Neural Networks in Human Epilepsy: Evidence of and Implications for Treatment

Spencer, Susan S.

doi:10.1046/j.1528-1157.2002.26901.x

Cited by 795 publications

(666 citation statements)

References 46 publications

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“…The theory that epileptogenic networks contribute to the generation of partial seizures has been advanced by multiple authors (Bragin, Wilson et al 2000;Spencer 2002). These networks are postulated to consist of local clusters of neurons distributed in multiple locations, possibly in multiple lobes (Colder et al, 1996;Bragin, Wilson et al 2000Bartolomei et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Cortical abnormalities in epilepsy revealed by local EEG synchrony

et al. 2007

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Abnormally strong functional linkage between cortical areas has been postulated to play a role in the pathogenesis of partial epilepsy. We explore the possibility that such linkages may be manifest in the interictal EEG apart from epileptiform disturbances or visually evident focal abnormalities. We analyzed samples of interictal intracranial EEG (ICEEG) recorded from subdural grids in nine patients with medically intractable partial epilepsy, measuring interelectrode synchrony using the mean phase coherence algorithm. This analysis revealed areas of elevated local synchrony, or "hypersynchrony" which had persistent spatiotemporal characteristics that were unique to each patient. Measuring local synchrony in a subdural grid results in a map of the cortical surface that provides information not visually apparent on either EEG or structural imaging. We explore the relationship of hypersynchronous areas to the clinical evidence of seizure localization in each case, and speculate that local hypersynchrony may be a marker of epileptogenic cortex, and may prove to be a valuable aid to clinical ICEEG interpretation.

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Section: Discussionmentioning

confidence: 99%

Cortical abnormalities in epilepsy revealed by local EEG synchrony

et al. 2007

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“…Over the last decade, the concept of focal epilepsy as a localized region of abnormality has evolved into a concept of diseased cortical networks with nodes and connections also affected in regions away from the SOZ (Antony et al, 2013; Bartolomei et al, 2017; Bernhardt, Bonilha, & Gross, 2015; Spencer, 2002; van Diessen, Diederen, Braun, Jansen, & Stam, 2013; van Diessen et al, 2014). In the context of epilepsy surgery, the focus on defining only a local SOZ is disputed, as the whole brain network operates together, as is clear from the expression of seizures (Spencer, 2002). It has been suggested that seizure freedom may be best achieved by removing a critical part of tissue that interrupts the epileptic network (Hebbink, Meijer, Huiskamp, van Gils, & Leijten, 2017).…”

Section: Introductionmentioning

confidence: 99%

Evoked directional network characteristics of epileptogenic tissue derived from single pulse electrical stimulation

Blooijs

Leijten

Rijen

et al. 2018

Human Brain Mapping

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We investigated effective networks constructed from single pulse electrical stimulation (SPES) in epilepsy patients who underwent intracranial electrocorticography. Using graph analysis, we compared network characteristics of tissue within and outside the epileptogenic area. In 21 patients with subdural electrode grids (1 cm interelectrode distance), we constructed a binary, directional network derived from SPES early responses (<100 ms). We calculated in‐degree, out‐degree, betweenness centrality, the percentage of bidirectional, receiving and activating connections, and the percentage of connections toward the (non‐)epileptogenic tissue for each node in the network. We analyzed whether these network measures were significantly different in seizure onset zone (SOZ)‐electrodes compared to non‐SOZ electrodes, in resected area (RA)‐electrodes compared to non‐RA electrodes, and in seizure free compared to not seizure‐free patients. Electrodes in the SOZ/RA showed significantly higher values for in‐degree and out‐degree, both at group level, and at patient level, and more so in seizure‐free patients. These differences were not observed for betweenness centrality. There were also more bidirectional and fewer receiving connections in the SOZ/RA in seizure‐free patients. It appears that the SOZ/RA is densely connected with itself, with only little input arriving from non‐SOZ/non‐RA electrodes. These results suggest that meso‐scale effective network measures are different in epileptogenic compared to normal brain tissue. Local connections within the SOZ/RA are increased and the SOZ/RA is relatively isolated from the surrounding cortex. This offers the prospect of enhanced prediction of epilepsy‐prone brain areas using SPES.

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“…Given the characteristics of a network‐level pathology in MTLE [Spencer, 2002], other studies have examined graph‐theory properties [Bullmore and Sporns, 2009] of both structural [Bernhardt et al, 2011; Bonilha et al, 2013] and functional data [Chiang et al, 2014; Liao et al, 2010; Vlooswijk et al, 2011]. These studies evaluated the relationships between the syndrome alterations and properties such as degree of connectivity, clustering coefficient and hub distribution, demonstrating alterations in MTLE characterized by reduced specificity and global efficiency [Bernhardt et al, 2011; Liao et al, 2010].…”

Section: Introductionmentioning

confidence: 99%

Large‐scale brain networks are distinctly affected in right and left mesial temporal lobe epilepsy

Campos

Coan

Yasuda

et al. 2016

Human Brain Mapping

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Mesial temporal lobe epilepsy (MTLE) with hippocampus sclerosis (HS) is associated with functional and structural alterations extending beyond the temporal regions and abnormal pattern of brain resting state networks (RSNs) connectivity. We hypothesized that the interaction of large‐scale RSNs is differently affected in patients with right‐ and left‐MTLE with HS compared to controls. We aimed to determine and characterize these alterations through the analysis of 12 RSNs, functionally parceled in 70 regions of interest (ROIs), from resting‐state functional‐MRIs of 99 subjects (52 controls, 26 right‐ and 21 left‐MTLE patients with HS). Image preprocessing and statistical analysis were performed using UF2C‐toolbox, which provided ROI‐wise results for intranetwork and internetwork connectivity. Intranetwork abnormalities were observed in the dorsal default mode network (DMN) in both groups of patients and in the posterior salience network in right‐MTLE. Both groups showed abnormal correlation between the dorsal‐DMN and the posterior salience, as well as between the dorsal‐DMN and the executive‐control network. Patients with left‐MTLE also showed reduced correlation between the dorsal‐DMN and visuospatial network and increased correlation between bilateral thalamus and the posterior salience network. The ipsilateral hippocampus stood out as a central area of abnormalities. Alterations on left‐MTLE expressed a low cluster coefficient, whereas the altered connections on right‐MTLE showed low cluster coefficient in the DMN but high in the posterior salience regions. Both right‐ and left‐MTLE patients with HS have widespread abnormal interactions of large‐scale brain networks; however, all parameters evaluated indicate that left‐MTLE has a more intricate bihemispheric dysfunction compared to right‐MTLE. Hum Brain Mapp 37:3137–3152, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

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Neural Networks in Human Epilepsy: Evidence of and Implications for Treatment

Cited by 795 publications

References 46 publications

Cortical abnormalities in epilepsy revealed by local EEG synchrony

Cortical abnormalities in epilepsy revealed by local EEG synchrony

Evoked directional network characteristics of epileptogenic tissue derived from single pulse electrical stimulation

Large‐scale brain networks are distinctly affected in right and left mesial temporal lobe epilepsy

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