HISTOMETRICAL and HISTOLOGICAL CHANGES OF THE SKELETAL MUSCLE IN NEUROMUSCULAR DISORDERS – AN AUTOPSY STUDY

Systemic hlstometrical and histological examinations of major skeletal muscles were performed by using autopsy cases with simple atrophy, neurogenic muscular atrophy, Duchenne type progressive muscular dystrophy, myositis of myasthenia gravis, and autopsy control cases. In hlstometrical studies, the shortest diameters of muscle fibers were measured and arranged in histograms. Volume ratio of stroma to muscle was measured by point-counting method.
Histometrical studies revealed the following results: (1) averages of muscle fiber diameters in controls showed the largest value In the muscles of the upper and lower extremities, and the smallest value in the lingual muscle; (2) in simple atrophy, neurogenic muscular atrophy, progressive muscular dystrophy and myositis, a decrease in muscle fiber diameters was more prominent in the muscles of the lower extremities than those of the upper extremities; (3) patterns of histograms of muscle fiber diameters were classified into six types, and in simple atrophy, almost one-half of muscles examined belonged to type 3 histogram, which had the mode situated at a relatively small diameter and a not so high kurtosls; (4) volume ratios of stroma to muscle Increased most in both muscular dystrophy and long-standing neurogenic muscular atrophy, moderately in myositis, and mildly in simple atrophy; and (5) hlstometrical changes In myasthenia gravis were minimal.