EEG in premature newborns

International audienc

Identifying neural drivers of benign childhood epilepsy with centrotemporal spikes

Epilepsy is a neurological disorder characterized by abnormal electrical discharges in a group of brain cells. Benign childhood epilepsy, which affect children under the age of 12years, has been reported to contribute to the cognitive impairment of these children, even in the absence of structural abnormalities. Functional connectivity models have been applied to provide a deeper understanding of the processes that control and regulate interictal activity of benign childhood epilepsy. These studies have shown regions of increased connectivity and activity, particularly at the epileptic zone, which is usually the central region around the sensorimotor cortex, and in the immediate regions surrounding the zone and reduced activity in distant regions, such as the frontal lobe and temporal regions. The present study was designed to identify the neural drivers involved in the initiation and propagation of epileptic activity and the causal relationships between brain regions with increased and decreased connectivity and functional activity. We used three different models to identify neural drivers and casual connectivity with dynamic causal modelling (DCM) of EEG data. All models showed that the central region, the source of the epileptic activity, is the major driver of the brain network during interictal discharges. Other regions include the temporoparietal junction and temporal pole. The central region also had influence on the frontal and contralateral hemisphere, which might explain the cognitive deficits observed in these patients. Keywords: Benign childhood epilepsy, EEG, Dynamic causal modelling, Interictal activit

Continuous monitoring of neonatal cortical activity: A major step forward.

Montazeri Moghadam et al.1 report an automated algorithm to visually convert EEG recordings to real-time quantified interpretations of EEG in neonates. The resulting measure of the brain state of the newborn (BSN) bridges several gaps in neurocritical care monitoring

Exploration de l'unité neurovasculaire dans l'épilepsie de l'enfant (approche multimodale haute densité couplant l'EEG à l'imagerie optique fonctionnelle)

L objectif de ce travail était d explorer l unité neurovasculaire épileptogène par une approche couplant l imagerie optique et EEG Haute Densité. Chez l animal, l imagerie optique mettait en évidence des modifications hémodynamiques débutant avant les pointes intercritiques. Chez l enfant, des modifications hémodynamiques complexes, associant variations du volume sanguin cérébral (qui pouvaient débuter avant les pointes épileptiques) à un couplage neurovasculaire, dont les caractéristiques différaient du modèle de Buxton, étaient observées, indifféremment, dans les épilepsies partielles, idiopathiques ou non. L analyse en temps-fréquence de l EEG retrouvait, des séquences hyper - désynchronisation, en miroir autour des pointes, dans les structures néocorticales et mésiales. Les modifications hémodynamiques et de synchronisation étaient spatialement concordantes avec le foyer épileptogène et apportaient des informations complémentaires sur la dynamique temporo-spatiale des réseaux intercritiques ainsi que sur les processus physiopathologiques liés aux pointes. Notre démarche, appliquée aux spasmes infantiles, retrouvait également des modifications hémodynamiques complexes (modifications du volume sanguin cérébral pouvant être suivies d un couplage neurovasculaire), qui suggéraient la mise en jeu d un réseau cortico-sous-corticale. Au total, l approche électro-hémodynamique développée apportait des éléments de compréhension sur les mécanismes physiopathologiques impliqués dans les pointes et des réseaux épileptiques, ouvrant de nouvelles perspectives sur des applications cliniques dans l identification du foyer épileptogène et du réseau intercritique des épilepsies partielles.We explored the epileptogenic neurovascular unit using a multimodal approach, coupling functional optical imaging and high density EEG. In an animal model, optical imaging highlighted hemodynamic changes which preceded interictal spikes. In children, complex hemodynamic changes, involving variations in cerebral blood volume (which could begin before epileptic spikes) and neurovascular coupling, which differed with the classical model described by Buxton, were observed, either in idiopathic or not idiopathic partial epilepsy. In time frequency domain, complex changes, consisted of alternating sequences of hyper-desynchronization, around epileptic spikes, in both mesial and neocortical structures were observed, regardless of the epileptic syndrome considered. Neuronal synchronization and hemodynamic changes were spatially concordant with the epileptogenic focus and provided additional information according to the temporo-spatial dynamic of interictal networks, like in pathophysiological processes associated with spikes. Our approach, applied to infantile spasms found initial changes in cerebral blood volume which could be followed by a neurovascular coupling suggesting the involvement of a complex cortico- subcortical network. In total, the multimodal approach developed about the epileptogenic neurovascular unit brought new understanding about the pathophysiological mechanisms involved in interictal spikes and in epileptic networks. In addition, the electro- hemodynamic approach opens new perspectives on clinical applications including the identification of epileptogenic focus and interictal network for pre-surgical assessment of partial refractory epilepsy.AMIENS-BU Santé (800212102) / SudocSudocFranceF

Non-invasive, multimodal analysis of cortical activity, blood volume and neurovascular coupling in infantile spasms using EEG-fNIRS monitoring

Although infantile spasms can be caused by a variety of etiologies, the clinical features are stereotypical. The neuronal and vascular mechanisms that contribute to the emergence of infantile spasms are not well understood. We performed a multimodal study by simultaneously recording electroencephalogram and functional Near-infrared spectroscopy in an intentionally heterogeneous population of six children with spasms in clusters. Regardless of the etiology, spasms were accompanied by two phases of hemodynamic changes; an initial change in the cerebral blood volume (simultaneously with each spasm) followed by a neurovascular coupling in all children except for the one with a large porencephalic cyst. Changes in cerebral blood volume, like the neurovascular coupling, occurred over frontal areas in all patients regardless of any brain damage suggesting a diffuse hemodynamic cortical response. The simultaneous motor activation and changes in cerebral blood volume might result from the involvement of the brainstem. The inconstant neurovascular coupling phase suggests a diffuse activation of the brain likely resulting too from the brainstem involvement that might trigger diffuse changes in cortical excitability. Keywords: Infantile spasm, Neurovascular coupling, Cerebral blood volume, Electroencephalography, Optical imagin

Behavioral-state development and sleep-state differentiation during early ontogenesis

International audienceSleep is a key process in neurodevelopment and essential for the maturation of fundamental brain functions. Premature birth can disturb the initial steps of sleep maturation, which may contribute to the impairment of neurodevelopment. It is thus fundamental to understand the maturation of the various sleep states and the quality of cerebral function in each vigilance state, as well as the development of sleep cyclicity, in at-risk neonatal infants, particularly those born premature. The objective of this review is to provide a precise description of sleep states and cycles and their rhythmic organization in premature and term newborns according to their gestational age. Technical aspects of polysomnography, which requires a high level of expertise in neonates, are also described. Principles of the visual interpretation of polysomnography, including the simultaneous analysis of behavioral (spontaneous motricity and eye movements), polysomnographic parameters (electro-oculogram, electrocardiogram, respiration), and electroencephalography patterns are presented. The neurophysiology of sleep ontogenesis and its interaction with brain maturation are discussed, highlighting the crucial-role of sleep states and their duration in premature newborns. In particular, the involvement of myoclonic twitches in functional connectivity in sensorimotor development is discussed. Indeed, sleep quality, determined by combined polysomnographic parameters, reflects either normal or pathological developmental processes during the neonatal period. The fundamental place of neurophysiological explorations in the early detection of sleep disorders is discussed, as well as their potential consequences on neurodevelopmental care to improve the prevention of neurodevelopmental impairment. (C) 2020 Elsevier Masson SAS. All rights reserved

EEG resting state analysis of cortical sources in patients with benign epilepsy with centrotemporal spikes

AbstractBenign epilepsy with centrotemporal spikes (BECTS) is the most common idiopathic childhood epilepsy, which is often associated with developmental disorders in children. In the present study, we analyzed resting state EEG spectral changes in the sensor and source spaces in eight BECTS patients compared with nine age-matched controls. Using high-resolution scalp EEG data, we assessed statistical differences in spatial distributions of EEG power spectra and cortical sources of resting state EEG rhythms in five frequency bands: δ (0.5–3.5 Hz), θ (4–8 Hz), α (8.5–13 Hz), β1 (13.5–20 Hz) and β2 (20.5–30 Hz) under the eyes-closed resting state condition. To further investigate the impact of centrotemporal spikes on EEG spectra, we split the EEG data of the patient group into EEG portions with and without spikes. Source localization demonstrated the homogeneity of our population of BECTS patients with a common epileptic zone over the right centrotemporal region. Significant differences in terms of both spectral power and cortical source densities were observed between controls and patients. Patients were characterized by significantly increased relative power in θ, α, β1 and β2 bands in the right centrotemporal areas over the spike zone and in the right temporo-parieto-occipital junction. Furthermore, the relative power in all bands significantly decreased in the bilateral frontal and parieto-occipital areas of patients regardless of the presence or absence of spikes in EEG segments. However, the spectral differences between patients and controls were more pronounced in the presence of spikes. This observation emphasized the impact of benign epilepsy on cortical source power, especially in the right centrotemporal regions. Spectral changes in bilateral frontal and parieto-occipital areas may also suggest alterations in the default mode network in BECTS patients