Identification of the Epileptogenic Zone from Stereo-EEG Signals: A Connectivity-Graph Theory Approach

Panzica, Ferruccio; Varotto, Giulia; Rotondi, Fabio; Spreafico, Roberto; Franceschetti, Silvana

doi:10.3389/fneur.2013.00175

Cited by 61 publications

(54 citation statements)

References 52 publications

(51 reference statements)

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“…This expanded concept of the EZ opened doors for sophisticated neuroimaging and electrophysiological analyses that explore the connections between various nodes of this epileptic network, using tools such as functional MRI and cortico-cortical evoked potentials (14), connectivity analyses (15), graph theory (16), and dynamic computational modeling (17,18). For example, a recent spatiotemporal model of seizure dynamics distinguishes various components of the network by their ability to sustain autonomous seizure activity, as well as whether or not epileptiform activity builds up preictally, generating a representation of the network that covers large areas of the brain surface (17).…”

Section: Surgical Definitionmentioning

confidence: 99%

The Epileptogenic Zone: Concept and Definition

2018

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A “concept” refers to what exists in the mind as a representation (as in something comprehended) or as a formulation (as in a plan). It is generally understood as “any idea of what a thing ought to be” (Merriam-Webster). From that premise, an “idea” cannot be compartmentalized or rigidly defined as exclusively belonging to any single individual or school of thought. The utility of a concept is inherently linked to its adaptability to the needs and conditions of the time. I state this upfront because over the past several decades, the concept of the epileptogenic zone (EZ) has become so crucial to the foundation of major schools of surgical epilepsy that discussions and opinions on the topic have essentially sought to legitimize one view while criticizing the other. This review is not a referendum on any specific definition of the EZ but rather a chronological analysis of the historical evolution of this concept and the invasive EEG tools used to study it. The goal is to highlight common ground necessary to tackle the ever-present challenge of defining the ideal resection for a patient with drug-resistant focal epilepsy.

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Section: Surgical Definitionmentioning

confidence: 99%

The Epileptogenic Zone: Concept and Definition

2018

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“…Indeed, in recent years, network analysis of EEG recordings has emerged as a major area of research (40, 41). Researchers have used principles from network science and graph theory to localize the EZ (42, 43), examine the events surrounding ictal onset (44) and predict surgical outcome (45) with increasing levels of success. Spike propagation is an intuitive method for visualizing connectivity patterns within the EZ, allowing researchers to quantify both the strength and directionality of pairwise connections (i.e., how often is a spike transmitted from channel A to B , and vice versa).…”

Section: Discussionmentioning

confidence: 99%

Spatiotemporal Mapping of Interictal Spike Propagation: A Novel Methodology Applied to Pediatric Intracranial EEG Recordings

et al. 2016

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Synchronized cortical activity is implicated in both normative cognitive functioning and many neurologic disorders. For epilepsy patients with intractable seizures, irregular synchronization within the epileptogenic zone (EZ) is believed to provide the network substrate through which seizures initiate and propagate. Mapping the EZ prior to epilepsy surgery is critical for detecting seizure networks in order to achieve postsurgical seizure control. However, automated techniques for characterizing epileptic networks have yet to gain traction in the clinical setting. Recent advances in signal processing and spike detection have made it possible to examine the spatiotemporal propagation of interictal spike discharges across the epileptic cortex. In this study, we present a novel methodology for detecting, extracting, and visualizing spike propagation and demonstrate its potential utility as a biomarker for the EZ. Eighteen presurgical intracranial EEG recordings were obtained from pediatric patients ultimately experiencing favorable (i.e., seizure-free, n = 9) or unfavorable (i.e., seizure-persistent, n = 9) surgical outcomes. Novel algorithms were applied to extract multichannel spike discharges and visualize their spatiotemporal propagation. Quantitative analysis of spike propagation was performed using trajectory clustering and spatial autocorrelation techniques. Comparison of interictal propagation patterns revealed an increase in trajectory organization (i.e., spatial autocorrelation) among Sz-Free patients compared with Sz-Persist patients. The pathophysiological basis and clinical implications of these findings are considered.

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“…The epileptogenic region in mesial temporal lobe epilepsy (MTLE) is known to extend beyond the hippocampus, to a network of cortical and subcortical structures, varying across patients. [5][6][7][8][9] These techniques have identified chronic network alterations associated with epilepsy, including impaired functional connectivity between ipsilateral anterior and posterior hippocampus, 10 increased resting state functional connectivity within the medial temporal lobe, 11,12 and reorganization of limbic, perilimbic, 13,14 and default mode networks. 4 Multiple noninvasive methods, including resting state functional magnetic resonance imaging (MRI), scalp electroencephalogram (EEG), positron emission tomography (PET), and diffusion tensor imaging, have been used to characterize epileptogenic networks.…”

Section: Introductionmentioning

confidence: 99%