Seizure burden and neurodevelopmental outcome in neonates with hypoxic-ischemic encephalopathy.
OBJECTIVE
To examine the relationship between electrographic seizures and long-term outcome in neonates with hypoxic-ischemic encephalopathy (HIE).


METHODS
Full-term neonates with HIE born in Cork University Maternity Hospital from 2003 to 2006 (pre-hypothermia era) and 2009 to 2012 (hypothermia era) were included in this observational study. All had early continuous electroencephalography monitoring. All electrographic seizures were annotated. The total seizure burden and hourly seizure burden were calculated. Outcome (normal/abnormal) was assessed at 24 to 48 months in surviving neonates using either the Bayley Scales of Infant and Toddler Development, Third Edition or the Griffiths Mental Development Scales; a diagnosis of cerebral palsy or epilepsy was also considered an abnormal outcome.


RESULTS
Continuous electroencephalography was recorded for a median of 57.1 hours (interquartile range 33.5-80.5h) in 47 neonates (31 males, 16 females); 29 out of 47 (62%) had electrographic seizures and 25 out of 47 (53%) had an abnormal outcome. The presence of seizures per se was not associated with abnormal outcome (p=0.126); however, the odds of an abnormal outcome increased over ninefold (odds ratio [OR] 9.56; 95% confidence interval [95% CI] 2.43-37.67) if a neonate had a total seizure burden of more than 40 minutes (p=0.001), and eightfold (OR: 8.00; 95% CI: 2.06-31.07) if a neonate had a maximum hourly seizure burden of more than 13 minutes per hour (p=0.003). Controlling for electrographic HIE grade or treatment with hypothermia did not change the direction of the relationship between seizure burden and outcome.


CONCLUSIONS
In HIE, a high electrographic seizure burden is significantly associated with abnormal outcome, independent of HIE severity or treatment with hypothermia.
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.|Department of Paediatrics and Child Health, University College Cork, Cork, Ireland.
Liudmila
L
Kharoshankaya
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.
Nathan J
NJ
Stevenson
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.
Vicki
V
Livingstone
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.|Department of Paediatrics and Child Health, University College Cork, Cork, Ireland.
Deirdre M
DM
Murray
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.|Department of Neonatology, Cork University Maternity Hospital, Cork, Ireland.
Brendan P
BP
Murphy
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.|Department of Paediatrics and Child Health, University College Cork, Cork, Ireland.
Caroline E
CE
Ahearne
Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.|Department of Paediatrics and Child Health, University College Cork, Cork, Ireland.
Geraldine B
GB
Boylan
D002675:Child, Preschool; D004569:Electroencephalography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods* / Q000706:statistics & numerical data; D020925:Hypoxia-Ischemia, Brain / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000628:therapy; D007231:Infant, Newborn; D007494:Ireland / Q000453:epidemiology; D008297:Male; D065886:Neurodevelopmental Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data; D012640:Seizures / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D012720:Severity of Illness Index