Evolution of syrinx in patients undergoing posterior correction for scoliosis associated with syringomyelia

While correction surgery for syringomyelia-associated scoliosis frequently results in an elongation of the spine and may potentially influence the natural history of syringomyelia, a paucity of data exists regarding the syrinx behavior in the postoperative course. This study aimed to investigate the natural evolution of syrinx in patients undergoing one-stage posterior instrumented spinal fusion for treatment of scoliosis associated with idiopathic syringomyelia (IS).

Twenty-two patients with IS-associated scoliosis treated with one-stage posterior correction and fusion were evaluated at a minimum of 12-month clinical and MRI follow-up (mean 29.6 months; range 12–57 months). All syringes were located within the cervical or cervicothoracic region. Standing anteroposterior radiographs were examined for primary curve magnitude and postoperative correction. On preoperative and follow-up T2-weighted MR images, location, configuration and size of the syrinx cavity were systematically assessed, and significant syrinx resolution was defined as any more than 20 % decrease in length or maximal syrinx/cord ratio.

Postoperative percent correction of the primary curve averaged 64.0 ± 15.7 % and was well maintained (58.5 ± 11.5 %) at latest evaluation. Regarding syrinx size, although paired t test revealed no statistically significant difference between pre- and postoperative maximal syrinx/cord ratios (0.44 versus 0.41; P > 0.05), 10 of 22 (45.5 %) patients were found to meet the criteria for significant syrinx resolution. Additionally, 11 (50.0 %) patients had syrinx stabilization, whereas syrinx deterioration was observed only in 1 case (4.5 %) at final follow-up. Using Spearman correlation test, improvement rate of the maximal syrinx/cord ratio was found to be strongly related to the coronal percent correction of the primary curve (r = −0.547, P = 0.008). There were no neurologic or other major complications related to the surgery.

For treatment of scoliosis associated with IS in the setting of minimal neurological deficits, one-stage spinal fusion with a lengthening of the vertebral column provides an effective coronal and sagittal correction without neurologic complications. Following surgery, the vast majority (95.5 %) of syringes shrank or remained stable, indicating that deformity correction did not exert a deleterious effect on the natural evolution of syringomyelia.