Hypothermia in mild neonatal hypoxic-ischemic encephalopathy: data study of a perinatal hospital in Portugal

Introduction and objectives: Therapeutic hypothermia (TH) is the standard of care for neonates with moderate and severe hypoxic-ischemic encephalopathy (HIE).There is a growing trend toward the use of TH in mild HIE, although current evidence regarding optimal management is lacking.This study aims to evaluate the incidence of newborns with mild HIE undergoing TH over the last 14 years, and to describe the severity of brain injury and short-term results.Methods: We conducted a retrospective, descriptive study of neonates admitted with mild HIE (Sarnat stage 1 encephalopathy) and treated with TH in a level III Neonatal Intensive Care Unit in Portugal, from January 2010 to June 2024.The data collected included information on birth details, clinical factors, and short-term outcomes.Results: A total of 176 neonates with HIE were treated with TH in the studied period.The sample included 12 neonates (6.8%) with mild HIE.The main results showed that: a sentinel event was identified in 58% of cases; the aEEG background was mainly classified as normal or moderately abnormal (83%); abnormal brain Magnetic Resonance Imaging was identified in five neonates (41.6%); the neurological examination at discharge was normal in 92% of the neonates; and none had epileptic activity on the EEG at discharge.Discussion: Brain injury may be identified in some neonates with mild hypoxic-ischemic encephalopathy.However, the clinical significance of these findings and the potential benefit or harm of hypothermia in this population remain uncertain.Larger, multicenter case-control studies are needed to clarify the impact of therapeutic hypothermia on brain injury patterns and neurodevelopmental outcomes in mild HIE.