Fetal Treatment of Galenic Malformations

This is a prospective, single-arm non-randomized interventional study of fetuses to assess the safety and efficacy of fetal embolization of Vein of Galen Malformation (VOGM). Subjects will receive a one-time study intervention of fetal embolization. Follow-up assessments will be collected every 4 weeks until delivery, as per standard of care. After delivery, neurological assessments will be performed every 6 months for 2 years (adjusted for gestational age). Data will be compared to historical cohorts.

Inclusion Criteria: * Pregnant woman carrying a fetus harboring a vein of Galen malformation in whom the straight sinus or falcine sinus draining the prosencephalic varix measures 7 mm or more on fetal MRI (medio-lateral diameter measured at the narrowest point of the sinus along the rostral-caudal axis, assessed on a T2-weighted coronal slice). * Fetal gestational age between 23 weeks and term as determined by clinical information and evaluation of first ultrasound. * Anatomic diagnosis of fetal vein of Galen malformation. * Well preserved brain parenchyma. * Maternal age of 18 years and older. * Eligible for continuous lumbar epidural anesthesia. * Able to travel to study site for study evaluation, procedures and visits. Exclusion Criteria: * Extensive fetal brain parenchymal injury/gliosis, \>10% of supratentorial brain volume (i.e., SFP presentation). This is a degree of fetal brain injury beyond which the risk of significant neurological morbidity is high, based on studies of prenatal ischemic stroke. * Irreversible fetal non-brain organ injury (e.g. hydrops fetalis as a manifestation of heart failure, a finding which portends fatal outcome in fetuses with vein of Galen malformation), i.e., SFP presentation. * Fetus with VOGM in whom the straight sinus or falcine sinus draining the prosencephalic varix measures less than 7 mm on fetal MRI (T2-weighted coronal slice, medio-lateral diameter measured at the narrowest point of the sinus along the anterior-posterior axis), fitting fetal MRI criteria for likely evolution into the IT cohort. * Severe maternal obesity pre-pregnancy as defined by body mass index (BMI) of 40 or greater. * Fetuses with major congenital anomalies. * Evidence of preterm labor, rupture of membranes or abruption. * Maternal coagulopathy: INR \> 1.2; PT/PTT above normal ranges for the lab; platelets \