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Lisgaras CP, Scharfman HE. Interictal spikes in Alzheimer's disease: Preclinical evidence for dominance of the dentate gyrus and cholinergic control by the medial septum. Neurobiol Dis 2023; 187:106294. [PMID: 37714307 PMCID: PMC10617404 DOI: 10.1016/j.nbd.2023.106294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/11/2023] [Accepted: 09/13/2023] [Indexed: 09/17/2023] Open
Abstract
Interictal spikes (IIS) are a common type of abnormal electrical activity in Alzheimer's disease (AD) and preclinical models. The brain regions where IIS are largest are not known but are important because such data would suggest sites that contribute to IIS generation. Because hippocampus and cortex exhibit altered excitability in AD models, we asked which areas dominate the activity during IIS along the cortical-CA1-dentate gyrus (DG) dorso-ventral axis. Because medial septal (MS) cholinergic neurons are overactive when IIS typically occur, we also tested the novel hypothesis that silencing the MS cholinergic neurons selectively would reduce IIS. We used mice that simulate aspects of AD: Tg2576 mice, presenilin 2 (PS2) knockout mice and Ts65Dn mice. To selectively silence MS cholinergic neurons, Tg2576 mice were bred with choline-acetyltransferase (ChAT)-Cre mice and offspring were injected in the MS with AAV encoding inhibitory designer receptors exclusively activated by designer drugs (DREADDs). We recorded local field potentials along the cortical-CA1-DG axis using silicon probes during wakefulness, slow-wave sleep (SWS) and rapid eye movement (REM) sleep. We detected IIS in all transgenic or knockout mice but not age-matched controls. IIS were detectable throughout the cortical-CA1-DG axis and occurred primarily during REM sleep. In all 3 mouse lines, IIS amplitudes were significantly greater in the DG granule cell layer vs. CA1 pyramidal layer or overlying cortex. Current source density analysis showed robust and early current sources in the DG, and additional sources in CA1 and the cortex also. Selective chemogenetic silencing of MS cholinergic neurons significantly reduced IIS rate during REM sleep without affecting the overall duration, number of REM bouts, latency to REM sleep, or theta power during REM. Notably, two control interventions showed no effects. Consistent maximal amplitude and strong current sources of IIS in the DG suggest that the DG is remarkably active during IIS. In addition, selectively reducing MS cholinergic tone, at times when MS is hyperactive, could be a new strategy to reduce IIS in AD.
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Affiliation(s)
- Christos Panagiotis Lisgaras
- Departments of Child & Adolescent Psychiatry, Neuroscience & Physiology, and Psychiatry, and the Neuroscience Institute New York University Langone Health, 550 First Ave., New York, NY 10016, United States of America; Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, New York State Office of Mental Health, 140 Old Orangeburg Road, Bldg. 35, Orangeburg, NY 10962, United States of America.
| | - Helen E Scharfman
- Departments of Child & Adolescent Psychiatry, Neuroscience & Physiology, and Psychiatry, and the Neuroscience Institute New York University Langone Health, 550 First Ave., New York, NY 10016, United States of America; Center for Dementia Research, The Nathan S. Kline Institute for Psychiatric Research, New York State Office of Mental Health, 140 Old Orangeburg Road, Bldg. 35, Orangeburg, NY 10962, United States of America
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Lévesque M, Wang S, Macey-Dare ADB, Salami P, Avoli M. Evolution of interictal activity in models of mesial temporal lobe epilepsy. Neurobiol Dis 2023; 180:106065. [PMID: 36907521 DOI: 10.1016/j.nbd.2023.106065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/22/2023] [Accepted: 03/02/2023] [Indexed: 03/12/2023] Open
Abstract
Interictal activity and seizures are the hallmarks of focal epileptic disorders (which include mesial temporal lobe epilepsy, MTLE) in humans and in animal models. Interictal activity, which is recorded with cortical and intracerebral EEG recordings, comprises spikes, sharp waves and high-frequency oscillations, and has been used in clinical practice to identify the epileptic zone. However, its relation with seizures remains debated. Moreover, it is unclear whether specific EEG changes in interictal activity occur during the time preceding the appearance of spontaneous seizures. This period, which is termed "latent", has been studied in rodent models of MTLE in which spontaneous seizures start to occur following an initial insult (most often a status epilepticus induced by convulsive drugs such as kainic acid or pilocarpine) and may mirror epileptogenesis, i.e., the process leading the brain to develop an enduring predisposition to seizure generation. Here, we will address this topic by reviewing experimental studies performed in MTLE models. Specifically, we will review data highlighting the dynamic changes in interictal spiking activity and high-frequency oscillations occurring during the latent period, and how optogenetic stimulation of specific cell populations can modulate them in the pilocarpine model. These findings indicate that interictal activity: (i) is heterogeneous in its EEG patterns and thus, presumably, in its underlying neuronal mechanisms; and (ii) can pinpoint to the epileptogenic processes occurring in focal epileptic disorders in animal models and, perhaps, in epileptic patients.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada.
| | - Siyan Wang
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada
| | - Anežka D B Macey-Dare
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada; Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Pariya Salami
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114, USA
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, McGill University, 3801 Rue University, Montreal, H3A 2B4, QC, Canada; Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, H3G 1Y6, QC, Canada
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3
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Lai N, Li Z, Xu C, Wang Y, Chen Z. Diverse nature of interictal oscillations: EEG-based biomarkers in epilepsy. Neurobiol Dis 2023; 177:105999. [PMID: 36638892 DOI: 10.1016/j.nbd.2023.105999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/07/2023] [Accepted: 01/09/2023] [Indexed: 01/11/2023] Open
Abstract
Interictal electroencephalogram (EEG) patterns, including high-frequency oscillations (HFOs), interictal spikes (ISs), and slow wave activities (SWAs), are defined as specific oscillations between seizure events. These interictal oscillations reflect specific dynamic changes in network excitability and play various roles in epilepsy. In this review, we briefly describe the electrographic characteristics of HFOs, ISs, and SWAs in the interictal state, and discuss the underlying cellular and network mechanisms. We also summarize representative evidence from experimental and clinical epilepsy to address their critical roles in ictogenesis and epileptogenesis, indicating their potential as electrophysiological biomarkers of epilepsy. Importantly, we put forwards some perspectives for further research in the field.
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Affiliation(s)
- Nanxi Lai
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zhisheng Li
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Cenglin Xu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yi Wang
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Zhong Chen
- Institute of Pharmacology & Toxicology, NHC and CAMS Key Laboratory of Medical Neurobiology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China; Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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Conrad EC, Shinohara RT, Gugger JJ, Revell AY, Das S, Stein JM, Marsh ED, Davis KA, Litt B. Implanting intracranial electrodes does not affect spikes or network connectivity in nearby or connected brain regions. Netw Neurosci 2022; 6:834-849. [PMID: 36607198 PMCID: PMC9810371 DOI: 10.1162/netn_a_00248] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 04/01/2022] [Indexed: 01/10/2023] Open
Abstract
To determine the effect of implanting electrodes on electrographic features of nearby and connected brain regions in patients with drug-resistant epilepsy, we analyzed intracranial EEG recordings from 10 patients with drug-resistant epilepsy who underwent implant revision (placement of additional electrodes) during their hospitalization. We performed automated spike detection and measured EEG functional networks. We analyzed the original electrodes that remained in place throughout the full EEG recording, and we measured the change in spike rates and network connectivity in these original electrodes in response to implanting new electrodes. There was no change in overall spike rate pre- to post-implant revision (t(9) = 0.1, p = 0.95). The peri-revision change in the distribution of spike rate and connectivity across electrodes was no greater than chance (Monte Carlo method, spikes: p = 0.40, connectivity: p = 0.42). Electrodes closer to or more functionally connected to the revision site had no greater change in spike rate or connectivity than more distant or less connected electrodes. Changes in electrographic features surrounding electrode implantation are no greater than baseline fluctuations occurring throughout the intracranial recording. These findings argue against an implant effect on spikes or network connectivity in nearby or connected brain regions.
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Affiliation(s)
- Erin C. Conrad
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Russell T. Shinohara
- Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, PA, USA
- Penn Statistics in Imaging and Visualization Center, University of Pennsylvania, Philadelphia, PA, USA
- Center for Biomedical Image Computing and Analytics, University of Pennsylvania, Philadelphia, PA, USA
| | - James J. Gugger
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew Y. Revell
- Medical Scientist Training Program, University of Pennsylvania, Philadelphia, PA, USA
| | - Sandhitsu Das
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Joel M. Stein
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Eric D. Marsh
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
- Division of Child Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kathryn A. Davis
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian Litt
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, USA
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Maharathi B, Patton J, Serafini A, Slavin K, Loeb JA. Highly consistent temporal lobe interictal spike networks revealed from foramen ovale electrodes. Clin Neurophysiol 2021; 132:2065-74. [PMID: 34284241 DOI: 10.1016/j.clinph.2021.06.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/18/2021] [Accepted: 06/22/2021] [Indexed: 11/22/2022]
Abstract
OBJECTIVE A major challenge that limits understanding and treatment of epileptic events from mesial temporal structures comes from our inability to detect and map interictal networks reproducibly using scalp electrodes. Here, we developed a novel approach to map interictal spike networks and demonstrate their relationships to seizure onset and lesions in patients with foramen ovale electrode implantations. METHODS We applied the direct Directed Transfer Function to reveal interictal spike propagation from bilateral foramen ovale electrodes on 10 consecutive patients and co-registered spatially with both seizure onset zones and temporal lobe lesions. RESULTS Highly reproducible, yet unique interictal spike networks were seen for each patient (correlation: 0.93 ± 0.13). Interictal spikes spread in both anterior and posterior directions within each temporal lobe, often reverberating between sites. Spikes propagated to the opposite temporal lobe predominantly through posterior pathways. Patients with structural lesions (N = 4), including tumors and sclerosis, developed reproducible spike networks adjacent to their lesions that were highly lateralized compared to patients without lesions. Only 5% of mesial temporal lobe spikes were time-locked with scalp electrode spikes. Our preliminary observation on two lesional patients suggested that along with lesion location, Interictal spike networks also partially co-registered with seizure onset zones suggesting interrelationship between seizure onset and a subset of spike networks. CONCLUSIONS This is the first demonstration of patient-specific, reproducible interictal spike networks in mesial temporal structures that are closely linked to both temporal lobe lesions and seizure onset zones. SIGNIFICANCE Interictal spike connectivity is a novel approach to map epileptic networks that could help advance invasive and non-invasive epilepsy treatments.
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Wu YJ, Chien ME, Chiang CC, Huang YZ, Durand DM, Hsu KS. Delta oscillation underlies the interictal spike changes after repeated transcranial direct current stimulation in a rat model of chronic seizures. Brain Stimul 2021; 14:771-779. [PMID: 33989818 DOI: 10.1016/j.brs.2021.04.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 04/27/2021] [Accepted: 04/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Transcranial direct current stimulation (tDCS) provides a noninvasive polarity-specific constant current to treat epilepsy, through a mechanism possibly involving excitability modulation and neural oscillation. OBJECTIVE To determine whether EEG oscillations underlie the interictal spike changes after tDCS in rats with chronic spontaneous seizures. METHODS Rats with kainic acid-induced spontaneous seizures were subjected to cathodal tDCS or sham stimulation for 5 consecutive days. Video-EEG recordings were collected immediately pre- and post-stimulation and for the subsequent 2 weeks following stimulation. The acute pre-post stimulation and subacute follow-up changes of interictal spikes and EEG oscillations in tDCS-treated rats were compared with sham. Ictal EEG with seizure behaviors, hippocampal brain-derived neurotrophic factor (BDNF) protein expression, and mossy fiber sprouting were compared between tDCS and sham rats. RESULTS Interictal spike counts were reduced immediately following tDCS with augmented delta and diminished beta and gamma oscillations compared with sham. Cathodal tDCS also enhanced delta oscillations in normal rats. However, increased numbers of interictal spikes with a decrease of delta and theta oscillations were observed in tDCS-treated rats compared with sham during the following 2 weeks after stimulation. Resuming tDCS suppressed the increase of interictal spike activity. In tDCS rats, hippocampal BDNF protein expression was decreased while mossy fiber sprouting did not change compared with sham. CONCLUSIONS The inverse relationship between the changes of delta oscillation and interictal spikes during tDCS on and off stimulation periods indicates that an enhanced endogenous delta oscillation underlies the tDCS inhibitory effect on epileptic excitability.
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Affiliation(s)
- Yi-Jen Wu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan; Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan.
| | - Miao-Er Chien
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70457, Taiwan
| | - Chia-Chu Chiang
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ying-Zu Huang
- Department of Neurology and Neuroscience Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan; Medical School and Healthy Aging Research Center, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Institute of Cognitive Neuroscience, National Central University, Taoyuan, Taiwan
| | - Dominique M Durand
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kuei-Sen Hsu
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
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Li R, Plummer C, Vogrin SJ, Woods WP, Kuhlmann L, Boston R, Liley DTJ, Cook MJ, Grayden DB. Interictal spike localization for epilepsy surgery using magnetoencephalography beamforming. Clin Neurophysiol 2021; 132:928-937. [PMID: 33636608 DOI: 10.1016/j.clinph.2020.12.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 11/25/2020] [Accepted: 12/03/2020] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Magnetoencephalography (MEG) kurtosis beamforming is an automated localization method for focal epilepsy. Visual examination of virtual sensors, which are source activities reconstructed by beamforming, can improve performance but can be time-consuming for neurophysiologists. We propose a framework to automate the method and evaluate its effectiveness against surgical resections and outcomes. METHODS We retrospectively analyzed MEG recordings of 13 epilepsy surgery patients who had one-year minimum post-operative follow-up. Kurtosis beamforming was applied and manual inspection was confined to morphological clusters. The region with the Maximum Interictal Spike Frequency (MISF) was validated against prospectively modelled sLORETA solutions and surgical resections linked to outcome. RESULTS Our approach localized spikes in 12 out of 13 patients. In eight patients with Engel I surgical outcomes, beamforming MISF regions were concordant with surgical resection at overlap level for five patients and at lobar level for three patients. The MISF regions localized to spike onset and propagation modelled by sLORETA in two and six patients, respectively. CONCLUSIONS Automated beamforming using MEG can predict postoperative seizure freedom at the lobar level but tends to localize propagated MEG spikes. SIGNIFICANCE MEG beamforming may contribute to non-invasive procedures to predict surgical outcome for patients with drug-refractory focal epilepsy.
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Affiliation(s)
- Rui Li
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC, Australia.
| | - Chris Plummer
- Department of Medicine, The University of Melbourne, Fitzroy, VIC, Australia; Department of Neurology, St. Vincent's Hospital, Fitzroy, VIC, Australia; School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - Simon J Vogrin
- Department of Medicine, The University of Melbourne, Fitzroy, VIC, Australia; Department of Neurology, St. Vincent's Hospital, Fitzroy, VIC, Australia; School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - William P Woods
- School of Health Sciences, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - Levin Kuhlmann
- Faculty of Information Technology, Monash University, Clayton, VIC 3168, Australia
| | - Ray Boston
- Department of Medicine, The University of Melbourne, Fitzroy, VIC, Australia; Department of Clinical Studies, New Bolton Centre, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, USA
| | - David T J Liley
- Department of Medicine, The University of Melbourne, Fitzroy, VIC, Australia; Centre for Human Psychopharmacology, Swinburne University of Technology, Hawthorn, VIC, Australia
| | - Mark J Cook
- Department of Medicine, The University of Melbourne, Fitzroy, VIC, Australia; Department of Neurology, St. Vincent's Hospital, Fitzroy, VIC, Australia; Graeme Clark Institute for Biomedical Engineering, The University of Melbourne, Parkville, VIC, Australia
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne, Parkville, VIC, Australia; Department of Medicine, The University of Melbourne, Fitzroy, VIC, Australia; Graeme Clark Institute for Biomedical Engineering, The University of Melbourne, Parkville, VIC, Australia
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Abstract
Magnetoencephalography (MEG) is a noninvasive neuroimaging technique that measures the electromagnetic fields generated by the human brain. This article highlights the benefits that pediatric MEG has to offer to clinical practice and pediatric research, particularly for infants and young children; reviews the existing literature on adult MEG systems for pediatric use; briefly describes the few pediatric MEG systems currently extant; and draws attention to future directions of research, with focus on the clinical use of MEG for patients with drug-resistant epilepsy.
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Aghaei-Lasboo A, Inoyama K, Fogarty AS, Kuo J, Meador KJ, Walter JJ, Le ST, Graber KD, Razavi B, Fisher RS. Tripolar concentric EEG electrodes reduce noise. Clin Neurophysiol 2019; 131:193-198. [PMID: 31809982 DOI: 10.1016/j.clinph.2019.10.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 10/21/2019] [Accepted: 10/26/2019] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To assay EEG signal quality recorded with tripolar concentric ring electrodes (TCREs) compared to regular EEG electrodes. METHODS EEG segments were recorded simultaneously by TCREs and regular electrodes, low-pass filtered at 35 Hz (REG35) and 70 Hz (REG70). Clips were rated blindly by nine electroencephalographers for presence or absence of key EEG features, relative to the "gold-standard" of the clinical report. RESULTS TCRE showed less EMG artifact (F = 15.4, p < 0.0001). Overall quality rankings were not significantly different. Focal slowing was better detected by TCRE and spikes were better detected by regular electrodes. Seizures (n = 85) were detected by TCRE in 64 cases (75.3%), by REG70 in 75 (88.2%) and REG35 in 69 (81.2%) electrodes. TCRE detected 9 (10.6%) seizures not detected by one of the other 2 methods. In contrast, 14 seizures (16.5%) were not detected by TCRE, but were by REG35 electrodes. Each electrode detected interictal spikes when the other did not. CONCLUSIONS TCRE produced similar overall quality and confidence ratings versus regular electrodes, but less muscle artifact. TCRE recordings detected seizures in 7% of instances where regular electrodes did not. SIGNIFICANCE The combination of the two types increased detection of epileptiform events compared to either alone.
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Affiliation(s)
- Anahita Aghaei-Lasboo
- Bass Medical Group, Department of Neurology, Suite 301, 400 Taylor Blvd, Pleasant Hill, CA 94523, USA
| | - Katherine Inoyama
- NYU Langone Comprehensive Epilepsy Center, 240 East 38th Street, New York, NY 10016, USA
| | - Adam S Fogarty
- Stanford University Department of Neurology and Neurological Sciences, Palo Alto, CA 94304, USA
| | - Jonathan Kuo
- Clinical Neurology, Keck School of Medicine USC, 1520 San Pablo St, Suite 3000, Los Angeles, CA 90033, USA
| | - Kimford J Meador
- Stanford University Department of Neurology and Neurological Sciences, Palo Alto, CA 94304, USA
| | - Jessica J Walter
- Stanford University Department of Neurology and Neurological Sciences, Palo Alto, CA 94304, USA
| | - Scheherazade T Le
- Stanford University Department of Neurology and Neurological Sciences, Palo Alto, CA 94304, USA
| | - Kevin D Graber
- Stanford University Department of Neurology and Neurological Sciences, Palo Alto, CA 94304, USA
| | - Babak Razavi
- Stanford University Department of Neurology and Neurological Sciences, Palo Alto, CA 94304, USA
| | - Robert S Fisher
- Stanford University Department of Neurology and Neurological Sciences, Palo Alto, CA 94304, USA.
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Maharathi B, Wlodarski R, Bagla S, Asano E, Hua J, Patton J, Loeb JA. Interictal spike connectivity in human epileptic neocortex. Clin Neurophysiol 2018; 130:270-279. [PMID: 30605889 DOI: 10.1016/j.clinph.2018.11.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/09/2018] [Accepted: 11/22/2018] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Interictal spikes are a biomarker of epilepsy, yet their precise roles are poorly understood. Using long-term neocortical recordings from epileptic patients, we investigated the spatial-temporal propagation patterns of interictal spiking. METHODS Interictal spikes were detected in 10 epileptic patients. Short time direct directed transfer function was used to map the spatial-temporal patterns of interictal spike onset and propagation across different cortical topographies. RESULTS Each patient had unique interictal spike propagation pattern that was highly consistent across times, regardless of the frequency band. High spiking brain regions were often not spike onset regions. We observed frequent spike propagations to shorter distances and that the central sulcus forms a strong barrier to spike propagation. Spike onset and seizure onset seemed to be distinct networks in most cases. CONCLUSIONS Patients in epilepsy have distinct and unique network of causal propagation pattern which are very consistent revealing the underlying epileptic network. Although spike are epileptic biomarkers, spike origin and seizure onset seems to be distinct in most cases. SIGNIFICANCE Understanding patterns of interictal spike propagation could lead to the identification patient-specific epileptic networks amenable to surgical or other treatments.
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Affiliation(s)
- Biswajit Maharathi
- Department of Neurology and Rehabilitation, University of Illinois, Chicago, IL, United States; Department of Bioengineering, University of Illinois, Chicago, IL, United States
| | - Richard Wlodarski
- Department of Neurology and Rehabilitation, University of Illinois, Chicago, IL, United States
| | - Shruti Bagla
- Department of and Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, United States
| | - Eishi Asano
- Department of Pediatrics, Wayne State University, Detroit, MI, United States; Department of Neurology, Wayne State University, Detroit, MI, United States
| | - Jing Hua
- Department of Computer Science, Wayne State University, Detroit, MI, United States
| | - James Patton
- Department of Bioengineering, University of Illinois, Chicago, IL, United States
| | - Jeffrey A Loeb
- Department of Neurology and Rehabilitation, University of Illinois, Chicago, IL, United States.
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Wu HC, Dachet F, Ghoddoussi F, Bagla S, Fuerst D, Stanley JA, Galloway MP, Loeb JA. Altered metabolomic-genomic signature: A potential noninvasive biomarker of epilepsy. Epilepsia 2017; 58:1626-1636. [PMID: 28714074 DOI: 10.1111/epi.13848] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2017] [Indexed: 01/21/2023]
Abstract
OBJECTIVE This study aimed to identify noninvasive biomarkers of human epilepsy that can reliably detect and localize epileptic brain regions. Having noninvasive biomarkers would greatly enhance patient diagnosis, patient monitoring, and novel therapy development. At the present time, only surgically invasive, direct brain recordings are capable of detecting these regions with precision, which severely limits the pace and scope of both clinical management and research progress in epilepsy. METHODS We compared high versus low or nonspiking regions in nine medically intractable epilepsy surgery patients by performing integrated metabolomic-genomic-histological analyses of electrically mapped human cortical regions using high-resolution magic angle spinning proton magnetic resonance spectroscopy, cDNA microarrays, and histological analysis. RESULTS We found a highly consistent and predictive metabolite logistic regression model with reduced lactate and increased creatine plus phosphocreatine and choline, suggestive of a chronically altered metabolic state in epileptic brain regions. Linking gene expression, cellular, and histological differences to these key metabolites using a hierarchical clustering approach predicted altered metabolic vascular coupling in the affected regions. Consistently, these predictions were validated histologically, showing both neovascularization and newly discovered, millimeter-sized microlesions. SIGNIFICANCE Using a systems biology approach on electrically mapped human cortex provides new evidence for spatially segregated, metabolic derangements in both neurovascular and synaptic architecture in human epileptic brain regions that could be a noninvasively detectable biomarker of epilepsy. These findings both highlight the immense power of a systems biology approach and identify a potentially important role that magnetic resonance spectroscopy can play in the research and clinical management of epilepsy.
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Affiliation(s)
- Helen C Wu
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan, U.S.A
| | - Fabien Dachet
- Department of Neurology and Rehabilitation, University of Illinois, Chicago, Illinois, U.S.A
| | - Farhad Ghoddoussi
- Department of Anesthesiology and Neuroimaging Center, Wayne State University, Detroit, Michigan, U.S.A
| | - Shruti Bagla
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan, U.S.A
| | - Darren Fuerst
- Department of Neurology and Rehabilitation, University of Illinois, Chicago, Illinois, U.S.A
| | - Jeffrey A Stanley
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan, U.S.A
| | - Matthew P Galloway
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan, U.S.A.,Department of Anesthesiology and Neuroimaging Center, Wayne State University, Detroit, Michigan, U.S.A
| | - Jeffrey A Loeb
- Department of Neurology and Rehabilitation, University of Illinois, Chicago, Illinois, U.S.A
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12
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Cam SL, Ranta R, Caune V, Korats G, Koessler L, Maillard L, Louis-Dorr V. SEEG dipole source localization based on an empirical Bayesian approach taking into account forward model uncertainties. Neuroimage 2017; 153:1-15. [PMID: 28323161 DOI: 10.1016/j.neuroimage.2017.03.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 01/18/2017] [Accepted: 03/14/2017] [Indexed: 11/24/2022] Open
Abstract
Electromagnetic brain source localization consists in the inversion of a forward model based on a limited number of potential measurements. A wide range of methods has been developed to regularize this severely ill-posed problem and to reduce the solution space, imposing spatial smoothness, anatomical constraint or sparsity of the activated source map. This last criteria, based on physiological assumptions stating that in some particular events (e.g., epileptic spikes, evoked potential) few focal area of the brain are simultaneously actives, has gained more and more interest. Bayesian approaches have the ability to provide sparse solutions under adequate parametrization, and bring a convenient framework for the introduction of priors in the form of probabilistic density functions. However the quality of the forward model is rarely questioned while this parameter has undoubtedly a great influence on the solution. Its construction suffers from numerous approximation and uncertainties, even when using realistic numerical models. In addition, it often encodes a coarse sampling of the continuous solution space due to the computational burden its inversion implies. In this work we propose an empirical Bayesian approach to take into account the uncertainties of the forward model by allowing constrained variations around a prior physical model, in the particular context of SEEG measurements. We demonstrate on simulations that the method enhance the accuracy of the source time-course estimation as well as the sparsity of the resulting source map. Results on real signals prove the applicability of the method in real contexts.
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Affiliation(s)
- S Le Cam
- Université de Lorraine, CRAN, UMR 7039, 54500 Vandœuvre-lès-Nancy, France; CNRS, CRAN, UMR, 7039, France.
| | - R Ranta
- Université de Lorraine, CRAN, UMR 7039, 54500 Vandœuvre-lès-Nancy, France; CNRS, CRAN, UMR, 7039, France
| | - V Caune
- Université de Lorraine, CRAN, UMR 7039, 54500 Vandœuvre-lès-Nancy, France; CNRS, CRAN, UMR, 7039, France
| | - G Korats
- Université de Lorraine, CRAN, UMR 7039, 54500 Vandœuvre-lès-Nancy, France; CNRS, CRAN, UMR, 7039, France; Ventspils University College, 101 Inzenieruiela, LV-3601 Ventspils, Latvia
| | - L Koessler
- Université de Lorraine, CRAN, UMR 7039, 54500 Vandœuvre-lès-Nancy, France; CNRS, CRAN, UMR, 7039, France
| | - L Maillard
- Université de Lorraine, CRAN, UMR 7039, 54500 Vandœuvre-lès-Nancy, France; CNRS, CRAN, UMR, 7039, France; CHU Nancy, Neurology Department, 54000 Nancy, France
| | - V Louis-Dorr
- Université de Lorraine, CRAN, UMR 7039, 54500 Vandœuvre-lès-Nancy, France; CNRS, CRAN, UMR, 7039, France
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13
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Abstract
Accumulating evidence suggest that TRPC channels play critical roles in various aspects of epileptogenesis. TRPC1/4 channels are major contributors to nonsynaptically derived epileptiform burst firing in the CA1 and the lateral septum. TRPC7 channels play a critical role in synaptically derived epileptiform burst firing. The reduction of spontaneous epileptiform bursting in the CA3 is correlated to a reduction in pilocarpine-induced SE in vivo in TRPC7 knockout mice. TRPC channels are also significant contributors to SE-induced neuronal cell death. Although the pilocarpine-induced SE itself is not significantly reduced, the SE-induced neuronal cell death is significantly reduced in the CA1 and the lateral septum, indicating that TRPC1/4 channels directly contribute to SE-induced neuronal cell death. Genetic ablation of TRPC5 also reduces SE-induced neuronal cell death in the CA1 and CA3 areas of the hippocampus.
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14
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Horak PC, Meisenhelter S, Song Y, Testorf ME, Kahana MJ, Viles WD, Bujarski KA, Connolly AC, Robbins AA, Sperling MR, Sharan AD, Worrell GA, Miller LR, Gross RE, Davis KA, Roberts DW, Lega B, Sheth SA, Zaghloul KA, Stein JM, Das SR, Rizzuto DS, Jobst BC. Interictal epileptiform discharges impair word recall in multiple brain areas. Epilepsia 2016; 58:373-380. [PMID: 27935031 DOI: 10.1111/epi.13633] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2016] [Indexed: 01/15/2023]
Abstract
OBJECTIVES Interictal epileptiform discharges (IEDs) have been linked to memory impairment, but the spatial and temporal dynamics of this relationship remain elusive. In the present study, we aim to systematically characterize the brain areas and times at which IEDs affect memory. METHODS Eighty epilepsy patients participated in a delayed free recall task while undergoing intracranial electroencephalography (EEG) monitoring. We analyzed the locations and timing of IEDs relative to the behavioral data in order to measure their effects on memory. RESULTS Overall IED rates did not correlate with task performance across subjects (r = 0.03, p = 0.8). However, at a finer temporal scale, within-subject memory was negatively affected by IEDs during the encoding and recall periods of the task but not during the rest and distractor periods (p < 0.01, p < 0.001, p = 0.3, and p = 0.8, respectively). The effects of IEDs during encoding and recall were stronger in the left hemisphere than in the right (p < 0.05). Of six brain areas analyzed, IEDs in the inferior-temporal, medial-temporal, and parietal areas significantly affected memory (false discovery rate < 0.05). SIGNIFICANCE These findings reveal a network of brain areas sensitive to IEDs with key nodes in temporal as well as parietal lobes. They also demonstrate the time-dependent effects of IEDs in this network on memory.
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Affiliation(s)
- Peter C Horak
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A
| | - Stephen Meisenhelter
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A
| | - Yinchen Song
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.,Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A
| | - Markus E Testorf
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.,Thayer School of Engineering at Dartmouth, Hanover, New Hampshire, U.S.A
| | - Michael J Kahana
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - Weston D Viles
- Department of Biomedical Data Science, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A
| | - Krzysztof A Bujarski
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.,Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A
| | - Andrew C Connolly
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A
| | - Ashlee A Robbins
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A
| | - Michael R Sperling
- Department of Neurology, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, U.S.A
| | - Ashwini D Sharan
- Department of Neurological Surgery, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, U.S.A
| | - Gregory A Worrell
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - Laura R Miller
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, U.S.A.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, U.S.A
| | - Robert E Gross
- Department of Neurosurgery, Emory University Hospital, Atlanta, Georgia, U.S.A
| | - Kathryn A Davis
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - David W Roberts
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.,Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A.,Department of Neurosurgery, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A
| | - Bradley Lega
- Department of Neurosurgery, University of Texas Southwestern Medical Center, Dallas, Texas, U.S.A
| | - Sameer A Sheth
- Department of Neurosurgery, Columbia University Medical Center, New York, New York, U.S.A
| | - Kareem A Zaghloul
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, U.S.A
| | - Joel M Stein
- Department of Neuroradiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - Sandhitsu R Das
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - Daniel S Rizzuto
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A
| | - Barbara C Jobst
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, U.S.A.,Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, U.S.A
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15
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Scarlatelli-Lima AV, Sukys-Claudino L, Watanabe N, Guarnieri R, Walz R, Lin K. How do people with drug-resistant mesial temporal lobe epilepsy sleep? A clinical and video-EEG with EOG and submental EMG for sleep staging study. eNeurologicalSci 2016; 4:34-41. [PMID: 29430547 PMCID: PMC5803108 DOI: 10.1016/j.ensci.2016.06.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 05/23/2016] [Accepted: 06/08/2016] [Indexed: 11/29/2022] Open
Abstract
This study aimed to assess subjective and objective sleep parameters in a homogeneous group of drug-resistant mesial temporal lobe epilepsy (MTLE) patients through internationally validated clinical questionnaires, video-electroencephalographic (VEEG) and polysomnographic (PSG) studies. Fifty-six patients with definite diagnosis of MTLE who were candidates for epilepsy surgery underwent a detailed clinical history, the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Stanford Sleepiness Scale (SSS), neurological examination, 1.5 T brain magnetic resonance imaging, VEEG and PSG. Sixteen percent of patients reported significant daytime sleepiness as measured by ESS and 27% reported low levels of sleep quality as measured by PSQI. Patients with medically resistant epilepsy by MTLE showed increased wakefulness after sleep onset (WASO) with mean ± standard deviation of 17.4 ± 15.6, longer non-rapid eye movement (NREM) 1 (7.5 ± 4.6%) and NREM3 sleep (26.6 ± 11.8%), abnormal rapid eye movement (REM) latency in 30/56 patients, shorter REM sleep (16.7 ± 6.6%), and abnormal alpha delta patterns were observed in 41/56 patients. The analysis of interictal epileptic discharges (IEDs) evidenced highest spiking rate during NREM3 sleep and higher concordance with imaging data when IEDs were recorded in sleep, mainly during REM sleep. We concluded that patients with MTLE showed disrupted sleep architecture that may result in daytime dysfunction and sleep complaints. Furthermore, NREM sleep activated focal IEDs and them - when recorded during sleep - had higher localizing value.
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Affiliation(s)
| | - Lucia Sukys-Claudino
- Centro de Epilepsia de Santa Catarina (CEPESC), Hospital Governador Celso Ramos (HGCR), Florianópolis, SC, Brazil
- Serviço de Neurologia, Departamento de Clínica Médica, Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
- Centro de Neurociências Aplicadas (CeNAp), Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
| | - Nancy Watanabe
- Centro de Neurociências Aplicadas (CeNAp), Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
| | - Ricardo Guarnieri
- Centro de Epilepsia de Santa Catarina (CEPESC), Hospital Governador Celso Ramos (HGCR), Florianópolis, SC, Brazil
- Centro de Neurociências Aplicadas (CeNAp), Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
| | - Roger Walz
- Centro de Epilepsia de Santa Catarina (CEPESC), Hospital Governador Celso Ramos (HGCR), Florianópolis, SC, Brazil
- Serviço de Neurologia, Departamento de Clínica Médica, Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
- Centro de Neurociências Aplicadas (CeNAp), Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
| | - Katia Lin
- Centro de Epilepsia de Santa Catarina (CEPESC), Hospital Governador Celso Ramos (HGCR), Florianópolis, SC, Brazil
- Serviço de Neurologia, Departamento de Clínica Médica, Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
- Centro de Neurociências Aplicadas (CeNAp), Hospital Universitário, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil
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16
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Abstract
Ever since the implementation of invasive EEG recordings in the clinical setting, it has been perceived that a considerable proportion of epileptic discharges present at a cortical level are missed by routine scalp EEG recordings. Several in vitro, in vivo, and simulation studies have been performed in the past decades aiming to clarify the interrelations of cortical sources with their scalp and invasive EEG correlates. The amplitude ratio of cortical potentials to their scalp EEG correlates, the extent of the cortical area involved in the discharge, as well as the localization of the cortical source and its geometry have been each independently linked to the recording of the cortical discharge with scalp electrodes. The need to elucidate these interrelations has been particularly imperative in the field of epilepsy surgery with its rapidly growing EEG-based localization technologies. Simultaneous multiscale EEG recordings with scalp, subdural and/or depth electrodes, applied in presurgical epilepsy workup, offer an excellent opportunity to shed some light to this fundamental issue. Whereas past studies have considered predominantly neocortical sources in the context of temporal lobe epilepsy, current investigations have included deep sources, as in mesial temporal epilepsy, as well as extratemporal sources. Novel computational tools may serve to provide surrogates for the shortcomings of EEG recording methodology and facilitate further developments in modern electrophysiology.
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Affiliation(s)
- Georgia Ramantani
- Division of Child Neurology, University Children's Hospital, Steinwiesstrasse 75, 8032 Zürich, Switzerland; Swiss Epilepsy Center, Bleulerstrasse 60, 8008 Zürich, Switzerland; Centre de Recherche en Automatique de Nancy (CRAN), University of Lorraine, CNRS, UMR 7039 Vandoeuvre, France.
| | - Louis Maillard
- Centre de Recherche en Automatique de Nancy (CRAN), University of Lorraine, CNRS, UMR 7039 Vandoeuvre, France; Department of Neurology, Central University Hospital, CHU de Nancy, Nancy, France; Medical Faculty, University of Lorraine, Nancy, France
| | - Laurent Koessler
- Centre de Recherche en Automatique de Nancy (CRAN), University of Lorraine, CNRS, UMR 7039 Vandoeuvre, France; Department of Neurology, Central University Hospital, CHU de Nancy, Nancy, France
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17
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Abstract
Ever since the implementation of invasive EEG recordings in the clinical setting, it has been perceived that a considerable proportion of epileptic discharges present at a cortical level are missed by routine scalp EEG recordings. Several in vitro, in vivo, and simulation studies have been performed in the past decades aiming to clarify the interrelations of cortical sources with their scalp and invasive EEG correlates. The amplitude ratio of cortical potentials to their scalp EEG correlates, the extent of the cortical area involved in the discharge, as well as the localization of the cortical source and its geometry have been each independently linked to the recording of the cortical discharge with scalp electrodes. The need to elucidate these interrelations has been particularly imperative in the field of epilepsy surgery with its rapidly growing EEG-based localization technologies. Simultaneous multiscale EEG recordings with scalp, subdural and/or depth electrodes, applied in presurgical epilepsy workup, offer an excellent opportunity to shed some light to this fundamental issue. Whereas past studies have considered predominantly neocortical sources in the context of temporal lobe epilepsy, current investigations have included deep sources, as in mesial temporal epilepsy, as well as extratemporal sources. Novel computational tools may serve to provide surrogates for the shortcomings of EEG recording methodology and facilitate further developments in modern electrophysiology.
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18
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Goncharova II, Alkawadri R, Gaspard N, Duckrow RB, Spencer DD, Hirsch LJ, Spencer SS, Zaveri HP. The relationship between seizures, interictal spikes and antiepileptic drugs. Clin Neurophysiol 2016; 127:3180-3186. [PMID: 27292227 DOI: 10.1016/j.clinph.2016.05.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 05/01/2016] [Accepted: 05/16/2016] [Indexed: 01/09/2023]
Abstract
OBJECTIVE A considerable decrease in spike rate accompanies antiepileptic drug (AED) taper during intracranial EEG (icEEG) monitoring. Since spike rate during icEEG monitoring can be influenced by surgery to place intracranial electrodes, we studied spike rate during long-term scalp EEG monitoring to further test this observation. METHODS We analyzed spike rate, seizure occurrence and AED taper in 130 consecutive patients over an average of 8.9days (range 5-17days). RESULTS We observed a significant relationship between time to the first seizure, spike rate, AED taper and seizure occurrence (F (3,126)=19.77, p<0.0001). A high spike rate was related to a longer time to the first seizure. Further, in a subset of 79 patients who experienced seizures on or after day 4 of monitoring, spike rate decreased initially from an on- to off-AEDs epoch (from 505.0 to 382.3 spikes per hour, p<0.00001), and increased thereafter with the occurrence of seizures. CONCLUSIONS There is an interplay between seizures, spikes and AEDs such that spike rate decreases with AED taper and increases after seizure occurrence. SIGNIFICANCE The direct relationship between spike rate and AEDs and between spike rate and time to the first seizure suggests that spikes are a marker of inhibition rather than excitation.
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Affiliation(s)
- Irina I Goncharova
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Rafeed Alkawadri
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Nicolas Gaspard
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Robert B Duckrow
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Neurosurgery, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Dennis D Spencer
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Lawrence J Hirsch
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Susan S Spencer
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Neurosurgery, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Hitten P Zaveri
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT 06520, USA.
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19
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Bajorat R, Goerss D, Brenndörfer L, Schwabe L, Köhling R, Kirschstein T. Interplay between interictal spikes and behavioral seizures in young, but not aged pilocarpine-treated epileptic rats. Epilepsy Behav 2016; 57:90-94. [PMID: 26926072 DOI: 10.1016/j.yebeh.2016.01.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 01/11/2016] [Accepted: 01/12/2016] [Indexed: 10/22/2022]
Abstract
Interictal spike activity is commonly observed in the EEG of patients with epilepsy, but the causal interrelationship between interictal spikes and behavioral seizures is poorly understood. We performed long-term video-EEG monitoring of 16 epileptic rats after pilocarpine-induced status epilepticus and five control animals. To quantify the interplay between periods of spikes and seizures, we calculated the time spent with spikes as well as the time spent with seizures for each animal. Within a given subject, we found a significant correlation between these two measures in 7/11 young epileptic rats (<400 days); this correlation was positive in six cases and negative in one. By contrast, none of five aged pilocarpine-treated animals exhibited significant correlation coefficients between spike periods and seizures (>600 days, P<0.05). Instead, aged epileptic rats showed a prominent predominance for either spike periods or seizures, which might explain the absence of significant correlation in this population. We found that there is a significant interplay between interictal periods of spikes and behavioral seizures in young epileptic animals, but this association is absent during aging.
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Affiliation(s)
- Rika Bajorat
- Oscar Langendorff Institute of Physiology, University of Rostock, Germany; Dept. of Anesthesiology and Intensive Medicine, University of Rostock, Germany.
| | - Doreen Goerss
- Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
| | - Linda Brenndörfer
- Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
| | - Lars Schwabe
- Dept. of Computer Science and Electrical Engineering, University of Rostock, Germany.
| | - Rüdiger Köhling
- Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
| | - Timo Kirschstein
- Oscar Langendorff Institute of Physiology, University of Rostock, Germany.
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20
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Strobbe G, Carrette E, López JD, Montes Restrepo V, Van Roost D, Meurs A, Vonck K, Boon P, Vandenberghe S, van Mierlo P. Electrical source imaging of interictal spikes using multiple sparse volumetric priors for presurgical epileptogenic focus localization. Neuroimage Clin 2016; 11:252-263. [PMID: 26958464 PMCID: PMC4773507 DOI: 10.1016/j.nicl.2016.01.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 10/09/2015] [Accepted: 01/17/2016] [Indexed: 11/07/2022]
Abstract
Electrical source imaging of interictal spikes observed in EEG recordings of patients with refractory epilepsy provides useful information to localize the epileptogenic focus during the presurgical evaluation. However, the selection of the time points or time epochs of the spikes in order to estimate the origin of the activity remains a challenge. In this study, we consider a Bayesian EEG source imaging technique for distributed sources, i.e. the multiple volumetric sparse priors (MSVP) approach. The approach allows to estimate the time courses of the intensity of the sources corresponding with a specific time epoch of the spike. Based on presurgical averaged interictal spikes in six patients who were successfully treated with surgery, we estimated the time courses of the source intensities for three different time epochs: (i) an epoch starting 50 ms before the spike peak and ending at 50% of the spike peak during the rising phase of the spike, (ii) an epoch starting 50 ms before the spike peak and ending at the spike peak and (iii) an epoch containing the full spike time period starting 50 ms before the spike peak and ending 230 ms after the spike peak. To identify the primary source of the spike activity, the source with the maximum energy from 50 ms before the spike peak till 50% of the spike peak was subsequently selected for each of the time windows. For comparison, the activity at the spike peaks and at 50% of the peaks was localized using the LORETA inversion technique and an ECD approach. Both patient-specific spherical forward models and patient-specific 5-layered finite difference models were considered to evaluate the influence of the forward model. Based on the resected zones in each of the patients, extracted from post-operative MR images, we compared the distances to the resection border of the estimated activity. Using the spherical models, the distances to the resection border for the MSVP approach and each of the different time epochs were in the same range as the LORETA and ECD techniques. We found distances smaller than 23 mm, with robust results for all the patients. For the finite difference models, we found that the distances to the resection border for the MSVP inversions of the full spike time epochs were generally smaller compared to the MSVP inversions of the time epochs before the spike peak. The results also suggest that the inversions using the finite difference models resulted in slightly smaller distances to the resection border compared to the spherical models. The results we obtained are promising because the MSVP approach allows to study the network of the estimated source-intensities and allows to characterize the spatial extent of the underlying sources. A Bayesian ESI technique is evaluated to localize interictal spike activity. Averaged spikes in six patients were used that were seizure free after surgery. We compared the technique with the LORETA an ECD technique. We evaluated both spherical and 5-layered finite difference forward models. Our approach is potentially useful to delineate the irritative zone.
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Affiliation(s)
- Gregor Strobbe
- Ghent University, Department of Electronics and Information Systems, MEDISIP, De Pintelaan 185, Building BB Floor 5, 9000 Ghent, Belgium; iMinds Medical IT Department, Belgium.
| | - Evelien Carrette
- Laboratory for Clinical and Experimental Neurophysiology, Ghent University Hospital, Ghent, Belgium.
| | - José David López
- SISTEMIC, Department of Electronic Engineering, Universidad de Antioquia UDEA, Calle 70 No. 52-21,Medellín, Colombia.
| | - Victoria Montes Restrepo
- Ghent University, Department of Electronics and Information Systems, MEDISIP, De Pintelaan 185, Building BB Floor 5, 9000 Ghent, Belgium; iMinds Medical IT Department, Belgium
| | - Dirk Van Roost
- Department of Neurosurgery, Ghent University Hospital, Ghent, Belgium.
| | - Alfred Meurs
- Laboratory for Clinical and Experimental Neurophysiology, Ghent University Hospital, Ghent, Belgium.
| | - Kristl Vonck
- Laboratory for Clinical and Experimental Neurophysiology, Ghent University Hospital, Ghent, Belgium.
| | - Paul Boon
- Laboratory for Clinical and Experimental Neurophysiology, Ghent University Hospital, Ghent, Belgium.
| | - Stefaan Vandenberghe
- Ghent University, Department of Electronics and Information Systems, MEDISIP, De Pintelaan 185, Building BB Floor 5, 9000 Ghent, Belgium; iMinds Medical IT Department, Belgium.
| | - Pieter van Mierlo
- Ghent University, Department of Electronics and Information Systems, MEDISIP, De Pintelaan 185, Building BB Floor 5, 9000 Ghent, Belgium; iMinds Medical IT Department, Belgium.
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21
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Behr C, Lévesque M, Ragsdale D, Avoli M. Lacosamide modulates interictal spiking and high-frequency oscillations in a model of mesial temporal lobe epilepsy. Epilepsy Res 2015; 115:8-16. [PMID: 26220372 PMCID: PMC4878889 DOI: 10.1016/j.eplepsyres.2015.05.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/28/2015] [Accepted: 05/12/2015] [Indexed: 01/19/2023]
Abstract
OBJECTIVE Nearly one third of patients presenting with mesial temporal lobe epilepsy (MTLE), the most prevalent lesion-related epileptic disorder in adulthood, do not respond to currently available antiepileptic medications. Thus, there is a need to identify and characterize new antiepileptic drugs. In this study, we used the pilocarpine model of MTLE to establish the effects of a third generation drug, lacosamide (LCM), on seizures, interictal spikes and high-frequency oscillations (HFOs, ripples: 80-200 Hz, fast ripples: 250-500 Hz). METHODS Sprague-Dawley rats (250-300 g) were injected with pilocarpine to induce a status epilepticus (SE) that was pharmacologically terminated after 1h. Eight pilocarpine-treated rats were then injected with LCM (30 mg/kg, i.p.) 4h after SE and daily for 14 days. Eight pilocarpine-treated rats were used as controls and treated with saline. Three days after SE, all rats were implanted with bipolar electrodes in the hippocampal CA3 region, entorhinal cortex (EC), dentate gyrus (DG) and subiculum and EEG-video monitored from day 4 to day 14 after SE. RESULTS LCM-treated animals showed lower rates of seizures (0.21 (± 0.11) seizures/day) than controls (2.6 (±0.57), p<0.05), and a longer latent period (LCM: 11 (± 1) days, controls: 6.25 (± 1), p<0.05). Rates of interictal spikes in LCM-treated rats were significantly lower than in controls in CA3 and subiculum (p<0.05). Rates of ripples and fast ripples associated with interictal spikes in CA3 and subiculum as well as rates of fast ripples occurring outside of interictal spikes in CA3 were also significantly lower in LCM-treated animals. In controls, interictal spikes and associated HFOs correlated to seizure clustering, while this was not the case for isolated HFOs. SIGNIFICANCE Our findings show that early treatment with LCM has powerful anti-ictogenic properties in the pilocarpine model of MTLE. These effects are accompanied by decreased rates of interictal spikes and associated HFOs. Isolated HFOs were also modulated by LCM, in a manner that appeared to be unrelated to its antiictogenic effects. These results thus suggest that distinct mechanisms may underlie interictal-associated and isolated HFOs in the pilocarpine model of MTLE.
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Affiliation(s)
- Charles Behr
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4
| | - Maxime Lévesque
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4
| | - David Ragsdale
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4
| | - Massimo Avoli
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4.
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Mittal S, Barkmeier D, Hua J, Pai DS, Fuerst D, Basha M, Loeb JA, Shah AK. Intracranial EEG analysis in tumor-related epilepsy: Evidence of distant epileptic abnormalities. Clin Neurophysiol 2015; 127:238-244. [PMID: 26493495 DOI: 10.1016/j.clinph.2015.06.028] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/04/2015] [Accepted: 06/10/2015] [Indexed: 01/12/2023]
Abstract
OBJECTIVE In patients with tumor-related epilepsy (TRE), surgery traditionally focuses on tumor resection; but identification and removal of associated epileptogenic zone may improve seizure outcome. Here, we study spatial relationship of tumor and seizure onset and early spread zone (SOSz). We also perform quantitative analysis of interictal epileptiform activities in patients with both TRE and non-lesional epilepsy in order to better understand the electrophysiological basis of epileptogenesis. METHODS Twenty-five patients (11 with TRE and 14 with non-lesional epilepsy) underwent staged surgery using intracranial electrodes. Tumors were outlined on MRI and images were coregistered with post-implantation CT images. For each electrode, distance to the nearest tumor margin was measured. Electrodes were categorized based on distance from tumor and involvement in seizure. Quantitative EEG analysis studying frequency, amplitude, power, duration and slope of interictal spikes was performed. RESULTS At least part of the SOSz was located beyond 1.5 cm from the tumor margin in 10/11 patients. Interictally, spike frequency and power were higher in the SOSz and spikes near tumor were smaller and less sharp. Interestingly, peritumoral electrodes had the highest spike frequencies and sharpest spikes, indicating greatest degree of epileptic synchrony. A complete resection of the SOSz resulted in excellent seizure outcome. CONCLUSIONS Seizure onset and early spread often involves brain areas distant from the tumor. SIGNIFICANCE Utilization of epilepsy surgery approach for TRE may provide better seizure outcome and study of the intracranial EEG may provide insight into pathophysiology of TRE.
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Affiliation(s)
- S Mittal
- Department of Neurosurgery, Wayne State University, Detroit, MI, USA; Department of Oncology, Wayne State University, Detroit, MI, USA; Comprehensive Epilepsy Center, Detroit Medical Center, Wayne State University, Detroit, MI, USA; Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA
| | - D Barkmeier
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, USA
| | - J Hua
- Department of Computer Science, Wayne State University, Detroit, MI, USA
| | - D S Pai
- Department of Computer Science, Wayne State University, Detroit, MI, USA
| | - D Fuerst
- Department of Neurology, Wayne State University, Detroit, MI, USA
| | - M Basha
- Comprehensive Epilepsy Center, Detroit Medical Center, Wayne State University, Detroit, MI, USA; Department of Neurology, Wayne State University, Detroit, MI, USA
| | - J A Loeb
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, USA; Department of Neurology and Rehabilitation, University of Illinois at Chicago, Chicago, IL, USA
| | - A K Shah
- Comprehensive Epilepsy Center, Detroit Medical Center, Wayne State University, Detroit, MI, USA; Department of Neurology, Wayne State University, Detroit, MI, USA.
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Sohrabpour A, Lu Y, Kankirawatana P, Blount J, Kim H, He B. Effect of EEG electrode number on epileptic source localization in pediatric patients. Clin Neurophysiol 2015; 126:472-80. [PMID: 25088733 PMCID: PMC4289666 DOI: 10.1016/j.clinph.2014.05.038] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 05/14/2014] [Accepted: 05/19/2014] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To investigate the relationship between EEG source localization and the number of scalp EEG recording channels. METHODS 128 EEG channel recordings of 5 pediatric patients with medically intractable partial epilepsy were used to perform source localization of interictal spikes. The results were compared with surgical resection and intracranial recordings. Various electrode configurations were tested and a series of computer simulations based on a realistic head boundary element model were also performed in order to further validate the clinical findings. RESULTS The improvement seen in source localization substantially decreases as the number of electrodes increases. This finding was evaluated using the surgical resection, intracranial recordings and computer simulation. It was also shown in the simulation that increasing the electrode numbers could remedy the localization error of deep sources. A plateauing effect was seen in deep and superficial sources with further increasing the electrode number. CONCLUSION The source localization is improved when electrode numbers increase, but the absolute improvement in accuracy decreases with increasing electrode number. SIGNIFICANCE Increasing the electrode number helps decrease localization error and thus can more ably assist the physician to better plan for surgical procedures.
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Affiliation(s)
- Abbas Sohrabpour
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Yunfeng Lu
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Pongkiat Kankirawatana
- Division of Pediatric Neurology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jeffrey Blount
- Division of Neurosurgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hyunmi Kim
- Division of Pediatric Neurology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Bin He
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA; Institute for Engineering in Medicine, University of Minnesota, Minneapolis, MN, USA.
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Lévesque M, Behr C, Avoli M. The anti-ictogenic effects of levetiracetam are mirrored by interictal spiking and high-frequency oscillation changes in a model of temporal lobe epilepsy. Seizure 2014; 25:18-25. [PMID: 25645630 DOI: 10.1016/j.seizure.2014.11.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 11/18/2014] [Accepted: 11/20/2014] [Indexed: 12/31/2022] Open
Abstract
PURPOSE Mesial temporal lobe epilepsy (MTLE) is the most prevalent type of partial epileptic disorders. In this study, we have analyzed the impact of levetiracetam (LEV) in the pilocarpine model of MTLE. METHODS Sprague-Dawley rats (n=19) were injected with pilocarpine (380 mg/kg, i.p.) to induce a status epilepticus. Twelve animals were used as controls and seven were treated with LEV. They were implanted with bipolar electrodes in the CA3 subfield of the hippocampus, entorhinal cortex (EC), dentate gyrus (DG) and subiculum and EEG-video monitored continuously from day 4 to day 14 after SE. RESULTS Only 29% of LEV-treated animals had seizures compared to all controls following a latent period that was similar in duration. Seizure rates were lower in LEV-treated animals. In LEV-treated animals without seizures, lower interictal spike rates were found in all regions compared to controls. Analysis of interictal high-frequency oscillations (HFO s) revealed that LEV-treated animals without seizures had lower rates of interictal spikes with ripples (80-200 Hz) in CA3, EC and subiculum (p<0.01), whereas rates of interictal spikes with fast ripples (250-500 Hz) were significantly lower in CA3 and subiculum, compared to controls. CONCLUSION Our findings indicate that the anti-ictogenic properties of LEV are mirrored by decreases of interictal spike rate in temporal lobe regions, and are accompanied by subregion-specific decreases of HFO occurrence in CA3 and subiculum. Overall, this evidence suggest that LEV may inhibit neural network activity in regions that are known to play important roles in MTLE.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, Montréal, Qc H3A 2B4, Canada
| | - Charles Behr
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, Montréal, Qc H3A 2B4, Canada
| | - Massimo Avoli
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, Montréal, Qc H3A 2B4, Canada.
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Nair S, Morse RP, Mott SH, Burroughs SA, Holmes GL. Transitory effect of spike and spike-and-wave discharges on EEG power in children. Brain Dev 2014; 36:505-9. [PMID: 23911277 PMCID: PMC3874075 DOI: 10.1016/j.braindev.2013.07.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/07/2013] [Accepted: 07/08/2013] [Indexed: 11/17/2022]
Abstract
BACKGROUND Spikes and spike-and-wave discharges on the EEG of children are a strong biomarker of epilepsy. There is increasing evidence that these EEG abnormalities also impair brain function and result in transitory cognitive impairment. Studies in animal models have shown that EEG spikes alters single cell firing and that such impairment in firing may extend beyond the duration of the spike-and-wave discharge. Whether interictal epileptiform discharges have lasting effects on EEG activity in humans is not known. METHODS AND RESULTS The EEGs of 60 consecutive children with focal or interictal spike-and-wave discharges were evaluated using power spectral analysis to determine if there were any changes in power spectra from before to after the interictal abnormalities. Neither focal spike-and-wave nor generalized spike-and-wave discharges had any effect on the EEG frequency or spectral power following the discharge. CONCLUSION While interictal EEG discharges temporarily alter neural activity during the duration of the spike-and-wave discharge, there is no evidence that alterations of spectral power continue beyond the duration of the interictal discharge. The effects of interictal activity on EEG rhythms therefore appear to be quite transient and confined to the duration of the interictal discharge.
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Affiliation(s)
- Swayamprabha Nair
- Department of Neurology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Hanover, NH, United States
| | - Richard P Morse
- Department of Neurology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Hanover, NH, United States
| | - Stephen H Mott
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, United States
| | - Scott A Burroughs
- Department of Neurology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Hanover, NH, United States
| | - Gregory L Holmes
- Department of Neurology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Hanover, NH, United States; Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, United States.
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Salami P, Lévesque M, Benini R, Behr C, Gotman J, Avoli M. Dynamics of interictal spikes and high-frequency oscillations during epileptogenesis in temporal lobe epilepsy. Neurobiol Dis 2014; 67:97-106. [PMID: 24686305 DOI: 10.1016/j.nbd.2014.03.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/10/2014] [Accepted: 03/20/2014] [Indexed: 02/01/2023] Open
Abstract
Mesial temporal lobe epilepsy (MTLE) is characterized in humans and in animal models by a seizure-free latent phase that follows an initial brain insult; this period is presumably associated to plastic changes in temporal lobe excitability and connectivity. Here, we analyzed the occurrence of interictal spikes and high frequency oscillations (HFOs; ripples: 80-200Hz and fast ripples: 250-500Hz) from 48h before to 96h after the first seizure in the rat pilocarpine model of MTLE. Interictal spikes recorded with depth EEG electrodes from the hippocampus CA3 area and entorhinal cortex (EC) were classified as type 1 (characterized by a spike followed by a wave) or type 2 (characterized by a spike with no wave). We found that: (i) there was a switch in the distribution of both types of interictal spikes before and after the occurrence of the first seizure; during the latent phase both types of interictal spikes predominated in the EC whereas during the chronic phase both types of spikes predominated in CA3; (ii) type 2 spike duration decreased in both regions from the latent to the chronic phase; (iii) type 2 spikes associated to fast ripples occurred at higher rates in EC compared to CA3 during the latent phase while they occurred at similar rates in both regions in the chronic phase; and (iv) rates of fast ripples outside of spikes were higher in EC compared to CA3 during the latent phase. Our findings demonstrate that the transition from the latent to the chronic phase is paralleled by dynamic changes in interictal spike and HFO expression in EC and CA3. We propose that these changes may represent biomarkers of epileptogenicity in MTLE.
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Affiliation(s)
- Pariya Salami
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada
| | - Maxime Lévesque
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada
| | - Ruba Benini
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada
| | - Charles Behr
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada
| | - Jean Gotman
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada
| | - Massimo Avoli
- Montreal Neurological Institute and Departments of Neurology & Neurosurgery and of Physiology, McGill University, Montréal, H3A 2B4 QC, Canada.
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27
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Behr C, D'Antuono M, Hamidi S, Herrington R, Lévesque M, Salami P, Shiri Z, Köhling R, Avoli M. Limbic networks and epileptiform synchronization: the view from the experimental side. Int Rev Neurobiol 2014; 114:63-87. [PMID: 25078499 DOI: 10.1016/b978-0-12-418693-4.00004-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In this review, we summarize findings obtained in acute and chronic epilepsy models and in particular experiments that have revealed how neuronal networks in the limbic system-which is closely involved in the pathophysiogenesis of mesial temporal lobe epilepsy (MTLE)-produce hypersynchronous discharges. MTLE is often associated with a typical pattern of brain damage known as mesial temporal sclerosis, and it is one of the most refractory forms of partial epilepsy in adults. Specifically, we will address the cellular and pharmacological features of abnormal electrographic events that, as in MTLE patients, can occur in in vivo and in vitro animal models; these include interictal and ictal discharges along with high-frequency oscillations. In addition, we will consider how different limbic structures made hyperexcitable by acute pharmacological manipulations interact during epileptiform discharge generation. We will also review the electrographic characteristics of two types of seizure onsets that are most commonly seen in human and experimental MTLE as well as in in vitro models of epileptiform synchronization. Finally, we will address the role played by neurosteroids in reducing epileptiform synchronization and in modulating epileptogenesis.
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Affiliation(s)
- Charles Behr
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada
| | - Margherita D'Antuono
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada
| | - Shabnam Hamidi
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada
| | - Rochelle Herrington
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada
| | - Maxime Lévesque
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada
| | - Pariya Salami
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada
| | - Zahra Shiri
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada
| | - Rüdiger Köhling
- Institute of Physiology, University of Rostock, Rostock, Germany
| | - Massimo Avoli
- Department of Neurology, Neurosurgery and Physiology, Montréal Neurological Institute, Montréal, Québec, Canada; Department of Experimental Medicine, Facoltà di Medicina e Odontoiatria, Sapienza Università di Roma, Roma, Italy.
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Hernan AE, Alexander A, Jenks KR, Barry J, Lenck-Santini PP, Isaeva E, Holmes GL, Scott RC. Focal epileptiform activity in the prefrontal cortex is associated with long-term attention and sociability deficits. Neurobiol Dis 2013; 63:25-34. [PMID: 24269731 DOI: 10.1016/j.nbd.2013.11.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/10/2013] [Accepted: 11/12/2013] [Indexed: 10/26/2022] Open
Abstract
There is a well-described association between childhood epilepsy and pervasive cognitive and behavioral deficits. Often these children not only have ictal EEG events, but also frequent interictal abnormalities. The precise role of these interictal discharges in cognition remains unclear. In order to understand the relationship between frequent epileptiform discharges during neurodevelopment and cognition later in life, we developed a model of frequent focal interictal spikes (IIS). Postnatal day (p) 21 rats received injections of bicuculline methiodine into the prefrontal cortex (PFC). Injections were repeated in order to achieve 5 consecutive days of transient inhibitory/excitatory imbalance resulting in IIS. Short-term plasticity (STP) and behavioral outcomes were studied in adulthood. IIS is associated with a significant increase in STP bilaterally in the PFC. IIS rats did not show working memory deficits, but rather showed marked inattentiveness without significant alterations in motivation, anxiety or hyperactivity. Rats also demonstrated significant deficits in social behavior. We conclude that GABAergic blockade during early-life and resultant focal IIS in the PFC disrupt neural networks and are associated with long-term consequences for behavior at a time when IIS are no longer present, and thus may have important implications for ADHD and autism spectrum disorder associated with childhood epilepsy.
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Affiliation(s)
- Amanda E Hernan
- Department of Neurology, Program in Experimental and Molecular Medicine Dartmouth, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA; Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA 05405.
| | - Abigail Alexander
- Department of Neurology, Program in Experimental and Molecular Medicine Dartmouth, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Kyle R Jenks
- Department of Neurology, Program in Experimental and Molecular Medicine Dartmouth, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Jeremy Barry
- Department of Neurology, Program in Experimental and Molecular Medicine Dartmouth, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA; Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA 05405
| | | | - Elena Isaeva
- State Key Laboratory for Molecular and Cellular Biology, Kiev 01601, Ukraine; Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA 05405
| | - Gregory L Holmes
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA 05405
| | - Rod C Scott
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA 05405; University College London, Institute of Child Health, London WC1N 1EH, UK.
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Jeong W, Kim JS, Chung CK. Localization of MEG pathologic gamma oscillations in adult epilepsy patients with focal cortical dysplasia. Neuroimage Clin 2013; 3:507-14. [PMID: 24273733 PMCID: PMC3830072 DOI: 10.1016/j.nicl.2013.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 09/09/2013] [Accepted: 09/26/2013] [Indexed: 12/02/2022]
Abstract
We aimed to evaluate the clinical value of gamma oscillations in MEG for intractable neocortical epilepsy patients with cortical dysplasia by comparing gamma and interictal spike events. A retrospective analysis of MEG recordings of 30 adult neocortical epilepsy patients was performed. Gamma (30–70 Hz) and interictal spike events were independently identified, their independent or concurrent presence determined, and their source localization rates compared. Of 30 patients, gamma activities were detected in 28 patients and interictal spikes in 24 patients. Gamma events alone appeared in 5 patients, interictal spikes alone in 1 patient, and no events in 1 patient. Gamma co-occurred with interictal spikes in 20.1 ± 22.1% and interictal spikes co-occurred with gamma in 15.0 ± 19.2%. Rates of event localization within the resection cavity were significantly different (p = 0.042) between gamma (63.3 ± 32.6%) and interictal spike (47.0 ± 41.3%) events. In 4 of the 5 gamma-only patients the mean localization rate was 42.5%. Compared with the interictal spike localization rate, 4 of 9 seizure-free patients had higher gamma localization rates, 4 had the same rate, and 1 had a lower rate. Individual gamma events can be detected independently from interictal spike presence. Gamma can be localized to the resection cavity at least comparably to or more frequently than that from interictal spikes. Even when interictal spikes were undetected, gamma sources were localized to the resection cavity. Gamma oscillations may be a useful indicator of epileptogenic focus. Gamma oscillations can be detected independently from interictal spikes in MEG. Gamma events were localized to the seizure onset zone and resting state network area. Gamma oscillation in MEG can be an important indicator of an epileptogenic focus.
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Affiliation(s)
- Woorim Jeong
- MEG Center, Department of Neurosurgery, Seoul National University Hospital, Seoul, South Korea
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Mohamed IS, Otsubo H, Ferrari P, Sharma R, Ochi A, Elliott I, Go C, Chuang S, Rutka J, Snead C, Cheyne D. Source localization of interictal spike-locked neuromagnetic oscillations in pediatric neocortical epilepsy. Clin Neurophysiol 2013; 124:1517-27. [PMID: 23523111 DOI: 10.1016/j.clinph.2013.01.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 01/28/2013] [Accepted: 01/30/2013] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To evaluate the utility of an event-related beamforming (ERB) algorithm in source localization of interictal discharges. METHODS We analyzed interictal magnetoencephalography data in 35 children with intractable neocortical epilepsy. We used a spatiotemporal beamforming method to estimate the spatial distribution of source power in individual interictal spikes. We compared ERB results to source localization using the equivalent current dipole model and to the seizure onset zones on intracranial EEG. RESULTS Focal beamformer localization was observed in 66% of patients and multifocal in the remaining 34%. ERB localized within 2 cm of the equivalent current dipole cluster centroid in 77% of the patients. ERB localization was concordant with the seizure onset zone on intracranial EEG at the gyral level in 69% of patients. Focal ERB localization area was included in the resection margin in 22/23 patients. However, focal ERB localization was not statistically associated with better surgical outcome. CONCLUSIONS ERB can be used for source localization of interictal spikes and can be predictive of the ictal onset zone in a subset of patients with neocortical epilepsy. SIGNIFICANCE These results support the utility of beamformer source localization as a fast semi-automated method for source localization of interictal spikes and planning the surgical strategy.
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Affiliation(s)
- Ismail S Mohamed
- Department of Pediatrics, IWK Health Center, Dalhousie University, Halifax, NS, Canada.
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