One-Stage Correction Surgery of Scoliosis Associated With Syringomyelia: Is it Safe to Leave Untreated a Syrinx Without Neurological Symptom?

STUDY
DESIGN: Retrospective study.
OBJECTIVE: To investigate the safety to leave a syrinx untreated in 1-stage correction surgery of scoliosis associated with syringomyelia without progressive neurological symptom. BACKGROUND MATERIAL: The present protocol for patients with scoliosis secondary to syringomyelia advocated to treat the syrinx first because of the increased risk in correction surgery. However, in daily life, these patients could still do lateral bending, in which spinal cord distracted albeit without any neurological symptom occurred.
MATERIALS AND METHODS: Twenty-one consecutive patients with scoliosis associated with syringomyelia with or without Chiari malformation underwent surgery in our department from 2003 to 2010 were included in this study. Patients with progressive neural deficits were excluded. Every patient received detailed neurological and radiologic examination before the surgery, including whole spine films, lateral-bending and fulcrum-bending films, 3-dimensional computed tomography scan, and magnetic resonance imaging. All the patients underwent 1-stage correction surgery without treatment of syrinx. During the surgery, Spinal Cord Monitor (SCM) and wake-up test were used to prevent serious neurological complications. At follow-up, patients received neurological examination and whole spine x-ray films.
RESULTS: There were 13 male and 8 female patients. Before the surgery, 3 patients complained wasting of the intrinsic muscles of hand, 1 complained numbness of left upper extremity, and 4 complained back pain. Negative abdomen reflex occurred on 12 of 21 patients. All the patients were single major curve, including 14 thoracic curves and 7 thoracolumbar curves. The mean preoperative Cobb angle of scoliosis was 68.05±20.1 degrees, on bending films was 39.48±21.56 degrees, postoperative was 23.19±14.14 degrees, at final follow-up was 25.76±14.46 degrees. The mean flexibility was 0.452±0.158, correction ratio was 0.685±0.140. During the operation, SCM showed motor evoked potential (MEP) loss transiently in 2 patients, and somatosensory evoked potential (SEP) was normal in all the patients. Wake-up test was normal for all the patients. No neurological complication was observed after the surgery and at follow-up; 2 patients complained back pain and 1 patient got early postoperative infection. The mean follow-up time was 4.5 years (1.6∼8.5 y).
CONCLUSIONS: For scoliosis patients associated with syringomyelia without neurological deficits, it might be safe and could be an option to leave a syrinx untreated before 1-stage correction surgery. Besides, a residual scoliosis was important to make sure the neural safety. The correction procedure during the surgery should be controlled by about 15 degrees or 50% more than on the bending film. Not placing the pedicle screw in the apical region was beneficial for controlling the correction rate.