OBJECTIVETo study the histochemical changes of muscle fibers and motor end-plates of paravertebral muscles, and analyze their relationship with the etiology of scoliosis associated with syringomyelia as compared with adolescent idiopathic scoliosis (AIS) and non-scoliotic patients.

METHODSAll the enrolled patients were divided into three groups: Group I consisted of 20 patients with scoliosis associated with syringomyelia, Group II included 16 patients with AIS, and Group III included 10 patients without scoliosis. Bilateral biopsy of paravertebral muscles was performed during scheduled spinal surgery. HE staining, nicotin-lateral biopsy of paravertebral muscles was performed during scheduled spinal surgery. HE staining, nicotinamide adenine dinucleotide hydrogen-tetrazolium reductase ( NADH-TR), and alpha-naphthyl acetate esterase staining techniques were used for histological evaluation. Neurogenic and myogenic pathological changes and changes of motor end-plates of paravertebral muscles were compared among these three groups.

RESULTSNeurogenic pathological changes of muscle fibers were found in 12 (60% ) patients in Group I but was not found in Group II and III. The numbers of both T0 type motor end-plates and pathological end-plates on the convex side were significantly larger than those on the concave side in Group I ( P < O. 05 ). In Group II , however, the numbers of both T0 type motor end-plates and pathological end-plates on the concave side were significantly larger than those on the convex side (P < 0.05). No significant difference was found between two sides in Group III.

CONCLUSIONThe histochemical changes of paravertebral muscles in patients with scoliosis and syringomyelia are different from those in AIS patients. It is suggested that a primary denervation of paravertebral muscles exist in scoliosis associated with syringomyelia, which may play a role in the pathogenesis of scoliosis.