Letter: Brain Imaging Findings Show Efficacy of Fetal Endoscopic Third Ventriculostomy as Prenatal Treatment for Induced Congenital Hydrocephalus in Fetal Lambs

To the Editor: We read with interest the article by Duru et al1 on imaging findings and efficacy of fetal endoscopic third ventriculostomy (ETV) as prenatal treatment for induced hydrocephalus in the ovine model of congenital hydrocephalus. We congratulate the authors for demonstrating radiological evidence of reduction in the ventricular size and compression of brain after ETV in fetal lambs.1 The authors additionally previously have demonstrated technical feasibility aspects of ETV in the ovine model of hydrocephalus.2 Prenatal ETV is an exciting and rapidly evolving field in the management of congenital hydrocephalus; however, there is limited evidence at present regarding long-term benefits for children with hydrocephalus. Indeed, ETV in human fetal hydrocephalus has also been reported previously.3,4 Peralta et al4 reported a 91% rate of technical feasibility. Peralta et al4 previously have demonstrated that despite 70% of this cohort having decreased or stabilized ventricular size, 80% of this cohort required insertion of ventriculoperitoneal shunt postnatally. As expected, duration of patency of such stoma generated in fetal life is likely to be short, paralleling high failure rate of ETV postnatally in children aged less than 1 month. Although many factors such as the technique and size of stoma may govern duration of patency, such failure rate suggests that fetal ETV at least at present is not a treatment strategy for fetal hydrocephalus, and therefore, indication for performing such procedures despite associated risks to fetus and the mother would hinge on long-term cognitive and developmental outcomes and how reduction in the ventricular size translates to real-life clinical benefit for the children. Furthermore, the impact of the procedure on developing fetal brain tissue and long-term effects are additional aspects that may need to be considered and researched. Overall, fetal ETV, although is an exciting step in prenatal management of hydrocephalus, requires consideration of the impact on long-term cognitive and developmental aspects of children to be justified as established treatment for fetal hydrocephalus.