Introduction: 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.
Discussion: 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.