Brain injury patterns in hypoxic ischemic encephalopathy of term neonates

Topographic patterns of brain injury in neonates can help with differentiation and prognostic categorization of hypoxic ischemic encephalopathy (HIE). In this study, we quantitatively and objectively characterized the location of hypoxic ischemic lesions in term neonates with varying severity of HIE.

We analyzed term neonates (born ≥37 postmenstrual gestational weeks) with MRI diffusion-weighted imaging (DWI) and diagnoses of HIE. Neonates' HIE was categorized into mild, moderate, and severe. The hypoxic ischemic lesions were segmented on DWI series with attention to T1- and T2-weighted images and then co-registered onto standard brain space to generate summation maps for each severity category. Applying voxel-wise general linear models, we also identified cerebral regions more likely to infarct with increasing severity of HIE, after correction for lesion volume and time-to-scan as covariates.

We included 33 neonates: 20 with mild, eight with moderate, and five with severe HIE. Infarct volumes (p = .00052) and Appearance, Pulse, Grimace, Activity, and Respiration scores at 1 minute (p = .032) differed between HIE severity categories. Hypoxic ischemic lesions in neonates with mild and moderate HIE were predominant in subcortical and deep white matter along the border zones of arterial supply territories, while severe HIE also involved basal ganglia, hippocampus, and thalamus. In voxel-wise analysis, higher severity of HIE was associated with the presence of lesions in hippocampus, thalamus, and lentiform nucleus.

In term neonates, mild/moderate HIE is associated with infarctions of arterial territory watershed zones, whereas severe HIE distinctively involves basal ganglia, thalami, and hippocampi.