To test the denervation of paraspinal muscles and further investigate the pathogenesis of scoliosis associated with syringomyelia via detecting the spread of acetylcholine receptor (AChR) beyond the confines of the functional neuromuscular junction. Patients were divided into three groups: Group A consisted of 25 patients with scoliosis associated with syringomyelia, Group B included 16 adolescents with idiopathic scoliosis, and Group C comprised 10 cases without scoliosis. Bilateral biopsy of paraspinal muscles was performed during scheduled spinal surgery. Histological evaluation used a double-stain immunofluorescence technique for AchR and acetylcholinesterase. Histological analysis showed that 14 of 25 patients in Group A scored positive for the presence of AchR outside of the neuromuscular junction. There was no significant difference of the positive rate between patients with different degrees of cerebellar tonsillar descent, between patients with distended and non-distended syrinx, with syringx length <or=10 vertebral bodies and >10 vertebral bodies, and with Cobb angle <or=45 degrees and >45 degrees (p>0.05). The denervation of paraspinal muscles is present in some patients with scoliosis associated with syringomyelia, suggesting that scoliosis may be caused by a strength imbalance of paraspinal muscles in these patients.