Morphological studies on the erector spinae muscle in sixty consecutive scoliotic patients.

Paraspinal muscle biopsy was done on the erector spinae muscles in sixty consecutive scoliotic patients. Together with the clinical and muscle biopsy findings, these sixty patients were classified into thirty-two patients with idiopathic scoliosis, eleven patients with myopathic scoliosis, nine patients with neuropathic scoliosis, and eight patients with miscellaneous scoliosis. Of the thirty-two patients with idiopathic scoliosis, nineteen cases displayed neurogenic changes in the grouping of the Type 1 fibers and target fiber formation more common on the convex side back muscles. The myopathies consisted of central core disease, nemalin myopathy, congenital fiber type disproportion, mitochondrial myopathy, congenital muscular dystrophy, and myositis. Patients with neuropathic scoliosis all showed loss of the normal mosaic pattern and grouping of both Type 1 and 2 fibers in their muscle biopsies. This result indicates that there is a variety of neuromuscular diseases in scoliotic patients. The neurogenic changes observed more commonly on the convex side muscle of idiopathic scoliotic patients deserve further investigation.