Successful Ventriculoamniotic Shunting for Fetal Hydrocephalus in the Ovine Model.

Introduction: Recent technological advances in fetal medicine have led some investigators to reconsider ventriculoamniotic shunting for fetal hydrocephalus, an intervention that was attempted in the 1980s but was abandoned due to perceived lack of effect. The objective of this manuscript describes outcomes after induction of hydrocephalus followed by ventriculoamniotic shunt placement and postmortem analysis in the ovine model.

Methods: Mixed-breed fetal sheep underwent induction of hydrocephalus by injection of BioGlue® into the cisterna magna at ∼85 days gestation followed by ventriculoamniotic shunt placement at ∼100 days gestation. Brains were inspected by transcranial ultrasound at the time of shunt placement and after delivery using the ventricle to hemisphere ratio (VHR). The VHR at the time of shunting was compared to the VHR at end of study. Pathologic analysis was performed on gestational age-matched normal brains, shunted brains, and unshunted hydrocephalic controls.

Results: Twenty-five fetal sheep underwent induction of hydrocephalus. Two fetuses were lost immediately. Of the 23 remaining fetuses, 20 (87%) developed hydrocephalus. Five fetuses served as hydrocephalic controls. Eighteen fetuses who developed hydrocephalus were assessed for a VHR by transcranial ultrasound at the time of shunt placement. The mean VHR was 0.71. Of the 20 fetuses that developed hydrocephalus, 12 underwent shunt placement. Eight shunted fetuses were available for VHR and pathologic analysis at end of study. The mean VHR at the time of shunt placement was compared to the VHR at end of study (n = 8, 0.70 ± 0.10 vs. 0.50 ± 0.16, p = 0.016). Histologically, shunted brains had better neuropreservation than unshunted hydrocephalic controls.

Conclusion: Hydrocephalus was induced in 87% of fetal sheep using this model. In an ovine model, ventriculoamniotic shunting both decreased the degree of hydrocephalus sonographically and improved brain histology compared to hydrocephalic controls. These findings demonstrate proof of concept in the animal model and support ongoing research in cerebrospinal fluid diversion for fetal obstructive hydrocephalus.