Muscle pathology in idiopathic scoliosis.

Muscles from patients with scoliosis were studied to determine the possible relationship between neuromuscular disease and idiopathic scoliosis. Biopsies taken from the paraspinal musculature, the gluteus maximus and other sites were examined and compared with control specimens taken from patients undergoing spinal surgery for other disorders. Morphological and morphometric examinations by light and electron microscopy revealed a wide range of pathological changes and an alteration in the normal distribution of fiber types in most muscles. Changes were mainly nonspecific, but one unusual feature in idiopathic scoliosis but not in the other types of scoliosis consisted of type I fiber atrophy in paraspinal and deltoid muscles of the concave side paraspinal muscle, the site of the maximum morphological changes. The localized muscle changes, which are disease and not deformity related, suggest that idiopathic scoliosis is a separate disease entity and that the central nervous system may be involved in its genesis.