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.

The study involves a single fetal intervention of maternal transuterine, fetal transcranial torcular puncture and median prosencephalic vein embolization. Detachable platinum coils (Target XL and XXL Detachable Coil, Stryker Neurovascular) will be used to pack the prosencephalic varix. This procedure will take place in an obstetric OR at Brigham and Women's Hospital. Data will be collected every 4 weeks post-procedure until delivery, as per standard of care. Data regarding delivery and post-delivery status will also be collected until the subject is discharged from the hospital. After delivery, neurological assessments will be performed every 6 months for 2 years (adjusted for gestational age). Data will be compared to historical cohorts.

Eligibility Criteria:
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 \<100.
* Medical disease requiring current anticoagulation including maternal deep vein thrombosis.
* Prior maternal medical history that would preclude epidural anesthesia.
* Multi-fetal pregnancy.
* Placenta previa or accreta.
* Participation in another fetal study that influences maternal and fetal morbidity and mortality.
* Known maternal hypersensitivity to 316LM stainless steel.
* Supine hypotensive syndrome.