Lower incidence of seizure among neonates treated with therapeutic hypothermia

Animal studies suggest that hypothermia decreases seizure burden, whereas limited human data are inconclusive. This retrospective cohort study examines the relationship between therapeutic hypothermia and seizure in neonates with hypoxic-ischemic encephalopathy. Our center admitted 224 neonates from July 2004 to December 2011 who met institutional cooling criteria. Seventy-three neonates were born during the pre-cooling era, prior to November 2007, and 151 were born during the cooling era. Among neonates with moderate encephalopathy, the incidence of seizure in cooled infants was less than half the incidence in those not cooled (26% cooling, 61% pre-cooling era; risk ratio = 0.43, 95% confidence interval = 0.30-0.61). Among neonates with severe encephalopathy, there was no difference in the incidence (83% vs. 87%; risk ratio = 1.05, 95% confidence interval = 0.78-1.39). These results support animal data and suggest a mechanism by which neonates with moderate encephalopathy can benefit more from cooling than neonates with severe encephalopathy.