Summary: A study of patients with operative scoliosis associated with a syrinx were compared to AIS patients and demonstrated similar preoperative curve magnitudes, but greater curve stiffness, more left thoracic curves, and greater kyphosis preoperatively in the syrinx patients. Despite this, curve correction was similar using a similar number of fusion levels as the AIS group and demonstrated similar coronal and sagittal balance at 2 years.
Introduction: Spinal deformity associated with a syringomyelia may be more challenging to treat than AIS due to kyphosis, curve stiffness and in deciding fusion levels. The purpose of this study is to quantify the differences between patients with syringomyelia‐associated scoliosis and AIS and to determine correct fusion levels to achieve a balanced spine in the coronal and sagittal planes.
Methods: An IRB‐Approved retrospective review of a consecutive series of patients who had scoliosis associated with syringomyelia (SS group) were compared to AIS patients (AIS group) matched by curve type and magnitude (1:2 ratio). Medical record and radiographs were reviewed preop, postop and at 2 years. Radiographic outcome was characterized as satisfactory at 2 years if the coronal and sagittal balance ≤2 cm.
Results: There was no difference between the SS (N= 38) and AIS group (N= 82) for age (13.3 vs 14.1 yrs), ethnicity and curve type, however, there were more males (39.5% vs 17.1%, p=0.01) in the SS group. The coronal major curve preoperatively was similar (62.6° vs 64.5°), but curves were stiffer (flexibility index: 39.7% vs 54.2%, p=0.001), and thoracic curves were more often to the left (51.5% vs 2.8%, p<.0001) in the SS group. Thoracic kyphosis was greater in the SS group preop (38.8° vs.21.2°, p<.0001), and at 2 years (31.7° vs.23.9°, p=0.01). Major coronal curve correction was similar postoperatively (56.1% vs 60.2%) and final followup (47.4% vs 53.5%), without a difference in number of fusion levels (10.7 vs 10.2). Preoperative coronal (1.6cm vs. 1.7cm) and sagittal balance (2.3cm vs. 2.6cm) and final follow‐up (1.3cm vs. 1.1cm) (3.4cm vs. 3.4cm) were similar. Selection of the LIV was no different between the SS and the AIS groups relative to the neutral (p=0.05), stable (p=0.08), distal end vertebra (p=0.2) or the last vertebra touched by the center sacral line (p=0.4).
Conclusion: Surgical treatment of scoliosis associated with a syrinx has a high likelihood of achieving a satisfactory result using similar fusion levels and selection of an LIV that is similar to AIS patients. The need to include more fusion levels for the SS group similar to a neuromuscular construct was not seen in this series.