CSF shunting in myelomeningocele-related hydrocephalus and the role of prenatal imaging.

Abstract

Hydrocephalus is commonly associated with myelomeningocele (MMC). Indication and timing of cerebrospinal fluid (CSF) shunting are still a topic of discussion. The aim of this study was to investigate whether the analysis of prenatal cerebral imaging studies could provide information that is predictive of the necessity of CSF shunting in the postnatal period. Among 73 infants operated on because of MMC between January 2003 and June 2020, 50 had undergone prenatal and postnatal MRI studies and were considered for analysis. For each patient, frontal horn width, atrial ventricle diameter, third ventricle diameter, and subarachnoid spaces (sinocortical width, craniocortical width, and the interhemispheric width) have been measured on prenatal, postnatal, and a follow-up MRI study. The need of CSF shunting device placement in relation to prenatal and early postnatal MRI data was investigated. Of the 50 infants, 31 (62%) developed a progressive hydrocephalus. Of these, 30 needed a CSF shunt and the majority of them (n=29) was operated on within 28 days after birth. One patient needed CSF shunt implantation at 45 days after birth and one child developed a late progressive hydrocephalus, successfully treated by ETV alone, at 14.2 months of age. All patients with an atrial ventricle diameter greater than 1.9 cm and a 3rd ventricle diameter larger than 0.3 cm on antenatal third trimester imaging have undergone CSF shunting within 1 month after birth. Conversely, all the children that did not undergo a CSF shunt placement showed an atrial cerebral ventricle diameter inferior to 1.2 cm and a 3rd ventricle width < 0.3 cm on antenatal imaging. Frontal horn width and subarachnoid CSF spaces' evolution did not seem to play a role. The prenatal MRI assessment of the associated prenatal ventriculomegaly in MMC provides parameters that have a predictive value heralding the probability of a CSF diversion procedure after birth. In the same way, the analysis of intrauterine MRI studies may identify those subjects that are less at risk of developing a progressive hydrocephalus after birth, therefore encouraging a more cautious attitude towards the early implantation of CSF shunting devices in the current clinical practice.