Congenital myopathy and cardiomyopathy with identical ultrastructural changes
D. G. Davis, K. R. Nelson and W. R. Markesbery
Department of Pathology, University of Kentucky Medical Center, Lexington 40536.
A 7-day-old girl with congenital hypotonia and unexplained episodes of
bradycardia had a broad spectrum of similar skeletal muscle and myocardial
degenerative ultrastructural abnormalities. Ultrastructural studies showed
obliteration of cross striations, myofilament disorganization, streaming,
smearing, clumping, and zigzag Z-band deformities. A decrease in glycogen,
mitochondria, and T-tubular system occurred in the regions showing Z-band
abnormalities of both skeletal muscle and myocardium. Concurrent structural
cardiomyopathy should be considered in patients with congenital myopathies,
particularly with unexplained cardiac conduction abnormalities or
contractile insufficiency. Ultrastructural evaluation of skeletal and
cardiac muscle may be necessary to define such disorders.
