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February 1970

Selective and Nonselective Susceptibility of Muscle Fiber Types: A New Approach to Human Neuromuscular Diseases

Arch Neurol. 1970;22(2):97-117. doi:10.1001/archneur.1970.00480200003001

DURING the past few years, our studies of the histochemical changes of skeletal muscle in human neuromuscular diseases and experimental animal models have gradually led to the development of an analytical approach which places major emphasis upon determining whether there is selective or nonselective involvement of muscle fiber types in each human and animal condition studied. Such determinations provide a new approach to the pathogenesis and etiology of the neuromuscular disorders. This report summarizes our current analytical techniques and conceptualizations, illustrated by examples from our present and previous investigations.

Background Data and Hypotheses.—  Histochemistry of fresh frozen muscle biopsy specimens from humans and animals demonstrates different degrees of enzyme activity in different fibers within the same muscle. The distinct histochemical characteristics of a given muscle fiber (which is a single, long, multinucleated cell) are maintained throughout its length, making it possible to obtain histochemical profiles of the individual