Abnormal Spreading and Subunit Expression of Junctional Acetylcholine Receptors of Paraspinal Muscles in Scoliosis Associated With Syringomyelia

STUDY DESIGN: A comparative study was performed among 2 groups of patients: Group A with scoliosis and syringomyelia and Group B with idiopathic scoliosis. OBJECTIVE: To investigate the denervation of paraspinal muscles and analyze its association with scoliosis in patients with syringomyelia. SUMMARY OF BACKGROUND DATA: The mechanism by which scoliosis develops secondary to syringomyelia remains unclear. Some authors hypothesize that scoliosis may be caused by an alteration in the innervation of the trunk musculature. Few studies, however, have been reported to testify the presence of denervation of the paraspinal muscles in scoliotic patients with syringomyelia. METHODS: Forty-one children were enrolled in the study and were divided into 2 groups. Group A consisted of 25 patients with scoliosis associated with syringomyelia. Group B included 16 adolescents with idiopathic scoliosis. Bilateral biopsy of paraspinal muscles was performed during scheduled spinal surgery. Distribution of acetylcholine receptors (AChRs) and acetylcholinesterase was investigated by immunofluorescence staining. RT-PCR was performed to determine the AChRs subunit mRNA expression. RESULTS: Immunostaining showed that 56% patients in Group A were scored positive for the loss of localization of AChRs to neuromuscular junction, while all Group B patients were negative. gamma-AChR subunit expression was detected in 65% patients in Group A while absent in all samples in Group B. There was no statistical significance of both the positive rate of abnormal spreading and that of gamma subunit expression of AChRs between the convex and concave side in Group A. CONCLUSION: The denervation of paraspinal muscles is present in some patients with scoliosis associated with syringomyelia. The size of the syrinx and the degree of cerebellar tonsillar descent might seem to have no relation to the denervation of paraspinal muscles.