FOCUS SESSION Fetal therapy for congenital hydrocephalus—where we came from and where we are going Jose L. Peiro 1,2 & Mateus Dal Fabbro 3 Received: 31 May 2020 /Accepted: 10 June 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Despite unfavorable outcomes during the early experience with in utero intervention for congenital hydrocephalus, improve- ments in prenatal diagnosis, patient selection, and fetal surgery techniques have led to a renewed interest in fetal intervention for congenital hydrocephalus. Research studies and clinical evidence shows that postnatal cerebrospinal fluid diversion to release intraventricular pressure and cerebral mantle compression usually arrives late to avoid irreversible brain damage. Make sense to decompress those lateral ventricles as soon as possible during the intrauterine life when hydrocephalus is antenatally detected. We present a historical review of research in animal models as well as clinical experience in the last decades, traveling until the last years when some research fetal therapy groups have made significant progress in recapitulating the prenatal intervention for fetuses with congenital obstructive hydrocephalus. Keywords Congenital hydrocephalus . Fetal therapy . Ventriculo-amniotic shunt . Endoscopic third ventriculostomy Abbreviations CSF Cerebrospinal fluid CNS Central nervous system U/S Ultrasounds MRI Magnetic resonance imaging AS Aqueductal stenosis ETV Endoscopic third ventriculostomy VAS Ventriculo-amniotic shunt VPS Ventriculo-peritoneal shunt Introduction Hydrocephalus is a brain anomaly characterized by the exces- sive accumulation of cerebrospinal fluid (CSF) in the cerebral ventricles and remains as a challenging clinical problem for neurosurgeons. Hydrocephalus can begin at any age, but con- genital hydrocephalus is characterized for an early onset dur- ing the intrauterine period, it is particularly difficult to treat, and often have poor neurological outcomes [96]. Congenital hydrocephalus can be caused by different de- velopmental abnormalities such as obstructions, neural tube defects, infections, intraventricular hemorrhage, trauma, and tumors. In fetuses, this condition is especially dangerous be- cause the enlarging ventricles increase the CSF pressure, and even the flexible skull can also enlarge, finally compress and damage adjacent brain mantle tissue [82]. Multiple etiologies and classifications exist, but all distinguish between “commu- nicating” (flow of CSF from the ventricular system to the subarachnoid spaces) and “obstructive” (blockage of the CSF flow anywhere in the ventricular system). Its incidence ranges from 0.3 to 0.8 per 1000 live births in the USA [23] and may reach 3.16 per 1000 live births in the developing coun- tries [13], representing an important cause of neonatal and infantile morbidity and mortality [21, 24, 59, 76, 90]. Neurological consequences, postnatally, include develop- mental delay, failure to thrive, apnea, bradycardias, and a * Jose L. Peiro Jose.peiro@cchmc.org 1 Cincinnati Fetal Center, The Center for Fetal and Placental Research, Pediatric General and Thoracic Surgery Division, Cincinnati Children’s Hospital Medical Center (CCHMC), Cincinnati, OH 45229, USA 2 University of Cincinnati (UC) College of Medicine, Cincinnati, OH, USA 3 Neurosurgery Division, Department of Neurology, State University of Campinas (UNICAMP), Campinas, SP, Brazil https://doi.org/10.1007/s00381-020-04738-9 / Published online: 29 June 2020 Child's Nervous System (2020) 36:1697–1712