Scoliosis associated with Chiari I malformation after posterior fossa decompression: a systematic review and meta-analysis of 380 pediatric patients.

purposeChiari I Malformation (CIM) is occasionally associated with scoliosis, especially in the presence of syringomyelia (SyM). While posterior fossa decompression (PFD) is often performed before spinal fusion, its impact on scoliosis progression remains unclear. Some studies report curve stabilization or improvement, while others show continued progression. This systematic review and meta-analysis aim to evaluate whether PFD influences CIM patients' scoliosis outcomes and identify predictive factors for curve behavior, improving multidisciplinary surgical management.

methodsA systematic literature search was conducted in PubMed, Cochrane, Embase, Medline, Scopus, and Web of Science up to June 2025, following PRISMA guidelines. Inclusion criteria included pediatric patients (< 19 years) diagnosed with CIM who underwent PFD as the first treatment and had concurrent scoliosis (major curve angle > 10°). Data from 11 retrospective studies comprising 380 patients were analyzed. Pooled proportions of improvement, stability, and progression were calculated using random-effects models. Subgroup analyses were performed for duroplasty, and metaregression explored predictors, including age at surgery and baseline Cobb angle.

resultsThe mean age at PFD was 10.3 years, with a mean preoperative curve of 37°. Syringomyelia was present in 92.6% of patients. After PFD, 55% (95% CI 46-63%) of curves improved or stabilized, while 45% (95% CI 37-54%) progressed. In the duroplasty subgroup (6 studies, 189 patients), success and progression rates were similar to the overall cohort (54% vs. 46%). Syrinx improvement was observed in 94% (95% CI 82-98%), with higher rates in duroplasty cases (97%). Metaregression demonstrated that older age at surgery (OR per year = 1.24, 95% CI 1.10-1.39; p < 0.001) and greater baseline Cobb angle (OR per + 5° = 0.79, 95% CI 0.65-0.96; p = 0.012) were independent predictors of scoliosis progression. Ultimately, 37.8% of patients required spinal fusion.

conclusionThis meta-analysis suggests that PFD is associated with scoliosis improvement in nearly half of pediatric patients with CIM, but a significant proportion still experiences curve progression. Younger age at surgery and lower preoperative major curve angle are associated with better outcomes. Future prospective studies with standardized criteria and extended follow-up periods are needed to refine treatment strategies.