A sporadic case of arthrogryposis multiplex congenita (AMC) is reported in which electrical and ultrastructural studies demonstrated the presence of a neuropathy. Muscle biopsy showed "dystrophoid" or "pseudomyopathic" changes, which were suggested to represent the effects of embryonic denervation and maturation arrest and faulty reinnervation. Histochemical studies revealed lack of differentiation of muscle fiber types as well as lack of oxidative enzymatic activity in the "cores" in the majority of fibers, which were also devoid of mitochondria on electron microscopic examination. The interpretation of myopathic changes in cases of AMC should be made cautiously, since neurogenic involvement early in gestation may cause changes resembling a primary myopathy.
Hooshmand H, Martinez AJ, Rosenblum WI. Arthrogryposis Multiplex Congenita: Simultaneous Involvement of Peripheral Nerve and Skeletal Muscle. Arch Neurol. 1971;24(6):561–572. doi:10.1001/archneur.1971.00480360095013
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