[A case of severe infantile form of congenital nemaline myopathy with extensive fatty replacement of the skeletal muscles]

Abstract

A case of severe infantile form of congenital nemaline myopathy who developed extensive fatty replacement of the skeletal muscles was described. A girl was born with severe hypotonia and flaccidity of the extremities. She was put on a ventilator because of the severe respiratory insufficiency. Muscle biopsy performed at 3 months of age revealed numerous nemaline rods in myofibers. She had an anoxic episode at 2 years of age and fell into a vegetative state after that. Serum creatine kinase and aldolase levels were normal. At 8 years of age, X-ray CT scan of the skeletal muscles revealed diffuse and severe fatty replacement of the skeletal muscles of the trunk and extremities; this was far more extensive than in the case of Duchenne muscular dystrophy of similar age. Second muscle biopsy performed in the anterior tibialis muscle at the age of 8 years revealed atrophic muscle fibers and extensive proliferation of connective and fatty tissues. Electron microscopy revealed, numerous rod-containing muscles fibers with severe disorganization and loss of myofilaments. Sural nerve biopsy performed at the same time showed decreased number of large myelinated fibers. Although a possibility could not be excluded completely that the episode of anoxia and chronic debilitation may have contributed to these pathological neuromuscular findings, it was presumed that severe degeneration and fatty replacement of the skeletal muscles progress rapidly after birth in some cases of severe infantile form of congenital nemaline myopathy.