Mediolateral Diameter of the Falcine Sinus as a Predictor of Clinical Outcomes in Fetal Vein of Galen Malformations

BACKGROUND: The mediolateral diameter of the falcine sinus (FS) on fetal magnetic resonance imaging is a robust predictor of aggressive neonatal presentation requiring early treatment in vein of Galen malformation. Given the need for better overall prognostication for fetal vein of Galen malformation, we aimed to assess whether FS provides a more comprehensive prediction of outcomes. METHODS: Patients were identified retrospectively from a single referral center cerebrovascular database. Overall, 59 patients (55% male and 45% female) diagnosed with vein of Galen malformation via fetal magnetic resonance imaging from 2002 to 2024 were included. Median gestational age was 34 weeks (interquartile range, 31.7–36.6 weeks). FS was measured by 2 pediatric neurointerventionalists, with interrater reliability measured via intraclass coefficient. Clinical outcomes were measured at 1, 6, and 12 months after discharge. Radiological outcomes were measured at birth, discharge, and 3 to 9 months after discharge. FS was correlated with clinical outcomes using logistic regression, with the predicted risk of the outcome per unit FS measurement calculated through marginal analysis. Regressions were adjusted for treatment effect with inverse probability weighting. RESULTS: The median FS was 6 mm (interquartile range, 4–9 mm; intraclass coefficient, 0.90). FS predicted mortality ( P =8.04×10 −9 ), right ventricular systolic dysfunction at discharge ( P =0.02), brain parenchymal abnormalities at birth ( P =0.02) and discharge ( P =0.02), ventriculomegaly at birth ( P =0.03), and developmental delay at 1 month ( P =0.001), 6 months ( P =0.001), and 12 months ( P =0.002). Inverse probability weighting showed that the treatment effect of embolization was negligible for most outcomes. Marginal analysis revealed that risk for mortality, brain parenchymal abnormalities, ventriculomegaly, and developmental delay increased significantly at FS=5 mm and FS=9 mm. CONCLUSIONS: A wide FS is robustly predictive of a high risk for mortality, cardiac dysfunction, brain parenchymal abnormalities at birth, and short- and intermediate-term neurodevelopmental delay. This finding can facilitate discussions between clinicians and families and corroborates that FS is useful for identifying cohorts that may benefit from fetal intervention.