OBJECTIVE: Craniocervical junction morphology has been associated with Chiari malformation type I (CMI) symptom severity
however, little is known about its deterministic effect on surgical outcomes in patients across age and sex differences. The goal of the present study was to assess the effects of age and sex on surgical outcomes in CMI. METHODS: In the present study, the authors examined MRI-based morphometric data from 115 individuals diagnosed with CMI (54 adults including 39 women and 15 men, and 61 children including 24 girls and 37 boys) and correlated them with Chicago Chiari Outcome Scale (CCOS) scores obtained 1 year after posterior fossa decompression. The authors assessed 7 craniocervical junction morphology-related measures that have been associated with CMI symptom severity: McRae line length, clivus length, Wackenheim angle, anterior and posterior CSF spaces, clivo-supraoccipital angle, and tonsillar position. RESULTS: In the pediatric cohort, none of the morphometric measures correlated with CCOS score, but both anterior and posterior CSF spaces did in adults. To further study sex and age effects, the authors used age group (children vs adults) and sex (female vs male) as independent variables and ran 3 separate ANOVA tests using CCOS score, anterior CSF space, and posterior CSF space as dependent variables, respectively. Both CCOS and anterior CSF space analyses resulted in significant interactions. Specifically, women showed lower CCOS scores and smaller anterior CSF spaces than girls, boys, or men. CONCLUSIONS: These results provide evidence that joint age and sex differences moderate the surgical outcome of CMI patients. In females, smaller anterior CSF space was associated with lower CCOS score.