Scripties UMCG - Rijksuniversiteit Groningen
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Mild neonatal hypoxic-ischemic encephalopathy : The relationship between survival of striatal neuronal phenotypes and epileptiform transients in the latent phase after asphyxia in near-term fetal sheep

(2018) Bensink, M. (Milou)

Introduction Neonates with mild hypoxic-ischemic encephalopathy (HIE) in the first 6 hours after birth are not eligible for therapeutic hypothermia, although there is increasing evidence that these neonates also have a significant risk of brain damage. This study tested the hypothesis that numbers of epileptiform transients in the latent phase may be a biomarker for the severity of hypoxic-ischemic injury of the striatum in near-term fetal sheep.
Methods Fetal sheep at 0.85 gestation received either sham (n = 9), 10 minutes (n = 8) or 15 minutes of umbilical cord occlusion (n = 7). Physiological parameters, electroencephalographic (EEG) amplitude, cortical impedance and carotid blood flow were assessed from 1 hour before to 6 hours after asphyxia and epileptiform events counted on the EEG. Fetuses were killed 3 days after occlusion and numbers of different striatal neuronal phenotypes were determined by immunohistochemistry.
Results The frequency of epileptiform discharges was greater after 15 minutes of occlusion than 10 minutes of occlusion (P < 0.05). Although there was no significant overall difference in the survival of striatal neuronal phenotypes between occlusion groups, loss of Calbindin-D28k positive neurons in the putamen was associated with a greater frequency of epileptiform discharges (r2 = 0.21, P < 0.05).
Conclusion These results suggest that epileptiform discharges are a potential biomarker for the severity of HIE. A limitation of this study is that there was no overall loss of striatal neurons after asphyxia; further analysis of more vulnerable brain regions such as the hippocampus and thalamus is essential.

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