Subcortical brain volumes in neonatal hypoxic-ischemic encephalopathy

Despite treatment with therapeutic hypothermia, hypoxic-ischemic encephalopathy (HIE) is associated with adverse developmental outcomes, suggesting the involvement of subcortical structures including the thalamus and basal ganglia, which may be vulnerable to perinatal asphyxia, particularly during the acute period. The aims were: (1) to examine subcortical macrostructure in neonates with HIE compared to age- and sex-matched healthy neonates within the first week of life; (2) to determine whether subcortical brain volumes are associated with HIE severity.

Neonates (n = 56; HIE: n = 28; Healthy newborns from the Developing Human Connectome Project: n = 28) were scanned with MRI within the first week of life. Subcortical volumes were automatically extracted from T1-weighted images. General linear models assessed between-group differences in subcortical volumes, adjusting for sex, gestational age, postmenstrual age, and total cerebral volumes. Within-group analyses evaluated the association between subcortical volumes and HIE severity.

Neonates with HIE had smaller bilateral thalamic, basal ganglia and right hippocampal and cerebellar volumes compared to controls (all, p < 0.02). Within the HIE group, mild HIE severity was associated with smaller volumes of the left and right basal ganglia (both, p < 0.007) and the left hippocampus and thalamus (both, p < 0.04).

Findings suggest that, despite advances in neonatal care, HIE is associated with significant alterations in subcortical brain macrostructure.

Compared to their healthy counterparts, infants with HIE demonstrate significant alterations in subcortical brain macrostructure on MRI acquired as early as 4 days after birth. Smaller subcortical volumes impacting sensory and motor regions, including the thalamus, basal ganglia, and cerebellum, were seen in infants with HIE. Mild and moderate HIE were associated with smaller subcortical volumes.