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Horrillo-Maysonnial A, Avigdor T, Abdallah C, Mansilla D, Thomas J, von Ellenrieder N, Royer J, Bernhardt B, Grova C, Gotman J, Frauscher B. Targeted density electrode placement achieves high concordance with traditional high-density EEG for electrical source imaging in epilepsy. Clin Neurophysiol 2023; 156:262-271. [PMID: 37704552 DOI: 10.1016/j.clinph.2023.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/27/2023] [Accepted: 08/12/2023] [Indexed: 09/15/2023]
Abstract
OBJECTIVE High-density (HD) electroencephalography (EEG) is increasingly used in presurgical epilepsy evaluation, but it is demanding in time and resources. To overcome these issues, we compared EEG source imaging (ESI) solutions with a targeted density and HD-EEG montage. METHODS HD-EEGs from patients undergoing presurgical evaluation were analyzed. A low-density recording was created by selecting the 25 electrodes of a standard montage from the 83 electrodes of the HD-EEG and adding 8-11 electrodes around the electrode with the highest amplitude interictal epileptiform discharges. The ESI solution from this "targeted" montage was compared to that from the HD-EEG using the distance between peak vertices, sublobar concordance and a qualitative similarity measure. RESULTS Fifty-eight foci of forty-three patients were included. The median distance between the peak vertices of the two montages was 13.2 mm, irrespective of focus' location. Tangential generators (n = 5/58) showed a higher distance than radial generators (p = 0.04). We found sublobar concordance in 54/58 of the foci (93%). Map similarity, assessed by an epileptologist, had a median score of 4/5. CONCLUSIONS ESI solutions obtained from a targeted density montage show high concordance with those calculated from HD-EEG. SIGNIFICANCE Requiring significantly fewer electrodes, targeted density EEG allows obtaining similar ESI solutions as traditional HD-EEG montage.
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Affiliation(s)
- A Horrillo-Maysonnial
- Clinical Neurophysiology Section, Clínica Universidad de Navarra, Pamplona, Spain; IdiSNA, Instituto de Investigación Sanitaria de Navarra, Pamplona, Spain; Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - T Avigdor
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Multimodal Functional Imaging Lab, Biomedical Engineering Department, McGill University, Canada.
| | - C Abdallah
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Multimodal Functional Imaging Lab, Biomedical Engineering Department, McGill University, Canada.
| | - D Mansilla
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
| | - J Thomas
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
| | - N von Ellenrieder
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
| | - J Royer
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Multimodal Imaging and Connectome Analysis Laboratory, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
| | - B Bernhardt
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Multimodal Imaging and Connectome Analysis Laboratory, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
| | - C Grova
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Multimodal Functional Imaging Lab, Biomedical Engineering Department, McGill University, Canada; Multimodal Functional Imaging Lab, PERFORM Center, Department of Physics, Concordia University, Montreal, QC, Canada.
| | - J Gotman
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
| | - B Frauscher
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada; Department of Neurology, Duke University Medical Center, Durham, NC, United States; Department of Biomedical Engineering, Duke Pratt School of Engineering, Durham, NC, United States.
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Gotman J. Has recording of seizures become obsolete? Rev Neurol (Paris) 2023; 179:872-876. [PMID: 36906456 DOI: 10.1016/j.neurol.2023.01.726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/04/2023] [Indexed: 03/11/2023]
Abstract
Some patients with medically intractable epilepsy are considered for surgical treatment. In some surgical candidates, the investigation includes the placement of intracerebral electrodes and long-term monitoring to find the region of seizure onset. This region is the primary determinant of the surgical resection but about one-third of patients are not offered surgery after electrode implantation and among those operated only about 55% are seizure free after five years. This paper discusses why the primary reliance on the seizure onset maybe suboptimal and may be in part responsible for the relatively low surgical success rate. It also proposes to consider some interictal markers that may have advantages over seizure onset and may be easier to obtain.
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Affiliation(s)
- J Gotman
- Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, Québec H3A 2B4, Canada.
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Latreille V, von Ellenrieder N, Dubeau F, Gotman J, Frauscher B. The human K-Complex: insights from combined scalp-intracranial EEG recordings. Sleep Med 2019. [DOI: 10.1016/j.sleep.2019.11.591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Cuello-Oderiz C, von Ellenrieder N, Sankhe R, Olivier A, Hall J, Dubeau F, Gotman J. Value of ictal and interictal epileptiform discharges and high frequency oscillations for delineating the epileptogenic zone in patients with focal cortical dysplasia. Clin Neurophysiol 2018. [PMID: 29523391 DOI: 10.1016/j.clinph.2018.02.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVES There are different neurophysiological markers of the Epileptogenic Zone (EZ), but their sensitivity and specificity for the EZ is not known in Focal Cortical Dysplasia (FCD) patients. METHODS We studied patients with FCD who underwent stereoelectroencephalography (SEEG) and surgery. We marked in the SEEG: (a) typical and atypical interictal epileptiform patterns, (b) ictal onset patterns, and (c) rates of ripples (80-250 Hz) and fast ripples (FRs) (>250 Hz). High frequency oscillations were marked automatically during one hour of deep sleep. Surgical outcome was defined as good (Engel I) or poor (Engel II-IV). We computed the sensitivity and, as a measure of specificity, the false positive rate to identify the EZ, and compared them across the different neurophysiological markers. RESULTS We studied 21 patients, 19 with FCD II. Ictal and typical interictal pattern were the markers with highest sensitivity, while the atypical interictal pattern had the lowest. We found no significant difference in specificity among markers. However, there is a tendency that FRs had the lowest false positive rate. CONCLUSION The typical interictal pattern has the highest sensitivity. The clinical use of FRs is limited by their low sensitivity. SIGNIFICANCE We suggest to analyze the typical interictal pattern first. FRs should be analyzed in a second step. If, for instance, a focus with FRs and no typical interictal pattern is found, this area could be considered for resection.
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Affiliation(s)
- C Cuello-Oderiz
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue University, Montréal, QC H3A 2B4, Canada.
| | - N von Ellenrieder
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue University, Montréal, QC H3A 2B4, Canada.
| | - R Sankhe
- McGill University, 845 Sherbrooke St W, Montréal, QC H3A 0G4, Canada.
| | - A Olivier
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue University, Montréal, QC H3A 2B4, Canada.
| | - J Hall
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue University, Montréal, QC H3A 2B4, Canada.
| | - F Dubeau
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue University, Montréal, QC H3A 2B4, Canada.
| | - J Gotman
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 Rue University, Montréal, QC H3A 2B4, Canada.
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Gotman J. S63: High frequency activity in the peri-ictal period. Clin Neurophysiol 2014. [DOI: 10.1016/s1388-2457(14)50062-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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He BJ, Nolte G, Nagata K, Takano D, Yamazaki T, Fujimaki Y, Maeda T, Satoh Y, Heckers S, George MS, Lopes da Silva F, de Munck JC, Van Houdt PJ, Verdaasdonk RM, Ossenblok P, Mullinger K, Bowtell R, Bagshaw AP, Keeser D, Karch S, Segmiller F, Hantschk I, Berman A, Padberg F, Pogarell O, Scharnowski F, Karch S, Hümmer S, Keeser D, Paolini M, Kirsch V, Koller G, Rauchmann B, Kupka M, Blautzik J, Pogarell O, Razavi N, Jann K, Koenig T, Kottlow M, Hauf M, Strik W, Dierks T, Gotman J, Vulliemoz S, Lu Y, Zhang H, Yang L, Worrell G, He B, Gruber O, Piguet C, Hubl D, Homan P, Kindler J, Dierks T, Kim K, Steinhoff U, Wakai R, Koenig T, Kottlow M, Melie-García L, Mucci A, Volpe U, Prinster A, Salvatore M, Galderisi S, Linden DEJ, Brandeis D, Schroeder CE, Kayser C, Panzeri S, Kleinschmidt A, Ritter P, Walther S, Haueisen J, Lau S, Flemming L, Sonntag H, Maess B, Knösche TR, Lanfer B, Dannhauer M, Wolters CH, Stenroos M, Haueisen J, Wolters C, Aydin U, Lanfer B, Lew S, Lucka F, Ruthotto L, Vorwerk J, Wagner S, Ramon C, Guan C, Ang KK, Chua SG, Kuah WK, Phua KS, Chew E, Zhou H, Chuang KH, Ang BT, Wang C, Zhang H, Yang H, Chin ZY, Yu H, Pan Y, Collins L, Mainsah B, Colwell K, Morton K, Ryan D, Sellers E, Caves K, Throckmorton S, Kübler A, Holz EM, Zickler C, Sellers E, Ryan D, Brown K, Colwell K, Mainsah B, Caves K, Throckmorton S, Collins L, Wennberg R, Ahlfors SP, Grova C, Chowdhury R, Hedrich T, Heers M, Zelmann R, Hall JA, Lina JM, Kobayashi E, Oostendorp T, van Dam P, Oosterhof P, Linnenbank A, Coronel R, van Dessel P, de Bakker J, Rossion B, Jacques C, Witthoft N, Weiner KS, Foster BL, Miller KJ, Hermes D, Parvizi J, Grill-Spector K, Recanzone GH, Murray MM, Haynes JD, Richiardi J, Greicius M, De Lucia M, Müller KR, Formisano E, Smieskova R, Schmidt A, Bendfeldt K, Walter A, Riecher-Rössler A, Borgwardt S, Fusar-Poli P, Eliez S, Schmidt A, Sekihara K, Nagarajan SS, Schoffelen JM, Guggisberg AG, Nolte G, Balazs S, Kermanshahi K, Kiesenhofer W, Binder H, Rattay F, Antal A, Chaieb L, Paulus W, Bodis-Wollner I, Maurer K, Fein G, Camchong J, Johnstone J, Cardenas-Nicolson V, Fiederer LDJ, Lucka F, Yang S, Vorwerk J, Dümpelmann M, Cosandier-Rimélé D, Schulze-Bonhage A, Aertsen A, Speck O, Wolters CH, Ball T, Fuchs M, Wagner M, Kastner J, Tech R, Dinh C, Haueisen J, Baumgarten D, Hämäläinen MS, Lau S, Vogrin SJ, D'Souza W, Haueisen J, Cook MJ, Custo A, Van De Ville D, Vulliemoz S, Grouiller F, Michel CM, Malmivuo J, Aydin U, Vorwerk J, Küpper P, Heers M, Kugel H, Wellmer J, Kellinghaus C, Scherg M, Rampp S, Wolters C, Storti SF, Boscolo Galazzo I, Del Felice A, Pizzini FB, Arcaro C, Formaggio E, Mai R, Manganotti P, Koessler L, Vignal J, Cecchin T, Colnat-Coulbois S, Vespignani H, Ramantani G, Maillard L, Rektor I, Kuba R, Brázdil M, Chrastina J, Rektorova I, van Mierlo P, Carrette E, Strobbe G, Montes-Restrepo V, Vonck K, Vandenberghe S, Ahmed B, Brodely C, Carlson C, Kuzniecky R, Devinsky O, French J, Thesen T, Bénis D, David O, Lachaux JP, Seigneuret E, Krack P, Fraix V, Chabardès S, Bastin J, Jann K, Gee D, Kilroy E, Cannon T, Wang DJ, Hale JR, Mayhew SD, Przezdzik I, Arvanitis TN, Bagshaw AP, Plomp G, Quairiaux C, Astolfi L, Michel CM, Mayhew SD, Mullinger KJ, Bagshaw AP, Bowtell R, Francis ST, Schouten AC, Campfens SF, van der Kooij H, Koles Z, Lind J, Flor-Henry P, Wirth M, Haase CM, Villeneuve S, Vogel J, Jagust WJ, Kambeitz-Ilankovic L, Simon-Vermot L, Gesierich B, Duering M, Ewers M, Rektorova I, Krajcovicova L, Marecek R, Mikl M, Bracht T, Horn H, Strik W, Federspiel A, Schnell S, Höfle O, Stegmayer K, Wiest R, Dierks T, Müller TJ, Walther S, Surmeli T, Ertem A, Eralp E, Kos IH, Skrandies W, Flüggen S, Klein A, Britz J, Díaz Hernàndez L, Ro T, Michel CM, Lenartowicz A, Lau E, Rodriguez C, Cohen MS, Loo SK, Di Lorenzo G, Pagani M, Monaco L, Daverio A, Giannoudas I, La Porta P, Verardo AR, Niolu C, Fernandez I, Siracusano A, Flor-Henry P, Lind J, Koles Z, Bollmann S, Ghisleni C, O'Gorman R, Poil SS, Klaver P, Michels L, Martin E, Ball J, Eich-Höchli D, Brandeis D, Salisbury DF, Murphy TK, Butera CD, Mathalon DH, Fryer SL, Kiehl KA, Calhoun VC, Pearlson GD, Roach BJ, Ford JM, McGlashan TH, Woods SW, Volpe U, Merlotti E, Vignapiano A, Montefusco V, Plescia GM, Gallo O, Romano P, Mucci A, Galderisi S, Mingoia G, Langbein K, Dietzek M, Wagner G, Smesny, Scherpiet S, Maitra R, Gaser C, Sauer H, Nenadic I, Gonzalez Andino S, Grave de Peralta Menendez R, Grave de Peralta Menendez R, Sanchez Vives M, Rebollo B, Gonzalez Andino S, Frølich L, Andersen TS, Mørup M, Belfiore P, Gargiulo P, Ramon C, Vanhatalo S, Cho JH, Vorwerk J, Wolters CH, Knösche TR, Watanabe T, Kawabata Y, Ukegawa D, Kawabata S, Adachi Y, Sekihara K, Sekihara K, Nagarajan SS, Wagner S, Aydin U, Vorwerk J, Herrmann C, Burger M, Wolters C, Lucka F, Aydin U, Vorwerk J, Burger M, Wolters C, Bauer M, Trahms L, Sander T, Faber PL, Lehmann D, Gianotti LRR, Pascual-Marqui RD, Milz P, Kochi K, Kaneko S, Yamashita S, Yana K, Kalogianni K, Vardy AN, Schouten AC, van der Helm FCT, Sorrentino A, Luria G, Aramini R, Hunold A, Funke M, Eichardt R, Haueisen J, Gómez-Aguilar F, Vázquez-Olvera S, Cordova-Fraga T, Castro-López J, Hernández-Gonzalez MA, Solorio-Meza S, Sosa-Aquino M, Bernal-Alvarado JJ, Vargas-Luna M, Vorwerk J, Magyari L, Ludewig J, Oostenveld R, Wolters CH, Vorwerk J, Engwer C, Ludewig J, Wolters C, Sato K, Nishibe T, Furuya M, Yamashiro K, Yana K, Ono T, Puthanmadam Subramaniyam N, Hyttinen J, Lau S, Güllmar D, Flemming L, Haueisen J, Sonntag H, Vorwerk J, Wolters CH, Grasedyck L, Haueisen J, Maeß B, Freitag S, Graichen U, Fiedler P, Strohmeier D, Haueisen J, Stenroos M, Hauk O, Grigutsch M, Felber M, Maess B, Herrmann B, Strobbe G, van Mierlo P, Vandenberghe S, Strobbe G, Cárdenas-Peña D, Montes-Restrepo V, van Mierlo P, Castellanos-Dominguez G, Vandenberghe S, Lanfer B, Paul-Jordanov I, Scherg M, Wolters CH, Ito Y, Sato D, Kamada K, Kobayashi T, Dalal SS, Rampp S, Willomitzer F, Arold O, Fouladi-Movahed S, Häusler G, Stefan H, Ettl S, Zhang S, Zhang Y, Li H, Kong X, Montes-Restrepo V, Strobbe G, van Mierlo P, Vandenberghe S, Wong DDE, Bidet-Caulet A, Knight RT, Crone NE, Dalal SS, Birot G, Spinelli L, Vulliémoz S, Seeck M, Michel CM, Emory H, Wells C, Mizrahi N, Vogrin SJ, Lau S, Cook MJ, Karahanoglu FI, Grouiller F, Caballero-Gaudes C, Seeck M, Vulliemoz S, Van De Ville D, Spinelli L, Megevand P, Genetti M, Schaller K, Michel C, Vulliemoz S, Seeck M, Genetti M, Tyrand R, Grouiller F, Vulliemoz S, Spinelli L, Seeck M, Schaller K, Michel CM, Grouiller F, Heinzer S, Delattre B, Lazeyras F, Spinelli L, Pittau F, Seeck M, Ratib O, Vargas M, Garibotto V, Vulliemoz S, Vogrin SJ, Bailey CA, Kean M, Warren AE, Davidson A, Seal M, Harvey AS, Archer JS, Papadopoulou M, Leite M, van Mierlo P, Vonck K, Boon P, Friston K, Marinazzo D, Ramon C, Holmes M, Koessler L, Rikir E, Gavaret M, Bartolomei F, Vignal JP, Vespignani H, Maillard L, Centeno M, Perani S, Pier K, Lemieux L, Clayden J, Clark C, Pressler R, Cross H, Carmichael DW, Spring A, Bessemer R, Pittman D, Aghakhani Y, Federico P, Pittau F, Grouiller F, Vulliémoz S, Gotman J, Badier JM, Bénar CG, Bartolomei F, Cruto C, Chauvel P, Gavaret M, Brodbeck V, van Leeuwen T, Tagliazzuchi E, Melloni L, Laufs H, Griskova-Bulanova I, Dapsys K, Klein C, Hänggi J, Jäncke L, Ehinger BV, Fischer P, Gert AL, Kaufhold L, Weber F, Marchante Fernandez M, Pipa G, König P, Sekihara K, Hiyama E, Koga R, Iannilli E, Michel CM, Bartmuss AL, Gupta N, Hummel T, Boecker R, Holz N, Buchmann AF, Blomeyer D, Plichta MM, Wolf I, Baumeister S, Meyer-Lindenberg A, Banaschewski T, Brandeis D, Laucht M, Natahara S, Ueno M, Kobayashi T, Kottlow M, Bänninger A, Koenig T, Schwab S, Koenig T, Federspiel A, Dierks T, Jann K, Natsukawa H, Kobayashi T, Tüshaus L, Koenig T, Kottlow M, Achermann P, Wilson RS, Mayhew SD, Assecondi S, Arvanitis TN, Bagshaw AP, Darque A, Rihs TA, Grouiller F, Lazeyras F, Ha-Vinh Leuchter R, Caballero C, Michel CM, Hüppi PS, Hauser TU, Hunt LT, Iannaccone R, Stämpfli P, Brandeis D, Dolan RJ, Walitza S, Brem S, Graichen U, Eichardt R, Fiedler P, Strohmeier D, Freitag S, Zanow F, Haueisen J, Lordier L, Grouiller F, Van de Ville D, Sancho Rossignol A, Cordero I, Lazeyras F, Ansermet F, Hüppi P, Schläpfer A, Rubia K, Brandeis D, Di Lorenzo G, Pagani M, Monaco L, Daverio A, Giannoudas I, Verardo AR, La Porta P, Niolu C, Fernandez I, Siracusano A, Tamura K, Karube C, Mizuba T, Matsufuji M, Takashima S, Iramina K, Assecondi S, Ostwald D, Bagshaw AP, Marecek R, Brazdil M, Lamos M, Slavícek T, Marecek R, Jan J, Meier NM, Perrig W, Koenig T, Minami T, Noritake Y, Nakauchi S, Azuma K, Minami T, Nakauchi S, Rodriguez C, Lenartowicz A, Cohen MS, Rodriguez C, Lenartowicz A, Cohen MS, Iramina K, Kinoshita H, Tamura K, Karube C, Kaneko M, Ide J, Noguchi Y, Cohen MS, Douglas PK, Rodriguez CM, Xia HJ, Zimmerman EM, Konopka CJ, Epstein PS, Konopka LM, Giezendanner S, Fisler M, Soravia L, Andreotti J, Wiest R, Dierks T, Federspiel A, Razavi N, Federspiel A, Dierks T, Hauf M, Jann K, Kamada K, Sato D, Ito Y, Okano K, Mizutani N, Kobayashi T, Thelen A, Murray M, Pastena L, Formaggio E, Storti SF, Faralli F, Melucci M, Gagliardi R, Ricciardi L, Ruffino G, Coito A, Macku P, Tyrand R, Astolfi L, He B, Wiest R, Seeck M, Michel C, Plomp G, Vulliemoz S, Fischmeister FPS, Glaser J, Schöpf V, Bauer H, Beisteiner R, Deligianni F, Centeno M, Carmichael DW, Clayden J, Mingoia G, Langbein K, Dietzek M, Wagner G, Smesny S, Scherpiet S, Maitra R, Gaser C, Sauer H, Nenadic I, Dürschmid S, Zaehle T, Pannek H, Chang HF, Voges J, Rieger J, Knight RT, Heinze HJ, Hinrichs H, Tsatsishvili V, Cong F, Puoliväli T, Alluri V, Toiviainen P, Nandi AK, Brattico E, Ristaniemi T, Grieder M, Crinelli RM, Jann K, Federspiel A, Wirth M, Koenig T, Stein M, Wahlund LO, Dierks T, Atsumori H, Yamaguchi R, Okano Y, Sato H, Funane T, Sakamoto K, Kiguchi M, Tränkner A, Schindler S, Schmidt F, Strauß M, Trampel R, Hegerl U, Turner R, Geyer S, Schönknecht P, Kebets V, van Assche M, Goldstein R, van der Meulen M, Vuilleumier P, Richiardi J, Van De Ville D, Assal F, Wozniak-Kwasniewska A, Szekely D, Harquel S, Bougerol T, David O, Bracht T, Jones DK, Horn H, Müller TJ, Walther S, Sos P, Klirova M, Novak T, Brunovsky M, Horacek J, Bares M, Hoschl C C, Fellhauer I, Zöllner FG, Schröder J, Kong L, Essig M, Schad LR, Arrubla J, Neuner I, Hahn D, Boers F, Shah NJ, Neuner I, Arrubla J, Hahn D, Boers F, Jon Shah N, Suriya Prakash M, Sharma R, Kawaguchi H, Kobayashi T, Fiedler P, Griebel S, Biller S, Fonseca C, Vaz F, Zentner L, Zanow F, Haueisen J, Rochas V, Rihs T, Thut G, Rosenberg N, Landis T, Michel C, Moliadze V, Schmanke T, Lyzhko E, Bassüner S, Freitag C, Siniatchkin M, Thézé R, Guggisberg AG, Nahum L, Schnider A, Meier L, Friedrich H, Jann K, Landis B, Wiest R, Federspiel A, Strik W, Dierks T, Witte M, Kober SE, Neuper C, Wood G, König R, Matysiak A, Kordecki W, Sieluzycki C, Zacharias N, Heil P, Wyss C, Boers F, Arrubla J, Dammers J, Kawohl W, Neuner I, Shah NJ, Braboszcz C, Cahn RB, Levy J, Fernandez M, Delorme A, Rosas-Martinez L, Milne E, Zheng Y, Urakami Y, Kawamura K, Washizawa Y, Hiyoshi K, Cichocki A, Giroud N, Dellwo V, Meyer M, Rufener KS, Liem F, Dellwo V, Meyer M, Jones-Rounds JD, Raizada R, Staljanssens W, Strobbe G, van Mierlo P, Van Holen R, Vandenberghe S, Pefkou M, Becker R, Michel C, Hervais-Adelman A, He W, Brock J, Johnson B, Ohla K, Hitz K, Heekeren K, Obermann C, Huber T, Juckel G, Kawohl W, Gabriel D, Comte A, Henriques J, Magnin E, Grigoryeva L, Ortega JP, Haffen E, Moulin T, Pazart L, Aubry R, Kukleta M, Baris Turak B, Louvel J, Crespo-Garcia M, Cantero JL, Atienza M, Connell S, Kilborn K, Damborská A, Brázdil M, Rektor I, Kukleta M, Koberda JL, Bienkiewicz A, Koberda I, Koberda P, Moses A, Tomescu M, Rihs T, Britz J, Custo A, Grouiller F, Schneider M, Debbané M, Eliez S, Michel C, Wang GY, Kydd R, Wouldes TA, Jensen M, Russell BR, Dissanayaka N, Au T, Angwin A, O'Sullivan J, Byrne G, Silburn P, Marsh R, Mellic G, Copland D, Bänninger A, Kottlow M, Díaz Hernàndez L, Koenig T, Díaz Hernàndez L, Bänninger A, Koenig T, Hauser TU, Iannaccone R, Mathys C, Ball J, Drechsler R, Brandeis D, Walitza S, Brem S, Boeijinga PH, Pang EW, Valica T, Macdonald MJ, Oh A, Lerch JP, Anagnostou E, Di Lorenzo G, Pagani M, Monaco L, Daverio A, Verardo AR, Giannoudas I, La Porta P, Niolu C, Fernandez I, Siracusano A, Shimada T, Matsuda Y, Monkawa A, Monkawa T, Hashimoto R, Watanabe K, Kawasaki Y, Matsuda Y, Shimada T, Monkawa T, Monkawa A, Watanabe K, Kawasaki Y, Stegmayer K, Horn H, Federspiel A, Razavi N, Bracht T, Laimböck K, Strik W, Dierks T, Wiest R, Müller TJ, Walther S, Koorenhof LJ, Swithenby SJ, Martins-Mourao A, Rihs TA, Tomescu M, Song KW, Custo A, Knebel JF, Murray M, Eliez S, Michel CM, Volpe U, Merlotti E, Vignapiano A, Montefusco V, Plescia GM, Gallo O, Romano P, Mucci A, Galderisi S, Laimboeck K, Jann K, Walther S, Federspiel A, Wiest R, Strik W, Horn H. Abstracts of Presentations at the International Conference on Basic and Clinical Multimodal Imaging (BaCI), a Joint Conference of the International Society for Neuroimaging in Psychiatry (ISNIP), the International Society for Functional Source Imaging (ISFSI), the International Society for Bioelectromagnetism (ISBEM), the International Society for Brain Electromagnetic Topography (ISBET), and the EEG and Clinical Neuroscience Society (ECNS), in Geneva, Switzerland, September 5-8, 2013. Clin EEG Neurosci 2013; 44:1550059413507209. [PMID: 24368763 DOI: 10.1177/1550059413507209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- B J He
- National Institutes of Health, Bethesda, MD, USA
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Châtillon CE, Zelmann R, Hall JA, Olivier A, Dubeau F, Gotman J. Influence of contact size on the detection of HFOs in human intracerebral EEG recordings. Clin Neurophysiol 2013; 124:1541-6. [PMID: 23578565 DOI: 10.1016/j.clinph.2013.02.113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 02/08/2013] [Accepted: 02/27/2013] [Indexed: 10/27/2022]
Abstract
OBJECTIVE High frequency oscillations (HFOs) are brief electroencephalographic events associated with epileptic activity, and likely representing biological markers of the epileptogenic zone. HFOs are usually detected with intracranial EEG and detection is influenced by contact size. The size of commercially available intracerebral electrodes varies widely. This study assesses HFO detection rates from adjacent electrode contacts in human intracerebral recordings. METHODS Intracerebral recordings were collected from 11 patients undergoing stereoelectroencephalographic investigation using hybrid depth electrodes containing adjacent large (0.8 or 5 mm(2)) and small (0.2 or 0.3 mm(2)) contacts. HFOs were marked manually during 5-min tracings in 131 pairs of adjacent large and small contacts. HFO rates per minute and mean event durations were compared between adjacent contacts. RESULTS A minimal but statistically significant advantage in ripple detection was found in a subgroup of large contacts. Otherwise, HFO rates and mean event durations were not statistically different between groups. CONCLUSION The size of clinical contacts within the studied range did not influence HFO detection in a clinically relevant manner. Larger contacts provide a minimal advantage for ripple detection. SIGNIFICANCE Our findings suggest that commercially available intracerebral electrodes with contacts between 0.2 and 5 mm(2) likely possess similar HFO detection abilities.
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Affiliation(s)
- C E Châtillon
- Department of Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada.
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8
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Jacobs J, Staba R, Asano E, Otsubo H, Wu JY, Zijlmans M, Mohamed I, Kahane P, Dubeau F, Navarro V, Gotman J. High-frequency oscillations (HFOs) in clinical epilepsy. Prog Neurobiol 2012; 98:302-15. [PMID: 22480752 PMCID: PMC3674884 DOI: 10.1016/j.pneurobio.2012.03.001] [Citation(s) in RCA: 284] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Revised: 03/04/2012] [Accepted: 03/06/2012] [Indexed: 11/18/2022]
Abstract
Epilepsy is one of the most frequent neurological diseases. In focal medically refractory epilepsies, successful surgical treatment largely depends on the identification of epileptogenic zone. High-frequency oscillations (HFOs) between 80 and 500Hz, which can be recorded with EEG, may be novel markers of the epileptogenic zone. This review discusses the clinical importance of HFOs as markers of epileptogenicity and their application in different types of epilepsies. HFOs are clearly linked to the seizure onset zone, and the surgical removal of regions generating them correlates with a seizure free post-surgical outcome. Moreover, HFOs reflect the seizure-generating capability of the underlying tissue, since they are more frequent after the reduction of antiepileptic drugs. They can be successfully used in pediatric epilepsies such as epileptic spasms and help to understand the generation of this specific type of seizures. While mostly recorded on intracranial EEGs, new studies suggest that identification of HFOs on scalp EEG or magnetoencephalography (MEG) is possible as well. Thus not only patients with refractory epilepsies and invasive recordings but all patients might profit from the analysis of HFOs. Despite these promising results, the analysis of HFOs is not a routine clinical procedure; most results are derived from relatively small cohorts of patients and many aspects are not yet fully understood. Thus the review concludes that even if HFOs are promising biomarkers of epileptic tissue, there are still uncertainties about mechanisms of generation, methods of analysis, and clinical applicability. Large multicenter prospective studies are needed prior to widespread clinical application.
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Affiliation(s)
- J Jacobs
- Department of Neuropediatrics and Muscular Diseases, University of Freiburg, Freiburg, Germany.
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Ayoubian L, Lacoma H, Gotman J. Automatic seizure detection in SEEG using high frequency activities in wavelet domain. Med Eng Phys 2012; 35:319-28. [PMID: 22647836 DOI: 10.1016/j.medengphy.2012.05.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 04/13/2012] [Accepted: 05/06/2012] [Indexed: 10/28/2022]
Abstract
Existing automatic detection techniques show high sensitivity and moderate specificity, and detect seizures a relatively long time after onset. High frequency (80-500 Hz) activity has recently been shown to be prominent in the intracranial EEG of epileptic patients but has not been used in seizure detection. The purpose of this study is to investigate if these frequencies can contribute to seizure detection. The system was designed using 30 h of intracranial EEG, including 15 seizures in 15 patients. Wavelet decomposition, feature extraction, adaptive thresholding and artifact removal were employed in training data. An EMG removal algorithm was developed based on two features: Lack of correlation between frequency bands and energy-spread in frequency. Results based on the analysis of testing data (36 h of intracranial EEG, including 18 seizures) show a sensitivity of 72%, a false detection of 0.7/h and a median delay of 5.7 s. Missed seizures originated mainly from seizures with subtle or absent high frequencies or from EMG removal procedures. False detections were mainly due to weak EMG or interictal high frequency activities. The system performed sufficiently well to be considered for clinical use, despite the exclusive use of frequencies not usually considered in clinical interpretation. High frequencies have the potential to contribute significantly to the detection of epileptic seizures.
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Affiliation(s)
- L Ayoubian
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
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Lopes R, Lina JM, Fahoum F, Gotman J. Detection of epileptic activity in fMRI without recording the EEG. Neuroimage 2012; 60:1867-79. [PMID: 22306797 DOI: 10.1016/j.neuroimage.2011.12.083] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 11/30/2011] [Accepted: 12/21/2011] [Indexed: 11/17/2022] Open
Abstract
EEG-fMRI localizes epileptic foci by detecting cerebral hemodynamic changes that are correlated to epileptic events visible in EEG. However, scalp EEG is insensitive to activity restricted to deep structures and recording the EEG in the scanner is complex and results in major artifacts that are difficult to remove. This study presents a new framework for identifying the BOLD manifestations of epileptic discharges without having to record the EEG. The first stage is based on the detection of epileptic events for each voxel by sparse representation in the wavelet domain. The second stage is to gather voxels according to proximity in time and space of detected activities. This technique was evaluated on data generated by superposing artificial responses at different locations and responses amplitude in the brain for 6 control subject runs. The method was able to detect effectively and consistently for responses amplitude of at least 1% above baseline. 46 runs from 15 patients with focal epilepsy were investigated. The results demonstrate that the method detected at least one concordant event in 37/41 runs. The maps of activation obtained from our method were more similar to those obtained by EEG-fMRI than to those obtained by the other method used in this context, 2D-Temporal Cluster Analysis. For 5 runs without event read on scalp EEG, 3 runs showed an activation concordant with the patient's diagnostic. It may therefore be possible, at least when spikes are infrequent, to detect their BOLD manifestations without having to record the EEG.
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Affiliation(s)
- R Lopes
- Montreal Neurological Institute, McGill University, Montreal, Québec, Canada.
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Abstract
OBJECTIVE This study aims to identify if oscillations at frequencies higher than the traditional EEG can be recorded on the scalp EEG of patients with focal epilepsy and to analyze the association of these oscillations with interictal discharges and the seizure onset zone (SOZ). METHODS The scalp EEG of 15 patients with focal epilepsy was studied. We analyzed the rates of gamma (40-80 Hz) and ripple (>80 Hz) oscillations, their co-occurrence with spikes, the number of channels with fast oscillations inside and outside the SOZ, and the specificity, sensitivity, and accuracy of gamma, ripples, and spikes to determine the SOZ. RESULTS Gamma and ripples frequently co-occurred with spikes (77.5% and 63% of cases). For all events, the proportion of channels with events was consistently higher inside than outside the SOZ: spikes (100% vs 70%), gamma (82% vs 33%), and ripples (48% vs 11%); p < 0.0001. The mean rates (events/min) were higher inside than outside the SOZ: spikes (2.64 ± 1.70 vs 0.69 ± 0.26, p = 0.02), gamma (0.77 ± 0.71 vs 0.20 ± 0.25, p = 0.02), and ripples (0.08 ± 0.12 vs 0.04 ± 0.09, p = 0.04). The sensitivity to identify the SOZ was spikes 100%, gamma 82%, and ripples 48%; the specificity was spikes 30%, gamma 68%, and ripples 89%; and the accuracy was spikes 43%, gamma 70%, and ripples 81%. CONCLUSION The rates and the proportion of channels with gamma and ripple fast oscillations are higher inside the SOZ, indicating that they can be used as interictal scalp EEG markers for the SOZ. These fast oscillations are less sensitive but much more specific and accurate than spikes to delineate the SOZ.
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Affiliation(s)
- L P Andrade-Valenca
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
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12
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Zelmann R, Mari F, Jacobs J, Zijlmans M, Chander R, Gotman J. Automatic detector of high frequency oscillations for human recordings with macroelectrodes. Annu Int Conf IEEE Eng Med Biol Soc 2011; 2010:2329-33. [PMID: 21096802 DOI: 10.1109/iembs.2010.5627464] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
High Frequency Oscillations (HFOs) in the EEG are a promising biomarker of epileptogenic tissue. Given that the visual marking of HFOs is highly time-consuming and subjective, automatic detectors are necessary. In this study, we present a novel automatic detector that detects HFOs by incorporating information of previously detected baselines. The detector was trained on 72 channels and tested on 278, achieving a mean sensitivity of 96.8% with a mean false positive rate of 4.86%. This low rate is reasonable since only visually marked baseline segments were considered as the true negatives. This detector could be useful for the systematic study of HFOs and for their eventual clinical application.
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Affiliation(s)
- R Zelmann
- Department of Biomedical Engineering at McGill University and the Montreal Neurological Institute, Montreal, QC, H3A 2B4, Canada.
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Moeller F, Tyvaert L, Nguyen DK, LeVan P, Bouthillier A, Kobayashi E, Tampieri D, Dubeau F, Gotman J. EEG-fMRI: adding to standard evaluations of patients with nonlesional frontal lobe epilepsy. Neurology 2009; 73:2023-30. [PMID: 19996077 DOI: 10.1212/wnl.0b013e3181c55d17] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE In patients with nonlesional frontal lobe epilepsy (FLE), the delineation of the epileptogenic zone is difficult. Therefore these patients are often not considered for surgery due to an unclear seizure focus. The aim of this study was to investigate whether EEG-fMRI can add useful information in the preoperative evaluation of these patients. METHODS Nine nonlesional FLE patients were studied with EEG-fMRI using a 3 T scanner. Spike-related blood oxygen level dependent (BOLD) signal changes were compared to the topography of the spikes and to PET and SPECT results if available. The structural MRIs were reviewed for subtle abnormalities in areas that showed BOLD responses. For operated patients, postoperative resection and histology were compared to BOLD responses. RESULTS Concordance between spike localization and positive BOLD response was found in 8 patients. PET and SPECT investigations corresponded with BOLD signal changes in 6 of 7 investigations. In 2 cases, reviewing the structural MRI guided by EEG-fMRI data resulted in considering a suspicious deep sulcus. Two patients were operated. In 1, the resected cortex corresponded with the suspicious sulcus and fMRI results and histology showed cortical dysplasia. In another, histology revealed an extended microdysgenesis not visible on structural MRI. EEG-fMRI had shown activation just adjacent to the resected pathologic area. CONCLUSIONS Our study provides different types of support (topography, concordance with PET and SPECT, structural peculiarities, postoperative histology) that EEG-fMRI may help to delineate the epileptic focus in patients with nonlesional frontal lobe epilepsy, a challenging group in the preoperative evaluation.
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Affiliation(s)
- F Moeller
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
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Tyvaert L, Chassagnon S, Sadikot A, LeVan P, Dubeau F, Gotman J. Thalamic nuclei activity in idiopathic generalized epilepsy: an EEG-fMRI study. Neurology 2009; 73:2018-22. [PMID: 19996076 DOI: 10.1212/wnl.0b013e3181c55d02] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Idiopathic generalized epilepsies (IGE) are characterized by specific EEG changes including 3- to 5-Hz generalized spike-and-wave discharges. The thalamus and its cortical interactions are considered essential in the production and propagation of spike-and-wave discharges. In animal studies, corticoreticular and limbic system property changes have been observed in absence seizures and during spike-and-wave discharges and suggest the involvement of different types of thalamic nuclei. With the development of deep brain stimulation in epilepsy, the role of the thalamic nuclei needs to be clarified in human IGE. METHODS Ten patients with IGE were recorded using 3T EEG-fMRI during spike-and-wave discharges. Hemodynamic response functions were calculated for 4 regions of interest corresponding to the anterior thalamic and centromedian and parafascicular (CM-Pf) nuclei of each thalamus. The time to peak of the hemodynamic response function was compared within thalamic structures (left compared to right) and between structures (anterior thalamic compared to CM-Pf nucleus). RESULTS CM-Pf and anterior nucleus are both activated during GSWDs. However, the positive time to peak in the CM-Pf (4.4 +/- 2.5 s) occurred significantly earlier than in the anterior nucleus (7.6 +/- 3.2 s). CONCLUSIONS We demonstrated in humans the involvement of the centromedian and parafascicular part of the corticoreticular system and of the anterior nucleus part of the limbic system during generalized spike-and-wave discharges. The different time courses suggest that the posterior intralaminar nuclei may be involved in epileptic discharge initiation or early propagation, while the anterior nucleus may only play a role in its maintenance. These results may help to understand the clinical effect of deep brain stimulation within thalamic nuclei in intractable idiopathic generalized epilepsy patients.
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Affiliation(s)
- L Tyvaert
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
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Moeller F, Siniatchkin M, LeVan P, Stephani U, Dubeau F, Gotman J. Dynamic analysis of absence seizures in humans – an EEG fMRI study. Neuroimage 2009. [DOI: 10.1016/s1053-8119(09)70724-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Abstract
OBJECTIVE High-frequency oscillations (HFOs) can be recorded in epileptic patients with clinical intracranial EEG. HFOs have been associated with seizure genesis because they occur in the seizure focus and during seizure onset. HFOs are also found interictally, partly co-occurring with epileptic spikes. We studied how HFOs are influenced by antiepileptic medication and seizure occurrence, to improve understanding of the pathophysiology and clinical meaning of HFOs. METHODS Intracerebral depth EEG was partly sampled at 2,000 Hz in 42 patients with intractable focal epilepsy. Patients with five or more usable nights of recording were selected. A sample of slow-wave sleep from each night was analyzed, and HFOs (ripples: 80-250 Hz, fast ripples: 250-500 Hz) and spikes were identified on all artifact-free channels. The HFOs and spikes were compared before and after seizures with stable medication dose and during medication reduction with no intervening seizures. RESULTS Twelve patients with five to eight nights were included. After seizures, there was an increase in spikes, whereas HFO rates remained the same. Medication reduction was followed by an increase in HFO rates and mean duration. CONCLUSIONS Contrary to spikes, high-frequency oscillations (HFOs) do not increase after seizures, but do so after medication reduction, similarly to seizures. This implies that spikes and HFOs have different pathophysiologic mechanisms and that HFOs are more tightly linked to seizures than spikes. HFOs seem to play an important role in seizure genesis and can be a useful clinical marker for disease activity.
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Affiliation(s)
- M Zijlmans
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
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Jacobs J, LeVan P, Dubeau F, Gotman J. 65. Generation of high frequency oscillations (80–500Hz) in different anatomical structures and their relation to the seizure onset zone. Clin Neurophysiol 2009. [DOI: 10.1016/j.clinph.2008.07.064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Tyvaert L, Hawco C, Kobayashi E, LeVan P, Dubeau F, Gotman J. Different structures involved during ictal and interictal epileptic activity in malformations of cortical development: an EEG-fMRI study. ACTA ACUST UNITED AC 2008; 131:2042-60. [PMID: 18669486 DOI: 10.1093/brain/awn145] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Malformations of cortical development (MCDs) are commonly complicated by intractable focal epilepsy. Epileptogenesis in these disorders is not well understood and may depend on the type of MCD. The cellular mechanisms involved in interictal and ictal events are notably different, and could be influenced independently by the type of pathology. We evaluated the relationship between interictal and ictal zones in eight patients with different types of MCD in order to better understand the generation of these activities: four had nodular heterotopia, two focal cortical dysplasia and two subcortical band heterotopia (double-cortex). We used the non-invasive EEG-fMRI technique to record simultaneously all cerebral structures with a high spatio-temporal resolution. We recorded interictal and ictal events during the same session. Ictal events were either electrical only or clinical with minimal motion. BOLD changes were found in the focal cortical dysplasia during interictal and ictal epileptiform events in the two patients with this disorder. Heterotopic and normal cortices were involved in BOLD changes during interictal and ictal events in the two patients with double cortex, but the maximum BOLD response was in the heterotopic band in both patients. Only two of the four patients with nodular heterotopia showed involvement of a nodule during interictal activity. During seizures, although BOLD changes affected the lesion in two patients, the maximum was always in the overlying cortex and never in the heterotopia. For two patients intracranial recordings were available and confirm our findings. The dysplastic cortex and the heterotopic cortex of band heterotopia were involved in interictal and seizure processes. Even if the nodular gray matter heterotopia may have the cellular substrate to produce interictal events, the often abnormal overlying cortex is more likely to be involved during the seizures. The non-invasive BOLD study of interictal and ictal events in MCD patients may help to understand the role of the lesion in epileptogenesis and also determine the potential surgical target.
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Affiliation(s)
- L Tyvaert
- Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4.
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Jacobs J, LeVan P, Dubeau F, Gotman J. Generation of High Frequency Oscillations (80–500Hz) in different anatomical structures and their relation to the seizure onset zone. KLIN NEUROPHYSIOL 2008. [DOI: 10.1055/s-2008-1072859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Chang N, Gotman J, Gulrajani R. Dipole localization using beamforming and RAP-MUSIC on simulated intracerebral recordings. Conf Proc IEEE Eng Med Biol Soc 2007; 2004:1010-3. [PMID: 17271852 DOI: 10.1109/iembs.2004.1403333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Interpreting intracerebral recordings in the search of an epileptic focus can be difficult because the amplitude of the potentials are misleading. Small generators located near the electrode site generate large potentials, which could swamp the signal of a nearby epileptic focus. In order to address this problem, two inverse problem algorithms, beamforming and recursively applied and projected multiple signal classification (RAP-MUSIC), were used with simulated intracerebral potentials to calculate equivalent dipole positions. Three dipoles were positioned in an infinite plane medium near three intracerebral electrodes. The potentials generated by the dipoles were simulated and contaminated with white noise. Initial localization simulations showed that both methods detected the sources accurately with RAP-MUSIC reporting lower orientation errors. A spatial resolution analysis for both methods was undertaken in which two dipoles were placed on a plane with the same orientation and overlapping time-courses. Beamforming was able to adequately distinguish the sources for separation distances of 1.2 cm, whereas RAP-MUSIC managed to separate the sources for dipoles as close as 0.4-0.6 cm.
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Affiliation(s)
- N Chang
- Neurological Inst., McGill Univ., Montreal, Que., Canada
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22
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Grova C, Makni S, Flandin G, Ciuciu P, Gotman J, Poline JB. Anatomically informed interpolation of fMRI data on the cortical surface. Neuroimage 2006; 31:1475-86. [PMID: 16650778 DOI: 10.1016/j.neuroimage.2006.02.049] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2005] [Revised: 02/23/2006] [Accepted: 02/23/2006] [Indexed: 10/24/2022] Open
Abstract
Analyzing functional magnetic resonance imaging (fMRI) data restricted to the cortical surface is of particular interest for two reasons: (1) to increase detection sensitivity using anatomical constraints and (2) to compare or use fMRI results in the context of source localization from magneto/electro-encephalography (MEEG) data, which requires data to be projected on the same spatial support. Designing an optimal scheme to interpolate fMRI raw data or resulting activation maps on the cortical surface relies on a trade-off between choosing large enough interpolation kernels, because of the distributed nature of the hemodynamic response, and avoiding mixing data issued from different anatomical structures. We propose an original method that automatically adjusts the level of such a trade-off, by defining interpolation kernels around each vertex of the cortical surface using a geodesic Voronoï diagram. This Voronoï-based interpolation method was evaluated using simulated fMRI activation maps, manually generated on an anatomical MRI, and compared with a more standard approach where interpolation kernels were defined as local spheres of radius r=3 or 5 mm. Several validation parameters were considered: the spatial resolution of the simulated activation map, the spatial resolution of the cortical mesh, the level of anatomical/functional data misregistration and the location of the vertices within the gray matter ribbon. Using an activation map at the spatial resolution of standard fMRI data, robustness to misregistration errors was observed for both methods, whereas only the Voronoï-based approach was insensitive to the position of the vertices within the gray matter ribbon.
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Affiliation(s)
- C Grova
- Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, EEG department, Room 009d, Quebec, Canada H3A 2B4.
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23
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Abstract
BACKGROUND Combined recording of EEG and fMRI has shown changes in blood oxygenation level dependent (BOLD) signal during focal interictal epileptic spikes. Due to difficult assessment of seizures inside the scanner little is known about BOLD changes during seizures. OBJECTIVES To describe BOLD changes related to brief focal electrographic seizures in a patient with right temporo-parietal gray matter nodular heterotopia. METHODS The patient underwent two EEG-fMRI sessions during which several focal seizures were recorded. EEG was acquired continuously during scanning and seizure timing was used for statistical analysis. Functional maps were thresholded to disclose positive (activation) and negative (deactivation) BOLD changes. RESULTS Twenty-five focal electrographic seizures were analyzed, consisting of runs of polyspikes lasting 2 to 6 s in the right temporal region. Activation included a large volume, involving the heterotopia and the abnormal temporo-parietal cortex overlying the nodule, with a clear maximum over the angular gyrus. Deactivation was bilateral and maximum in the occipital regions. The hemodynamic response function showed a return to baseline of the BOLD signal 30 s after seizure end. CONCLUSIONS The brief focal seizures resulted in high amplitude and widespread blood oxygenation level dependent (BOLD) responses taking 30 s to return to baseline. This suggests that such brief events could have important behavioral consequences despite absent overt manifestations. A clear focal BOLD peak was found at some distance from the main EEG discharge, raising the possibility that the seizure could have started in a region that did not generate a visible EEG change despite its superficial location.
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Affiliation(s)
- E Kobayashi
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada.
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Abstract
Discrete high-frequency oscillations (HFOs) in the range of 100-500 Hz have previously been recorded in human epileptic brains using depth microelectrodes. We describe for the first time similar oscillations in a cohort of unselected focal epileptic patients implanted with EEG macroelectrodes. Spectral analysis and visual inspection techniques were used to study seizures from 10 consecutive patients undergoing pre-surgical evaluation for medically refractory focal epilepsy. Four of these patients had focal seizure onset in the mesial temporal lobe, and in all 12 of their seizures, well-localized, segmental, very high frequency band (VHF: 250-500 Hz) oscillations were visually identified near the time of seizure onset from contacts in this zone. Increased high-frequency band (HF: 100-200 Hz) activity compared with the background was distinguished both visually and with spectral analysis later in the seizures of 3/4 mesial temporal patients, involving contacts in the generator region and, in one patient, areas of contralateral peri-hippocampal propagation. Three patients with well-defined neocortical seizure-onset areas also demonstrated focal HF or VHF oscillations confined to the seizure-onset channels during their eight seizures. No discrete HF or VHF activity was present in the poorly localized seizures from the remaining three patients. These results show that discrete HFOs can be recorded from human focal epileptic brain using depth macroelectrodes, and that they occur mostly in regions of primary epileptogenesis and rarely in regions of secondary spread. Absent high-frequency activity seems to indicate poor localization, whereas the presence of focal HFOs near the time of seizure onset may signify proximity to the epileptogenic focus in mesial temporal lobe and neocortical seizures. We postulate that focal HFOs recorded with depth macroelectrodes reflect the partial synchronization of very local oscillations such as those previously studied using microelectrodes, and result from interconnected small neuronal ensembles. Our finding that localized HFOs occur in varying anatomical structures and pathological conditions perhaps indicates commonality to diverse epileptogenic aetiologies.
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Affiliation(s)
- J D Jirsch
- Montreal Neurological Institute and Hospital, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada
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LeVan P, Urrestarazu E, Gotman J. A system for automatic artifact removal in ictal scalp EEG based on independent component analysis and Bayesian classification. Clin Neurophysiol 2006; 117:912-27. [PMID: 16458594 DOI: 10.1016/j.clinph.2005.12.013] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 11/15/2005] [Accepted: 12/13/2005] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To devise an automated system to remove artifacts from ictal scalp EEG, using independent component analysis (ICA). METHODS A Bayesian classifier was used to determine the probability that 2s epochs of seizure segments decomposed by ICA represented EEG activity, as opposed to artifact. The classifier was trained using numerous statistical, spectral, and spatial features. The system's performance was then assessed using separate validation data. RESULTS The classifier identified epochs representing EEG activity in the validation dataset with a sensitivity of 82.4% and a specificity of 83.3%. An ICA component was considered to represent EEG activity if the sum of the probabilities that its epochs represented EEG exceeded a threshold predetermined using the training data. Otherwise, the component represented artifact. Using this threshold on the validation set, the identification of EEG components was performed with a sensitivity of 87.6% and a specificity of 70.2%. Most misclassified components were a mixture of EEG and artifactual activity. CONCLUSIONS The automated system successfully rejected a good proportion of artifactual components extracted by ICA, while preserving almost all EEG components. The misclassification rate was comparable to the variability observed in human classification. SIGNIFICANCE Current ICA methods of artifact removal require a tedious visual classification of the components. The proposed system automates this process and removes simultaneously multiple types of artifacts.
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Affiliation(s)
- P LeVan
- Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Que., Canada H3A 2B4.
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Urrestarazu E, LeVan P, Gotman J. Independent component analysis identifies ictal bitemporal activity in intracranial recordings at the time of unilateral discharges. Clin Neurophysiol 2006; 117:549-61. [PMID: 16461002 DOI: 10.1016/j.clinph.2005.10.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Revised: 10/12/2005] [Accepted: 10/18/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To apply independent component analysis (ICA) in intracranial recordings to analyze interactions during temporal lobe seizures. METHODS Seizures from 20 patients with bitemporal implantation were classified as unilateral or bilateral and analyzed with ICA. During the period preceding bilateral activity, correlation coefficients were calculated between ICA components having ictal activity during the unilateral seizure phase (early ICA components) and every channel of the original EEG. ICA components were classified as unilateral if the correlation was >0.2 exclusively with channels in one hemisphere; and bilateral if both hemispheres were involved. RESULTS One hundred twenty-three seizures were analyzed. Thirty-two percent of visually classified unilateral seizures and 64% of bilateral seizures (during the unilateral phase) had bilateral ICA components. The proportion of early ICA components that were bilateral and the proportion of channels contralateral to the visually identified seizure with correlation higher than 0.2 with at least one early ICA component were significantly lower in seizures that stayed unilateral than in seizures that later became bilateral by visual inspection (11 and 10%, respectively, in unilateral seizures; 33 and 28% in bilateral seizures; P=0.001). CONCLUSIONS In patients with bitemporal epilepsy, approximately 20% of the components extracted using ICA have a bitemporal distribution even at the time when the seizures are apparently unilateral. The presence of early contralateral ictal activity is more frequent and extensive in seizures that later become evidently bilateral. SIGNIFICANCE Minimal contralateral seizure activity is present even when the discharge appears unilateral and this is more frequent in seizures which later spread to the contralateral temporal lobe.
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Affiliation(s)
- E Urrestarazu
- Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Que., Canada H3A 2B4.
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Grova C, Daunizeau J, Lina JM, Bénar CG, Benali H, Gotman J. Evaluation of EEG localization methods using realistic simulations of interictal spikes. Neuroimage 2006; 29:734-53. [PMID: 16271483 DOI: 10.1016/j.neuroimage.2005.08.053] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Revised: 07/06/2005] [Accepted: 08/23/2005] [Indexed: 10/25/2022] Open
Abstract
Performing an accurate localization of sources of interictal spikes from EEG scalp measurements is of particular interest during the presurgical investigation of epilepsy. The purpose of this paper is to study the ability of six distributed source localization methods to recover extended sources of activated cortex. Due to the frequent lack of a gold standard to evaluate source localization methods, our evaluation was performed in a controlled environment using realistic simulations of EEG interictal spikes, involving several anatomical locations with several spatial extents. Simulated data were corrupted by physiological EEG noise. Simulations involving pairs of sources with the same amplitude were also studied. In addition to standard validation criteria (e.g., geodesic distance or mean square error), we proposed an original criterion dedicated to assess detection accuracy, based on receiver operating characteristic (ROC) analysis. Six source localization methods were evaluated: the minimum norm, the minimum norm weighted by multivariate source prelocalization (MSP), cortical LORETA with or without additional minimum norm regularization, and two derivations of the maximum entropy on the mean (MEM) approach. Results showed that LORETA-based and MEM-based methods were able to accurately recover sources of different spatial extents, with the exception of sources in temporo-mesial and fronto-mesial regions. Several spurious sources were generated by those methods, however, whereas methods using the MSP always located very accurately the maximum of activity but not its spatial extent. These findings suggest that one should always take into account the results from different localization methods when analyzing real interictal spikes.
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Affiliation(s)
- C Grova
- Montreal Neurological Institute, McGill University, EEG Department, Room 009d, 3801 University Street, Montreal, Quebec, Canada H3A 2B4.
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Aghakhani Y, Kobayashi E, Bagshaw AP, Hawco C, Bénar CG, Dubeau F, Gotman J. Cortical and thalamic fMRI responses in partial epilepsy with focal and bilateral synchronous spikes. Clin Neurophysiol 2006; 117:177-91. [PMID: 16314143 DOI: 10.1016/j.clinph.2005.08.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Revised: 08/18/2005] [Accepted: 08/22/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To determine the blood oxygen level-dependent (BOLD) responses to epileptic discharges in the thalamus and cerebral cortex in patients with partial epilepsy. METHODS Among 64 tested patients, 40 had EEG spikes during scanning and were divided in two groups: unilateral or bilateral independent spikes (29 patients) and bilaterally synchronous spikes (11 patients). Each spike topography was analyzed separately, yielding 40 studies in the first group and 17 in the second. RESULTS Forty-five percent of focal spike studies showed significant BOLD responses. Cortical activation (positive BOLD) represented the dominant response and had a better correlation with spike location than cortical deactivation (negative BOLD). In the second group, all patients had significant BOLD responses; they were more widespread compared to the first group, and deactivated areas were as important as activated regions. A thalamic response was seen in 12.5% of studies in the first group and 55% in the second. CONCLUSIONS The thalamus is involved in partial epilepsy during interictal discharges. This involvement and also cortical deactivation are more commonly seen with bilateral spikes than focal discharges. SIGNIFICANCE These findings show evidence for a role for the thalamus and a more important role for inhibition in secondary bilateral synchrony.
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Affiliation(s)
- Y Aghakhani
- Montreal Neurological Institute and Hospital, McGill University, Montréal, Que., Canada
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Jones-Gotman M, Sziklas V, Djordjevic J, Dubeau F, Gotman J, Angle M, Tampieri D, Olivier A, Andermann F. Etomidate speech and memory test (eSAM): A new drug and improved intracarotid procedure. Neurology 2005; 65:1723-9. [PMID: 16344513 DOI: 10.1212/01.wnl.0000187975.78433.cb] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The intracarotid amobarbital procedure (IAP) is an important part of comprehensive investigation of patients who are candidates for surgical treatment of epilepsy. Owing to repeated and lengthy shortages of amobarbital, causing delays in elective surgery, attempts have been made to find a suitable alternative anesthetic. The authors report their experience using etomidate, a widely used agent for the induction of anesthesia. METHODS Sixteen consecutive patients requiring IAP to evaluate memory or to lateralize speech underwent the procedure using etomidate. Prior to the procedure a catheter was placed in the internal carotid artery and an angiogram was performed. EEG was recorded and read online by an electroencephalographer. An anesthetist injected the drug, administered by bolus followed by an infusion, which was maintained until each speech measure had been sampled and new memory items had been introduced. The infusion was then stopped and testing continued as in a standard IAP. RESULTS In all cases (30 hemispheres) contralateral hemiplegia followed injection. EEG slow waves were observed in every injected hemisphere, with some contralateral slowing anteriorly in 18. Global aphasia with preserved attention and cooperation followed dominant-hemisphere injections. These phenomena remained during infusion, and upon its termination returned gradually to baseline over a period of about 4 minutes. CONCLUSIONS Etomidate is a viable alternative to amobarbital, and its administration by bolus followed by infusion offers an improvement over the traditional intracarotid amobarbital procedure. Cognitive tests can be performed during an assured hemianesthesia of the injected hemisphere.
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Affiliation(s)
- M Jones-Gotman
- Montreal Neurological Institute and Hospital, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada.
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Gotman J, Grova C, Bagshaw A, Kobayashi E, Aghakhani Y, Dubeau F. Generalized epileptic discharges show thalamocortical activation and suspension of the default state of the brain. Proc Natl Acad Sci U S A 2005; 102:15236-40. [PMID: 16217042 PMCID: PMC1257704 DOI: 10.1073/pnas.0504935102] [Citation(s) in RCA: 410] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 08/26/2005] [Indexed: 11/18/2022] Open
Abstract
Our objective was to evaluate the brain regions showing increased and decreased metabolism in patients at the time of generalized bursts of epileptic discharges in order to understand their mechanism of generation and effect on brain function. By recording the electroencephalogram during the functional MRI, changes in the blood oxygenation level-dependent signal were obtained in response to epileptic discharges observed in the electroencephalogram of 15 patients with idiopathic generalized epilepsy. A group analysis was performed to determine the regions of positive (activation) and negative (deactivation) blood oxygenation level-dependent responses that were common to the patients. Activations were found bilaterally and symmetrically in the thalamus, mesial midfrontal region, insulae, and midline and bilateral cerebellum and on the borders of the lateral ventricles. Deactivations were bilateral and symmetrical in the anterior frontal and parietal regions and in the posterior cingulate gyri and were seen in the left posterior temporal region. Activations in thalamus and midfrontal regions confirm known involvement of these regions in the generation or spread of generalized epileptic discharges. Involvement of the insulae in generalized discharges had not previously been described. Cerebellar activation is not believed to reflect the generation of discharges. Deactivations in frontal and parietal regions remarkably followed the pattern of the default state of brain function. Thalamocortical activation and suspension of the default state may combine to cause the actual state of reduced responsiveness observed in patients during spike-and-wave discharges. This brief lapse of responsiveness may therefore not result only from the epileptic discharge but also from its effect on normal brain function.
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Affiliation(s)
- J Gotman
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4.
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Kobayashi E, Bagshaw AP, Jansen A, Andermann F, Andermann E, Gotman J, Dubeau F. Intrinsic epileptogenicity in polymicrogyric cortex suggested by EEG-fMRI BOLD responses. Neurology 2005; 64:1263-6. [PMID: 15824359 DOI: 10.1212/01.wnl.0000154640.23656.a3] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Polymicrogyria (PMG) is a widespread cortical malformation frequently associated with seizures and EEG spikes. Its epileptogenicity is poorly understood. Nine patients with simultaneous EEG and fMRI were studied to assess the blood oxygenation level-dependent response to spikes. Sixteen of 18 studies showed responses, with maximum activation involving the lesion in 61.5%, but often limited to a small fraction of that lesion, suggesting intrinsic epileptogenicity in small areas of the PMG cortex.
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Affiliation(s)
- E Kobayashi
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
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Abstract
OBJECTIVE A new method for automatic seizure detection and onset warning is proposed. The system is based on determining the seizure probability of a section of EEG. Operation features a user-tuneable threshold to exploit the trade-off between sensitivity and detection delay and an acceptable false detection rate. METHODS The system was designed using 652 h of scalp EEG, including 126 seizures in 28 patients. Wavelet decomposition, feature extraction and data segmentation were employed to compute the a priori probabilities required for the Bayesian formulation used in training, testing and operation. RESULTS Results based on the analysis of separate testing data (360 h of scalp EEG, including 69 seizures in 16 patients) initially show a sensitivity of 77.9%, a false detection rate of 0.86/h and a median detection delay of 9.8 s. Results after use of the tuning mechanism show a sensitivity of 76.0%, a false detection rate of 0.34/h and a median detection delay of 10 s. Missed seizures are characterized mainly by subtle or focal activity, mixed frequencies, short duration or some combination of these traits. False detections are mainly caused by short bursts of rhythmic activity, rapid eye blinking and EMG artifact caused by chewing. Evaluation of the traditional seizure detection method of using both data sets shows a sensitivity of 50.1%, a false detection rate of 0.5/h and a median detection delay of 14.3 s. CONCLUSIONS The system performed well enough to be considered for use within a clinical setting. In patients having an unacceptable level of false detection, the tuning mechanism provided an important reduction in false detections with minimal loss of detection sensitivity and detection delay. SIGNIFICANCE During prolonged EEG monitoring of epileptic patients, the continuous recording may be marked where seizures are likely to have taken place. Several methods of automatic seizure detection exist, but few can operate as an on-line seizure alert system. We propose a seizure detection system that can alert medical staff to the onset of a seizure and hence improve clinical diagnosis.
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Affiliation(s)
- M E Saab
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Que., Canada H3A 2B4
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Aghakhani Y, Rosati A, Olivier A, Gotman J, Andermann F, Dubeau F. The predictive localizing value of tonic limb posturing in supplementary sensorimotor seizures. Neurology 2004; 62:2256-61. [PMID: 15210891 DOI: 10.1212/wnl.62.12.2256] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To determine whether early tonic limb posturing is reliable in lateralizing or localizing of the seizure generator in 14 patients with pharmacoresistent supplementary sensorimotor area (SSMA) seizures. METHODS All patients underwent high-quality MRI scans and stereo-EEG recordings. RESULTS The SSMA seizure semiology predicted focal or regional ictal onset in the SSMA in six (43%) patients: Three had a focal SSMA seizure onset, and three had a regional seizure onset with involvement of one SSMA plus adjacent neocortex. The eight remaining patients had diffuse uni- or bilateral seizure onset. Eight of 14 patients underwent a frontal or central cortical resection, but a good outcome was seen in only 3: 2 with no SSMA resection and 1 with an extensive central removal. CONCLUSIONS SSMA semiology is suggestive of early involvement of this region but is by no means a reliable indicator that the primary SSMA contains the seizure focus.
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Affiliation(s)
- Y Aghakhani
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
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Aghakhani Y, Bagshaw AP, Bénar CG, Hawco C, Andermann F, Dubeau F, Gotman J. fMRI activation during spike and wave discharges in idiopathic generalized epilepsy. Brain 2004; 127:1127-44. [PMID: 15033899 DOI: 10.1093/brain/awh136] [Citation(s) in RCA: 311] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The objectives of this study were to evaluate the haemodynamic response of the cerebral cortex and thalamus during generalized spike and wave or polyspike and wave (GSW) bursts in patients with idiopathic generalized epilepsy (IGE). The haemodynamic response is measured by fMRI [blood oxygenation level-dependent (BOLD) effect]. We used combined EEG-functional MRI, a method that allows the unambiguous measurement of the BOLD effect during bursts, compared with measurements during the inter-burst interval. Fifteen patients with IGE had GSW bursts during scanning and technically acceptable studies. fMRI cortical changes as a result of GSW activity were present in 14 patients (93%). Changes in the form of activation (increased BOLD) or deactivation (decreased BOLD) occurred symmetrically in the cortex of both hemispheres, involved anterior as much as posterior head regions, but were variable across patients. Bilateral thalamic changes were also found in 12 patients (80%). Activation predominated over deactivation in the thalamus, whereas the opposite was seen in the cerebral cortex. These results bring a new light to the pathophysiolocal mechanisms generating GSW. The spatial distribution of BOLD responses to GSW was unexpected: it involved as many posterior as anterior head regions, contrary to the usual fronto-central predominance seen in EEG. The presence of a thalamic BOLD response in most patients provided, for the first time in a group of human patients, confirmation of the evidence of thalamic involvement seen in animal models. The possible mechanisms underlying these phenomena are discussed.
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Affiliation(s)
- Y Aghakhani
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, Canada
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Serles W, Li LM, Antel SB, Cendes F, Gotman J, Olivier A, Andermann F, Dubeau F, Arnold DL. Time Course of Postoperative Recovery of N-Acetyl-Aspartate in Temporal Lobe Epilepsy. Epilepsia 2003. [DOI: 10.1046/j.1528-1157.2001.4220190.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
BACKGROUND Automatic seizure detection is often used during long-term monitoring, and is particularly important during intracerebral investigations. Existing methods make many false detections, particularly in intracerebral electroencephalogram (EEG) because of frequent large amplitude rhythmic activity bursts that are non-epileptiform. OBJECTIVE To develop a seizure detection method for intracerebral monitoring that is as sensitive as existing methods but has fewer false detections. METHODS To capture the rhythmic nature of seizure discharges, we developed a wavelet-based method, examining how different frequency ranges fluctuate compared to the background. In particular, the system remembers rhythmic bursts occurring commonly in the background to avoid detecting them as seizures. RESULTS The method was evaluated on test data from 11 patients, including 229 h and 66 seizures, and its performance compared to the method of Gotman (Electroencephalogr clin Neurophysiol 76 (1990) 317). Detection sensitivity was unchanged at close to 90%, but false detections were reduced from 2.4 to 0.3/h. CONCLUSIONS Perfect sensitivity is unlikely because the morphology of seizure discharges is so variable. Nevertheless, the 87% sensitivity obtained in the combined training and testing data is quite high. We reduced the average false alarm rate to one per 3 h of recording, or 6 per 24-h period. Given how rapidly one can decide visually that a detection is erroneous, false detections should not cause any burden to the reviewer. SIGNIFICANCE In intracerebral EEG it is possible to detect seizures automatically with high sensitivity and high specificity.
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Affiliation(s)
- Y U Khan
- Montreal Neurological Institute and Department of Neurology and Neurosurgery, McGill University, Room 767, 3801 University Street, Quebec, Canada H3A 2B4
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Rosati A, Aghakhani Y, Bernasconi A, Olivier A, Andermann F, Gotman J, Dubeau F. Intractable temporal lobe epilepsy with rare spikes is less severe than with frequent spikes. Neurology 2003; 60:1290-5. [PMID: 12707431 DOI: 10.1212/01.wnl.0000058761.12715.0e] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To analyze clinical, electrophysiologic, and neuroradiologic characteristics of a group of patients with nonlesional intractable temporal lobe epilepsy (TLE) and rare or absent interictal epileptiform abnormalities (IEA). METHODS Between 1990 and 2000, 31 patients (11 men; mean +/- SD age 34.3 +/- 11.7 years) with nonlesional intractable TLE were consecutively selected on the basis of the absence or paucity of IEA (<1/h) on serial scalp EEG recording; these were defined as "oligospikers." The clinical and laboratory characteristics of oligospikers were compared with those of a group of 27 age-matched control subjects (10 men; mean +/- SD age 38.5 +/- 11 years), randomly selected from a pool of patients with nonlesional TLE with frequent IEA. RESULTS Oligospikers showed a later age at seizure onset (mean +/- SD 19.1 +/- 14.4 versus 10.2 +/- 7.4 years; p = 0.004), lower monthly frequency of complex partial seizures (median 6 versus 12; p = 0.035), lower incidence of secondarily generalized tonic-clonic seizures (10 versus 81%; p < 0.001), and no status epilepticus (0 versus 22%) than control subjects. Also, hippocampal atrophy (HA) was less commonly found in oligospikers (55 versus 96%; p = 0.001). However, there were no differences between the two groups in the frequency of family history of epilepsy, risk factors, febrile convulsions, and type of medication. Twenty-three (74%) oligospikers and 25 (93%) control patients underwent either a selective amygdalohippocampectomy or corticoamygdalohippocampectomy. Excellent surgical outcome (Engel's Class Ia) was found in 14 of 23 (61%) oligospikers and 17 of 25 (67%) control patients. CONCLUSIONS This study identified a subgroup of patients with nonlesional intractable TLE with no or few IEA. Oligospikers have a later age at seizure onset, less frequent and less severe seizures, besides a lower incidence of HA. The similarity of etiologic factors compared with patients with frequent IEA suggests that the rarity of spikes could reflect a disease not really distinct but less severe, even though still intractable and incapacitating enough to consider surgery. In spite of the absence or paucity of IEA, oligospikers have excellent surgical outcome.
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Affiliation(s)
- A Rosati
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, Quebec, Canada
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Flanagan D, Agarwal R, Wang YH, Gotman J. Improvement in the performance of automated spike detection using dipole source features for artefact rejection. Clin Neurophysiol 2003; 114:38-49. [PMID: 12495762 DOI: 10.1016/s1388-2457(02)00296-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We evaluated the use of an efficient dipole source algorithm to improve performance of automated spike detection by identifying false detections caused by artefacts. METHODS Automated spike detections were acquired from 26 patients undergoing prolonged electroencephalograph (EEG) monitoring. Data from 6 patients were used to develop the method and data from 20 patients were used to test the method. To provide a standard against which to evaluate the results, an electroencephalographer (EEGer) visually categorized all automated detections before the dipole models were calculated for all events. The event categories (as defined by the EEGer) were then combined with properties of the dipole model and features were identified that differentiated spike and artefact detections. The resulting method was then applied to the testing data set. RESULTS Residual variance and eccentricity of the dipole models differentiated artefact and spike detections. A separate set of rules defining eye blink artefact was also developed. The combined criteria removed a mean of 53.2% of artefact from the testing data set. Some spike detections (4.3%) were also lost. CONCLUSIONS The features of the dipole source of a detected event can be used to differentiate artefacts from spikes. This algorithm is computationally light and could be implemented on-line.
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Affiliation(s)
- D Flanagan
- Stellate Systems, 345 Victoria Avenue, Québec, H3Z 2N2, Montreal, Canada
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Abstract
OBJECTIVES In order to obtain accurate EEG inverse solutions in patients subjected to surgery, we have studied the feasibility and influence of incorporating brain and skull defects in realistic head models. METHODS We first measured the conductivity of the methacrylate used for cranioplasty. Then, we designed realistic boundary element method head models with a skull burr hole, a methacrylate plug or a temporal-lobe resection. We simulated the potentials that would be produced at 71 electrode locations (10/10 system) by dipoles located near the defects. Then, we fitted dipoles on these potentials using a defect-free head model. We also ran simulations in a noisy situation and with higher skull and cerebrospinal fluid (CSF) conductivity. RESULTS The largest errors were found for burr holes, with a localization error up to 20 mm for a radial dipole located 30 mm below the hole and an amplification factor of 8. Methacrylate plugs lead to errors up to 5 mm and 0.5; the resection only lead to errors of 2 mm and 1.3. Results obtained with noise were consistent with those obtained without noise. Doubling the skull conductivity led to errors that were reduced by 10-20%, while doubling CSF conductivity increased the errors by up to 31%. CONCLUSIONS We have shown that it is important to incorporate skull defects in realistic head models when sources are located near the defects and precision is sought. Brain cavities of the size of a typical anterior temporal lobe resection may be omitted without a significant impact on dipole localization.
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Affiliation(s)
- C G Bénar
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4
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Abstract
To address the subjectivity in manual scoring of polysomnograms, a computer-assisted sleep staging method is presented in this paper. The method uses the principles of segmentation and self-organization (clustering) based on primitive sleep-related features to find the pseudonatural stages present in the record. Sample epochs of these natural stages are presented to the user, who can classify them according to the Rechtschaffen and Kales (RK) or any other standard. The method then learns from these samples to complete the classification. This step allows the active participation of the operator in order to customize the staging to his/her preferences. The method was developed and tested using 12 records of varying types (normal, abnormal, male, female, varying age groups). Results showed an overall concurrence of 80.6% with manual scoring of 20-s epochs according to RK standard. The greatest amount of errors occurred in the identification of the highly transitional Stage 1, 54% of which was misclassified into neighboring stages 2 or Wake.
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Affiliation(s)
- R Agarwal
- Stellate Systems, 345 Victoria Ave., Suite 300, Montreal, QC H3Z 2N2, Canada. ragarwalstellate.com
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Abstract
OBJECTIVES Inaccurate information about the electrode locations on the scalp will introduce errors in electroencephalogram dipole source localization results. The present study uses computer simulations to evaluate such errors in a realistic head model and in the context of noise. METHODS A realistic head model was constructed from magnetic resonance imaging scans and 29 electrodes placed on the head according to the 10-20 International System. Twenty sets of electrode displacements, with a mean value of 5 mm, were generated and 200 single dipoles evenly located in the brain were used as test sources. The boundary element method was employed for the forward calculation and dipole fitting was carried out at different noise levels. RESULTS For a noise-free signal, the source localization error due to electrode misplacement is about 5 mm, whereas it is about 2 mm for normal noisy signals. CONCLUSIONS For realistic head models, dipole estimation error due to electrode misplacement is negligible compared with errors caused by noise.
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Affiliation(s)
- Y Wang
- The Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4
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Affiliation(s)
- R Agarwal
- Dept. of Electrical and Computer Engineering, Concordia University, Stellate Systems, Montreal.
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Gotman J. Editorial A brief history of EEG analysis before the 2001 odyssey. Epileptic Disord 2001; Spec Issue:7-10. [PMID: 11781197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- J Gotman
- Montreal Neurological Institute, 3801 University Street and Department of Neurology and Neurosurgery McGill University, Montréal, Québec, Canada, H3A 2B4
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Gotman J. Can seizure analysis tell us where the focus is? Adv Neurol 2001; 84:299-305. [PMID: 11091874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- J Gotman
- Montreal Neurological Institute, McGill University, Quebec, Canada
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Abstract
OBJECTIVE In order to evaluate the feasibility of modeling seizures and the reliability of dipole models, we compared source localizations of scalp seizures with the distribution of simultaneous intracerebral electroencephalogram (SEEG). METHODS In a first session, only scalp electroencephalogram (EEG) was recorded from 15 patients. We averaged the first detectable ictal activity in two consecutive segments of stable topography and morphology. Spatio-temporal dipole sources were estimated for each segment and projected on 3D-magnetic resonance images. In a second session, SEEG was recorded simultaneously with control scalp electrodes, allowing the identification of ictal patterns similar to those submitted to dipole modeling. RESULTS Ictal discharges could be analyzed in only 6 of 15 patients. In the remaining 9, scalp discharges were undetectable or non-reproducible in 6, and solutions were unstable despite an apparently stable discharge in 3. In the 6 patients successfully modeled, dipoles were found in regions where SEEG discharges were present. However, when intracerebral discharges were very focal, there was no corresponding scalp activity. When intracerebral signals were maximal in the mesial temporal regions at the seizure onset, only lateral neocortical dipoles were found. When discharges reached the frontal lobes, we could identify lateral and mesial frontal sources. CONCLUSIONS In most seizures, it was not possible to obtain satisfactory dipole models, probably a reflection of the high noise level or widespread generators. When modeling was possible, our results suggested that mesial temporal seizure discharges did not contribute to scalp EEG activity. This activity appears to reflect signals synchronized and distributed over the lateral temporal or frontal neocortex, as well as signals generated in mesial frontal areas.
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Affiliation(s)
- I Merlet
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, 3801 University Street, Montreal, H3A 2B4, Quebec, Canada
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Kobayashi K, Merlet I, Gotman J. Separation of spikes from background by independent component analysis with dipole modeling and comparison to intracranial recording. Clin Neurophysiol 2001; 112:405-13. [PMID: 11222961 DOI: 10.1016/s1388-2457(01)00457-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Epileptiform discharges can be objectively separated from the EEG background by independent component analysis (ICA) into the discharge's waveform and its spatial distribution. The correspondence between ICA components, including epileptiform transients extracted from the scalp EEG and intracranial epileptic fields, was investigated. METHODS In 11 spike patterns from 8 patients, the scalp EEG data were decomposed by ICA. The corresponding averaged intracranial data were compared with the extracted epileptic components regarding the number of source patterns and source locations estimated from ICA maps. RESULTS Clear epileptic components could be separated in 10/11 spike patterns. The number of epileptic components was identical to the number of intracranial field peaks in 7 spike patterns with simple intracranial fields, and was less in the remaining 3 patterns with complex intracranial peaks. The distance between the contact of the maximal intracranial field and the dipole location estimated by the single dipole model for the clearest epileptic component ranged from 4.7 to 31.9 mm. CONCLUSIONS The number of epileptic ICA components largely matched the number of intracranial field patterns, and the dipole location estimated for the map of the clearest epileptic component was generally correct. This establishes the validity of epileptic components extracted by ICA from the scalp background.
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Affiliation(s)
- K Kobayashi
- Department of Child Neurology, Okayama University Medical School, 5-1 Shikatacho-2 Chome, 700-8558, Okayama, Japan.
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Serles W, Li LM, Antel SB, Cendes F, Gotman J, Olivier A, Andermann F, Dubeau F, Arnold DL. Time course of postoperative recovery of N-acetyl-aspartate in temporal lobe epilepsy. Epilepsia 2001; 42:190-7. [PMID: 11240588 DOI: 10.1046/j.1528-1157.2001.01300.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess the time course of increases in N-acetyl-aspartate/creatine (NAA/Cr), which can be measured using proton MR spectroscopic imaging (1H-MRSI), in patients with intractable nonlesional temporal lobe epilepsy (TLE) after successful epilepsy surgery. METHODS We performed pre- and postoperative 1H-MRSI in 16 seizure-free (SF) patients and 16 not seizure-free (NSF) TLE patients. We calculated a mixed-design analysis of variance (ANOVA) between SF and NSF groups, ipsi- and contralateral to the side of operation, and pre- and postoperative NAA/Cr measurements. We applied nonlinear regression between pre- and postoperative NAA/Cr differences and the time interval between 1H-MRSI scans to fit a negative exponential model to NAA recovery. RESULTS Mixed-design ANOVA revealed that (a) postoperative NAA/Cr was significantly higher in SF than in NSF patients (p = 0.02) and that (b) in the SF group, postoperative NAA/Cr values were significantly higher than preoperative values (p < 0.05) and returned to the normal range in most patients. According to our nonlinear regression model, in SF patients, there was a 50% increase relative to preoperative NAA/Cr values after 5.8 months, whereas an improvement of 95% was reached after 25 months. CONCLUSIONS Our results extend preliminary observations of postoperative NAA recovery of SF patients by characterizing the time course of recovery as an exponential function with a half-time of approximately 6 months. The reversal of neuronal metabolic dysfunction remote from the epileptic focus may underlie the clinical observation of improvement of cognitive dysfunction after successful epilepsy surgery.
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Affiliation(s)
- W Serles
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada, H3A 2B4
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Bernasconi A, Bernasconi N, Lassonde M, Toussaint PJ, Meyer E, Reutens DC, Gotman J, Andermann F, Villemure JG. Sensorimotor organization in patients who have undergone hemispherectomy: a study with (15)O-water PET and somatosensory evoked potentials. Neuroreport 2000; 11:3085-90. [PMID: 11043528 DOI: 10.1097/00001756-200009280-00010] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
To identify cortical structures that subserve residual motor and sensory function in patients with congenital hemiparesis due to a porencephalic cyst, we examined, using [(15)O]H2O, PET and somatosensory evoked potentials (SEPs) in three patients with left-sided hemiparesis who had undergone hemispherectomy. Motor stimulation of the affected hand produced ipsilateral activation in the premotor area in all patients, the SMA in two patients, and SII in two patients. Vibrotactile stimulation resulted in activation of the ipsilateral SII in all subjects. Median nerve stimulation of the affected hand produced ipsilateral long-latency SEPs in fronto-centro-parietal areas, whereas stimulation of the non-affected hand produced normal early cortical potentials in the contralateral hemisphere. Our results suggest that residual function in the paretic hand is warranted through non-primary motor and sensory areas, and higher order associative areas in the intact hemisphere.
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Affiliation(s)
- A Bernasconi
- Montreal Neurological Hospital and Institute, Department of Neurology and Brain Imaging Center, McGill University, Quebec, Canada
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