EEG and long-term outcome of term infants with neonatal hypoxic-ischemic encephalopathy

Objective: The prognostic value of a burst suppression pattern (BSP) on the electroencephalograph (EEG) in the prediction of long-term outcome for full term newborns with hypoxic-ischemic encephalopathy (HIE) is well established. The purpose of our study was to compare the patterns of burst suppression on EEG with long-term neurological outcome in term infants with HIE. Methods: We retrospectively analyzed all records of all full-term newborn infants born at the University of Alberta Hospital between January 1, 1991 and December 31, 1992, who had clinical evidence of HIE and had at least one EEG during the first week of life. The EEGs were reviewed and blindly subclassified into a BSP, or if the pattern was not continuous or was incomplete, a modified burst suppression pattern (MBSP), based on specified electrophysiological criteria. The long-term neurological outcome was then correlated with the EEG pattern. Results: Twenty-three full-term infants were studied. Fifteen had a BSP on EEG and 8 had a MBSP. Six of 15 infants with a BSP died. Of the 9 survivors with a BSP, 7 are disabled and two are normal. Of the 8 infants in the MBSP group, one infant died, two are disabled and 5 are normal. In the BSP group, 6/7 disabled infants developed cerebral palsy while in the MBSP group, only one developed cerebral palsy. Conclusion: The results are suggestive of a better outcome for infants with neonatal HIE and MBSP on EEG compared with those with a BSP. Subclassification of the EEG changes of neonatal HIE into BSP and MBSP may give a more accurate prediction of outcome in perinatal asphyxia and assist in discussion with parents about prognosis.