Volumetric changes in brain MRI of infants with hypoxic-ischemic encephalopathy and abnormal neurodevelopment who underwent therapeutic hypothermia

Background:Hypoxic-ischemic encephalopathy (HIE) is a severe neonatal complication that can result in 40-60 % of long-term morbidity. Magnetic Resonance Imaging (MRI) is a noninvasive method which is usually performed before discharge to visually assess acquired cerebral lesions associated with HIE and severity of lesions possibly providing a guide for detecting adverse outcomes. This study aims to evaluate the impact of HIE on brain volume changes observed in MRI scans performed at a mean 10 days of life, which can serve as a prognostic indicator for abnormal neurodevelopmental (ND) outcomes at 18-24 months among HIE infants.Methods: We retrospectively identified a cohort of HIE patients between June 2013 and March 2017. The inclusion criteria for therapeutic hypothermia (TH) were a gestational age >= 35 weeks, a birth weight >= 1800 g, and the presence of >= moderate HIE. Brain MRI was performed at a mean 10 days of life and brain volumes (total brain volume, cerebral volume, cerebellar volume, brain stem volume, and ventricle volume) were measured for quantitative assessment. At 18-24 months, the infants returned for follow-up evaluations, during which their cognitive, language, and motor skills were assessed using the Bayley Scales of Infant and Toddler Development III.Results: The study recruited a total of 240 infants between 2013 and 2017 for volumetric brain MRI evaluation. Among these, 83 were normal control infants, 107 were TH-treated HIE infants and 37 were HIE infants who did not receive TH due to contraindications. Clinical evaluation was further proceeded. We compared the brain volumes between the normal control infants (n = 83) with normal ND but TH-treated HIE infants (n = 76), abnormal ND TH-treated HIE infants (n = 31), and the severe HIE MRI group with no TH (n = 37). The abnormal ND TH-treated HIE infants demonstrated a significant decrease in brainstem volume and an increase in ventricle size (p < 0.001) (Table 4). Lastly, the severe brain MRI group who did not receive TH showed significantly smaller brain stem (p = 0.006), cerebellar (p = 0.006) and cerebrum volumes (p = 0.027), accompanied by larger ventricular size (p = 0.013) compared to the normal control group (Table 5).Conclusion: In addition to assessing the location of brain injuries in MRI scans, the reduction in brain stem volume coupled with an increase in ventricular volume in HIE infants may serve as a biomarker indicating severe HIE and adverse long-term ND outcomes among HIE infants who either received therapeutic hypothermia (TH) treatment or not.