New insights into the pathogenesis of perinatal hypoxic-ischemic brain injury

Pathogenesis of perinatal hypoxic-ischemic brain injury (HIE) is complex. In this study, we examined the role of neuroinflammation, oxidative stress and growth factors in perinatal hypoxic-ischemic brain damage.

Ninety neonates (>32 weeks' gestation) with perinatal HIE were enrolled prospectively. Perinatal HIE was categorized into three stages according to the Sarnat and Sarnat clinical scoring system and changes seen on amplitude integrated electroencephalography. Cerebrospinal fluid (CSF) for interleukin-6 (IL-6) and glutathione peroxidase analysis was taken in the first 48 h of life and subsequent CSF for neuron-specific enolase (NSE) and vascular endothelial growth factor (VEGF) analysis 72 h after birth. Neurodevelopmental outcome was assessed at 12 months of corrected gestational age using the Denver Developmental Screening Test.

Concentrations of NSE in CSF correlated with severity of HIE (P < 0.0001) and corresponded well with subsequent neurodevelopmental outcome. Concentrations of IL-6 in CSF were markedly increased in neonates with severe HIE (P < 0.0001) and those with subsequent neurological sequels, but were normal in the majority of neonates with mild and moderate HIE. Glutathione peroxidase activity in CSF was significant with the stage of HIE (P < 0.0001) and gestational age (P < 0.0001) and corresponded well with subsequent neurodevelopmental outcome. Advanced stage of HIE was associated with increased concentrations of VEGF in CSF (P < 0.0001). Neurological outcomes at 12 months of age correlated best with CSF level of NSE (P < 0.001) and IL-6 (P < 0.001).

Our results suggest that neuroinflammation plays a principal role in perinatal hypoxic-ischemic brain damage and we postulate that oxidative stress and upregulation of VEGF might be important contributing factors in the pathogenesis of hypoxic-ischemic brain injury, particularly in preterm neonates.