Assessing Neurovascular Coupling Using Wavelet Coherence in Neonates with Asphyxia

Brain monitoring is important in neonates with asphyxia in order to assess the severity of hypoxic ischaemic encephalopathy (HIE) and identify neonates at risk of adverse neurodevelopmental outcome. Previous studies suggest that neurovascular coupling (NVC), quantified as the interaction between electroencephalography (EEG) and near-infrared spectroscopy (NIRS)-derived regional cerebral oxygen saturation (rSO2) is a promising biomarker for HIE severity and outcome. In this study, we explore how wavelet coherence can be used to assess NVC. Wavelet coherence was computed in 18 neonates undergoing therapeutic hypothermia in the first 3 days of life, with varying HIE severities (mild, moderate, severe). We compared two pre-processing methods of the EEG prior to wavelet computation: amplitude integrated EEG (aEEG) and EEG bandpower. Furthermore, we proposed average real coherence as a biomarker for NVC. Our results indicate that NVC as assessed by wavelet coherence between EEG bandpower and rSO2 can be a valuable biomarker for HIE severity in neonates with peripartal asphyxia. More specifically, average real coherence in a very low frequency range (0.21-0.83 mHz) tends to be high (positive) in neonates with mild HIE, low (positive) in neonates with moderate HIE, and negative in neonates with severe HIE. Further investigation in a larger patient cohort is needed to validate our findings.