title: The temporal characteristics of seizures in neonatal hypoxic ischemic encephalopathy treated with hypothermia.
abstract: OBJECTIVE
  The characteristics of electrographic seizures in newborns with hypoxic-ischaemic encephalopathy (HIE) treated with therapeutic hypothermia (TH) are poorly described. This retrospective, observational study provides reference data on the characteristics of seizures and their evolution over time in newborns with HIE receiving whole-body TH.
  
  
  METHODS
  The cohort under analysis included 23 infants with HIE and seizures defined by multi-channel EEG recordings. Clinical presentation, details of TH and antiepileptic drugs used were recorded. Time from first to last-recorded electrographic seizure (seizure period) was calculated. Temporal characteristics of seizures - total burden, duration, number, burden in minutes per hour, distribution of burden over time (temporal evolution), time from seizure onset to maximum seizure burden (Tmsb), T1, and time from Tmsb to seizure offset, T2 - were analysed.
  
  
  RESULTS
  The median age at electrographic seizure onset was 13.1h (IQR: 11.4 to 22.0). Tmsb was reached at a median age of 19.4 hours (IQR: 12.2 to 29.7). Median seizure period was 16.5h (IQR: 7.0 to 49.7), median number of seizures per hour was 1.9 (IQR: 1.0 to 3.3). The seizure burden was 4.0 min/h (IQR: 2.0 to 7.0). There was no consistent pattern in the temporal evolution of seizures in neonates treated with TH. The skewness was neither positive nor negative (p-value=0.15), there was no difference between the duration of T1 and T2 (p-value=0.09) and no difference in the seizure burden between T1 and T2 (p=0.09). There was an association between Tmsb and Phenobarbital (PB) administration (r=0.76, p-value<0.001).
  
  
  CONCLUSIONS
  There is no consistent temporal evolution of seizure burden in neonates treated with TH. Seizures are diffuse, and their characteristics are variable.
authors.affiliation: Department of Paediatrics and Child Health, University College Cork; Neonatal Brain Research Group, Irish Centre for Fetal and Neonatal Translational Research, University College Cork.
authors.forename: Niamh E
authors.initials: NE
authors.lastname: Lynch
authors.affiliation: Neonatal Brain Research Group, Irish Centre for Fetal and Neonatal Translational Research, University College Cork.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Stevenson
authors.affiliation: Neonatal Brain Research Group, Irish Centre for Fetal and Neonatal Translational Research, University College Cork.
authors.forename: Vicki
authors.initials: V
authors.lastname: Livingstone
authors.affiliation: Elizabeth Garrett Anderson Institute for Women's Health, University College London Hospitals, London.
authors.forename: Sean
authors.initials: S
authors.lastname: Mathieson
authors.affiliation: Department of Paediatrics and Child Health, University College Cork; Neonatal Brain Research Group, Irish Centre for Fetal and Neonatal Translational Research, University College Cork.
authors.forename: Brendan P
authors.initials: BP
authors.lastname: Murphy
authors.affiliation: Elizabeth Garrett Anderson Institute for Women's Health, University College London Hospitals, London.
authors.forename: Janet M
authors.initials: JM
authors.lastname: Rennie
authors.affiliation: Department of Paediatrics and Child Health, University College Cork; Neonatal Brain Research Group, Irish Centre for Fetal and Neonatal Translational Research, University College Cork. Electronic address: g.boylan@ucc.ie.
authors.forename: Geraldine B
authors.initials: GB
authors.lastname: Boylan
mesh_terms: D000927:Anticonvulsants / Q000627:therapeutic use; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D020925:Hypoxia-Ischemia, Brain / Q000150:complications* / Q000628:therapy*; D007223:Infant; D008297:Male; D012189:Retrospective Studies; D012640:Seizures / Q000209:etiology* / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000927:Anticonvulsants
keywords: Electroencephalogram; Hypoxic-ischaemic encephalopathy; Neonatal seizures; Therapeutic hypothermia