Factors associated with spinal fusion after posterior fossa decompression in pediatric patients with Chiari I malformation and scoliosis

Abstract

OBJECTIVE The authors performed a study to identify clinical characteristics of pediatric patients diagnosed with Chiari I malformation and scoliosis associated with a need for spinal fusion after posterior fossa decompression when managing the scoliotic curve. METHODS The authors conducted a multicenter retrospective review of 44 patients, aged 18 years or younger, diagnosed with Chiari I malformation and scoliosis who underwent posterior fossa decompression from 2000 to 2010. The outcome of interest was the need for spinal fusion after decompression. RESULTS Overall, 18 patients (40%) underwent posterior fossa decompression alone, and 26 patients (60%) required a spinal fusion after the decompression. The mean Cobb angle at presentation and the proportion of patients with curves > 35° differed between the decompression-only and fusion cohorts (30.7° ± 11.8° vs 52.1° ± 26.3°, p = 0.002; 5 of 18 vs 17 of 26, p = 0.031). An odds ratio of 1.0625 favoring a need for fusion was established for each 1° of increase in Cobb angle (p = 0.012, OR 1.0625, 95% CI 1.0135-1.1138). Among the 14 patients older than 10 years of age with a primary Cobb angle exceeding 35°, 13 (93%) ultimately required fusion. Patients with at least 1 year of follow-up whose curves progressed more 10° after decompression were younger than those without curve progression (6.1 ± 3.0 years vs 13.7 ± 3.2 years, p = 0.001, Mann-Whitney U-test). Left apical thoracic curves constituted a higher proportion of curves in the decompression-only group (8 of 16 vs 1 of 21, p = 0.002). CONCLUSIONS The need for fusion after posterior fossa decompression reflected the curve severity at clinical presentation. Patients presenting with curves measuring > 35°, as well as those greater than 10 years of age, may be at greater risk for requiring fusion after posterior fossa decompression, while patients less than 10 years of age may require routine monitoring for curve progression. Left apical thoracic curves may have a better response to Chiari malformation decompression.

Management of Chiari I deformity in Children and Adolescents: A report from the Consensus Taskforce of the Brazilian Society of Pediatric Neurosurgery

“…58 The author recommended that rigid fixation with screws and rods could be performed in patients older > 6 years old, and in younger children rib grafts should be harvested. Similar results were reported by Mackel et al 59 and Kim et al 60 Kennedy et al have also demonstrated that most young children undergoing atlatoaxial and occipitocervical fusion with rigid internal fixation continue to have good cervical alignment and continued growth within the fused levels during a prolonged follow-up period. 61 10) Is there any evidence to support a genetic component in the genesis of CID?…”

Selective thoracic fusion for adolescent thoracic scoliosis secondary to Chiari I malformation: a comparison between the left and the right curves

“…Moreover, Sengupta et al [14] documented that curve improvement appeared more probable in patients with left thoracic curves, with 75% (6 of 8) avoiding scoliosis surgery after PFD. In another study reported by Mackel et al [9], a better response to PFD was also found in CMS patients with left thoracic curve. However, Faloon et al [24] found no difference in the proportion of pooled neuraxial abnormalities in right and left curves.…”

“…Compared with idiopathic scoliosis (IS), the prevalence of LTC is remarkably higher in CMI patients. Several studies have shown that the prevalence of LTC among patients with CMI ranges from 24.0 to 41.7% [9][10][11]. Although the mechanism underlying the development of scoliosis secondary to CMI and syringomyelia remains poorly understood, the correlation between curve direction and the side of tonsillar ectopia and syrinx deviation has been explored in recent studies, suggesting that the curve convexity could be influenced by deviation of the tonsillar and syrinx [12,13].…”

Chiari-related scoliosis: a single-center experience with long-term radiographic follow-up and relationship to deformity correction

“…Although this factor did not retain its significance on multivariate modeling (p = 0.06), we believe that initial Cobb angle is important for the progression of thoracolumbar scoliosis requiring surgical correction; the small sample size of the cohort may have limited the ability of the analysis to detect its association. Mackel et al 20 found that fusion after posterior fossa decompression surgery was a reflection of curve severity and that patients with curves > 35º and patients 10 years of age or older were at greater risk for requiring fusion/correction surgery; their study only included patients with CM-I and excluded CM-1.5 patients. Age as a risk factor has previously been reported.…”