Neonatal frontal lobe: sonographic reference values and suggested clinical use

Intraventricular hemorrhage (IVH) and post-hemorrhagic hydrocephalus (PHHC) remain major problems among premature infants. The need, timing and type of ventricular drainage are based on sonographic ventricular measures, without assessment of the dimensions of the frontal lobe. The aim of our study was to establish new reference values for sonographic frontal lobe cortico-ventricular thickness (FL-CVT) in a large cohort of infants.

All normal head ultrasound scans that were performed in our center during the first 4 days of life between January 2014 and December 2016 were retrospectively evaluated.

Scans were evaluated and plotted to create a reference range for the thickness of the frontal lobe in normal infants of 24-40 weeks' gestation. The FL-CVT increased significantly during gestation. Calculating the area under the curve of the FL-CVT in 9 infants with post-hemorrhagic-hydrocephalus (PHHC) reveals a 20% mean loss of FL-CVT. The impact of increasing ventricular dilatation and of the various ventricular drainage procedures on the frontal lobe growth were described in two infants demonstrating the potential clinical value of this tool.

Head ultrasound provides a simple, non-invasive method for measuring the thickness of the frontal lobe, which grows significantly between 24 and 40 weeks' gestation. In premature infants with PHHC, we suggest the use of the FL-CVT measure, in addition to ventricular size measures, as a direct assessment of the impact of the enlarged ventricles on the surrounding brain parenchyma. This could assist in the management of PHHC and determine the need and optimal timing for intervention.