Abstract

Charcot-Marie-Tooth disease type 1A, caused by duplications in the PMP22 gene, typically presents in the first two decades with slowly progressive, symmetrical muscle weakness, wasting and sensory loss of the distal limbs, the legs being most affected. Pes cavus is often present. We present a 45 years old Caucasian male who experienced progressive, invalidating, exertion-induced muscle cramps from his early twenties. He has always had a muscular appearance, not related to exercise, similar to his mother and 16 years old son. Mother also had muscle cramps. He displayed generalized muscle hypertrophy of trunk and limbs, without pes cavus. Muscle strength and sensation were normal, tendon reflexes were slightly depressed. Electrophysiological studies showed a diffuse demyelinating sensomotor neuropathy with motor nerve conduction velocities of 31 m/s in the arms and 25 m/s in the legs. A duplication in the PMP22 gene confirmed the diagnosis CMT1A. The cramps resolved on carbamazepine 200 mg and during the current follow up of 3.5 years, no other symptoms or signs have evolved except for sleep apnea. CMT1A can demonstrate a phenotype with muscle cramps and muscle hypertrophy. Electrophysiological studies are useful in the diagnostic work up of muscle cramps.