Neonatal ventriculomegaly: diagnostic and prognostic implications

Abstract

Enlargement of the cerebral ventricles is a relatively common phenomenon especially in extremely premature neonates, born below 28 weeks gestational age. In developed countries, the two main entities underlying neonatal ventricular enlargement – apart from congenital malformations – are, first, pressure driven post-haemorrhagic ventricular dilatation (PHVD) due to impaired cerebrospinal fluid dynamics following an intraventricular haemorrhage and, second, ex-vacuo ventriculomegaly due to diffuse white matter injury. Early recognition of neonatal ventriculomegaly and identification of the underlying condition is essential for clinicians to define the need for intervention and may, additionally, yield significant prognostic information. The main aims of this thesis were to optimize the early recognition of ventricular enlargement in neonates at risk and to explore the prognostic implications of cerebral ventriculomegaly among preterm infants. New reference values were established for several dimensions of the neonatal ventricles on cranial ultrasound, based on a cohort of 625 neonates born between 24-42 weeks gestational age. These reference values may further contribute to the timely diagnosis of neonatal ventriculomegaly and aid the clinician in evaluating the need for intervention for PHVD. At present, the optimal diagnostic and therapeutic approaches to neonates with PHVD are still a matter of debate. A survey among 32 European centres underlines the need to collaborate on an international consensus on the diagnosis and treatment of PHVD in order to achieve optimal care and long-term neurodevelopmental outcome for these infants. This thesis draws attention to specific effects of PHVD on the immature brain and elucidates potential mechanisms by which PHVD may affect neurodevelopmental outcome. PHVD was independently associated with altered brain volumes and white matter diffusion parameters in premature infants at term-equivalent age, in spite of early intervention in the majority of infants with PHVD. Reduced volumes were observed for deep grey matter, cerebellum, and extracerebral cerebrospinal volume on term MRI, whereas ventricular volumes were increased in association with PHVD. Ex-vacuo ventriculomegaly on cranial ultrasound or MRI at term-equivalent age was identified as an independent prognostic marker for adverse cognitive and motor outcome among preterm born infants.