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Epilepsy surgery, MEG

Pierre Mégevand, Margitta Seeck
PURPOSE OF REVIEW: Source localization of cerebral activity using electroencephalography (EEG) or magnetoencephalography (MEG) can reveal noninvasively the generators of the abnormal signals recorded in epilepsy, such as interictal epileptic discharges (IEDs) and seizures. Here, we review recent progress showcasing the usefulness of these techniques in treating patients with drug-resistant epilepsy. RECENT FINDINGS: The source localization of IEDs by high-density EEG and MEG has now been proved in large patient cohorts to be accurate and clinically relevant, with positive and negative predictive values rivaling those of structural MRI...
February 9, 2018: Current Opinion in Neurology
Abbas Babajani-Feremi, Christen M Holder, Shalini Narayana, Stephen P Fulton, Asim F Choudhri, Frederick A Boop, James W Wheless
OBJECTIVE: To predict the postoperative language outcome using the support vector regression (SVR) and results of multimodal presurgical language mapping. METHODS: Eleven patients with epilepsy received presurgical language mapping using functional MRI (fMRI), magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), and high-gamma electrocorticography (hgECoG), as well as pre- and postoperative neuropsychological evaluation of language. We constructed 15 (24 -1) SVR models by considering the extent of resected language areas identified by all subsets of four modalities as input feature vector and the postoperative language outcome as output...
March 2018: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
A Koptelova, R Bikmullina, M Medvedovsky, S Novikova, A Golovteev, O Grinenko, M Korsakova, A Kozlova, N Arkhipova, A Vorobyev, A Melikyan, R Paetau, T Stroganova, L Metsähonkala
PURPOSE: Drug resistant epilepsy (DRE) is common in patients with tuberous sclerosis (TS). Interictal MEG has been shown as a valuable instrument in the presurgical workup. The goal of our study was to evaluate the role of ictal MEG in epileptogenic tuber selection, especially in patients with multiple irritative zones. METHODS: The clinical and MEG data of 23 patients with TS and DRE from two medical/research centers were reviewed. Seven pediatric patients, who had seizures during MEG recording and underwent resection or disconnection surgery, were included into the study...
December 27, 2017: Epilepsy Research
Steven Kemp, Garreth Prendergast, Theodoros Karapanagiotidis, Gus Baker, Thomas P Kelly, Tufail Patankar, Simon S Keller
The Wada test remains the traditional test for lateralizing language and memory function prior to epilepsy surgery. Functional imaging, particularly functional MRI (fMRI), has made progress in the language domain, but less so in the memory domain. Magnetoencephalography (MEG) has received less research attention, but shows promise, particularly for language lateralization. We recruited a consecutive sample of 19 patients with epilepsy who had completed presurgical work-up, including the Wada test, and compared fMRI (memory) and MEG (language and memory) with Wada test results...
December 12, 2017: Epilepsy & Behavior: E&B
Jayabal Velmurugan, Srikantan S Nagarajan, Narayanan Mariyappa, Shankar G Ravi, Kandavel Thennarasu, Ravindranadh C Mundlamuri, Kenchaiah Raghavendra, Rose Dawn Bharath, Jitender Saini, Arimappamagan Arivazhagan, Jamuna Rajan, Anita Mahadevan, Malla B Rao, Parthasarathy Satishchandra, Sanjib Sinha
OBJECTIVE: Specificity of ictal high-frequency oscillations (HFOs) in identifying epileptogenic abnormality is significant, compared to the spikes and interictal HFOs. The objectives of the study were to detect and to localize ictal HFOs by magnetoencephalography (MEG) for identifying the seizure onset zone (SOZ), evaluate the cortical excitability from preictal to ictal transition, and establish HFO concordance rates with other modalities and postsurgical resection. METHODS: Sixty-seven patients with drug-resistant epilepsy had at least 1 spontaneous seizure each during MEG acquisition, and analysis was carried out on 20 seizures from 20 patients...
November 7, 2017: Epilepsia
Sarah Collinge, Garreth Prendergast, Steven T Mayers, David Marshall, Poppy Siddell, Elizabeth Neilly, Colin D Ferrie, Gayatri Vadlamani, Jeremy Macmullen-Price, Daniel J Warren, Arshad Zaman, Paul Chumas, John Goodden, Matthew C H J Morrall
PURPOSE: A review of all published evidence for mapping eloquent (motor, language and memory) cortex using advanced functional neuroimaging (functional magnetic resonance imaging [fMRI] and magnetoencephalography [MEG]) for paediatric epilepsy surgery candidates has not been conducted previously. Research in this area has predominantly been in adult populations and applicability of these techniques to paediatric populations is less established. METHODS: A review was performed using an advanced systematic search and retrieval of all published papers examining the use of functional neuroimaging for paediatric epilepsy surgery candidates...
November 2017: Seizure: the Journal of the British Epilepsy Association
Imane Samah Chibane, Olivier Boucher, François Dubeau, Thi Phuoc Yen Tran, Ismail Mohamed, Richard McLachlan, R Mark Sadler, Richard Desbiens, Lionel Carmant, Dang Khoa Nguyen
BACKGROUND: Orbitofrontal epilepsy (OFE) is less known and is poorly characterized in comparison with temporal lobe epilepsy, partly because it is rare and possibly because it is unrecognized and therefore underestimated. OBJECTIVE: This paper aimed to better characterize seizure semiology, presurgical findings, and surgical outcomes in patients with OFE. METHODS: We retrospectively reviewed all confidently established OFE cases from six Canadian epilepsy monitoring units between 1988 and 2014, and in the literature between 1972 and 2017...
November 2017: Epilepsy & Behavior: E&B
Garima Shukla, Jin Kazutaka, Ajay Gupta, John Mosher, Stephen Jones, Andreas Alexopoulos, Richard C Burgess
PURPOSE: Children with generalized seizures are often excluded as epilepsy surgery candidates. This prospective study was conducted to evaluate the utility of magnetoencephalography (MEG) to refine the location of the "irritative zone" in children with single lesions on magnetic resonance imaging (MRI) but with generalized ictal electroencephalographic (EEG) findings. METHODS: Patients admitted with refractory epilepsy with imaging studies showing focal or hemispheric abnormalities but scalp video EEG showing generalized or multiregional epileptiform abnormalities were included...
October 2017: Journal of Child Neurology
Andrew C Papanicolaou, Roozbeh Rezaie, Shalini Narayana, Asim F Choudhri, Abbas-Babajani-Feremi, Frederick A Boop, James W Wheless
Cortical Stimulation Mapping (CSM) and the Wada procedure have long been considered the gold standard for localizing motor and language-related cortical areas and for determining the language and memory-dominant hemisphere, respectively. In recent years, however, non-invasive methods such as magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI), and transcranial magnetic stimulation (TMS) have emerged as promising alternatives to the aforementioned procedures, particularly in cases where the invasive localization of eloquent cortex has proven to be challenging...
July 3, 2017: Epilepsy Research
Nicole van Klink, Frank van Rosmalen, Jukka Nenonen, Sergey Burnos, Liisa Helle, Samu Taulu, Paul Lawrence Furlong, Maeike Zijlmans, Arjan Hillebrand
High frequency oscillations (HFOs, 80-500 Hz) in invasive EEG are a biomarker for the epileptic focus. Ripples (80-250 Hz) have also been identified in non-invasive MEG, yet detection is impeded by noise, their low occurrence rates, and the workload of visual analysis. We propose a method that identifies ripples in MEG through noise reduction, beamforming and automatic detection with minimal user effort. We analysed 15 min of presurgical resting-state interictal MEG data of 25 patients with epilepsy. The MEG signal-to-noise was improved by using a cross-validation signal space separation method, and by calculating ~ 2400 beamformer-based virtual sensors in the grey matter...
2017: NeuroImage: Clinical
Manoj Raghavan, Zhimin Li, Chad Carlson, Christopher T Anderson, Jeffrey Stout, David S Sabsevitz, Sara J Swanson, Jeffrey R Binder
OBJECTIVE: Methods employed to determine hemispheric language dominance using magnetoencephalography (MEG) have differed significantly across studies in the choice of language-task, the nature of the physiological response studied, recording hardware, and source modeling methods. Our goal was to determine whether an analysis based on distributed source modeling can replicate the results of prior studies that have used dipole-modeling of event-related fields (ERFs) generated by an auditory word-recognition task to determine language dominance in patients with epilepsy...
June 26, 2017: Epilepsy & Behavior: E&B
Osama Muthaffar, Klajdi Puka, Luc Rubinger, Cristina Go, O Carter Snead, James T Rutka, Elysa Widjaja
OBJECTIVE Although epilepsy surgery is an effective treatment option, at least 20%-40% of patients can continue to experience uncontrolled seizures resulting from incomplete resection of the lesion, epileptogenic zone, or secondary epileptogenesis. Reoperation could eliminate or improve seizures. Authors of this study evaluated outcomes following reoperation in a pediatric population. METHODS A retrospective single-center analysis of all patients who had undergone resective epilepsy surgery in the period from 2001 to 2013 was performed...
August 2017: Journal of Neurosurgery. Pediatrics
Ü Aydin, S Rampp, A Wollbrink, H Kugel, J -H Cho, T R Knösche, C Grova, J Wellmer, C H Wolters
In recent years, the use of source analysis based on electroencephalography (EEG) and magnetoencephalography (MEG) has gained considerable attention in presurgical epilepsy diagnosis. However, in many cases the source analysis alone is not used to tailor surgery unless the findings are confirmed by lesions, such as, e.g., cortical malformations in MRI. For many patients, the histology of tissue resected from MRI negative epilepsy shows small lesions, which indicates the need for more sensitive MR sequences...
July 2017: Brain Topography
Yuichi Kubota, Taku Ochiai, Tomokatsu Hori, Takakazu Kawamata
OBJECTIVE: Surgical options for medial temporal lobe epilepsy (MTLE) include anterior temporal lobectomy (ATL) and selective amygdalohippocampectomy (SAH). Optimal criteria for choosing the appropriate surgical approach remain uncertain. This article reports 11 consecutive cases in which electrophysiological findings of stereoelectroencephalography (SEEG) were used to determine the optimal surgical approach. PATIENTS AND METHODS: Eleven consecutive patients with MTLE underwent SEEG evaluation and were placed in either the medial or the medial+lateral group based on the findings...
July 2017: Clinical Neurology and Neurosurgery
Yuguang Guan, Sichang Chen, Changqing Liu, Xiuyu Du, Yao Zhang, Shuai Chen, Jie Wang, Tianfu Li, Guoming Luan
OBJECTIVE: To describe the surgery outcomes of RE patients in one centerto identify the indication for surgical treatment that results in the most favorable outcome. METHOD: Forty-five RE patients from a single center were retrospectively reviewed. Preoperative evaluations included assessments of clinical manifestations, cognitive status, a physical examination, MRI, positron emission tomography (PET), electroencephalography (EEG), and magnetoencephalography (MEG)...
March 22, 2017: Epilepsy Research
V Jayabal, Ashok Pillai, S Sinha, N Mariyappa, P Satishchandra, S Gopinath, Kurupath Radhakrishnan
In selected patients with drug-resistant focal epilepsies (DRFE), who otherwise are likely to be excluded from epilepsy surgery (ES) because of the absence of a magnetic resonance imaging (MRI)-demonstrable lesion or discordant anatomo-electro-clinical (AEC) data, magnetoencephalography (MEG) may help to generate an AEC hypothesis and stereo-electroencephalography (SEEG) may help to verify the hypothesis and proceed with ES. The sensitivity of MEG is much better in localizing the spiking zone in relation to lateral temporal and extratemporal cortical regions compared to the mesial temporal structures...
2017: Neurology India
Eleonora Tamilia, Joseph R Madsen, Patricia Ellen Grant, Phillip L Pearl, Christos Papadelis
Up to one-third of patients with epilepsy are medically intractable and need resective surgery. To be successful, epilepsy surgery requires a comprehensive preoperative evaluation to define the epileptogenic zone (EZ), the brain area that should be resected to achieve seizure freedom. Due to lack of tools and methods that measure the EZ directly, this area is defined indirectly based on concordant data from a multitude of presurgical non-invasive tests and intracranial recordings. However, the results of these tests are often insufficiently concordant or inconclusive...
2017: Frontiers in Neurology
Christos Papadelis, Eleonora Tamilia, Steven Stufflebeam, Patricia E Grant, Joseph R Madsen, Phillip L Pearl, Naoaki Tanaka
Crucial to the success of epilepsy surgery is the availability of a robust biomarker that identifies the Epileptogenic Zone (EZ). High Frequency Oscillations (HFOs) have emerged as potential presurgical biomarkers for the identification of the EZ in addition to Interictal Epileptiform Discharges (IEDs) and ictal activity. Although they are promising to localize the EZ, they are not yet suited for the diagnosis or monitoring of epilepsy in clinical practice. Primary barriers remain: the lack of a formal and global definition for HFOs; the consequent heterogeneity of methodological approaches used for their study; and the practical difficulties to detect and localize them noninvasively from scalp recordings...
December 6, 2016: Journal of Visualized Experiments: JoVE
Jessica Falco-Walter, Christian Owen, Mishu Sharma, Christopher Reggi, Mandy Yu, Travis R Stoub, Michael A Stein
The success of epilepsy surgery is highly dependent on correctly identifying the entire epileptogenic region. Current state-of-the-art for localizing the extent of surgically amenable areas involves combining high resolution three-dimensional magnetic resonance imaging (MRI) with electroencephalography (EEG) and magnetoencephalography (MEG) source modeling of interictal epileptiform activity. Coupling these techniques with newer quantitative structural MRI techniques, such as cortical thickness measurements, however, may improve the extent to which the abnormal epileptogenic region can be visualized...
January 2017: Neurotherapeutics: the Journal of the American Society for Experimental NeuroTherapeutics
Seung-Hyun Jin, Chun Kee Chung
The main aim of the present study was to evaluate whether resting-state functional connectivity of magnetoencephalography (MEG) signals can differentiate patients with mesial temporal lobe epilepsy (MTLE) from healthy controls (HC) and can differentiate between right and left MTLE as a diagnostic biomarker. To this end, a support vector machine (SVM) method among various machine learning algorithms was employed. We compared resting-state functional networks between 46 MTLE (right MTLE=23; left MTLE=23) patients with histologically proven HS who were free of seizure after surgery, and 46 HC...
November 23, 2016: Epilepsy Research
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