Supplementary Material for: Association of Two Neonatal Encephalopathy Scores with Neurophysiology in Newborns with Suspected Hypoxic Ischemic Encephalopathy

Background/Objective: Severity of hypoxic-ischemic encephalopathy (HIE) is traditionally assessed by neurologic exam; however, electroencephalography (EEG) is a more standardized, reproducible measure of NE. We aimed to compare two numeric NE scores with neurophysiological measures of encephalopathy, to describe EEG patterns in newborns with low NE scores, and to assess evolution of NE scores within 6 hours after birth.
Study Design/Methods: We retrospectively analyzed associations between two NE scores, aEEG, and cEEG in 321 newborns in a 14-center collaborative NE Registry.
Results: There was a significant association between both NE scores and aEEG/cEEG (p<0.001), with higher scores in newborns with more abnormal aEEG background patterns. A minority of newborns with low NE scores (<4) had abnormal aEEG/cEEG, but all were treated with therapeutic hypothermia (TH). Most newborns with serial NE scores (74%) had evolution of encephalopathy; more newborns had decreasing/improving (48%) than increasing/worsening (26%) NE scores. Newborns with improving versus worsening scores were more likely to have a first NE score completed before 1 hour after birth.
Conclusions: Both NE scores showed a significant correlation with neurophysiology, but NE scores have limitations. Since HIE evolves in most newborns, serial NE exams are recommended with the initial or at least confirmatory NE exam completed at >1 hour of age. aEEG/cEEG may be particularly useful for identifying more substantial NE warranting TH treatment in newborns with mild NE by exam. Data from this study support standardized use of neurophysiology in evaluating asphyxiated, encephalopathic newborns.