99 - Early EEG in Infants with Mild Hypoxic-ischaemic Encephalopathy and 2-year Outcome

Poster Number: 99
Publication Number: 99.336

Aisling A. Garvey, INFANT Centre, Ireland/Brigham and Womens Hospital, USA, Cork, Cork, Ireland; Geraldine B. Boylan, University College Cork, Cork, Cork, Ireland; Andreea M. Pavel, University College Cork, Cork, Cork, Ireland; John M.. O'Toole, INFANT Research Centre, University College Cork, Ireland, Cork, Cork, Ireland; Brian Walsh, University College Cork, Cork, Cork, Ireland; Eugene Dempsey, university college cork, Cork, Cork, Ireland; Deirdre Murray, University College Cork, Cork, Cork, Ireland

Background: Infants with mild hypoxic-ischaemic encephalopathy (HIE) are at significant risk of poor long-term developmental outcome. Early identification of infants at risk may allow for targeted interventions in the neonatal period and beyond. Early EEG before 6 hours of age demonstrates differences in qualitative and quantitative measures in infants with mild HIE compared to healthy term infants.

Objective: This study aimed to examine if detailed EEG analysis (in the first 6 hours after birth) in infants with mild HIE is associated with neurodevelopmental outcome at 2 years.

Design/Methods: Infants > 36 weeks with mild HIE, not undergoing therapeutic hypothermia (TH), with EEG recording within 6 hours of age and standardised neurodevelopmental follow-up at approximately 2 years were identified from 4 previous prospective studies in Cork, Ireland (2003-2019). EEGs within 6 hours of birth were independently analysed by 2 neonatal neurophysiologists blinded to outcome using a previously published grading system and quantitatively assessed using multiple features of amplitude, spectral shape and inter-hemispheric connectivity.

Results: Forty-eight infants with mild HIE were included. Infants were followed up at a median age of 24 months (IQR 22-29). Twelve infants (25%) had an abnormal outcome at follow up. Seventy-three percent (35/48) of infants had at least one abnormal feature on EEG at 6 hours on qualitative analysis, 9 of whom (26%) had an abnormal outcome. Of the 13 infants with normal early qualitative EEG, 3 (23%) had an abnormal outcome. Qualitative EEG features at 6 hours were not associated with outcome. Quantitative analysis of spectral difference was significantly associated with adverse outcome at the lower frequency bands (correlation coefficient -0.37, p=0.01)

Conclusion(s): Early quantitative EGG features may be better in identifying infants with mild HIE at risk of poor neurodevelopmental outcome than qualitative EEG analysis alone. Infants with mild HIE have an increased risk of learning, emotional and behavioural difficulties which may not be evident until school age or beyond and longer term follow up will be important in this cohort.