The Association Between Chiari Malformation I and Syndromic and Non-syndromic Craniosynostosis: A Systematic Review

Introduction: Chiari malformation I (CM1) often results from craniocerebral disproportion such as that caused by craniosynostosis (CS). The association between CM1 and CS has been described in several retrospective studies, but a comprehensive meta-analysis of the cumulative data has not been reported. This systematic review and meta-analysis aims to quantify the association between CM1 and CS, including both non-syndromic and syndromic subtypes. Methods: A systematic review and meta-analysis was performed following PRISMA guidelines. Search terms related to Chiari malformation and craniosynostosis (including multi-sutural and single-suture variants) were applied to 3 databases—OVID (Medline), CINAHL, and Scopus—as well as 1 trial register, Cochrane Trials. Three independent reviewers screened records by review. Studies were included if they reported on the presence of CM1 in patients with any type of craniosynostosis. Results: The initial search yielded 688 articles with 21 meeting inclusion criteria. A total of 1617 patients were included in the study. CM1 was reported in 11% (n = 71) patients with non-syndromic single suture craniosynostosis, 22.7% of patients with syndromic craniosynostosis, and 28.0% of patients with non-syndromic multi-suture craniosynostosis. In patients with single-suture synostosis, the rates were highest in lambdoid synostosis (45.5%) and uni-coronal synostosis (7.14%). Among syndromic cases, the rates were highest in patients with Pfieffer syndrome (68.2%), Crouzon syndrome (44.9%), and Apert syndrome (18.1%). Conclusion: This meta-analysis demonstrates a strong association between Chiari malformation type I (CM1) and both lambdoid craniosynostosis and multi-suture craniosynostosis. Furthermore, CM1 is significantly associated with syndromic craniosynostosis, particularly in patients with Pfeiffer, Crouzon, and Apert syndrome. These results underscore the need for thorough assessment and vigilant screening for CM1 in higher-risk craniosynostosis subtypes, as this may optimize clinical decision-making, guide surgical strategies, and improve overall patient care.