Comparison of neonatal hippocampal volume and development status at 4-6 months of age in hypoxic-ischemic encephalopathy.

UNLABELLED: Perinatal hypoxia and ischemia, which lead to hypoxic-ischemic encephalopathy (HIE), are leading causes of long-term neurodevelopmental disability in low- to middle-income countries. The hippocampus is particularly vulnerable to hypoxic-ischemic insult, and the impact of hippocampal volume on developmental outcomes in newborns with HIE remains underexplored. The current study was conducted to compare the hippocampal volume measured by magnetic resonance (MR) brain imaging of neonates with HIE between those with normal development and those with delayed development at 4-6 months of age. This longitudinal observational study was conducted at a tertiary care center in western India. Neonates with HIE were enrolled, and the hippocampal volume was assessed via brain MRI. A repeat assessment of hippocampal volume was performed at the age of 4-6 months, along with a developmental evaluation via the Hammersmith Infant Neurological Examination (HINE). Hippocampal volume at the neonatal stage and at 4-6 months was compared between infants with and without developmental delay. Sixty neonates meeting the inclusion and exclusion criteria were enrolled, 44 of whom were available for assessment at 4-6 months. Compared with infants without developmental delay, asphyxiated newborns with developmental delay at 4-6 months of age presented a lower hippocampal volume (0.7 cm3 vs. 1.13 cm3, p = 0.002). Similarly, the hippocampal volume was significantly reduced at 4-6 months of age in infants with developmental delay (0.69 cm3 vs. 1.16 cm3, p = 0.001). The hippocampal volume during the neonatal period or at 4-6 months of age did not differ significantly across the stages of HIE.

CONCLUSION: Hippocampal volume measured during the neonatal period in HIE neonates can predict neurodevelopmental outcomes at 4-6 months of age, with the potential to identify high-risk neonates for developmental delay and the initiation of early intervention. Early recognition of neonatal hippocampal volume may result in better development outcomes.

WHAT IS KNOWN: • Neonatal HIE is a leading cause of neurodevelopmental morbidity and Hippocampus, due to its high metabolic demand, is selectively vulnerable to Hypoxic Ischemic Injury. • Hippocampal atrophy as measured by volumetric MRI correlates with long-term cognitive impairment.

WHAT IS NEW: • Quantitative neonatal hippocampal volumetry predicts neurodevelopmental outcome at 4-6 months in neonatal HIE and infants with developmental delay exhibit reduced hippocampal volume and hippocampal-to-brain volume ratio (HFV/TBV). • Early hippocampal volumetry therefore provides a sensitive, region-specific biomarker for prognostication and early neurorehabilitative stratification in neonatal HIE.