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Hao G, Yan H, Wang X, Gao R, Xue Y, Zhang X, Ni D, Shu W, Qiao L, He L, Yu T. The role of magnetoencephalography in preoperative localization and postoperative outcome prediction in patients with posterior cortical epilepsy. CNS Neurosci Ther 2024; 30:e14602. [PMID: 38332652 PMCID: PMC10853654 DOI: 10.1111/cns.14602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/16/2023] [Accepted: 01/01/2024] [Indexed: 02/10/2024] Open
Abstract
OBJECTIVE We aimed to explore the value of magnetoencephalography in the presurgical evaluation of patients with posterior cortex epilepsy. METHODS A total of 39 patients with posterior cortex epilepsy (PCE) and intact magnetoencephalography (MEG) images were reviewed from August 2019 to July 2022. MEG dipole clusters were classified into single clusters, multiple clusters, and scatter dipoles based on tightness criteria. The association of the surgical outcome with MEG dipole classifications was evaluated using Fisher's exact tests. RESULTS Among the 39 cases, there were 24 cases of single clusters (61.5%), nine cases of multiple clusters (23.1%), and six cases of scattered dipoles (15.4%). Patients with single dipole clusters were more likely to become seizure-free. Among single dipole cluster cases (n = 24), complete MEG dipole resection yielded a more favorable surgical outcome than incomplete resection (83.3% vs. 16.7%, p = 0.007). Patients with concordant MRI and MEG findings achieved a significantly more favorable surgical outcome than discordant patients (66.7% vs. 33.3%, p = 0.044), especially in single dipole cluster patients (87.5% vs. 25.0%, p = 0.005). SIGNIFICANCE MEG can provide additional valuable information regarding surgical candidate selection, epileptogenic zone localization, electrode implantation schedule, and final surgical planning in patients with posterior cortex epilepsy.
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Affiliation(s)
- Guiliang Hao
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Hao Yan
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Xueyuan Wang
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Runshi Gao
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Yansong Xue
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Xiating Zhang
- Department of Neurology, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Duanyu Ni
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Wei Shu
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Liang Qiao
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Liu He
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Tao Yu
- Department of Functional Neurosurgery, Beijing Institute of Functional Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
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Geller AS, Teale P, Kronberg E, Ebersole JS. Magnetoencephalography for Epilepsy Presurgical Evaluation. Curr Neurol Neurosci Rep 2024; 24:35-46. [PMID: 38148387 DOI: 10.1007/s11910-023-01328-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2023] [Indexed: 12/28/2023]
Abstract
PURPOSE OF THE REVIEW Magnetoencephalography (MEG) is a functional neuroimaging technique that records neurophysiology data with millisecond temporal resolution and localizes it with subcentimeter accuracy. Its capability to provide high resolution in both of these domains makes it a powerful tool both in basic neuroscience as well as clinical applications. In neurology, it has proven useful in its ability to record and localize epileptiform activity. Epilepsy workup typically begins with scalp electroencephalography (EEG), but in many situations, EEG-based localization of the epileptogenic zone is inadequate. The complementary sensitivity of MEG can be crucial in such cases, and MEG has been adopted at many centers as an important resource in building a surgical hypothesis. In this paper, we review recent work evaluating the extent of MEG influence of presurgical evaluations, novel analyses of MEG data employed in surgical workup, and new MEG instrumentation that will likely affect the field of clinical MEG. RECENT FINDINGS MEG consistently contributes to presurgical evaluation and these contributions often change the plan for epilepsy surgery. Extensive work has been done to develop new analytic methods for localizing the source of epileptiform activity with MEG. Systems using optically pumped magnetometry (OPM) have been successfully deployed to record and localize epileptiform activity. MEG remains an important noninvasive tool for epilepsy presurgical evaluation. Continued improvements in analytic methodology will likely increase the diagnostic yield of the test. Novel instrumentation with OPM may contribute to this as well, and may increase accessibility of MEG by decreasing cost.
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Affiliation(s)
- Aaron S Geller
- Department of Neurology, CU Anschutz Medical School, Aurora, CO, USA.
| | - Peter Teale
- Department of Neurology, CU Anschutz Medical School, Aurora, CO, USA
| | - Eugene Kronberg
- Department of Neurology, CU Anschutz Medical School, Aurora, CO, USA
| | - John S Ebersole
- Department of Neurology, Atlantic Neuroscience Institute, Summit, NJ, USA
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Withers CP, Diamond JM, Yang B, Snyder K, Abdollahi S, Sarlls J, Chapeton JI, Theodore WH, Zaghloul KA, Inati SK. Identifying sources of human interictal discharges with travelling wave and white matter propagation. Brain 2023; 146:5168-5181. [PMID: 37527460 PMCID: PMC11046055 DOI: 10.1093/brain/awad259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/30/2023] [Accepted: 07/19/2023] [Indexed: 08/03/2023] Open
Abstract
Interictal epileptiform discharges have been shown to propagate from focal epileptogenic sources as travelling waves or through more rapid white matter conduction. We hypothesize that both modes of propagation are necessary to explain interictal discharge timing delays. We propose a method that, for the first time, incorporates both propagation modes to identify unique potential sources of interictal activity. We retrospectively analysed 38 focal epilepsy patients who underwent intracranial EEG recordings and diffusion-weighted imaging for epilepsy surgery evaluation. Interictal discharges were detected and localized to the most likely source based on relative delays in time of arrival across electrodes, incorporating travelling waves and white matter propagation. We assessed the influence of white matter propagation on distance of spread, timing and clinical interpretation of interictal activity. To evaluate accuracy, we compared our source localization results to earliest spiking regions to predict seizure outcomes. White matter propagation helps to explain the timing delays observed in interictal discharge sequences, underlying rapid and distant propagation. Sources identified based on differences in time of receipt of interictal discharges are often distinct from the leading electrode location. Receipt of activity propagating rapidly via white matter can occur earlier than more local activity propagating via slower cortical travelling waves. In our cohort, our source localization approach was more accurate in predicting seizure outcomes than the leading electrode location. Inclusion of white matter in addition to travelling wave propagation in our model of discharge spread did not improve overall accuracy but allowed for identification of unique and at times distant potential sources of activity, particularly in patients with persistent postoperative seizures. Since distant white matter propagation can occur more rapidly than local travelling wave propagation, combined modes of propagation within an interictal discharge sequence can decouple the commonly assumed relationship between spike timing and distance from the source. Our findings thus highlight the clinical importance of recognizing the presence of dual modes of propagation during interictal discharges, as this may be a cause of clinical mislocalization.
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Affiliation(s)
- C Price Withers
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joshua M Diamond
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Braden Yang
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kathryn Snyder
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shervin Abdollahi
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joelle Sarlls
- NIH MRI Research Facility, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Julio I Chapeton
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - William H Theodore
- Clinical Epilepsy Section, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kareem A Zaghloul
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sara K Inati
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
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Sindhu DM, Mundlamuri RC, Goutham B, Narayanan M, Raghavendra K, Asranna A, Vishwanathan LG, Kulanthaivelu K, Saini J, Mangalore S, Bharath RD, Sadashiva N, Mahadevan A, Jamuna R, Arivazhagan A, Rao MB, Sinha S. Role of magnetoencephalography in predicting the epileptogenic zone and post-operative seizure outcome - A retrospective study. Seizure 2023; 113:41-47. [PMID: 37976800 DOI: 10.1016/j.seizure.2023.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 11/07/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023] Open
Abstract
PURPOSE Study assessed the role of MSI in predicting the post-operative seizure outcome. METHODS This retrospective study included patients who underwent MEG and epilepsy surgery and had a minimum 6 months of postoperative follow-up. Concordance of MEG cluster with post-surgical resection cavity was classified as follows Class I) Concordant and region-specific, Class II) Concordant and region non-specific, Class III) Concordant lateralization only and Class IV) Discordant lateralization. The relationship between MSI concordance and post-operative seizure outcome was assessed. RESULTS A total of 183 patients (M: F = 109:74) were included. The mean age at onset of seizures: 8.0 ± 6.4 years. The dipoles were frequent in 123(67.2 %). The primary cluster orientation was regular in 59 (32.2 %) and mixed in 124 (67.8 %) patients. Concordance between MEG and resection cavity: Class I - 124 (67.8 %), class II- 30 (16.4 %), class III- 23 (12.6 %), and class IV- 6 (3.3 %). The post-surgically mean duration of follow-up was 19.52 ± 11.27 months. At 6-month follow-up period, 144 (78.7 %) patients had complete seizure freedom out of which 106 (73.6 %) had class I concordance. Concordance of MEG with resection cavity was associated with a good outcome at 6 months (p = 0.001), 1 year (p = 0.001), 2 years (p = 0.0005) and 5 years (p = 0.04). MEG cluster characteristics had no association with seizure outcome except the strength of the cluster and outcome at 3 years (p = 0.02) follow-up. CONCLUSION The study supports that the complete resection of the MEG cluster had high chance of seizure-freedom and can be used as a complementary noninvasive presurgical evaluation tool.
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Affiliation(s)
| | | | - Bhargava Goutham
- MEG research Lab, NIMHANS, Hosur Road, Bangalore, India; Department of Neurology, NIMHANS, Hosur road, Bangalore, India
| | - Mariyappa Narayanan
- MEG research Lab, NIMHANS, Hosur Road, Bangalore, India; Department of Neurology, NIMHANS, Hosur road, Bangalore, India
| | | | - Ajay Asranna
- Department of Neurology, NIMHANS, Hosur road, Bangalore, India
| | | | - Karthik Kulanthaivelu
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur road, Bangalore, India
| | - Jitender Saini
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur road, Bangalore, India
| | - Sandhya Mangalore
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur road, Bangalore, India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur road, Bangalore, India
| | | | - Anita Mahadevan
- Department of Neuropathology, NIMHANS, Hosur road, Bangalore, India
| | - Rajeswaran Jamuna
- Department of Clinical Psychology, NIMHANS, Hosur road, Bangalore, India
| | | | | | - Sanjib Sinha
- MEG research Lab, NIMHANS, Hosur Road, Bangalore, India; Department of Neurology, NIMHANS, Hosur road, Bangalore, India.
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Chikara RK, Jahromi S, Tamilia E, Madsen JR, Stufflebeam SM, Pearl PL, Papadelis C. Electromagnetic source imaging predicts surgical outcome in children with focal cortical dysplasia. Clin Neurophysiol 2023; 153:88-101. [PMID: 37473485 PMCID: PMC10528204 DOI: 10.1016/j.clinph.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 05/25/2023] [Accepted: 06/15/2023] [Indexed: 07/22/2023]
Abstract
OBJECTIVE To evaluate the diagnostic accuracy of electromagnetic source imaging (EMSI) in localizing spikes and predict surgical outcome in children with drug resistant epilepsy (DRE) due to focal cortical dysplasia (FCD). METHODS We retrospectively analyzed magnetoencephalography (MEG) and high-density (HD-EEG) data from 23 children with FCD-associated DRE who underwent intracranial EEG and surgery. We localized spikes using equivalent current dipole (ECD) fitting, dipole clustering, and dynamical statistical parametric mapping (dSPM) on EMSI, electric source imaging (ESI), and magnetic source imaging (MSI). We calculated the distance from the seizure onset zone (DSOZ) and resection (DRES). We estimated receiver operating characteristic (ROC) curves with Youden's index (J) to predict outcome. RESULTS EMSI presented shorter DSOZ (15.18 ± 9.06 mm) and DRES (8.56 ± 6.24 mm) compared to ESI (DSOZ: 25.04 ± 16.20 mm, p < 0.009; DRES: 18.88 ± 17.30 mm, p < 0.03) and MSI (DSOZ: 23.37 ± 8.98 mm, p < 0.03; DRES: 15.51 ± 10.11 mm, p < 0.02) for clustering in patients with good outcome. Clustering showed shorter DSOZ and DRES compared to ECD fitting and dSPM (p < 0.05). EMSI had higher performance as outcome predictor (J = 70.63%) compared to ESI (J = 41.27%) and MSI (J = 33.33%) for clustering. CONCLUSIONS EMSI provides superior localization and improved predictive performance than individual modalities. SIGNIFICANCE EMSI can help the surgical planning and facilitate the localization of epileptogenic foci.
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Affiliation(s)
- Rupesh Kumar Chikara
- Jane and John Justin Institute for Mind Health, Neuroscience Research, Cook Children's Health Care System, Fort Worth, TX, USA; Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA
| | - Saeed Jahromi
- Jane and John Justin Institute for Mind Health, Neuroscience Research, Cook Children's Health Care System, Fort Worth, TX, USA; Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA
| | - Eleonora Tamilia
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Joseph R Madsen
- Division of Epilepsy Surgery, Department of Neurosurgery, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Steve M Stufflebeam
- Athinoula Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Phillip L Pearl
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Christos Papadelis
- Jane and John Justin Institute for Mind Health, Neuroscience Research, Cook Children's Health Care System, Fort Worth, TX, USA; Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA; School of Medicine, Texas Christian University, Fort Worth, TX, USA.
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Katagiri M, Wang ZI, Hirfanoglu T, Aldosari MM, Aung T, Wang S, Kobayashi K, Bulacio J, Bingaman W, Najm IM, Alexopoulos AV, Burgess RC. Clinical significance of ictal magnetoencephalography in patients undergoing epilepsy surgery. Clin Neurophysiol 2023; 145:108-118. [PMID: 36443170 DOI: 10.1016/j.clinph.2022.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/30/2022] [Accepted: 10/11/2022] [Indexed: 11/03/2022]
Abstract
OBJECTIVE The significance of ictal magnetoencephalography (MEG) is not well appreciated. We evaluated the relationships between ictal MEG, MRI, intracranial electroencephalography (ICEEG), surgery and postoperative seizure outcome. METHODS A total of 45 patients (46 cases) with ictal MEG who underwent epilepsy surgery was included. We examined the localization of each modality, surgical resection area and seizure freedom after surgery. RESULTS Twenty-one (45.7%) out of 46 cases were seizure-free at more than 6 months follow-up. Median duration of postoperative follow-up was 16.5 months. The patients in whom ictal, interictal single equivalent current dipole (SECD) and MRI lesion localization were completely included in the resection had a higher chance of being seizure-free significantly (p < 0.05). Concordance between ictal and interictal SECD localizations was significantly associated with seizure-freedom. Concordance between MRI lesion and ictal SECD, concordance between ictal ICEEG and ictal and interictal SECD, as well as concordance between ictal ICEEG and MRI lesion were significantly associated with seizure freedom. CONCLUSIONS Ictal MEG can contribute useful information for delineating the resection area in epilepsy surgery. SIGNIFICANCE Resection should include ictal, interictal SECDs and MRI lesion localization, when feasible. Concordant ictal and interictal SECDs on MEG can be a favorable predictor of seizure freedom.
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Affiliation(s)
- Masaya Katagiri
- Epilepsy Center, Cleveland Clinic, OH, USA; Department of Neurosurgery, Graduate School of Medicine, Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | | | - Tugba Hirfanoglu
- Epilepsy Center, Cleveland Clinic, OH, USA; Department of Pediatric Neurology, Gazi University School of Medicine, Ankara, Turkey
| | - Mubarak M Aldosari
- Epilepsy Center, Cleveland Clinic, OH, USA; Epilepsy Program, National Neurosciences Institute, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Thandar Aung
- Epilepsy Center, Cleveland Clinic, OH, USA; Comprehensive Epilepsy Center, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Shan Wang
- Epilepsy Center, Cleveland Clinic, OH, USA; Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Katsuya Kobayashi
- Epilepsy Center, Cleveland Clinic, OH, USA; Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, Japan
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Coan AC, Cavalcante CM, Burgess RC. Utility of Functional MRI and Magnetoencephalography in the Diagnosis of Infantile Spasms and Hypsarrhythmia. J Clin Neurophysiol 2022; 39:544-551. [PMID: 35323155 DOI: 10.1097/wnp.0000000000000501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SUMMARY Neuroimaging and neurophysiology techniques can add a significant contribution to the comprehension of infantile spasms (IS) and hypsarrhythmia. Functional MRI and magnetoencephalography (MEG) are two noninvasive tools that can be used in young children with IS. In the past two decades, interesting data about IS have emerged from functional MRI and MEG studies. Regarding their clinical utility, MEG has supported the concept that epileptic spasms can have a focal origin. Moreover, MEG might contribute to the localization of the epileptogenic zone in children with IS under investigation for epilepsy surgery. Functional MRI data have contributed to improve the knowledge about the physiopathology of IS and hypsarrhythmia. It has demonstrated abnormal brainstem involvement during the high-amplitude slow waves of hypsarrhythmia and cortical involvement during the epileptiform discharges. Since the feasibility of these techniques has been demonstrated in infants, it is possible that, in the future, larger functional MRI and MEG studies might contribute to the treatment and the definition of the long-term prognosis of children with IS.
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Affiliation(s)
- Ana Carolina Coan
- Department of Neurology, Child Neurology Unit, University of Campinas (UNICAMP), Campinas, SP, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), at UNICAMP, Campinas, SP, Brazil; and
| | - Charlington M Cavalcante
- Department of Neurology, Child Neurology Unit, University of Campinas (UNICAMP), Campinas, SP, Brazil
- Brazilian Institute of Neuroscience and Neurotechnology (BRAINN), at UNICAMP, Campinas, SP, Brazil; and
| | - Richard C Burgess
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
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Anand A, Magnotti JF, Smith DN, Gadot R, Najera RA, Hegazy MIR, Gavvala JR, Shofty B, Sheth SA. Predictive value of magnetoencephalography in guiding the intracranial implant strategy for intractable epilepsy. J Neurosurg 2022; 137:1237-1247. [PMID: 35303696 DOI: 10.3171/2022.1.jns212943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 01/31/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Magnetoencephalography (MEG) is a useful component of the presurgical evaluation of patients with epilepsy. Due to its high spatiotemporal resolution, MEG often provides additional information to the clinician when forming hypotheses about the epileptogenic zone (EZ). Because of the increasing utilization of stereo-electroencephalography (sEEG), MEG clusters are used to guide sEEG electrode targeting with increasing frequency. However, there are no predefined features of an MEG cluster that predict ictal activity. This study aims to determine which MEG cluster characteristics are predictive of the EZ. METHODS The authors retrospectively analyzed all patients who had an MEG study (2017-2021) and underwent subsequent sEEG evaluation. MEG dipoles and sEEG electrodes were reconstructed in the same coordinate space to calculate overlap among individual contacts on electrodes and MEG clusters. MEG cluster features-including number of dipoles, proximity, angle, density, magnitude, confidence parameters, and brain region-were used to predict ictal activity in sEEG. Logistic regression was used to identify important cluster features and to train a binary classifier to predict ictal activity. RESULTS Across 40 included patients, 196 electrodes (42.2%) sampled MEG clusters. Electrodes that sampled MEG clusters had higher rates of ictal and interictal activity than those that did not sample MEG clusters (ictal 68.4% vs 39.8%, p < 0.001; interictal 71.9% vs 44.6%, p < 0.001). Logistic regression revealed that the number of dipoles (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.04-1.14, t = 3.43) and confidence volume (OR 0.02, 95% CI 0.00-0.86, t = -2.032) were predictive of ictal activity. This model was predictive of ictal activity with 77.3% accuracy (sensitivity = 80%, specificity = 74%, C-statistic = 0.81). Using only the number of dipoles had a predictive accuracy of 75%, whereas a threshold between 14 and 17 dipoles in a cluster detected ictal activity with 75.9%-85.2% sensitivity. CONCLUSIONS MEG clusters with approximately 14 or more dipoles are strong predictors of ictal activity and may be useful in the preoperative planning of sEEG implantation.
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Affiliation(s)
| | - John F Magnotti
- 2Department of Neurosurgery, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | | | | | | | | | - Jay R Gavvala
- 3Neurology, Baylor College of Medicine, Houston, Texas; and
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Fujiwara H, Kadis DS, Greiner HM, Holland KD, Arya R, Aungaroon G, Fong SL, Arthur TM, Kremer KM, Lin N, Liu W, Mangano DO FT, Skoch J, Horn PS, Tenney JR. Clinical validation of magnetoencephalography network analysis for presurgical epilepsy evaluation. Clin Neurophysiol 2022; 142:199-208. [DOI: 10.1016/j.clinph.2022.07.506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 06/29/2022] [Accepted: 07/20/2022] [Indexed: 11/27/2022]
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Zhang C, Liu W, Zhang J, Zhang X, Huang P, Sun B, Zhan S, Cao C. Utility of magnetoencephalography combined with stereo-electroencephalography in resective epilepsy surgery: a 2-year follow-up. Seizure 2022; 97:94-101. [DOI: 10.1016/j.seizure.2022.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 11/25/2022] Open
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Laohathai C, Ebersole JS, Mosher JC, Bagić AI, Sumida A, Von Allmen G, Funke ME. Practical Fundamentals of Clinical MEG Interpretation in Epilepsy. Front Neurol 2021; 12:722986. [PMID: 34721261 PMCID: PMC8551575 DOI: 10.3389/fneur.2021.722986] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 09/06/2021] [Indexed: 11/29/2022] Open
Abstract
Magnetoencephalography (MEG) is a neurophysiologic test that offers a functional localization of epileptic sources in patients considered for epilepsy surgery. The understanding of clinical MEG concepts, and the interpretation of these clinical studies, are very involving processes that demand both clinical and procedural expertise. One of the major obstacles in acquiring necessary proficiency is the scarcity of fundamental clinical literature. To fill this knowledge gap, this review aims to explain the basic practical concepts of clinical MEG relevant to epilepsy with an emphasis on single equivalent dipole (sECD), which is one the most clinically validated and ubiquitously used source localization method, and illustrate and explain the regional topology and source dynamics relevant for clinical interpretation of MEG-EEG.
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Affiliation(s)
- Christopher Laohathai
- Division of Child Neurology, Department of Pediatrics, McGovern Medical School at UTHealth, Houston, TX, United States
- Department of Neurology, Saint Louis University, Saint Louis, MO, United States
| | - John S. Ebersole
- Northeast Regional Epilepsy Group, Atlantic Health Neuroscience Institute, Summit, NJ, United States
| | - John C. Mosher
- Department of Neurology, McGovern Medical School at UTHealth, Houston, TX, United States
| | - Anto I. Bagić
- University of Pittsburgh Comprehensive Epilepsy Center (UPCEC), Department of Neurology, University of Pittsburgh Medical Center, Pittsburg, PA, United States
| | - Ai Sumida
- Department of Neurology, McGovern Medical School at UTHealth, Houston, TX, United States
| | - Gretchen Von Allmen
- Division of Child Neurology, Department of Pediatrics, McGovern Medical School at UTHealth, Houston, TX, United States
| | - Michael E. Funke
- Division of Child Neurology, Department of Pediatrics, McGovern Medical School at UTHealth, Houston, TX, United States
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Xu N, Shan W, Qi J, Wu J, Wang Q. Presurgical Evaluation of Epilepsy Using Resting-State MEG Functional Connectivity. Front Hum Neurosci 2021; 15:649074. [PMID: 34276321 PMCID: PMC8283278 DOI: 10.3389/fnhum.2021.649074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 06/07/2021] [Indexed: 11/21/2022] Open
Abstract
Epilepsy is caused by abnormal electrical discharges (clinically identified by electrophysiological recording) in a specific part of the brain [originating in only one part of the brain, namely, the epileptogenic zone (EZ)]. Epilepsy is now defined as an archetypical hyperexcited neural network disorder. It can be investigated through the network analysis of interictal discharges, ictal discharges, and resting-state functional connectivity. Currently, there is an increasing interest in embedding resting-state connectivity analysis into the preoperative evaluation of epilepsy. Among the various neuroimaging technologies employed to achieve brain functional networks, magnetoencephalography (MEG) with the excellent temporal resolution is an ideal tool for estimating the resting-state connectivity between brain regions, which can reveal network abnormalities in epilepsy. What value does MEG resting-state functional connectivity offer for epileptic presurgical evaluation? Regarding this topic, this paper introduced the origin of MEG and the workflow of constructing source-space functional connectivity based on MEG signals. Resting-state functional connectivity abnormalities correlate with epileptogenic networks, which are defined by the brain regions involved in the production and propagation of epileptic activities. This paper reviewed the evidence of altered epileptic connectivity based on low- or high-frequency oscillations (HFOs) and the evidence of the advantage of using simultaneous MEG and intracranial electroencephalography (iEEG) recordings. More importantly, this review highlighted that MEG-based resting-state functional connectivity has the potential to predict postsurgical outcomes. In conclusion, resting-state MEG functional connectivity has made a substantial progress toward serving as a candidate biomarker included in epileptic presurgical evaluations.
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Affiliation(s)
- Na Xu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Wei Shan
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jing Qi
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jianping Wu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- National Clinical Research Center for Neurological Diseases, Beijing, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Qun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
- National Clinical Research Center for Neurological Diseases, Beijing, China
- Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Neuromodulation, Beijing, China
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Gautham B, Abdulhak A, Mundlamuri RC, Narayanan M, Jayabal V, Kenchaiah R, Asranna A, Dawn BR, Jitender S, Nagaraj C, Mangalore S, Karthik K, Sadashiva N, Mahadevan A, Rajeswaran J, Kumar K, Arivazhagan A, Rao MB, Sinha S. Magnetic source imaging in presurgical evaluation of paediatric focal drug-resistant epilepsy and its predictive value of surgical outcome in lesional cases: A single-centre experience from South India. Seizure 2021; 91:22-28. [PMID: 34058605 DOI: 10.1016/j.seizure.2021.05.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 05/14/2021] [Accepted: 05/16/2021] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE This study aims to evaluate the utility of magnetoencephalography in presurgical planning and in predicting post-surgical seizure outcome. METHODS This study included a cohort of 231 children (1-18 years) with focal drug-resistant epilepsy who underwent MEG as a part of their presurgical workup. Characteristics of MEG observations were described in all children. The concordance and agreement of Magnetic Source Imaging (MSI) of interictal discharges (IED) was estimated with either of the 3 subgroups - MRI lesion; presumed epileptogenic zone (EZ); or resection cavity. In operated children group, MEG dipole characteristics between good and poor outcome groups were assessed. RESULTS A total of 153 cases (66.2%) showed frequent IEDs (60 spikes/60 min). Of the 173 cases where MSI showed clusters (74.9%), 151 had lesions and 22 were non-lesional. amongst patients with lesional epilepsy and MEG clusters, class I concordance (MEG localization either completely included or overlapped at least 60% with the MRI lesion) was seen in 60.92% with a Cohen's kappa of 0.608. In non-lesional epilepsy, class I concordance of MEG with presumed EZ was found in (81.81%) with an agreement of 0.317. Fifty-three children underwent surgery of whom 39 (73.58%) showed a good outcome (Engel I). In operated children, concordance between MEG focus and resection cavity was observed in 23 (58.97%) with good outcome and in 12 (86.72%) with poor outcome with no significant difference (p>0.05). However, MEG cluster regular organization and clusterectomy are associated with good seizure outcome postoperatively (p< 0.05). Presence of scatters were associated with poor outcome (p<0.05) in children with focal cortical dysplasia. CONCLUSIONS MEG provides useful information that can serve as a biomarker for prognosticating the surgical outcome in paediatric epilepsy. Cluster removal and regular cluster organization shows predictive power in post-surgical prognostication in children and the presence of scatters predicts poor outcome in children with focal cortical dysplasia.
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Affiliation(s)
- Bhargava Gautham
- MEG research Centre, NIMHANS, Hosur Road, Bangalore, India; Department of Neurology, NIMHANS, Hosur Road, Bangalore, India
| | - Asheeb Abdulhak
- Department of Neurology, NIMHANS, Hosur Road, Bangalore, India
| | | | - Mariyappa Narayanan
- MEG research Centre, NIMHANS, Hosur Road, Bangalore, India; Department of Neurology, NIMHANS, Hosur Road, Bangalore, India
| | | | | | - Ajay Asranna
- Department of Neurology, NIMHANS, Hosur Road, Bangalore, India
| | - Bharath Rose Dawn
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur Road, Bangalore, India
| | - Saini Jitender
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur Road, Bangalore, India
| | - Chandana Nagaraj
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur Road, Bangalore, India
| | - Sandhya Mangalore
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur Road, Bangalore, India
| | - Kulanthaivelu Karthik
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Hosur Road, Bangalore, India
| | | | - Anita Mahadevan
- Department of Neuropathology, NIMHANS, Hosur Road, Bangalore, India
| | - Jamuna Rajeswaran
- Department of Clinical Psychology, NIMHANS, Hosur Road, Bangalore, India
| | - Keshav Kumar
- Department of Clinical Psychology, NIMHANS, Hosur Road, Bangalore, India
| | | | | | - Sanjib Sinha
- MEG research Centre, NIMHANS, Hosur Road, Bangalore, India; Department of Neurology, NIMHANS, Hosur Road, Bangalore, India.
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14
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Shirozu H, Hashizume A, Masuda H, Kakita A, Otsubo H, Kameyama S. Surgical strategy for focal cortical dysplasia based on the analysis of the spike onset and peak zones on magnetoencephalography. J Neurosurg 2020; 133:1850-1862. [PMID: 31585422 DOI: 10.3171/2019.6.jns191058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/24/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The aim of this study was to elucidate the surgical strategy for focal cortical dysplasia (FCD) based on the interictal analysis on magnetoencephalography (MEG). For this purpose, the correlation between the spike onset zone (Sp-OZ) and the spike peak zone (Sp-PZ) on MEG was evaluated to clarify the differences in the Sp-OZ and its correlation with Sp-PZ in FCD subtypes to develop an appropriate surgical strategy. METHODS Forty-one FCD patients (n = 17 type I, n = 13 type IIa, and n = 11 type IIb) were included. The Sp-OZ was identified by the summation of gradient magnetic-field topography (GMFT) magnitudes at interictal MEG spike onset, and Sp-PZ was defined as the distribution of the equivalent current dipole (ECD) at spike peak. Correlations between Sp-OZ and Sp-PZ distributions were evaluated and compared with clinical factors and seizure outcomes retrospectively. RESULTS Good seizure outcomes (Engel class I) were obtained significantly more often in patients with FCD type IIb (10/11, 90.9%) than those with type IIa (4/13, 30.8%; p = 0.003) and type I (6/17, 35.3%; p = 0.004). The Sp-OZ was significantly smaller (1 or 2 gyri) in type IIb (10, 90.9%) than in type IIa (4, 30.8%; p = 0.003) or type I (9, 53.0%; p = 0.036). Concordant correlations between the Sp-OZ and Sp-PZ were significantly more frequent in type IIb (7, 63.6%) than in type IIa (1, 7.7%; p = 0.015) or type I (1, 5.8%; p = 0.004). Complete resection of the Sp-OZ achieved significantly better seizure outcomes (Engel class I: 9/10, 90%) than incomplete resection (11/31, 35.5%) (p = 0.003). In contrast, complete resection of the Sp-PZ showed no significant difference in good seizure outcomes (9/13, 69.2%) compared with incomplete resection (11/28, 39.3%). CONCLUSIONS The Sp-OZ detected by MEG using GMFT and its correlation with Sp-PZ were related to FCD subtypes. A discordant distribution between Sp-OZ and Sp-PZ in type I and IIa FCD indicated an extensive epileptogenic zone and a complex epileptic network. Type IIb showed a restricted epileptogenic zone with the smaller Sp-OZ and concordance between Sp-OZ and Sp-PZ. Complete resection of the Sp-OZ provided significantly better seizure outcomes than incomplete resection. Complete resection of the Sp-PZ was not related to seizure outcomes. There was a definite difference in the epileptogenic zone among FCD subtypes; hence, an individual surgical strategy taking into account the correlation between the Sp-OZ and Sp-PZ should be considered.
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Affiliation(s)
- Hiroshi Shirozu
- 1Department of Functional Neurosurgery, National Hospital Organization, Nishiniigata Chuo Hospital, Niigata
| | - Akira Hashizume
- 2Department of Neurosurgery, Takanobashi Central Hospital, Hiroshima
| | - Hiroshi Masuda
- 1Department of Functional Neurosurgery, National Hospital Organization, Nishiniigata Chuo Hospital, Niigata
| | - Akiyoshi Kakita
- 3Department of Pathology, Brain Research Institute, Niigata University, Niigata, Japan; and
| | - Hiroshi Otsubo
- 4Division of Neurology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Shigeki Kameyama
- 1Department of Functional Neurosurgery, National Hospital Organization, Nishiniigata Chuo Hospital, Niigata
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Stefan H, Rampp S. Interictal and Ictal MEG in presurgical evaluation for epilepsy surgery. ACTA EPILEPTOLOGICA 2020. [DOI: 10.1186/s42494-020-00020-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
AbstractAlthough presurgical evaluation of patients with pharamacoresistent focal epilepsies provides essential information for successful epilepsy surgery, there is still a need for further improvement. Developments of noninvasive electrophysiological recording and analysis techniques offer additional information based on interictal and ictal epileptic activities. In this review, we provide an overview on the application of ictal magnetoencephalography (MEG). The results of a literature research for published interictal/ictal MEG findings and experiences with own cases are demonstrated and discussed. Ictal MEG may provide added value in comparison to interictal recordings. The results may be more focal and closer to the invasively determined seizure onset zone. In some patients without clear interictal findings, ictal MEG could provide correct localization. Novel recording and analysis techniques facilitate ictal recordings. However, extended recording durations, movement and artifacts still represent practical limitations. Ictal MEG may provide added value regarding the localization of the seizure onset zone but depends on the selection of patients and the application of optimal analysis techniques.
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Conrad EC, Tomlinson SB, Wong JN, Oechsel KF, Shinohara RT, Litt B, Davis KA, Marsh ED. Spatial distribution of interictal spikes fluctuates over time and localizes seizure onset. Brain 2020; 143:554-569. [PMID: 31860064 DOI: 10.1093/brain/awz386] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 10/15/2019] [Accepted: 10/25/2019] [Indexed: 12/21/2022] Open
Abstract
The location of interictal spikes is used to aid surgical planning in patients with medically refractory epilepsy; however, their spatial and temporal dynamics are poorly understood. In this study, we analysed the spatial distribution of interictal spikes over time in 20 adult and paediatric patients (12 females, mean age = 34.5 years, range = 5-58) who underwent intracranial EEG evaluation for epilepsy surgery. Interictal spikes were detected in the 24 h surrounding each seizure and spikes were clustered based on spatial location. The temporal dynamics of spike spatial distribution were calculated for each patient and the effects of sleep and seizures on these dynamics were evaluated. Finally, spike location was assessed in relation to seizure onset location. We found that spike spatial distribution fluctuated significantly over time in 14/20 patients (with a significant aggregate effect across patients, Fisher's method: P < 0.001). A median of 12 sequential hours were required to capture 80% of the variability in spike spatial distribution. Sleep and postictal state affected the spike spatial distribution in 8/20 and 4/20 patients, respectively, with a significant aggregate effect (Fisher's method: P < 0.001 for each). There was no evidence of pre-ictal change in the spike spatial distribution for any patient or in aggregate (Fisher's method: P = 0.99). The electrode with the highest spike frequency and the electrode with the largest area of downstream spike propagation both localized the seizure onset zone better than predicted by chance (Wilcoxon signed-rank test: P = 0.005 and P = 0.002, respectively). In conclusion, spikes localize seizure onset. However, temporal fluctuations in spike spatial distribution, particularly in relation to sleep and post-ictal state, can confound localization. An adequate duration of intracranial recording-ideally at least 12 sequential hours-capturing both sleep and wakefulness should be obtained to sufficiently sample the interictal network.
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Affiliation(s)
- Erin C Conrad
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Samuel B Tomlinson
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.,School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY, USA
| | - Jeremy N Wong
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kelly F Oechsel
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Russell T Shinohara
- Penn Statistics in Imaging and Visualization Center, Department of Biostatistics, Epidemiology and Informatics and Center for Biomedical Image Computing and Analytics, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian Litt
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Kathryn A Davis
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Eric D Marsh
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA.,Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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Choi JY, Wang ZI. Merging Magnetoencephalography into Epilepsy Presurgical Work-up Under the Framework of Multimodal Integration. Neuroimaging Clin N Am 2020; 30:249-259. [PMID: 32336411 DOI: 10.1016/j.nic.2020.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Multimodal image integration is the procedure that puts together imaging data from multiple sources into the same space by a computerized registration process. This procedure is relevant to patients with difficult-to-localize epilepsy undergoing presurgical evaluation, who typically have many tests performed, including MR imaging, PET, ictal single-photon emission computed tomography, magnetoencephalography (MEG), and intracranial electroencephalogram (EEG). This article describes the methodology of such integration, focusing on integration of MEG. Also discussed is the clinical value of integration of MEG, in terms of planning of intracranial EEG implantation, interpretation of intracranial EEG data, planning of final resection, and addressing surgical failures.
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Affiliation(s)
- Joon Yul Choi
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Desk S51, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Zhong Irene Wang
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Desk S51, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
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18
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Mohamed IS, Toffa DH, Robert M, Cossette P, Bérubé AA, Saint-Hilaire JM, Bouthillier A, Nguyen DK. Utility of magnetic source imaging in nonlesional focal epilepsy: a prospective study. Neurosurg Focus 2020; 48:E16. [DOI: 10.3171/2020.1.focus19877] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 01/28/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVEFor patients with nonlesional refractory focal epilepsy (NLRFE), localization of the epileptogenic zone may be more arduous than for other types of epilepsy and frequently requires information from multiple noninvasive presurgical modalities and intracranial EEG (icEEG). In this prospective, blinded study, the authors assessed the clinical added value of magnetic source imaging (MSI) in the presurgical evaluation of patients with NLRFE.METHODSThis study prospectively included 57 consecutive patients with NLRFE who were considered for epilepsy surgery. All patients underwent noninvasive presurgical evaluation and then MSI. To determine the surgical plan, discussion of the results of the presurgical evaluation was first undertaken while discussion participants were blinded to the MSI results. MSI results were then presented. MSI influence on the initial management plan was assessed.RESULTSMSI results influenced patient management in 32 patients. MSI results led to the following changes in surgical strategy in 14 patients (25%): allowing direct surgery in 6 patients through facilitating the detection of subtle cortical dysplasia in 4 patients and providing additional concordant diagnostic information to other presurgical workup in another 2 patients; rejection of surgery in 3 patients originally deemed surgical candidates; change of plan from direct surgery to icEEG in 2 patients; and allowing icEEG in 3 patients deemed not surgical candidates. MSI results led to changed electrode locations and contact numbers in another 18 patients. Epilepsy surgery was performed in 26 patients influenced by MSI results and good surgical outcome was achieved in 21 patients.CONCLUSIONSThis prospective, blinded study showed that information provided by MSI allows more informed icEEG planning and surgical outcome in a significant percentage of patients with NLRFE and should be included in the presurgical workup in those patients.
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Affiliation(s)
- Ismail Sidky Mohamed
- Departments of 4Pediatrics, Division of Neurology, and
- 5Neurology, University of Alabama, Birmingham, Alabama
| | | | - Manon Robert
- 3Neuropsychology and Cognition Research Center, Psychology Department, Université de Montréal, Quebec, Canada; and
| | | | | | | | - Alain Bouthillier
- 2Neurosurgery, Montreal University Health Center, Université de Montréal, and
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Mouthaan BE, Rados M, Boon P, Carrette E, Diehl B, Jung J, Kimiskidis V, Kobulashvili T, Kuchukhidze G, Larsson PG, Leitinger M, Ryvlin P, Rugg-Gunn F, Seeck M, Vulliémoz S, Huiskamp G, Leijten FSS, Van Eijsden P, Trinka E, Braun KPJ. Diagnostic accuracy of interictal source imaging in presurgical epilepsy evaluation: A systematic review from the E-PILEPSY consortium. Clin Neurophysiol 2019; 130:845-855. [PMID: 30824202 DOI: 10.1016/j.clinph.2018.12.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 11/16/2018] [Accepted: 12/20/2018] [Indexed: 10/27/2022]
Abstract
OBJECTIVE Interictal high resolution (HR-) electric source imaging (ESI) and magnetic source imaging (MSI) are non-invasive tools to aid epileptogenic zone localization in epilepsy surgery candidates. We carried out a systematic review on the diagnostic accuracy and quality of evidence of these modalities. METHODS Embase, Pubmed and the Cochrane database were searched on 13 February 2017. Diagnostic accuracy studies taking post-surgical seizure outcome as reference standard were selected. Quality appraisal was based on the QUADAS-2 framework. RESULTS Eleven studies were included: eight MSI (n = 267), three HR-ESI (n = 127) studies. None was free from bias. This mostly involved: selection of operated patients only, interference of source imaging with surgical decision, and exclusion of indeterminate results. Summary sensitivity and specificity estimates were 82% (95% CI: 75-88%) and 53% (95% CI: 37-68%) for overall source imaging, with no statistical difference between MSI and HR-ESI. Specificity is higher when partially concordant results were included as non-concordant (p < 0.05). Inclusion of indeterminate test results as non-concordant lowered sensitivity (p < 0.05). CONCLUSIONS Source imaging has a relatively high sensitivity but low specificity for identification of the epileptogenic zone. SIGNIFICANCE We need higher quality studies allowing unbiased test evaluation to determine the added value and diagnostic accuracy of source imaging in the presurgical workup of refractory focal epilepsy.
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Affiliation(s)
- Brian E Mouthaan
- Department of (Child) Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85090, 3508 AB Utrecht, The Netherlands
| | - Matea Rados
- Department of (Child) Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85090, 3508 AB Utrecht, The Netherlands
| | - Paul Boon
- Reference Center for Refractory Epilepsy, Department of Neurology, Ghent University Hospital, Belgium
| | - Evelien Carrette
- Reference Center for Refractory Epilepsy, Department of Neurology, Ghent University Hospital, Belgium
| | - Beate Diehl
- National Hospital for Neurology and Neurosurgery, University College London Hospitals, London, United Kingdom; Department of Clinical and Experimental Epilepsy, University College, London, UK
| | - Julien Jung
- Department of Functional Neurology and Epileptology, Institute of Epilepsies (IDEE), Hospices Civils de Lyon, Lyon, France
| | - Vasilios Kimiskidis
- Laboratory of Clinical Neurophysiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - Teia Kobulashvili
- Department of Neurology, Christian-Doppler University Hospital, Paracelsus Medical University, and Centre for Cognitive Neuroscience, Salzburg, Austria
| | - Giorgi Kuchukhidze
- Department of Neurology, Christian-Doppler University Hospital, Paracelsus Medical University, and Centre for Cognitive Neuroscience, Salzburg, Austria
| | - Pål G Larsson
- Department of Neurosurgery, Clinic of Surgery and Neuroscience, Oslo University Hospital, Norway
| | - Markus Leitinger
- Department of Neurology, Christian-Doppler University Hospital, Paracelsus Medical University, and Centre for Cognitive Neuroscience, Salzburg, Austria
| | - Philippe Ryvlin
- Department of Clinical Neurosciences, Lausanne University Hospital, Lausanne, Switzerland
| | - Fergus Rugg-Gunn
- National Hospital for Neurology and Neurosurgery, University College London Hospitals, London, United Kingdom; Department of Clinical and Experimental Epilepsy, University College, London, UK
| | - Margitta Seeck
- EEG and Epilepsy Unit, Department of Clinical Neurosciences, University Hospital of Geneva, Switzerland
| | - Serge Vulliémoz
- EEG and Epilepsy Unit, Department of Clinical Neurosciences, University Hospital of Geneva, Switzerland
| | - Geertjan Huiskamp
- Department of (Child) Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85090, 3508 AB Utrecht, The Netherlands
| | - Frans S S Leijten
- Department of (Child) Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85090, 3508 AB Utrecht, The Netherlands
| | - Pieter Van Eijsden
- Department of (Child) Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85090, 3508 AB Utrecht, The Netherlands
| | - Eugen Trinka
- Department of Neurology, Christian-Doppler University Hospital, Paracelsus Medical University, and Centre for Cognitive Neuroscience, Salzburg, Austria; Institute of Public Health, Medical Decision Making and HTA, UMIT, Private University for Health Sciences, Medical Informatics and Technology, Hall in Tyrol, Austria
| | - Kees P J Braun
- Department of (Child) Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, PO Box 85090, 3508 AB Utrecht, The Netherlands.
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The association of epileptic focus estimated by magnetoencephalography with cognitive function in non-lesional epilepsy with continuous spikes and waves during slow wave sleep (ECSWS) children. Brain Dev 2019; 41:163-172. [PMID: 30342800 DOI: 10.1016/j.braindev.2018.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 09/16/2018] [Accepted: 09/18/2018] [Indexed: 01/03/2023]
Abstract
OBJECTIVE Epilepsy with continuous spikes and waves during slow sleep (ECSWS) is associated with cognitive deficits. The underlying mechanism is thought to relate to disturbance of functions of the foci by the persistent epileptic activity. However, the relationship between epileptic foci and cognitive deficits remains largely unknown, except for in Landau-Kleffner syndrome. The aim of this study was to evaluate the relationship of epileptic foci estimated from magnetoencephalography (MEG) with cognitive functions at the period of diagnosis in non-lesional ECSWS children, excluding those with Landau-Kleffner syndrome. METHODS MEG data and the Wechsler intelligence scale for children-III scores at ECSWS diagnosis, and medical records, were reviewed. Multiple regression analysis was performed to examine the relationship of parameters of MEG spike dipole clusters, including anatomical location or laterality, with the Wechsler intelligence scale for children-III scores at ECSWS diagnosis. RESULTS Sixteen patients were included, all of whom were right-handed. Epilepsy onset (first unprovoked seizure) ranged from 31 to 110 months (mean, 68.5). The age at ECSWS diagnosis ranged from 72 to 156 months (mean, 108.9). The dipole clusters were estimated on the right Rolandic area (RA) in 4 patients (25%), right supramarginal gyrus (SMG) in 3 (19%), left RA in 2 (13%), left SMG in 2 (13%), bilateral RA in 3 (19%), multiple anatomical locations in 2 (13%). The age at epilepsy onset had the strongest prognostic effect, and full-scale intelligence quotient was relatively less-affected if the cluster was found on the SMG (β = 14.7, p = 0.031). Cases with only a right side cluster exhibited reduced impairment of perceptual organization compared with those with only a left side cluster or bilateral clusters (β = 17.48, p = 0.02). In 12 patients, long-term intellectual prognosis was evaluated, and was associated with intellectual level at the period of ECSWS diagnosis. CONCLUSION In non-lesional ECSWS, the relationship between epileptic focus and cognitive deficits differs from that observed in adults. Rather, it is similar to epilepsies associated with congenital or early infantile brain insults, in that the left epileptic foci in right-handed patients were associated with lower non-verbal functions. Future studies are required to determine the role of plasticity of the immature brain in driving these differences.
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21
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Magnetoencephalography: Clinical and Research Practices. Brain Sci 2018; 8:brainsci8080157. [PMID: 30126121 PMCID: PMC6120049 DOI: 10.3390/brainsci8080157] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/07/2018] [Accepted: 08/11/2018] [Indexed: 11/25/2022] Open
Abstract
Magnetoencephalography (MEG) is a neurophysiological technique that detects the magnetic fields associated with brain activity. Synthetic aperture magnetometry (SAM), a MEG magnetic source imaging technique, can be used to construct both detailed maps of global brain activity as well as virtual electrode signals, which provide information that is similar to invasive electrode recordings. This innovative approach has demonstrated utility in both clinical and research settings. For individuals with epilepsy, MEG provides valuable, nonredundant information. MEG accurately localizes the irritative zone associated with interictal spikes, often detecting epileptiform activity other methods cannot, and may give localizing information when other methods fail. These capabilities potentially greatly increase the population eligible for epilepsy surgery and improve planning for those undergoing surgery. MEG methods can be readily adapted to research settings, allowing noninvasive assessment of whole brain neurophysiological activity, with a theoretical spatial range down to submillimeter voxels, and in both humans and nonhuman primates. The combination of clinical and research activities with MEG offers a unique opportunity to advance translational research from bench to bedside and back.
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Murakami H, Wang ZI, Marashly A, Krishnan B, Prayson RA, Kakisaka Y, Mosher JC, Bulacio J, Gonzalez-Martinez JA, Bingaman WE, Najm IM, Burgess RC, Alexopoulos AV. Correlating magnetoencephalography to stereo-electroencephalography in patients undergoing epilepsy surgery. Brain 2018; 139:2935-2947. [PMID: 27567464 DOI: 10.1093/brain/aww215] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 07/06/2016] [Indexed: 11/15/2022] Open
Affiliation(s)
- Hiroatsu Murakami
- Department of Neurosurgery, Brain Research Institute, Niigata University, Niigata, Japan.,Epilepsy Center, Cleveland Clinic, Cleveland, OH, USA
| | - Zhong I Wang
- Epilepsy Center, Cleveland Clinic, Cleveland, OH, USA
| | - Ahmad Marashly
- Department of Child Neurology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Balu Krishnan
- Epilepsy Center, Cleveland Clinic, Cleveland, OH, USA
| | - Richard A Prayson
- Department of Anatomic Pathology, Cleveland Clinic, Cleveland, OH, USA
| | - Yosuke Kakisaka
- Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan
| | - John C Mosher
- Epilepsy Center, Cleveland Clinic, Cleveland, OH, USA
| | - Juan Bulacio
- Epilepsy Center, Cleveland Clinic, Cleveland, OH, USA
| | | | | | - Imad M Najm
- Epilepsy Center, Cleveland Clinic, Cleveland, OH, USA
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Magnetoencephalographic Spike Analysis in Patients With Focal Cortical Dysplasia: What Defines a "Dipole Cluster"? Pediatr Neurol 2018; 83:25-31. [PMID: 29685607 PMCID: PMC5988951 DOI: 10.1016/j.pediatrneurol.2018.03.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 03/09/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND The purpose of this study is to clarify the source distribution patterns of magnetoencephalographic spikes correlated with postsurgical seizure-free outcome in pediatric patients with focal cortical dysplasia. PATIENTS AND METHODS Thirty-two patients with pathologically confirmed focal cortical dysplasia were divided into seizure-free and seizure-persistent groups according to their surgical outcomes based on Engel classification. In each patient, presurgical magnetoencephalography was reviewed. Dipole sources of magnetoencephalographic spikes were calculated according to a single dipole model. We obtained the following quantitative indices for evaluating dipole distribution: maximum distance over all pairs of dipoles, standard deviation of the distances between each dipole and the mean coordinate of all dipoles, average nearest neighbor distance, the rate of dipoles located within 10, 20, and 30 mm from the mean coordinate, and the rate of dipoles included in the resection. These indices were compared between the two patient groups. RESULTS Average nearest neighbor distance was significantly smaller in the seizure-free group than in the seizure-persistent group (P = 0.008). The rates of dipoles located within 10, 20, and 30 mm from the mean coordinate were significantly higher in the seizure-free group (P = 0.001, 0.001, 0.005, respectively). The maximum distance, standard deviation, and resection rate of dipoles did not show a significant difference between the two groups. CONCLUSIONS A spatially restricted dipole distribution of magnetoencephalographic spikes is correlated with postsurgical seizure-free outcomes in patients with focal cortical dysplasia. The distribution can be assessed by quantitative indices that are clinically useful in the presurgical evaluation of these patients.
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Janca R, Krsek P, Jezdik P, Cmejla R, Tomasek M, Komarek V, Marusic P, Jiruska P. The Sub-Regional Functional Organization of Neocortical Irritative Epileptic Networks in Pediatric Epilepsy. Front Neurol 2018; 9:184. [PMID: 29628910 PMCID: PMC5876241 DOI: 10.3389/fneur.2018.00184] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/09/2018] [Indexed: 11/13/2022] Open
Abstract
Between seizures, irritative network generates frequent brief synchronous activity, which manifests on the EEG as interictal epileptiform discharges (IEDs). Recent insights into the mechanism of IEDs at the microscopic level have demonstrated a high variance in the recruitment of neuronal populations generating IEDs and a high variability in the trajectories through which IEDs propagate across the brain. These phenomena represent one of the major constraints for precise characterization of network organization and for the utilization of IEDs during presurgical evaluations. We have developed a new approach to dissect human neocortical irritative networks and quantify their properties. We have demonstrated that irritative network has modular nature and it is composed of multiple independent sub-regions, each with specific IED propagation trajectories and differing in the extent of IED activity generated. The global activity of the irritative network is determined by long-term and circadian fluctuations in sub-region spatiotemporal properties. Also, the most active sub-region co-localizes with the seizure onset zone in 12/14 cases. This study demonstrates that principles of recruitment variability and propagation are conserved at the macroscopic level and that they determine irritative network properties in humans. Functional stratification of the irritative network increases the diagnostic yield of intracranial investigations with the potential to improve the outcomes of surgical treatment of neocortical epilepsy.
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Affiliation(s)
- Radek Janca
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Pavel Krsek
- Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Petr Jezdik
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Roman Cmejla
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Martin Tomasek
- Department of Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Vladimir Komarek
- Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Petr Marusic
- Department of Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Premysl Jiruska
- Department of Developmental Epileptology, Institute of Physiology, The Czech Academy of Sciences, Prague, Czechia
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25
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Diagnostic evaluation and surgical management of pediatric insular epilepsy utilizing magnetoencephalography and invasive EEG monitoring. Epilepsy Res 2018; 140:72-81. [DOI: 10.1016/j.eplepsyres.2017.12.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 11/28/2017] [Accepted: 12/11/2017] [Indexed: 11/21/2022]
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26
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Shukla G, Kazutaka J, Gupta A, Mosher J, Jones S, Alexopoulos A, Burgess RC. Magnetoencephalographic Identification of Epileptic Focus in Children With Generalized Electroencephalographic (EEG) Features but Focal Imaging Abnormalities. J Child Neurol 2017; 32:981-995. [PMID: 28828916 DOI: 10.1177/0883073817724903] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
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. Patients were encouraged into natural sleep, and simultaneous whole-head MEG/EEG was recorded. Source localization of epileptic spikes on MEG was carried out while blinded to other results. Acceptable dipoles were classified into 3 groups: focal, hemispheric clusters, and single focal cluster with additional widespread dipoles. RESULTS Nine patients (4 female, 5 males; ages 10 months to 15 years) were included. Two had focal features on clinical semiology, whereas all had generalized or multiregional interictal and ictal EEG. Etiologies included tuberous sclerosis complex (2), postencephalitic sequelae (1), focal cortical dysplasia (1), and unknown (2). Five patients had clear focal lesions on brain MRI whereas the other 2 had focal positron emission tomography (PET) abnormalities. An average of 38 spikes were accepted (average goodness of fit = 85.3%). A single tight cluster of dipoles was identified in 5 patients, 1 had dipoles with propagation from left occipital to right temporal. One patient had 2 distinct dipole clusters. MEG demonstrated focal findings 9 times more often than the simultaneously recorded scalp EEG, and 3 times more often than the associated multiday video EEG recordings. CONCLUSION This study shows that neurophysiologic evidence of focal epileptiform abnormalities in patients with focal brain lesions and generalized EEG findings can be strengthened using MEG. Further feasibility of surgical candidacy should be evaluated in these patients.
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Affiliation(s)
- Garima Shukla
- 1 Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, USA.,2 Department of Neurology, All India Institute of Medical Sciences, New Delhi, India
| | - Jin Kazutaka
- 1 Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, USA.,3 Department of Epileptology, Graduate School of Medicine, Tohoku University, Sendai, Japan
| | - Ajay Gupta
- 1 Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, USA
| | - John Mosher
- 1 Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, USA
| | - Stephen Jones
- 1 Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, USA
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27
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Magnetoencephalographic Recordings in Infants Using a Standard-Sized Array. J Clin Neurophysiol 2017; 34:461-468. [DOI: 10.1097/wnp.0000000000000400] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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28
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Deep Source Localization with Magnetoencephalography Based on Sensor Array Decomposition and Beamforming. SENSORS 2017; 17:s17081860. [PMID: 28800118 PMCID: PMC5579488 DOI: 10.3390/s17081860] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/31/2017] [Accepted: 08/02/2017] [Indexed: 11/17/2022]
Abstract
In recent years, the source localization technique of magnetoencephalography (MEG) has played a prominent role in cognitive neuroscience and in the diagnosis and treatment of neurological and psychological disorders. However, locating deep brain activities such as in the mesial temporal structures, especially in preoperative evaluation of epilepsy patients, may be more challenging. In this work we have proposed a modified beamforming approach for finding deep sources. First, an iterative spatiotemporal signal decomposition was employed for reconstructing the sensor arrays, which could characterize the intrinsic discriminant features for interpreting sensor signals. Next, a sensor covariance matrix was estimated under the new reconstructed space. Then, a well-known vector beamforming approach, which was a linearly constraint minimum variance (LCMV) approach, was applied to compute the solution for the inverse problem. It can be shown that the proposed source localization approach can give better localization accuracy than two other commonly-used beamforming methods (LCMV, MUSIC) in simulated MEG measurements generated with deep sources. Further, we applied the proposed approach to real MEG data recorded from ten patients with medically-refractory mesial temporal lobe epilepsy (mTLE) for finding epileptogenic zone(s), and there was a good agreement between those findings by the proposed approach and the clinical comprehensive results.
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29
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Wang Q, Teng P, Luan G. Magnetoencephalography in Preoperative Epileptic Foci Localization: Enlightenment from Cognitive Studies. Front Comput Neurosci 2017; 11:58. [PMID: 28701945 PMCID: PMC5487414 DOI: 10.3389/fncom.2017.00058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/12/2017] [Indexed: 02/02/2023] Open
Abstract
Over 30% epileptic patients are refractory to medication, who are amenable to neurosurgical treatment. Non-invasive brain imaging technologies including video-electroencephalogram (EEG), magnetic resonance imaging (MRI), and magnetoencephalography (MEG) are widely used in presurgical assessment of epileptic patients. This review mainly discussed the current development of clinical MEG imaging as a diagnose approach, and its correlations with the golden standard intracranial electroencephalogram (iEEG). More importantly, this review discussed the possible applications of functional networks in preoperative epileptic foci localization in future studies.
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Affiliation(s)
- Qian Wang
- Beijing Key Laboratory of Epilepsy, Sanbo Brain Hospital, Capital Medical UniversityBeijing, China.,Department of Neurosurgery, Epilepsy Center, Sanbo Brain Hospital, Capital Medical UniversityBeijing, China
| | - Pengfei Teng
- Department of Neurosurgery, Epilepsy Center, Sanbo Brain Hospital, Capital Medical UniversityBeijing, China
| | - Guoming Luan
- Beijing Key Laboratory of Epilepsy, Sanbo Brain Hospital, Capital Medical UniversityBeijing, China.,Department of Neurosurgery, Epilepsy Center, Sanbo Brain Hospital, Capital Medical UniversityBeijing, China.,Beijing Institute for Brain Disorders, Capital Medical UniversityBeijing, China
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30
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Shirozu H, Hashizume A, Masuda H, Ito Y, Nakayama Y, Higashijima T, Fukuda M, Kameyama S. Analysis of ictal magnetoencephalography using gradient magnetic-field topography (GMFT) in patients with neocortical epilepsy. Clin Neurophysiol 2017. [PMID: 28646743 DOI: 10.1016/j.clinph.2017.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE We aimed to validate the usefulness of gradient magnetic-field topography (GMFT) for analysis of ictal magnetoencephalography (MEG) in patients with neocortical epilepsy. METHODS We identified 13 patients presenting with an ictal event during preoperative MEG. We applied equivalent current dipole (ECD) estimation and GMFT to detect and localize the ictal MEG onset, and compared these methods with the ictal onset zone (IOZ) derived from chronic intracranial electroencephalography. The surgical resection areas and outcomes were also evaluated. RESULTS GMFT detected and localized the ictal MEG onset in all patients, whereas ECD estimation showed localized ECDs in only 2. The delineation of GMFT was concordant with the IOZ at the gyral-unit level in 10 of 12 patients (83.3%). The detectability and precision of delineation of ictal MEG activity by GMFT were significantly superior to those of ECD (p<0.05 and p<0.01, respectively). Complete resection of the IOZ in the concordant group provided seizure freedom in 3 patients, whereas seizures remained in 9 patients who had incomplete resections. CONCLUSIONS Because of its higher spatial resolution, GMFT of ictal MEG is superior to conventional ECD estimation in patients with neocortical epilepsy. SIGNIFICANCE Ictal MEG study is a useful tool to estimate the seizure onset in patients with neocortical epilepsy.
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Affiliation(s)
- Hiroshi Shirozu
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital, 1-14-1, Masago, Nishi-ku, Niigata 950-2085, Japan.
| | - Akira Hashizume
- Department of Neurosurgery, Takanobashi Central Hospital, 2-4-16, Kokutaiji-chou, Naka-ku, Hiroshima 730-0042, Japan
| | - Hiroshi Masuda
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital, 1-14-1, Masago, Nishi-ku, Niigata 950-2085, Japan
| | - Yosuke Ito
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital, 1-14-1, Masago, Nishi-ku, Niigata 950-2085, Japan
| | - Yoko Nakayama
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital, 1-14-1, Masago, Nishi-ku, Niigata 950-2085, Japan
| | - Takefumi Higashijima
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital, 1-14-1, Masago, Nishi-ku, Niigata 950-2085, Japan
| | - Masafumi Fukuda
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital, 1-14-1, Masago, Nishi-ku, Niigata 950-2085, Japan
| | - Shigeki Kameyama
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital, 1-14-1, Masago, Nishi-ku, Niigata 950-2085, Japan
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31
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Magnetoencephalography with temporal spread imaging to visualize propagation of epileptic activity. Clin Neurophysiol 2017; 128:734-743. [DOI: 10.1016/j.clinph.2017.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 12/11/2016] [Accepted: 01/04/2017] [Indexed: 11/18/2022]
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33
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Stefan H, Trinka E. Magnetoencephalography (MEG): Past, current and future perspectives for improved differentiation and treatment of epilepsies. Seizure 2017; 44:121-124. [DOI: 10.1016/j.seizure.2016.10.028] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 10/25/2016] [Indexed: 01/23/2023] Open
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34
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Shirozu H, Hashizume A, Masuda H, Fukuda M, Ito Y, Nakayama Y, Higashijima T, Kameyama S. Spatiotemporal Accuracy of Gradient Magnetic-Field Topography (GMFT) Confirmed by Simultaneous Magnetoencephalography and Intracranial Electroencephalography Recordings in Patients with Intractable Epilepsy. Front Neural Circuits 2016; 10:65. [PMID: 27594827 PMCID: PMC4990550 DOI: 10.3389/fncir.2016.00065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 08/03/2016] [Indexed: 11/13/2022] Open
Abstract
Gradient magnetic-field topography (GMFT) is one method for analyzing magnetoencephalography (MEG) and representing the spatiotemporal dynamics of activity on the brain surface. In contrast to spatial filters, GMFT does not include a process reconstructing sources by mixing sensor signals with adequate weighting. Consequently, noisy sensors have localized and limited effects on the results, and GMFT can handle MEG recordings with low signal-to-noise ratio. This property is derived from the principle of the planar-type gradiometer, which obtains maximum gradient magnetic-field signals just above the electrical current source. We assumed that this characteristic allows GMFT to represent even faint changes in brain activities that cannot be achieved with conventional equivalent current dipole analysis or spatial filters. GMFT is thus hypothesized to represent brain surface activities from onset to propagation of epileptic discharges. This study aimed to validate the spatiotemporal accuracy of GMFT by analyzing epileptic activities using simultaneous MEG and intracranial electroencephalography (iEEG) recordings. Participants in this study comprised 12 patients with intractable epilepsy. Epileptic spikes simultaneously detected on both MEG and iEEG were analyzed by GMFT and voltage topography (VT), respectively. Discrepancies in spatial distribution between GMFT and VT were evaluated for each epileptic spike. On the lateral cortices, areas of GMFT activity onset were almost concordant with VT activities arising at the gyral unit level (concordance rate, 66.7-100%). Median time lag between GMFT and VT at onset in each patient was 11.0-42.0 ms. On the temporal base, VT represented basal activities, whereas GMFT failed but instead represented propagated activities of the lateral temporal cortices. Activities limited to within the basal temporal or deep brain region were not reflected on GMFT. In conclusion, GMFT appears to accurately represent brain activities of the lateral cortices at the gyral unit level. The slight time lag between GMFT and VT is likely attributable to differences in the detection principles underlying MEG and iEEG. GMFT has great potential for investigating the spatiotemporal dynamics of lateral brain surface activities.
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Affiliation(s)
- Hiroshi Shirozu
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital Niigata, Japan
| | - Akira Hashizume
- Department of Neurosurgery, Takanobashi Central Hospital Hiroshima, Japan
| | - Hiroshi Masuda
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital Niigata, Japan
| | - Masafumi Fukuda
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital Niigata, Japan
| | - Yosuke Ito
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital Niigata, Japan
| | - Yoko Nakayama
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital Niigata, Japan
| | - Takefumi Higashijima
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital Niigata, Japan
| | - Shigeki Kameyama
- Department of Functional Neurosurgery, Nishi-Niigata Chuo National Hospital Niigata, Japan
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Kim D, Joo EY, Seo DW, Kim MY, Lee YH, Kwon HC, Kim JM, Hong SB. Accuracy of MEG in localizing irritative zone and seizure onset zone: Quantitative comparison between MEG and intracranial EEG. Epilepsy Res 2016; 127:291-301. [PMID: 27693985 DOI: 10.1016/j.eplepsyres.2016.08.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 07/25/2016] [Accepted: 08/14/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND We conducted the study to examine accuracy of the magnetoencephalography (MEG) spike source localization in presurgical evaluation of patients with medically refractory focal epilepsy. METHODS Ten consecutive patients with refractory focal epilepsy who were candidates for two-stage surgery with long-term intracranial electroencephalography (ICEEG) monitoring were enrolled. Interictal MEG recordings with simultaneous scalp EEG were obtained within 7days before the ICEEG electrode implantation. The location of each MEG spike source was quantitatively compared with ICEEG spike foci (focal area of interictal spikes) and ICEEG ictal foci (earliest cortical origin of seizures). Gyral-width concordance and sublobar concordance were also determined for all MEG spike sources. Gyral-width concordance was defined by distance of 15mm or less between MEG spike sources and ICEEG spike foci or ICEEG ictal foci. RESULTS Visual analyses of the MEG traces of all 10 patients revealed 292 spikes (29.2±24.0 per patient). Spike yield of the MEG was similar to the simultaneously recorded scalp EEG. MEG spike sources were closely located with ICEEG spike foci (distance: 9.3±10.8mm). Clustered MEG spike sources were even closer to ICEEG spike foci (distance: 7.3±6.4mm). MEG spike sources, even clustered ones, were less concordant with ICEEG ictal foci and had significant longer distance from ICEEG ictal foci (distance: 21.5±15.6mm for all sources, 19.7±13.7mm for clustered sources). Gyral-width concordance rate and sublobar concordance rate were also higher with ICEEG interictal spike foci than with ICEEG ictal foci. On the other hand, 53.4% of interictal spike foci from ICEEG were not detected by interictal MEG recordings. CONCLUSIONS MEG spike sources, especially clustered ones, from interictal recording could localize the irritative zone of ICEEG with a high accuracy. However, MEG spike sources have relatively poor correlation with seizure onset zone and lower sensitivity in identifying all irritative zones of ICEEG. This limitation should be considered in the interpretation of MEG results.
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Affiliation(s)
- Daeyoung Kim
- Department of Neurology, Chungnam National University Hospital, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Eun Yeon Joo
- Department of Neurology, Samsung Medical Center, Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Dae-Won Seo
- Department of Neurology, Samsung Medical Center, Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Min-Young Kim
- Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
| | - Yong-Ho Lee
- Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
| | - Hyuk Chan Kwon
- Center for Biosignals, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
| | - Jae-Moon Kim
- Department of Neurology, Chungnam National University Hospital, Chungnam National University School of Medicine, Daejeon, Republic of Korea.
| | - Seung Bong Hong
- Department of Neurology, Samsung Medical Center, Samsung Advanced Institute for Health Sciences & Technology (SAIHST), Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; Samsung Biomedical Research Institute, Seoul, Republic of Korea.
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El Tahry R, Wang ZI, Kakisaka Y, Murakami H, Shibata S, Krishnan B, Kotagal P, Alexopoulos A, Burgess RC. A single tight MEG cluster may only represent a fragment of type I FCD. Clin Neurophysiol 2016; 127:2570-2. [DOI: 10.1016/j.clinph.2016.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 02/25/2016] [Accepted: 04/02/2016] [Indexed: 10/21/2022]
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37
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Ahmed R, Rutka JT. The role of MEG in pre-surgical evaluation of epilepsy: current use and future directions. Expert Rev Neurother 2016; 16:795-801. [DOI: 10.1080/14737175.2016.1181544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Raheel Ahmed
- Division of Neurosurgery, The Hospital for Sick Children, Toronto, Canada
| | - James T. Rutka
- Division of Neurosurgery, The Hospital for Sick Children, Toronto, Canada
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38
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Migliorelli C, Alonso JF, Romero S, Mañanas MA, Nowak R, Russi A. Influence of metallic artifact filtering on MEG signals for source localization during interictal epileptiform activity. J Neural Eng 2016; 13:026029. [DOI: 10.1088/1741-2560/13/2/026029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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39
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Anninos P, Adamopoulos A, Kotini A. MEG as a Medical Diagnostic Tool in the Greek Population. ACTA MEDICA (HRADEC KRÁLOVÉ) 2015; 58:71-8. [DOI: 10.14712/18059694.2015.100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Magnetoencephalography (MEG) is the recording of the magnetic field produced by the flowing of ions in the brain. This article reports our experience in the application of MEG in patients and healthy volunteers in the Greek population. We provide a brief description of our research work. The MEG data were recorded in a magnetically shielded room with a whole-head 122 channel or an one-channel biomagnetometer. Our results lead us to believe that the MEG is an important research field which is evolving quickly with a number of interesting findings with respect to normal and abnormal functions of the human brain. It could provide clinical practice with an easy to perform non invasive method, which could be adjunct to conventional methods for the evaluation of brain disorders.
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40
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Shen HM, Lee KM, Hu L, Foong S, Fu X. Effects of reconstructed magnetic field from sparse noisy boundary measurements on localization of active neural source. Med Biol Eng Comput 2015; 54:177-89. [PMID: 26358243 DOI: 10.1007/s11517-015-1381-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 08/22/2015] [Indexed: 10/23/2022]
Abstract
Localization of active neural source (ANS) from measurements on head surface is vital in magnetoencephalography. As neuron-generated magnetic fields are extremely weak, significant uncertainties caused by stochastic measurement interference complicate its localization. This paper presents a novel computational method based on reconstructed magnetic field from sparse noisy measurements for enhanced ANS localization by suppressing effects of unrelated noise. In this approach, the magnetic flux density (MFD) in the nearby current-free space outside the head is reconstructed from measurements through formulating the infinite series solution of the Laplace's equation, where boundary condition (BC) integrals over the entire measurements provide "smooth" reconstructed MFD with the decrease in unrelated noise. Using a gradient-based method, reconstructed MFDs with good fidelity are selected for enhanced ANS localization. The reconstruction model, spatial interpolation of BC, parametric equivalent current dipole-based inverse estimation algorithm using reconstruction, and gradient-based selection are detailed and validated. The influences of various source depths and measurement signal-to-noise ratio levels on the estimated ANS location are analyzed numerically and compared with a traditional method (where measurements are directly used), and it was demonstrated that gradient-selected high-fidelity reconstructed data can effectively improve the accuracy of ANS localization.
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Affiliation(s)
- Hui-min Shen
- State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou, China
| | - Kok-Meng Lee
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA. .,State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, China.
| | - Liang Hu
- State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou, China.
| | - Shaohui Foong
- Engineering Product Development Pillar, Singapore University of Technology and Design, Singapore, Singapore
| | - Xin Fu
- State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou, China
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Ueda Y, Egawa K, Ito T, Takeuchi F, Nakajima M, Otsuka K, Asahina N, Takahashi K, Nakane S, Kohsaka S, Shiraishi H. The presence of short and sharp MEG spikes implies focal cortical dysplasia. Epilepsy Res 2015; 114:141-6. [DOI: 10.1016/j.eplepsyres.2015.04.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2014] [Revised: 03/10/2015] [Accepted: 04/24/2015] [Indexed: 11/30/2022]
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Kharkar S, Knowlton R. Magnetoencephalography in the presurgical evaluation of epilepsy. Epilepsy Behav 2015; 46:19-26. [PMID: 25555504 DOI: 10.1016/j.yebeh.2014.11.029] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 11/24/2014] [Accepted: 11/27/2014] [Indexed: 11/27/2022]
Abstract
Magnetoencephalography (MEG) is an important tool in the presurgical evaluation of patients with medically refractory epilepsy. The appropriate utilization and interpretation of MEG studies can increase the proportion of patients who may be able to further pursue surgical evaluation, refine surgical planning, and potentially increase the probability of seizure freedom after surgery. The aim of this paper is to provide the reader with a comprehensive but accessible guide to MEG, with particular emphasis on acquiring a working knowledge of MEG analysis, identifying patient groups that are most likely to benefit, and clarifying the limitations of this technology.
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Affiliation(s)
| | - Robert Knowlton
- Department of Neurology, University of California at San Francisco, USA; Department of Radiology, University of California at San Francisco, USA; Department of Neurological Surgery, University of California at San Francisco, USA
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Aydin Ü, Vorwerk J, Dümpelmann M, Küpper P, Kugel H, Heers M, Wellmer J, Kellinghaus C, Haueisen J, Rampp S, Stefan H, Wolters CH. Combined EEG/MEG can outperform single modality EEG or MEG source reconstruction in presurgical epilepsy diagnosis. PLoS One 2015; 10:e0118753. [PMID: 25761059 PMCID: PMC4356563 DOI: 10.1371/journal.pone.0118753] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/06/2015] [Indexed: 11/25/2022] Open
Abstract
We investigated two important means for improving source reconstruction in presurgical epilepsy diagnosis. The first investigation is about the optimal choice of the number of epileptic spikes in averaging to (1) sufficiently reduce the noise bias for an accurate determination of the center of gravity of the epileptic activity and (2) still get an estimation of the extent of the irritative zone. The second study focuses on the differences in single modality EEG (80-electrodes) or MEG (275-gradiometers) and especially on the benefits of combined EEG/MEG (EMEG) source analysis. Both investigations were validated with simultaneous stereo-EEG (sEEG) (167-contacts) and low-density EEG (ldEEG) (21-electrodes). To account for the different sensitivity profiles of EEG and MEG, we constructed a six-compartment finite element head model with anisotropic white matter conductivity, and calibrated the skull conductivity via somatosensory evoked responses. Our results show that, unlike single modality EEG or MEG, combined EMEG uses the complementary information of both modalities and thereby allows accurate source reconstructions also at early instants in time (epileptic spike onset), i.e., time points with low SNR, which are not yet subject to propagation and thus supposed to be closer to the origin of the epileptic activity. EMEG is furthermore able to reveal the propagation pathway at later time points in agreement with sEEG, while EEG or MEG alone reconstructed only parts of it. Subaveraging provides important and accurate information about both the center of gravity and the extent of the epileptogenic tissue that neither single nor grand-averaged spike localizations can supply.
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Affiliation(s)
- Ümit Aydin
- Institute for Biomagnetism and Biosignalanalysis, Westfälische Wilhelms-Universität Münster, Münster, Germany
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, Ilmenau, Germany
- * E-mail:
| | - Johannes Vorwerk
- Institute for Biomagnetism and Biosignalanalysis, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Matthias Dümpelmann
- Epilepsy Center, Universitätsklinikum Freiburg, Freiburg im Breisgau, Germany
| | - Philipp Küpper
- Institute for Biomagnetism and Biosignalanalysis, Westfälische Wilhelms-Universität Münster, Münster, Germany
- Department of Neurology, Klinikum Osnabrück, Osnabrück, Germany
| | - Harald Kugel
- Department of Clinical Radiology, Universitätsklinikum Münster, Münster, Germany
| | - Marcel Heers
- Epilepsy Center, Universitätsklinikum Freiburg, Freiburg im Breisgau, Germany
- Ruhr-Epileptology Department of Neurology, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Jörg Wellmer
- Ruhr-Epileptology Department of Neurology, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
| | | | - Jens Haueisen
- Institute for Biomedical Engineering and Informatics, Technische Universität Ilmenau, Ilmenau, Germany
| | - Stefan Rampp
- Ruhr-Epileptology Department of Neurology, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
- Epilepsy Center, Department of Neurology, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Hermann Stefan
- Epilepsy Center, Department of Neurology, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Carsten H. Wolters
- Institute for Biomagnetism and Biosignalanalysis, Westfälische Wilhelms-Universität Münster, Münster, Germany
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Ito T, Otsubo H, Shiraishi H, Yagyu K, Takahashi Y, Ueda Y, Takeuchi F, Takahashi K, Nakane S, Kohsaka S, Saitoh S. Advantageous information provided by magnetoencephalography for patients with neocortical epilepsy. Brain Dev 2015; 37:237-42. [PMID: 24819913 DOI: 10.1016/j.braindev.2014.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 04/04/2014] [Accepted: 04/08/2014] [Indexed: 11/29/2022]
Abstract
PURPOSE We evaluated whether magnetoencephalography (MEG), in addition to surgery, was valuable for the diagnosis and management of epileptic syndromes in patients with neocortical epilepsy (NE). METHODS We studied MEG in 73 patients (29 females; aged 1-26years; mean 10.3years) for the clinical diagnosis of epilepsy and for preoperative evaluation. MEG data were recorded by 204-channel whole head gradiometers with a 600Hz sampling rate. MEG spike sources were localized on magnetic resonance images (MRI) using a single dipole model to project equivalent current dipoles. RESULTS MEG localized an epileptic focus with single clustered dipoles in 24 (33%) of 73 NE patients: 16 (25%) of 64 symptomatic localization-related epilepsy (SLRE) patients and eight (89%) of nine idiopathic localization-related epilepsy (ILRE) patients. MEG provided advantageous information in 12 (50%) of 24 patients with clustered dipoles and confirmed the diagnosis in the remaining 12 (50%). Furthermore, the use of MEG resulted in changes to surgical treatments in nine (38%) patients and in medical management in eight (33%). MEG confirmed the diagnosis in eight (16%) of 49 patients with scattered dipoles. MRI identified a single lesion (28 patients, 38%), multiple lesions (5, 7%), and no lesion (40, 55%). MRI provided confirming information in 19 of 28 patients with a single lesion and 18 of them required surgical resections. MRI did not provide any supportive information in 54 (74%) patients with a single (9), multiple (5) and no lesion (40). CONCLUSION Our study shows that MEG provides fundamental information to aid the choice of diagnostic and therapeutic procedures including changes in medication in addition to surgical treatments for NE.
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Affiliation(s)
- Tomoshiro Ito
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hiroshi Otsubo
- Division of Neurology, Department of Pediatrics, The Hospital for Sick Children and The University of Toronto, Toronto, Canada.
| | - Hideaki Shiraishi
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Kazuyori Yagyu
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Yumi Takahashi
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Yuki Ueda
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Fumiya Takeuchi
- Faculty of Health Sciences, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Kayoko Takahashi
- Division of Magnetoencephalography, Hokkaido University Hospital, Sapporo, Japan
| | - Shingo Nakane
- Division of Magnetoencephalography, Hokkaido University Hospital, Sapporo, Japan
| | - Shinobu Kohsaka
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Shinji Saitoh
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan; Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
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45
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Bagić A, Ebersole JS. Does MEG/MSI dipole variability mean unreliability? Clin Neurophysiol 2015; 126:209-11. [DOI: 10.1016/j.clinph.2014.01.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/20/2014] [Accepted: 01/23/2014] [Indexed: 11/28/2022]
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46
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Birbilis T, Anninos P, Seimenis I, Adamopoulos A, Kotini A. MEG localization of spike sources in human patients with brain tumors. J Integr Neurosci 2014; 13:519-28. [DOI: 10.1142/s0219635214500150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
Magnetoencephalography (MEG) is a functional modality to register magnetic brain activity with high spatiotemporal resolution. Since distortion of magnetic fields by the skin, skull and cerebrospinal fluids is negligible, the technique offers an almost undistorted view on brain activity. While MEG systems are still expensive and complex, the technique's characteristics offer promising possibilities for the investigation of epilepsy patients, for example, for focus localization and presurgical functional mapping. This review gives an overview of the method and discusses advantages and limitations in the clinical context of presurgical epilepsy diagnosis.
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Affiliation(s)
- Stefan Rampp
- Epilepsy Center (ZEE), Department of Neurology, University Hospital, Schwabachanlage 6, 91054 Erlangen, Germany.
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49
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Wennberg R, Cheyne D. Reliability of MEG source imaging of anterior temporal spikes: analysis of an intracranially characterized spike focus. Clin Neurophysiol 2013; 125:903-18. [PMID: 24210513 DOI: 10.1016/j.clinph.2013.08.032] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Revised: 07/28/2013] [Accepted: 08/21/2013] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To assess the reliability of MEG source imaging (MSI) of anterior temporal spikes through detailed analysis of the localization and orientation of source solutions obtained for a large number of spikes that were separately confirmed by intracranial EEG to be focally generated within a single, well-characterized spike focus. METHODS MSI was performed on 64 identical right anterior temporal spikes from an anterolateral temporal neocortical spike focus. The effects of different volume conductors (sphere and realistic head model), removal of noise with low frequency filters (LFFs) and averaging multiple spikes were assessed in terms of the reliability of the source solutions. RESULTS MSI of single spikes resulted in scattered dipole source solutions that showed reasonable reliability for localization at the lobar level, but only for solutions with a goodness-of-fit exceeding 80% using a LFF of 3 Hz. Reliability at a finer level of intralobar localization was limited. Spike averaging significantly improved the reliability of source solutions and averaging 8 or more spikes reduced dependency on goodness-of-fit and data filtering. CONCLUSIONS MSI performed on topographically identical individual spikes from an intracranially defined classical anterior temporal lobe spike focus was limited by low reliability (i.e., scattered source solutions) in terms of fine, sublobar localization within the ipsilateral temporal lobe. Spike averaging significantly improved reliability. SIGNIFICANCE MSI performed on individual anterior temporal spikes is limited by low reliability. Reduction of background noise through spike averaging significantly improves the reliability of MSI solutions.
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Affiliation(s)
- Richard Wennberg
- Krembil Neuroscience Centre, Division of Neurology, Toronto Western Hospital, University of Toronto, 399 Bathurst Street, Toronto, ON M5T 2S8, Canada.
| | - Douglas Cheyne
- Program in Neurosciences and Mental Health, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, ON M5G 1X8, Canada
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50
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Mohamed IS, Gibbs SA, Robert M, Bouthillier A, Leroux JM, Khoa Nguyen D. The utility of magnetoencephalography in the presurgical evaluation of refractory insular epilepsy. Epilepsia 2013; 54:1950-9. [DOI: 10.1111/epi.12376] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Ismail S. Mohamed
- Division of Neurology; Department of Pediatrics; IIWK Health Center; Halifax NS Canada
| | - Steve A. Gibbs
- Division of Neurology; Notre-Dame Hospital (CHUM); University of Montreal; Montreal QC Canada
| | - Manon Robert
- Department of Psychology; Neuropsychology and Cognition Research Center; University of Montreal, Montreal; QC Canada
| | - Alain Bouthillier
- Division of Neurosurgery; Notre-Dame Hospital (CHUM); University of Montreal, Montreal; QC Canada
| | - Jean-Maxime Leroux
- Department of Radiology; Notre-Dame Hospital (CHUM); University of Montreal, Montreal; QC Canada
| | - Dang Khoa Nguyen
- Division of Neurology; Notre-Dame Hospital (CHUM); University of Montreal; Montreal QC Canada
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