Study of the Term Neonatal Brain Injury with combined Diffuse Optical Tomography and Electroencephalography

This thesis describes the application of combined diffuse optical tomography (DOT) and electroencephalography (EEG) in the investigation of neonatal term brain injury. With hypoxic ischaemic encephalopathy (HIE) and perinatal stroke being the most frequent contributors to brain injury in the term neonatal population, the first part of the thesis focuses on the description and ongoing requirement for their further investigation. In continuation to that, the characteristics and unique properties of both DOT and EEG are described and explored. The combination of these two modalities was utilised in elucidating the relationship between neuronal activity and cerebral haemodynamics both in physiological processes as well as in disease, by the infant’s cot side. This work differs to previous studies using near-infrared technologies and EEG, as a denser whole head array was used, offering the potential of 3-dimensional image reconstruction of the cortical haemodynamic events in relation to electro-cortical activity. These methods were applied in the study of critically ill infants presenting with seizures in the first few days of life. The relevant results are presented in three separate chapters of the thesis. Distinct neurophysiological phenomena such as seizures and burst suppression were detected and studied in association to underlying HIE. On the grounds of a pre-existing pilot study of our research group, distinct prolonged de-oxygenated cortical areas were identified following electrical seizure activity. Further exploration of infants with seizures provided limited supporting evidence. The investigation of burst suppression in HIE led to the first ever identification of repeated, waveform, cortical haemodynamic events in response to bursts of electrical activity with some spatial correlation to regions of brain injury. Further analysis of the low frequencies within the diffuse optical signal in cases of perinatal stroke, showed a consistent interhemispheric difference between the healthy and stroke-affected brain regions. The limitations, prospects and conclusions are presented in the final chapter. The use of simultaneous DOT and EEG offers a unique neuro-monitoring and neuro-investigating tool in the neonatal intensive care environment, which is safe, portable, and cost-effective, Ongoing research is required for the exploration and development of the methodology and its potential diagnostic properties

Sleep State Modulates Resting-State Functional Connectivity in Neonates.

The spontaneous cerebral activity that gives rise to resting-state networks (RSNs) has been extensively studied in infants in recent years. However, the influence of sleep state on the presence of observable RSNs has yet to be formally investigated in the infant population, despite evidence that sleep modulates resting-state functional connectivity in adults. This effect could be extremely important, as most infant neuroimaging studies rely on the neonate to remain asleep throughout data acquisition. In this study, we combine functional near-infrared spectroscopy with electroencephalography to simultaneously monitor sleep state and investigate RSNs in a cohort of healthy term born neonates. During active sleep (AS) and quiet sleep (QS) our newborn neonates show functional connectivity patterns spatially consistent with previously reported RSN structures. Our three independent functional connectivity analyses revealed stronger interhemispheric connectivity during AS than during QS. In turn, within hemisphere short-range functional connectivity seems to be enhanced during QS. These findings underline the importance of sleep state monitoring in the investigation of RSNs

Practical Approaches to the Treatment of Neonatal Seizures

Purpose of review: This paper critically reviews the current literature and evidence on diagnosis, classification, clinical approach, and management of neonatal seizures. A stepwise approach for the treatment of neonatal seizures is presented. Recent findings: In a recent randomized controlled trial comparing phenobarbital to levetiracetam as a first-choice anti-seizure medication with primary outcome seizure free for 24 h, the former was found superior (80% vs 28%, p < 0.001). Summary: Neonatal seizures require immediate diagnostic and therapeutic interventions. Phenobarbital is the first-line anti-seizure drug for neonatal seizures, but there is little evidence regarding second-line pharmacotherapy. There is a need for more randomized controlled trials for the use of other existing anti-seizure drugs, yet unlicensed in neonates, and the development of new drugs specifically for neonates

Pacific decadal oscillation and the decadal change in the intensity of the interannual variability of the South China Sea summer monsoon

The decadal variation of the intensity of the interannual variability (IIV) of the South China Sea summer monsoon (SCSSM) was partly modulated by the Pacific Decadal Oscillation (PDO) during the twentieth century. The SCSSM shows larger (smaller) IIV in the warm (cold) phase of the PDO. Results show that the IIV of the tropical Pacific SST and the ENSO–SCSSM relationship play key roles in the modulation of the PDO on the SCSSM IIV. In the warm phase of the PDO, the variability of the SST in the tropical Pacific tends to be larger than that in the cold phase, along with stronger ENSO events. Subsequently, the interaction between the tropical Pacific SST and the SCSSM becomes stronger via changing the strength and position of the Walker circulation and the anomalous western North Pacific anticyclone. Therefore, the large IIV of the tropical Pacific SST and the close ENSO–SCSSM relationship lead to the large IIV of the SCSSM in the warm phase of the PDO, and vice versa