Introduction
Fetal ventriculomegaly is the most common detectable central nervous system abnormality affecting 1% of fetuses and is associated with abnormal neurodevelopment in childhood. Neurodevelopmental outcome is partially predictable by the 2D size of the ventricles in the absence of other abnormalities while the aetiology of the dilatation remains unknown. The main aim of this study was to investigate brain development in the presence of isolated ventriculomegaly during fetal and neonatal life.
Methods
Fetal brain MRI (1.5T) was performed in 60 normal fetuses and 65 with isolated ventriculomegaly from 22-38 gestational weeks. Volumetric analysis of the ventricles and supratentorial brain structures was performed on 3D reconstructed datasets while cortical maturation was assessed using a detailed cortical scoring system. The metabolic profile of the fetal brain was assessed using magnetic resonance spectroscopy. During neonatal life, volumetric analysis of ventricular and supratentorial brain tissue was performed while white matter microstructure was assessed using Diffusion Tensor Imaging. The neurodevelopmental outcome of these children was evaluated at 1 and 2 years of age.
Results
Fetuses with isolated ventriculomegaly had significantly increased cortical volumes when compared to controls while cortical maturation of the calcarine sulcus and parieto-occipital fissure was delayed. NAA:Cho, MI:Cho and MI:Cr ratios were lower whilst Cho:Cr ratios were higher in fetuses with ventriculomegaly. Neonates with prenatally diagnosed ventriculomegaly had increased ventricular and supratentorial brain tissue volumes and reduced FA values in the splenium of the corpus callosum, sagittal striatum and corona radiata. At year 2 of age, only 37.5% of the children assessed had a normal neurodevelopment. Conclusions
The presence of relative cortical overgrowth, delayed cortical maturation and aberrant white matter development in fetuses with ventriculomegaly may represent the neurobiological substrate for cognitive, language and behavioural deficits in these children.