title: Limited predictive value of early changes in EEG spectral power for neural injury after asphyxia in preterm fetal sheep.
abstract: BACKGROUND
  This study examined whether spectral analysis of the electroencephalogram (EEG) can discriminate between mild and severe hypoxic-ischemic injury in the immature brain.
  
  
  RESULTS
  Total EEG power was profoundly suppressed after umbilical cord occlusion and recovered to baseline by 5 h after 15-min of occlusion, in contrast with transient recovery in the 25-min (P < 0.05). Power spectra were not different between groups in the first 3 h; α and β power were significantly higher in the 15-min group from 4 h, and Δ and θ power from 5 h (P < 0.05). The 25-min group showed severe neuronal loss in hippocampal regions and basal ganglia at 3 days, in contrast with no/minimal injury in the 15-min group.
  
  
  CONCLUSIONS
  EEG power after asphyxia did not discriminate between mild and severe injury in the first 3 h in preterm fetal sheep. Severe subcortical neural injury was associated with persistent loss of high-frequency activity.
  
  
  METHODS
  Chronically instrumented fetal sheep at 0.7 gestation (101-104 days; term is 147 days) received either 15-min (n = 13) or 25-min (n = 13) of complete umbilical cord occlusion. The Δ (0-3.9 Hz), θ (4-7.9 Hz), α (8-12.9 Hz), and β (13-22 Hz) components of the EEG were determined by power spectral analysis. Brains were taken at 3 days for histopathology.
authors.affiliation: Fetal Physiology and Neuroscience Group, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Keogh
authors.forename: Paul P
authors.initials: PP
authors.lastname: Drury
authors.forename: Laura
authors.initials: L
authors.lastname: Bennet
authors.forename: Joanne O
authors.initials: JO
authors.lastname: Davidson
authors.forename: Sam
authors.initials: S
authors.lastname: Mathai
authors.forename: Eleanor R
authors.initials: ER
authors.lastname: Gunn
authors.forename: Lindsea C
authors.initials: LC
authors.lastname: Booth
authors.forename: Alistair J
authors.initials: AJ
authors.lastname: Gunn
mesh_terms: D000818:Animals; D001237:Asphyxia / Q000378:metabolism*; D001921:Brain / Q000196:embryology*; D002245:Carbon Dioxide / Q000737:chemistry; D004569:Electroencephalography / Q000379:methods*; D004576:Electromyography / Q000379:methods; D005260:Female; D006624:Hippocampus / Q000473:pathology; D000860:Hypoxia / Q000473:pathology; D007511:Ischemia / Q000473:pathology; D009474:Neurons / Q000473:pathology; D010477:Perfusion; D011237:Predictive Value of Tests; D011247:Pregnancy; D011270:Pregnancy, Animal; D012756:Sheep; D013997:Time Factors; D014470:Umbilical Cord / Q000473:pathology
chemical_list: D002245:Carbon Dioxide