SP26. Chiari 1 Malformation in Non-Syndromic and Syndromic Craniosynostoses: A Meta-Analysis

PURPOSE: Chiari I malformation (CM) is typically the result of either caudal traction or craniocerebral disproportion. Craniosynostosis (CS), the premature fusion of cranial sutures, can result in craniocerebral disproportion and thus has been associated with CM. Although there are studies with small sample sizes evaluating the association between CM and CS, a comprehensive meta-analysis of the cumulative data has not been reported. Moreover, most patients with CS who develop CM are diagnosed incidentally and have asymptomatic presentations [1]. For this reason, knowing the distribution of CM among different phenotypic presentations of CS will help in clinical evaluation. We aim to highlight the prevalence of CM amongst diverse phenotypic presentations of CS. METHODS: A meta-analysis via PRISMA guidelines was conducted with keywords for Chiari malformation OR terms related to Chiari malformation AND craniosynostosis OR multi-sutural craniosynostosis OR single-suture craniosynostosis OR related terms. These terms were applied to databases OVID (Medline), Cumulated Index to Nursing and Allied Health Literature (CINAHL), Scopus, and the register Cochrane Trials on 1/11/24, with the yield of 688 articles with 264 duplicates. Records were further screened by three independent reviewers with perusal of individual abstracts, with the inclusion criteria of specific discussion of craniosynostosis (single suture, multi-suture, or syndromic) and CM as diagnosed by cerebellar tonsillar herniation at or below 5 mm. Logistic regression analyses were performed for suture types and syndromes independently. The coronal suture and Saethre-Chotzen syndrome served as the reference categories for regression analysis, respectively. RESULTS: Based on the inclusion criteria, 23 reports were sought for retrieval. Based on the cumulative data in all reports, 30.2% of single-suture CS was associated with CM. Specifically, 43.9% of lambdoid, 6.7% of coronal, 6.5% of sagittal, 0.8% of metopic, and 20.5% of multi-sutural CS were associated with CM. Additionally, 22.2% of all syndromic cases presented with CM. By specific syndrome, 73.0% of Pfeiffer, 43.0% of Crouzon, 30.6% of Crouzon-Pfeiffer, 17.2% of Apert, 7.7% of Muenke, and 1.2% of Saethre-Chotzen presented with CM.The results highlight a significant positive association between CM and lambdoid CS (β = 2.38, p < 0.001) and multi-suture CS (β = 1.28, p = 0.001). Conversely, metopic suture involvement demonstrated a negative association with CM (β = -2.20, p = 0.038), while sagittal CS showed no significant association (β = -0.034, p = 0.932). There was a significantly greater association of CM with the syndromes Apert (β = 2.81, p = 0.00579), Crouzon (β = 4.10, p < 0.0001), Crouzon-Pfeiffer (β = 3.56, p = 0.000495), and Pfeiffer (β = 5.38, p < 0.000001). CONCLUSION: Based on this meta-analysis, the rates of CM are significantly associated with lambdoid CS and with multisutural CS. Additionally, there is a significant association between CM and the syndromes Apert, Crouzon, Pfeiffer, and Crouzon-Pfeiffer. These data emphasize the importance of careful evaluation of at-risk phenotypes of CS for CM.