Neonatal Hypoxic-Ischemic Encephalopathy Spectrum: Severity-Stratified Analysis of Neuroimaging Modalities and Association with Neurodevelopmental Outcomes

Abstract

To compare hypoxic-ischemic injury on early cranial ultrasonography (cUS) and post-rewarming brain magnetic resonance imaging (MRI) in newborn infants with hypoxic-ischemic encephalopathy (HIE) and to correlate that neuroimaging with neurodevelopmental outcomes. This was a retrospective cohort study of infants with mild, moderate, and severe HIE treated with therapeutic hypothermia and evaluated with early cUS and postrewarming MRI. Validated scoring systems were used to compare the severity of brain injury on cUS and MRI. Neurodevelopmental outcomes were assessed at 18months of age. Among the 149 included infants, abnormal white matter (WM) and deep gray matter (DGM) hyperechogenicity on cUS in the first 48hours after birth were more common in the severe HIE group than the mild HIE group (81% vs 39% and 50% vs 0%, respectively; P<.001). In infants with a normal cUS, 95% had normal or mildly abnormal brain MRIs. In infants with severely abnormal cUS, none had normal and 83% had severely abnormal brain MRIs. Total abnormality scores on cUS were higher in neonates with near-total brain injury on MRI than in neonates with normal MRI or WM-predominant injury pattern (adjusted P<.001 for both). In the multivariable model, a severely abnormal MRI was the only independent risk factor for adverse outcomes (OR: 19.9, 95% CI: 4.0-98.1; P<.001). The present study shows the complementary utility of cUS in the first 48hours after birth as a predictive tool for the presence of hypoxic-ischemic injury on brain MRI.