Outcomes of Infants with Mild Hypoxic Ischemic Encephalopathy Who Did Not Receive Therapeutic Hypothermia

INTRODUCTION: Accurately diagnosing and treating infants with mild forms of hypoxic ischemic encephalopathy (HIE) is important, as the majority of neonates with signs and symptoms of HIE after birth do not meet clinical criteria for moderate or severe disease. Emerging evidence, however, suggests that infants with mild HIE (mHIE) have an increased risk for neurodevelopmental impairment (NDI). METHODS: This retrospective descriptive study examined all inborn infants ≥35 week's gestational age at a single, level III neonatal intensive care unit (NICU) in California between January 1, 2012, and December 31, 2015. International Classification of Diseases codes were used as a proxy to identify neonates with mHIE but who did not receive therapeutic hypothermia (TH). Short- and long-term neurodevelopmental outcomes were documented, including abnormal (1) brain magnetic resonance imaging within 10 days of birth suggestive of HIE, (2) electroencephalogram with electrographic seizures, (3) neurologic discharge examination, or (4) NDI following NICU discharge. RESULTS: Over the 4-year study period, 25 infants met inclusion criteria. Eight of 25 (32%) infants demonstrated neurologic impairment, defined by an abnormality in at least one of the four categories. The remaining 17 infants were without documented evidence for adverse outcomes. CONCLUSION: Our results indicate that children with mHIE are at significant risk for neurologic injury and may benefit from more aggressive interventions. Further prospective studies should be completed to determine the efficacy of TH in this specific patient population.