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Bartolomei F, Lagarde S, Wendling F, McGonigal A, Jirsa V, Guye M, Bénar C. Defining epileptogenic networks: Contribution of SEEG and signal analysis. Epilepsia 2017; 58:1131-1147. [DOI: 10.1111/epi.13791] [Citation(s) in RCA: 262] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Fabrice Bartolomei
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
- AP-HM; Service de Neurophysiologie Clinique; Hôpital de la Timone; Marseille France
| | - Stanislas Lagarde
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
- AP-HM; Service de Neurophysiologie Clinique; Hôpital de la Timone; Marseille France
| | - Fabrice Wendling
- U1099; INSERM; Rennes France
- Laboratoire de Traitement du Signal et de l'Image; Université de Rennes 1; Rennes France
| | - Aileen McGonigal
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
- AP-HM; Service de Neurophysiologie Clinique; Hôpital de la Timone; Marseille France
| | - Viktor Jirsa
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
| | - Maxime Guye
- Centre d'Exploration Métabolique par Résonance Magnétique (CEMEREM); APHM; Hôpitaux de la Timone; Marseille France
| | - Christian Bénar
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
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53
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Stefan H, Trinka E. Magnetoencephalography (MEG): Past, current and future perspectives for improved differentiation and treatment of epilepsies. Seizure 2017; 44:121-124. [DOI: 10.1016/j.seizure.2016.10.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 10/25/2016] [Indexed: 01/23/2023] Open
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Tomlinson SB, Bermudez C, Conley C, Brown MW, Porter BE, Marsh ED. Spatiotemporal Mapping of Interictal Spike Propagation: A Novel Methodology Applied to Pediatric Intracranial EEG Recordings. Front Neurol 2016; 7:229. [PMID: 28066315 PMCID: PMC5165024 DOI: 10.3389/fneur.2016.00229] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 11/30/2016] [Indexed: 12/19/2022] Open
Abstract
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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Affiliation(s)
- Samuel B Tomlinson
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA; School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY, USA
| | - Camilo Bermudez
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Chiara Conley
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Merritt W Brown
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia , Philadelphia, PA , USA
| | - Brenda E Porter
- Department of Neurology and Neurological Science, Stanford School of Medicine , Palo Alto, CA , USA
| | - Eric D Marsh
- Department of Pediatrics, Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Courtens S, Colombet B, Trébuchon A, Brovelli A, Bartolomei F, Bénar CG. Graph Measures of Node Strength for Characterizing Preictal Synchrony in Partial Epilepsy. Brain Connect 2016; 6:530-9. [DOI: 10.1089/brain.2015.0397] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Sandra Courtens
- Aix-Marseille Université, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Bruno Colombet
- Aix-Marseille Université, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
| | - Agnès Trébuchon
- Aix-Marseille Université, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
- AP-HM, Hôpital de la Timone, Service de Neurophysiologie Clinique, Marseille, France
| | - Andrea Brovelli
- Institut de Neurosciences de la Timone UMR 7289, Aix Marseille Université, CNRS, 13385 Marseille, France
| | - Fabrice Bartolomei
- Aix-Marseille Université, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
- AP-HM, Hôpital de la Timone, Service de Neurophysiologie Clinique, Marseille, France
| | - Christian G. Bénar
- Aix-Marseille Université, INSERM, Institut de Neurosciences des Systèmes, Marseille, France
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Hassan M, Merlet I, Mheich A, Kabbara A, Biraben A, Nica A, Wendling F. Identification of Interictal Epileptic Networks from Dense-EEG. Brain Topogr 2016; 30:60-76. [PMID: 27549639 DOI: 10.1007/s10548-016-0517-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 08/16/2016] [Indexed: 01/09/2023]
Abstract
Epilepsy is a network disease. The epileptic network usually involves spatially distributed brain regions. In this context, noninvasive M/EEG source connectivity is an emerging technique to identify functional brain networks at cortical level from noninvasive recordings. In this paper, we analyze the effect of the two key factors involved in EEG source connectivity processing: (i) the algorithm used in the solution of the EEG inverse problem and (ii) the method used in the estimation of the functional connectivity. We evaluate four inverse solutions algorithms (dSPM, wMNE, sLORETA and cMEM) and four connectivity measures (r 2, h 2, PLV, and MI) on data simulated from a combined biophysical/physiological model to generate realistic interictal epileptic spikes reflected in scalp EEG. We use a new network-based similarity index to compare between the network identified by each of the inverse/connectivity combination and the original network generated in the model. The method will be also applied on real data recorded from one epileptic patient who underwent a full presurgical evaluation for drug-resistant focal epilepsy. In simulated data, results revealed that the selection of the inverse/connectivity combination has a significant impact on the identified networks. Results suggested that nonlinear methods (nonlinear correlation coefficient, phase synchronization and mutual information) for measuring the connectivity are more efficient than the linear one (the cross correlation coefficient). The wMNE inverse solution showed higher performance than dSPM, cMEM and sLORETA. In real data, the combination (wMNE/PLV) led to a very good matching between the interictal epileptic network identified from noninvasive EEG recordings and the network obtained from connectivity analysis of intracerebral EEG recordings. These results suggest that source connectivity method, when appropriately configured, is able to extract highly relevant diagnostic information about networks involved in interictal epileptic spikes from non-invasive dense-EEG data.
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Affiliation(s)
- Mahmoud Hassan
- INSERM, U1099, Rennes, 35000, France.
- LTSI, Université de Rennes 1, Rennes, 35000, France.
| | - Isabelle Merlet
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
| | - Ahmad Mheich
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
- AZM Center-EDST, Lebanese University, Tripoli, Lebanon
| | - Aya Kabbara
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
- AZM Center-EDST, Lebanese University, Tripoli, Lebanon
| | - Arnaud Biraben
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
- Neurology Department, CHU, Rennes, 35000, France
| | - Anca Nica
- Neurology Department, CHU, Rennes, 35000, France
| | - Fabrice Wendling
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
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Zerouali Y, Pouliot P, Robert M, Mohamed I, Bouthillier A, Lesage F, Nguyen DK. Magnetoencephalographic signatures of insular epileptic spikes based on functional connectivity. Hum Brain Mapp 2016; 37:3250-61. [PMID: 27220112 DOI: 10.1002/hbm.23238] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 04/19/2016] [Accepted: 04/21/2016] [Indexed: 11/10/2022] Open
Abstract
Failure to recognize insular cortex seizures has recently been identified as a cause of epilepsy surgeries targeting the temporal, parietal, or frontal lobe. Such failures are partly due to the fact that current noninvasive localization techniques fare poorly in recognizing insular epileptic foci. Our group recently demonstrated that magnetoencephalography (MEG) is sensitive to epileptiform spikes generated by the insula. In this study, we assessed the potential of distributed source imaging and functional connectivity analyses to distinguish insular networks underlying the generation of spikes. Nineteen patients with operculo-insular epilepsy were investigated. Each patient underwent MEG as well as T1-weighted magnetic resonance imaging (MRI) as part of their standard presurgical evaluation. Cortical sources of MEG spikes were reconstructed with the maximum entropy on the mean algorithm, and their time courses served to analyze source functional connectivity. The results indicate that the anterior and posterior subregions of the insula have specific patterns of functional connectivity mainly involving frontal and parietal regions, respectively. In addition, while their connectivity patterns are qualitatively similar during rest and during spikes, couplings within these networks are much stronger during spikes. These results show that MEG can establish functional connectivity-based signatures that could help in the diagnosis of different subtypes of insular cortex epilepsy. Hum Brain Mapp 37:3250-3261, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Younes Zerouali
- Département De Génie Électrique, École Polytechnique De Montréal, Montreal, Quebec, Canada.,Research Centre, Centre Hospitalier De L'Université De Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Philippe Pouliot
- Département De Génie Électrique, École Polytechnique De Montréal, Montreal, Quebec, Canada.,Institut De Cardiologie De Montréal, Montreal, Quebec, Canada
| | - Manon Robert
- Research Centre, Centre Hospitalier De L'Université De Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Ismail Mohamed
- Division of Neurology, Department of Pediatrics, IWK Health Centre, Halifax, Nova Scotia, Canada
| | - Alain Bouthillier
- Research Centre, Centre Hospitalier De L'Université De Montréal (CRCHUM), Montreal, Quebec, Canada
| | - Frédéric Lesage
- Département De Génie Électrique, École Polytechnique De Montréal, Montreal, Quebec, Canada.,Institut De Cardiologie De Montréal, Montreal, Quebec, Canada
| | - Dang K Nguyen
- Research Centre, Centre Hospitalier De L'Université De Montréal (CRCHUM), Montreal, Quebec, Canada.,Division of Neurology, Department of Medicine, CHUM - Hôpital Notre-Dame, Montreal, Quebec, Canada
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What is the concordance between the seizure onset zone and the irritative zone? A SEEG quantified study. Clin Neurophysiol 2016; 127:1157-1162. [DOI: 10.1016/j.clinph.2015.10.029] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 09/30/2015] [Accepted: 10/03/2015] [Indexed: 11/15/2022]
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60
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Pittau F, Mégevand P, Sheybani L, Abela E, Grouiller F, Spinelli L, Michel CM, Seeck M, Vulliemoz S. Mapping epileptic activity: sources or networks for the clinicians? Front Neurol 2014; 5:218. [PMID: 25414692 PMCID: PMC4220689 DOI: 10.3389/fneur.2014.00218] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 10/08/2014] [Indexed: 01/03/2023] Open
Abstract
Epileptic seizures of focal origin are classically considered to arise from a focal epileptogenic zone and then spread to other brain regions. This is a key concept for semiological electro-clinical correlations, localization of relevant structural lesions, and selection of patients for epilepsy surgery. Recent development in neuro-imaging and electro-physiology and combinations, thereof, have been validated as contributory tools for focus localization. In parallel, these techniques have revealed that widespread networks of brain regions, rather than a single epileptogenic region, are implicated in focal epileptic activity. Sophisticated multimodal imaging and analysis strategies of brain connectivity patterns have been developed to characterize the spatio-temporal relationships within these networks by combining the strength of both techniques to optimize spatial and temporal resolution with whole-brain coverage and directional connectivity. In this paper, we review the potential clinical contribution of these functional mapping techniques as well as invasive electrophysiology in human beings and animal models for characterizing network connectivity.
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Affiliation(s)
- Francesca Pittau
- EEG and Epilepsy Unit, Neurology Department, University Hospitals and Faculty of Medicine of Geneva , Geneva , Switzerland
| | - Pierre Mégevand
- Laboratory for Multimodal Human Brain Mapping, Hofstra North Shore LIJ School of Medicine , Manhasset, NY , USA
| | - Laurent Sheybani
- Functional Brain Mapping Laboratory, Department of Fundamental Neurosciences, University of Geneva , Geneva , Switzerland
| | - Eugenio Abela
- Support Center of Advanced Neuroimaging (SCAN), Institute for Diagnostic and Interventional Neuroradiology, University Hospital Inselspital , Bern , Switzerland
| | - Frédéric Grouiller
- Radiology Department, University Hospitals and Faculty of Medicine of Geneva , Geneva , Switzerland
| | - Laurent Spinelli
- EEG and Epilepsy Unit, Neurology Department, University Hospitals and Faculty of Medicine of Geneva , Geneva , Switzerland
| | - Christoph M Michel
- Functional Brain Mapping Laboratory, Department of Fundamental Neurosciences, University of Geneva , Geneva , Switzerland
| | - Margitta Seeck
- EEG and Epilepsy Unit, Neurology Department, University Hospitals and Faculty of Medicine of Geneva , Geneva , Switzerland
| | - Serge Vulliemoz
- EEG and Epilepsy Unit, Neurology Department, University Hospitals and Faculty of Medicine of Geneva , Geneva , Switzerland
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Abstract
Limbic epilepsy refers to a condition that consists of epileptic seizures that originate in or preferentially involve the limbic system. The majority of cases are medically refractory, necessitating surgical resection when possible. However, even resection of structures thought to be responsible for seizure generation may not leave a patient seizure free. While mesial temporal lobe limbic structures are centrally involved, there is growing evidence that the epileptogenic network consists of a broader area, involving structures outside of the temporal lobe and the limbic system. Information on structural, functional, and metabolic connectivity in patients with limbic epilepsy is available from a large body of studies employing methods such as MRI, EEG, MEG, fMRI, PET, and SPECT scanning, implicating the involvement of various brain regions in the epileptogenic network. To date, there are no consistent and conclusive findings to define the exact boundaries of this network, but it is possible that in the future studies of network connectivity in the individual patient may allow more tailored treatment and prognosis in terms of surgical resection.
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