Does Severity of Brain Injury on Magnetic Resonance Imaging Predict Short-Term Outcome in Neonates Who Received Therapeutic Hypothermia?

Objective The National Institute of Child Health and Human Development (NICHD) magnetic resonance imaging (MRI) pattern of brain injury is a known biomarker of childhood outcome following therapeutic hypothermia for neonatal hypoxic-ischemic encephalopathy (HIE). However, usefulness of this classification has not been evaluated to predict short-term outcomes. The study aimed to test the hypothesis that infants with NICHD MRI pattern of severe hypoxic-ischemic brain injury will be sicker with more severe asphyxia-induced multiorgan dysfunction resulting in prolonged length of stay (LOS) following therapeutic hypothermia. We also evaluated the role of other risk factors which may prolong LOS. Study Design We retrospectively reviewed the medical records of 71 consecutively cooled neonates to examine the ability of MRI patterns of brain injury to predict the LOS. A neuroradiologist masked to outcomes classified the patterns of brain injury on MRI as per NICHD. Pattern 2A (basal ganglia thalamic, internal capsule, or watershed infarction), 2B (2A with cerebral lesions), and 3 (hemispheric devastation) of brain injury was deemed severe injury. Results Out of 71 infants, 59 surviving infants had both MRI and LOS data. LOS was higher for infants who had Apgar's score of ≤5 at 10 minutes, severe HIE, seizures, coagulopathy, or needed vasopressors or inhaled nitric oxide, or had persistent feeding difficulty, or remained intubated following cooling. However, median LOS did not differ between the infants with and without MRI pattern of severe injury (15 days, interquartile range [IQR]: 9-28 vs. 12 days, IQR: 10-20; p = 0.4294). On multivariate linear regression analysis, only persistent feeding difficulty (β coefficient = 11, p = 0.001; or LOS = 11 days longer if had feeding difficulty) and ventilator days (β coefficient 1.7, p < 0.001; or LOS increased 1.7 times for each day of ventilator support) but not the severity of brain injury predicted LOS. Conclusion Unlike neurodevelopmental outcome, LOS is not related to severity of brain injury as defined by the NICHD. Key Points The NICHD pattern of brain injury on MRI predicts neurodevelopmental outcome following hypothermia treatment for neonatal HIE. LOS did not differ between the infants with and without MRI patterns of severe injury. The severity of brain injury as defined by the NICHD was not predictive of the LOS following therapeutic hypothermia.