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Labate A, Bertino S, Morabito R, Smorto C, Militi A, Cammaroto S, Anfuso C, Tomaiuolo F, Tonin P, Marino S, Cerasa A, Quartarone A. MR-Guided Focused Ultrasound for Refractory Epilepsy: Where Are We Now? J Clin Med 2023; 12:7070. [PMID: 38002683 PMCID: PMC10672423 DOI: 10.3390/jcm12227070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
Epilepsy is one of the most common neurological diseases in both adults and children. Despite improvements in medical care, 20 to 30% of patients are still resistant to the best medical treatment. The quality of life, neurologic morbidity, and even mortality of patients are significantly impacted by medically intractable epilepsy. Nowadays, conservative therapeutic approaches consist of increasing medication dosage, changing to a different anti-seizure drug as monotherapy, and combining different antiseizure drugs using an add-on strategy. However, such measures may not be sufficient to efficiently control seizure recurrence. Resective surgery, ablative procedures and non-resective neuromodulatory (deep-brain stimulation, vagus nerve stimulation) treatments are the available treatments for these kinds of patients. However, invasive procedures may involve lengthy inpatient stays for the patients, risks of long-term neurological impairment, general anesthesia, and other possible surgery-related complications (i.e., hemorrhage or infection). In the last few years, MR-guided focused ultrasound (MRgFUS) has been proposed as an emerging treatment for neurological diseases because of technological advancements and the goal of minimally invasive neurosurgery. By outlining the current knowledge obtained from both preclinical and clinical studies and discussing the technical opportunities of this therapy for particular epileptic phenotypes, in this perspective review, we explore the various mechanisms and potential applications (thermoablation, blood-brain barrier opening for drug delivery, neuromodulation) of high- and low-intensity ultrasound, highlighting possible novel strategies to treat drug-resistant epileptic patients who are not eligible or do not accept currently established surgical approaches. Taken together, the available studies support a possible role for lesional treatment over the anterior thalamus with high-intensity ultrasound and neuromodulation of the hippocampus via low-intensity ultrasound in refractory epilepsy. However, more studies, likely conceiving epilepsy as a network disorder and bridging together different scales and modalities, are required to make ultrasound delivery strategies meaningful, effective, and safe.
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Affiliation(s)
- Angelo Labate
- Neurophysiopathology and Movement Disorders Unit, BIOMORF Department, University of Messina, 98124 Messina, Italy;
| | - Salvatore Bertino
- Department of Clinical and Experimental Medicine, University of Messina, 98122 Messina, Italy; (S.B.); (F.T.)
| | - Rosa Morabito
- IRCCS Centro Neurolesi “Bonino Pulejo”, 98124 Messina, Italy; (R.M.); (C.S.); (A.M.); (S.C.); (C.A.); (S.M.); (A.Q.)
| | - Chiara Smorto
- IRCCS Centro Neurolesi “Bonino Pulejo”, 98124 Messina, Italy; (R.M.); (C.S.); (A.M.); (S.C.); (C.A.); (S.M.); (A.Q.)
| | - Annalisa Militi
- IRCCS Centro Neurolesi “Bonino Pulejo”, 98124 Messina, Italy; (R.M.); (C.S.); (A.M.); (S.C.); (C.A.); (S.M.); (A.Q.)
| | - Simona Cammaroto
- IRCCS Centro Neurolesi “Bonino Pulejo”, 98124 Messina, Italy; (R.M.); (C.S.); (A.M.); (S.C.); (C.A.); (S.M.); (A.Q.)
| | - Carmelo Anfuso
- IRCCS Centro Neurolesi “Bonino Pulejo”, 98124 Messina, Italy; (R.M.); (C.S.); (A.M.); (S.C.); (C.A.); (S.M.); (A.Q.)
| | - Francesco Tomaiuolo
- Department of Clinical and Experimental Medicine, University of Messina, 98122 Messina, Italy; (S.B.); (F.T.)
| | | | - Silvia Marino
- IRCCS Centro Neurolesi “Bonino Pulejo”, 98124 Messina, Italy; (R.M.); (C.S.); (A.M.); (S.C.); (C.A.); (S.M.); (A.Q.)
| | - Antonio Cerasa
- S.Anna Institute, 88900 Crotone, Italy;
- Institute for Biomedical Research and Innovation (IRIB), National Research Council of Italy, 98164 Messina, Italy
- Pharmacotechnology Documentation and Transfer Unit, Preclinical and Translational Pharmacology, Department of Pharmacy, Health Science and Nutrition, University of Calabria, 87036 Rende, Italy
| | - Angelo Quartarone
- IRCCS Centro Neurolesi “Bonino Pulejo”, 98124 Messina, Italy; (R.M.); (C.S.); (A.M.); (S.C.); (C.A.); (S.M.); (A.Q.)
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Huels ER, Kafashan M, Hickman LB, Ching S, Lin N, Lenze EJ, Farber NB, Avidan MS, Hogan RE, Palanca BJA. Central-positive complexes in ECT-induced seizures: Possible evidence for thalamocortical mechanisms. Clin Neurophysiol 2023; 146:77-86. [PMID: 36549264 PMCID: PMC10273093 DOI: 10.1016/j.clinph.2022.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 10/20/2022] [Accepted: 11/27/2022] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Central-positive complexes (CPCs) are elicited during electroconvulsive therapy (ECT) as generalized high-amplitude waveforms with maximum positive voltage over the vertex. While these complexes have been qualitatively assessed in previous literature, quantitative analyses are lacking. This study aims to characterize CPCs across temporal, spatial, and spectral domains. METHODS High-density 64-electrode electroencephalogram (EEG) recordings during 50 seizures acquired from 11 patients undergoing right unilateral ECT allowed for evaluation of spatiotemporal characteristics of CPCs via source localization and spectral analysis. RESULTS Peak-amplitude CPC scalp topology was consistent across seizures, showing maximal positive polarity over the midline fronto-central region and maximal negative polarity over the suborbital regions. The sources of these peak potentials were localized to the bilateral medial thalamus and cingulate cortical regions. Delta, beta, and gamma oscillations were correlated with the peak amplitude of CPCs during seizures induced during ketamine, whereas delta and gamma oscillations were associated with CPC peaks during etomidate anesthesia (excluding the dose-charge titration). CONCLUSIONS Our findings demonstrate the consistency of CPC presence across participant, stimulus charge, time, and anesthetic agent, with peaks localized to bilateral medial thalamus and cingulate cortical regions and associated with delta, beta, and gamma band oscillations (depending on the anesthetic condition). SIGNIFICANCE The consistency and reproducibility of CPCs offers ECT as a new avenue for studying the dynamics of generalized seizure activity and thalamocortical networks.
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Affiliation(s)
- Emma R Huels
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA; Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA; Center for Consciousness Science, University of Michigan, Ann Arbor, MI, USA
| | - MohammadMehdi Kafashan
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Center on Biological Rhythms and Sleep, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - L Brian Hickman
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - ShiNung Ching
- Department of Electrical & Systems Engineering, Washington University in St. Louis, St. Louis, MO, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Nan Lin
- Department of Mathematics and Statistics, Washington University in St. Louis, St. Louis, MO, USA
| | - Eric J Lenze
- Department of Psychiatry, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Nuri B Farber
- Department of Psychiatry, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Michael S Avidan
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Department of Psychiatry, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - R Edward Hogan
- Department of Neurology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Ben Julian A Palanca
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Center on Biological Rhythms and Sleep, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Department of Psychiatry, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA; Neuroimaging Labs Research Center, Washington University School of Medicine in St. Louis, St. Louis, MO, USA.
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Zheng B, Liu DD, Theyel BB, Abdulrazeq H, Kimata AR, Lauro PM, Asaad WF. Thalamic neuromodulation in epilepsy: A primer for emerging circuit-based therapies. Expert Rev Neurother 2023; 23:123-140. [PMID: 36731858 DOI: 10.1080/14737175.2023.2176752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Epilepsy is a common, often debilitating disease of hyperexcitable neural networks. While medically intractable cases may benefit from surgery, there may be no single, well-localized focus for resection or ablation. In such cases, approaching the disease from a network-based perspective may be beneficial. AREAS COVERED Herein, the authors provide a narrative review of normal thalamic anatomy and physiology and propose general strategies for preventing and/or aborting seizures by modulating this structure. Additionally, they make specific recommendations for targeting the thalamus within different contexts, motivated by a more detailed discussion of its distinct nuclei and their respective connectivity. By describing important principles governing thalamic function and its involvement in seizure networks, the authors aim to provide a primer for those now entering this fast-growing field of thalamic neuromodulation for epilepsy. EXPERT OPINION The thalamus is critically involved with the function of many cortical and subcortical areas, suggesting it may serve as a compelling node for preventing or aborting seizures, and so it has increasingly been targeted for the surgical treatment of epilepsy. As various thalamic neuromodulation strategies for seizure control are developed, there is a need to ground such interventions in a mechanistic, circuit-based framework.
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Affiliation(s)
- Bryan Zheng
- The Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Neurosurgery, Rhode Island Hospital, Providence, RI, USA
| | - David D Liu
- The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Brian B Theyel
- Department of Psychiatry, Rhode Island Hospital, Providence, RI, USA.,Department of Neuroscience, Brown University, Providence, RI, USA
| | - Hael Abdulrazeq
- Department of Neurosurgery, Rhode Island Hospital, Providence, RI, USA
| | - Anna R Kimata
- The Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Neurosurgery, Rhode Island Hospital, Providence, RI, USA
| | - Peter M Lauro
- The Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Neuroscience, Brown University, Providence, RI, USA
| | - Wael F Asaad
- Department of Neurosurgery, Rhode Island Hospital, Providence, RI, USA.,Department of Neuroscience, Brown University, Providence, RI, USA.,The Carney Institute for Brain Science, Brown University, Providence, RI, USA.,The Norman Prince Neurosciences Institute, Rhode Island Hospital, Providence, RI, USA
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Piper RJ, Richardson RM, Worrell G, Carmichael DW, Baldeweg T, Litt B, Denison T, Tisdall MM. Towards network-guided neuromodulation for epilepsy. Brain 2022; 145:3347-3362. [PMID: 35771657 PMCID: PMC9586548 DOI: 10.1093/brain/awac234] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 05/30/2022] [Accepted: 06/16/2022] [Indexed: 11/30/2022] Open
Abstract
Epilepsy is well-recognized as a disorder of brain networks. There is a growing body of research to identify critical nodes within dynamic epileptic networks with the aim to target therapies that halt the onset and propagation of seizures. In parallel, intracranial neuromodulation, including deep brain stimulation and responsive neurostimulation, are well-established and expanding as therapies to reduce seizures in adults with focal-onset epilepsy; and there is emerging evidence for their efficacy in children and generalized-onset seizure disorders. The convergence of these advancing fields is driving an era of 'network-guided neuromodulation' for epilepsy. In this review, we distil the current literature on network mechanisms underlying neurostimulation for epilepsy. We discuss the modulation of key 'propagation points' in the epileptogenic network, focusing primarily on thalamic nuclei targeted in current clinical practice. These include (i) the anterior nucleus of thalamus, now a clinically approved and targeted site for open loop stimulation, and increasingly targeted for responsive neurostimulation; and (ii) the centromedian nucleus of the thalamus, a target for both deep brain stimulation and responsive neurostimulation in generalized-onset epilepsies. We discuss briefly the networks associated with other emerging neuromodulation targets, such as the pulvinar of the thalamus, piriform cortex, septal area, subthalamic nucleus, cerebellum and others. We report synergistic findings garnered from multiple modalities of investigation that have revealed structural and functional networks associated with these propagation points - including scalp and invasive EEG, and diffusion and functional MRI. We also report on intracranial recordings from implanted devices which provide us data on the dynamic networks we are aiming to modulate. Finally, we review the continuing evolution of network-guided neuromodulation for epilepsy to accelerate progress towards two translational goals: (i) to use pre-surgical network analyses to determine patient candidacy for neurostimulation for epilepsy by providing network biomarkers that predict efficacy; and (ii) to deliver precise, personalized and effective antiepileptic stimulation to prevent and arrest seizure propagation through mapping and modulation of each patients' individual epileptogenic networks.
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Affiliation(s)
- Rory J Piper
- Department of Neurosurgery, Great Ormond Street Hospital, London, UK
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - R Mark Richardson
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, USA
| | | | | | - Torsten Baldeweg
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
| | - Brian Litt
- Department of Neurology and Bioengineering, University of Pennsylvania, Philadelphia, USA
| | | | - Martin M Tisdall
- Department of Neurosurgery, Great Ormond Street Hospital, London, UK
- Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, University College London, London, UK
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Maher C, D'Souza A, Zeng R, Barnett M, Kavehei O, Nikpour A, Wang C. White matter alterations in focal to bilateral tonic-clonic seizures. Front Neurol 2022; 13:972590. [PMID: 36188403 PMCID: PMC9515421 DOI: 10.3389/fneur.2022.972590] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
We examined the white matter of patients with and without focal to bilateral tonic-clonic seizures (FBTCS), and control participants. A neural network based tract segmentation model (Tractseg) was used to isolate tract-specific, track-weighted tensor-based measurements from the tracts of interest. We compared the group differences in the track-weighted tensor-based measurements derived from whole and hemispheric tracts. We identified several regions that displayed significantly altered white matter in patients with focal epilepsy compared to controls. Furthermore, patients without FBTCS showed significantly increased white matter disruption in the inferior fronto-occipital fascicle and the striato-occipital tract. In contrast, the track-weighted tensor-based measurements from the FBTCS cohort exhibited a stronger resemblance to the healthy controls (compared to the non-FBTCS group). Our findings revealed marked alterations in a range of subcortical tracts considered critical in the genesis of seizures in focal epilepsy. Our novel application of tract-specific, track-weighted tensor-based measurements to a new clinical dataset aided the elucidation of specific tracts that may act as a predictive biomarker to distinguish patients likely to develop FBTCS.
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Affiliation(s)
- Christina Maher
- School of Biomedical Engineering, Faculty of Engineering, The University of Sydney, Sydney, NSW, Australia
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Australian Research Council Training Centre for Innovative BioEngineering, The University of Sydney, Sydney, NSW, Australia
- *Correspondence: Christina Maher
| | - Arkiev D'Souza
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Translational Research Collective, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Rui Zeng
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Translational Research Collective, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Michael Barnett
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Department of Neurology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
- Sydney Neuroimaging Analysis Centre, Camperdown, NSW, Australia
| | - Omid Kavehei
- School of Biomedical Engineering, Faculty of Engineering, The University of Sydney, Sydney, NSW, Australia
- Australian Research Council Training Centre for Innovative BioEngineering, The University of Sydney, Sydney, NSW, Australia
| | - Armin Nikpour
- Department of Neurology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
- Central Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Chenyu Wang
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Translational Research Collective, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
- Sydney Neuroimaging Analysis Centre, Camperdown, NSW, Australia
- Chenyu Wang
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Zillgitt AJ, Haykal MA, Chehab A, Staudt MD. Centromedian thalamic neuromodulation for the treatment of idiopathic generalized epilepsy. Front Hum Neurosci 2022; 16:907716. [PMID: 35992953 PMCID: PMC9381751 DOI: 10.3389/fnhum.2022.907716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 07/13/2022] [Indexed: 11/20/2022] Open
Abstract
Idiopathic generalized epilepsy (IGE) is a common type of epilepsy and despite an increase in the number of available anti-seizure medications, approximately 20–30% of people with IGE continue to experience seizures despite adequate medication trials. Unlike focal epilepsy, resective surgery is not a viable treatment option for IGE; however, neuromodulation may be an effective surgical treatment for people with IGE. Thalamic stimulation through deep brain stimulation (DBS) and responsive neurostimulation (RNS) have been explored for the treatment of generalized and focal epilepsies. Although the data regarding DBS and RNS in IGE is limited to case reports and case series, the results of the published studies have been promising. The current manuscript will review the published literature of DBS and RNS within the centromedian nucleus of the thalamus for the treatment of IGE, as well as highlight an illustrative case.
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Affiliation(s)
- Andrew J. Zillgitt
- Department of Neurology, Beaumont Health Adult Comprehensive Epilepsy Center, Neuroscience Center, Royal Oak, MI, United States
| | - M. Ayman Haykal
- Department of Neurology, Beaumont Health Adult Comprehensive Epilepsy Center, Neuroscience Center, Royal Oak, MI, United States
| | - Ahmad Chehab
- Department of Neurosurgery, Beaumont Neuroscience Center, Royal Oak, MI, United States
| | - Michael D. Staudt
- Department of Neurosurgery, Beaumont Neuroscience Center, Royal Oak, MI, United States
- Department of Neurosurgery, Oakland University William Beaumont School of Medicine, Rochester, MI, United States
- Michigan Head and Spine Institute, Southfield, MI, United States
- *Correspondence: Michael D. Staudt,
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Drug-resistant focal epilepsy in children is associated with increased modal controllability of the whole brain and epileptogenic regions. Commun Biol 2022; 5:394. [PMID: 35484213 PMCID: PMC9050895 DOI: 10.1038/s42003-022-03342-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 04/06/2022] [Indexed: 02/06/2023] Open
Abstract
Network control theory provides a framework by which neurophysiological dynamics of the brain can be modelled as a function of the structural connectome constructed from diffusion MRI. Average controllability describes the ability of a region to drive the brain to easy-to-reach neurophysiological states whilst modal controllability describes the ability of a region to drive the brain to difficult-to-reach states. In this study, we identify increases in mean average and modal controllability in children with drug-resistant epilepsy compared to healthy controls. Using simulations, we purport that these changes may be a result of increased thalamocortical connectivity. At the node level, we demonstrate decreased modal controllability in the thalamus and posterior cingulate regions. In those undergoing resective surgery, we also demonstrate increased modal controllability of the resected parcels, a finding specific to patients who were rendered seizure free following surgery. Changes in controllability are a manifestation of brain network dysfunction in epilepsy and may be a useful construct to understand the pathophysiology of this archetypical network disease. Understanding the mechanisms underlying these controllability changes may also facilitate the design of network-focussed interventions that seek to normalise network structure and function.
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Ozgur M, Özyurt MG, Arkan S, Cavdar S. The Effects of Optogenetic Activation of Astrocytes on Spike-and-Wave Discharges in Genetic Absence Epileptic Rats. Ann Neurosci 2022; 29:53-61. [PMID: 35875425 PMCID: PMC9305907 DOI: 10.1177/09727531211072423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/29/2021] [Indexed: 11/16/2022] Open
Abstract
Background: Absence seizures (petit mal seizures) are characterized by a brief loss of consciousness without loss of postural tone. The disease is diagnosed by an electroencephalogram (EEG) showing spike–wave discharges (SWD) caused by hypersynchronous thalamocortical (TC) oscillations. There has been an explosion of research highlighting the role of astrocytes in supporting and modulating neuronal activity. Despite established in vitro evidence, astrocytes’ influence on the TC network remains to be elucidated in vivo in the absence epilepsy (AE). Purpose: In this study, we investigated the role of astrocytes in the generation and modulation of SWDs. We hypothesize that disturbances in astrocytes’ function may affect the pathomechanism of AE. Methods: To direct the expression of channelrhodopsin-2 (ChR2) rAAV8-GFAP-ChR2(H134R)-EYFP or to control the effect of surgical intervention, AAV-CaMKIIa-EYFP was injected into the ventrobasal nucleus (VB) of the thalamus of 18 animals. After four weeks following the injection, rats were stimulated using blue light (~473 nm) and, simultaneously, the electrophysiological activity of the frontal cortical neurons was recorded for three consecutive days. The animals were then perfused, and the brain tissue was analyzed by confocal microscopy. Results: A significant increase in the duration of SWD without affecting the number of SWD in genetic absence epileptic rats from Strasbourg (GAERS) compared to control injections was observed. The duration of the SWD was increased from 12.50 ± 4.41 s to 17.44 ± 6.07 following optogenetic stimulation in GAERS. The excitation of the astrocytes in Wistar Albino Glaxo Rijswijk (WAG-Rij) did not change the duration of SWD; however, stimulation resulted in a significant increase in the number of SWD from 18.52 ± 11.46 bursts/30 min to 30.17 ± 18.43 bursts/30 min. Whereas in control injection, the duration and the number of SWDs were similar at pre- and poststimulus. Both the background and poststimulus average firing rates of the SWD in WAG-Rij were significantly higher than the firing recorded in GAERS. Conclusion: These findings suggest that VB astrocytes play a role in modulating the SWD generation in both rat models with distinct mechanisms and can present an essential target for the possible therapeutic approach for AE.
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Affiliation(s)
- Merve Ozgur
- Graduate School of Health Sciences, Division of Neuroscience, Koc University, Istanbul Turkey
- Department of Anatomy, Faculty of Medicine, Izmir University of Economics, Izmir, Turkey
- Department of Anatomy, Koç University School of Medicine, Istanbul, Turkey
| | - Mustafa Görkem Özyurt
- Department of Anatomy, Koç University School of Medicine, Istanbul, Turkey
- Graduate School of Sciences and Engineering, Koç University, Istanbul, Turkey
| | - Sertan Arkan
- Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Safiye Cavdar
- Department of Experimental Medical Science, Molecular Neurobiology Unit, Lund University, Lund, Sweden
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9
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Karakis I. Using stereo-electroencephalography to unlock the ictal secrets of the thalamus. Clin Neurophysiol 2022; 137:177-178. [DOI: 10.1016/j.clinph.2022.02.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 11/03/2022]
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10
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Brodovskaya A, Batabyal T, Shiono S, Sun H, Kapur J. Distinct roles of rodent thalamus and corpus callosum in seizure generalization. Ann Neurol 2022; 91:682-696. [PMID: 35226367 PMCID: PMC9315027 DOI: 10.1002/ana.26338] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/25/2022] [Accepted: 02/25/2022] [Indexed: 11/30/2022]
Abstract
Objective Bilateral synchronous cortical activity occurs during sleep, attention, and seizures. Canonical models place the thalamus at the center of bilateral cortical synchronization because it generates bilateral sleep spindle oscillations and primarily generalized absence seizures. However, classical studies suggest that the corpus callosum mediates bilateral cortical synchronization. Methods We mapped the spread of right frontal lobe‐onset, focal to bilateral seizures in mice and modified it using chemo and optogenetic suppression of motor thalamic nucleus and corpus callosotomy. Results Seizures from the right cortex spread faster to the left cortex than to the left thalamus. The 2 thalami have minimal monosynaptic commissural connections compared to the massive commissure corpus callosum. Chemogenetic and closed‐loop optogenetic inhibition of the right ventrolateral thalamic nucleus did not alter inter‐hemispheric seizure spread. However, anterior callosotomy delayed bilateral seizure oscillations. Interpretation Thalamocortical oscillations amplify focal onset motor seizures, and corpus callosum spreads them bilaterally. ANN NEUROL 2022;91:682–696
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Affiliation(s)
- Anastasia Brodovskaya
- Department of Neurology, University of Virginia, Charlottesville, Virginia, 22908, USA
| | - Tamal Batabyal
- Department of Neurology, University of Virginia, Charlottesville, Virginia, 22908, USA
| | - Shinnosuke Shiono
- Department of Neurology, University of Virginia, Charlottesville, Virginia, 22908, USA
| | - Huayu Sun
- Department of Neurology, University of Virginia, Charlottesville, Virginia, 22908, USA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, Virginia, 22908, USA.,UVA Brain Institute, University of Virginia, Charlottesville, Virginia, 22908, USA
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Kozyrev DA, Soleman J, Tsering D, Keating RF, Hersh DS, Boop FA, Spennato P, Cinalli G, Tamburrini G, Thomale UW, Bollo RJ, Chatterjee S, Lalgudi Srinivasan H, Constantini S, Roth J. Pediatric thalamic incidentalomas: an international retrospective multicenter study. J Neurosurg Pediatr 2022; 29:141-149. [PMID: 34715651 DOI: 10.3171/2021.6.peds20976] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/16/2021] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Widespread use of modern neuroimaging has led to a surge in diagnosing pediatric brain incidentalomas. Thalamic lesions have unique characteristics such as deep location, surgical complexity, and proximity to eloquent neuronal structures. Currently, the natural course of incidental thalamic lesions is unknown. Therefore, the authors present their experience in treating such lesions. METHODS A retrospective, international multicenter study was carried out in 8 tertiary pediatric centers from 5 countries. Patients were included if they had an incidental thalamic lesion suspected of being a tumor and were diagnosed before the age of 20 years. Treatment strategy, imaging characteristics, pathology, and the outcome of operated and unoperated cases were analyzed. RESULTS Overall, 58 children (23 females and 35 males) with a mean age of 10.8 ± 4.0 years were included. The two most common indications for imaging were nonspecific reasons (n = 19; e.g., research and developmental delay) and headache unrelated to small thalamic lesions (n = 14). Eleven patients (19%) underwent early surgery and 47 were followed, of whom 10 underwent surgery due to radiological changes at a mean of 11.4 ± 9.5 months after diagnosis. Of the 21 patients who underwent surgery, 9 patients underwent resection and 12 underwent biopsy. The two most frequent pathologies were pilocytic astrocytoma and WHO grade II astrocytoma (n = 6 and n = 5, respectively). Three lesions were high-grade gliomas. CONCLUSIONS The results of this study indicate that pediatric incidental thalamic lesions include both low- and high-grade tumors. Close and long-term radiological follow-up is warranted in patients who do not undergo immediate surgery, as tumor progression may occur.
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Affiliation(s)
- Danil A Kozyrev
- 1Department of Pediatric Neurosurgery, Dana Children's Hospital, Tel Aviv Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Jehuda Soleman
- 1Department of Pediatric Neurosurgery, Dana Children's Hospital, Tel Aviv Medical Center, Tel Aviv University, Tel Aviv, Israel
- 9Department of Neurosurgery and Pediatric Neurosurgery, University and Children's Hospital of Basel, Switzerland
- 10Faculty of Medicine, University of Basel, Switzerland
| | - Deki Tsering
- 2Division of Neurosurgery, Children's National Medical Center, Washington, DC
| | - Robert F Keating
- 2Division of Neurosurgery, Children's National Medical Center, Washington, DC
| | - David S Hersh
- 3Department of Surgery, St. Jude Children's Research Hospital, Memphis, Tennessee
- 11Department of Surgery, Connecticut Children's, Hartford, Connecticut; and
- 12Departments of Surgery and Pediatrics, UConn School of Medicine, Farmington, Connecticut
| | - Frederick A Boop
- 3Department of Surgery, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Pietro Spennato
- 4Department of Neurosurgery, Santobono-Pausilipon Children's Hospital, Naples, Italy
| | - Giuseppe Cinalli
- 4Department of Neurosurgery, Santobono-Pausilipon Children's Hospital, Naples, Italy
| | - Gianpiero Tamburrini
- 5Institute of Neurosurgery, Catholic University of the Sacred Heart, Milan, Italy
| | - Ulrich-Wilhelm Thomale
- 6Pediatric Neurosurgery, Campus Virchow Klinikum, Charité Universitätsmedizin, Berlin, Germany
| | - Robert J Bollo
- 7Division of Pediatric Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
| | | | | | - Shlomi Constantini
- 1Department of Pediatric Neurosurgery, Dana Children's Hospital, Tel Aviv Medical Center, Tel Aviv University, Tel Aviv, Israel
| | - Jonathan Roth
- 1Department of Pediatric Neurosurgery, Dana Children's Hospital, Tel Aviv Medical Center, Tel Aviv University, Tel Aviv, Israel
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12
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Hect JL, Fernandez LD, Welch WP, Abel TJ. Deep brain stimulation of the centromedian thalamic nucleus for the treatment of FIRES. Epilepsia Open 2021; 7:187-193. [PMID: 34862854 PMCID: PMC8886094 DOI: 10.1002/epi4.12568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/16/2021] [Accepted: 11/28/2021] [Indexed: 11/10/2022] Open
Abstract
Febrile infection‐related epilepsy syndrome (FIRES) is a rare, life‐threatening complication of febrile illness in previously healthy individuals followed by super‐refractory status epilepticus. Deep brain stimulation (DBS) has been demonstrated to be a promising therapy for the treatment of intractable epilepsy. Here, we present a pediatric patient with FIRES whose seizures were mitigated by acute DBS of the bilateral centromedian thalamic nucleus (CMTN). This is a previously healthy 11‐year‐old female who presented emergently with altered mental status, fever, and malaise after 1 week of lethargy, anorexia, fever, and abdominal pain. The patient began having seizures shortly after admission. After thorough workup for encephalitis and other potential etiologies, this patient was diagnosed with FIRES due to super‐refractory status epilepticus. Status epilepticus persisted despite pharmacologic management, immunotherapy, and vagus nerve stimulation. DBS of the bilateral CMTN (CM‐DBS) was pursued after 56 days of hospitalization, and she demonstrated considerable improvement in baseline mental status 30 days after DBS insertion. This report highlights application of CM‐DBS for super‐refractory status epilepticus in FIRES. This region is a diffusely connected brain region and has been shown to modulate neural networks contributing to seizure propagation and consciousness; therefore, neurostimulation is a potential therapeutic intervention for patients with super‐refractory status epilepticus.
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Affiliation(s)
- Jasmine L Hect
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Luis D Fernandez
- Division of Pediatric Neurology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - William P Welch
- Division of Pediatric Neurology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Taylor J Abel
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.,Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, Pennsylvania, USA
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13
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Cho KH, Lee HJ, Heo K, Kim SE, Lee DA, Park KM. Intrinsic Thalamic Network in Temporal Lobe Epilepsy With Hippocampal Sclerosis According to Surgical Outcomes. Front Neurol 2021; 12:721610. [PMID: 34512532 PMCID: PMC8429827 DOI: 10.3389/fneur.2021.721610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/06/2021] [Indexed: 11/26/2022] Open
Abstract
Background: The aim of this study was to identify the differences of intrinsic amygdala, hippocampal, or thalamic networks according to surgical outcomes in temporal lobe epilepsy (TLE) patients with hippocampal sclerosis (HS). Methods: We enrolled 69 pathologically confirmed TLE patients with HS. All patients had pre-operative three-dimensional T1-weighted MRI using a 3.0 T scanner. We obtained the structural volumes of the amygdala nuclei, hippocampal subfields, and thalamic nuclei. Then, we investigated the intrinsic networks based on volumes of these structures using structural covariance and graph theoretical analysis. Results: Of the 69 TLE patients with HS, 21 patients (42.1%) had poor surgical outcomes, whereas 40 patients (57.9%) had good surgical outcomes. The volumes in the amygdala nuclei, hippocampal subfields, and thalamic nuclei were not different according to surgical outcome. In addition, the intrinsic amygdala and hippocampal networks were not different between the patients with poor and good surgical outcomes. However, there was a significant difference in the intrinsic thalamic network in the ipsilateral hemisphere between them. The eccentricity and small-worldness index were significantly increased, whereas the characteristic path length was decreased in the patients with poor surgical outcomes compared to those with good surgical outcomes. Conclusion: We successfully demonstrated significant differences in the intrinsic thalamic network in the ipsilateral hemisphere between TLE patients with HS with poor and good surgical outcomes. This result suggests that the pre-operative intrinsic thalamic network can be related with surgical outcomes in TLE patients with HS.
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Affiliation(s)
- Kyoo Ho Cho
- Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea.,Department of Neurology, Seoul Hospital, Ewha Womans University College of Medicine, Seoul, South Korea
| | - Ho-Joon Lee
- Department of Radiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, South Korea
| | - Kyoung Heo
- Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea
| | - Sung Eun Kim
- Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, South Korea
| | - Dong Ah Lee
- Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, South Korea
| | - Kang Min Park
- Department of Neurology, Haeundae Paik Hospital, Inje University College of Medicine, Busan, South Korea
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14
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Piper RJ, Tangwiriyasakul C, Shamshiri EA, Centeno M, He X, Richardson MP, Tisdall MM, Carmichael DW. Functional Connectivity of the Anterior Nucleus of the Thalamus in Pediatric Focal Epilepsy. Front Neurol 2021; 12:670881. [PMID: 34408719 PMCID: PMC8365837 DOI: 10.3389/fneur.2021.670881] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/27/2021] [Indexed: 11/13/2022] Open
Abstract
Objective: Whilst stimulation of the anterior nucleus of the thalamus has shown efficacy for reducing seizure frequency in adults, alterations in thalamic connectivity have not been explored in children. We tested the hypotheses that (a) the anterior thalamus has increased functional connectivity in children with focal epilepsy, and (b) this alteration in the connectome is a persistent effect of the disease rather than due to transient epileptiform activity. Methods: Data from 35 children (7–18 years) with focal, drug-resistant epilepsy and 20 healthy children (7–17 years) were analyzed. All subjects underwent functional magnetic resonance imaging (fMRI) whilst resting and were simultaneously monitored with scalp electroencephalography (EEG). The fMRI timeseries were extracted for each Automated Anatomical Labeling brain region and thalamic subregion. Graph theory metrics [degree (DC) and eigenvector (EC) centrality] were used to summarize the connectivity profile of the ipsilateral thalamus, and its thalamic parcellations. The effect of interictal epileptiform discharges (IEDs) captured on EEG was used to determine their effect on DC and EC. Results: DC was significantly higher in the anterior nucleus (p = 0.04) of the thalamus ipsilateral to the epileptogenic zone in children with epilepsy compared to controls. On exploratory analyses, we similarly found a higher DC in the lateral dorsal nucleus (p = 0.02), but not any other thalamic subregion. No differences in EC measures were found between patients and controls. We did not find any significant difference in DC or EC in any thalamic subregion when comparing the results of children with epilepsy before, and after the removal of the effects of IEDs. Conclusions: Our data suggest that the anterior and lateral dorsal nuclei of the thalamus are more highly functionally connected in children with poorly controlled focal epilepsy. We did not detect a convincing change in thalamic connectivity caused by transient epileptiform activity, suggesting that it represents a persistent alteration to network dynamics.
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Affiliation(s)
- Rory J Piper
- Department of Neurosurgery, John Radcliffe Hospital, Oxford, United Kingdom.,Department of Neurosurgery, Great Ormond Street Hospital for Children, UCL Great Ormond Street Institute of Child Health, London, United Kingdom.,Wellcome EPSRC Centre for Medical Imaging, Department of Biomedical Engineering, King's College London, London, United Kingdom
| | - Chayanin Tangwiriyasakul
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry Psychology and Neuroscience, King's College London, London, United Kingdom.,School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | - Elhum A Shamshiri
- San Francisco Veterans Affairs Health Care System (SFVAHCS), San Francisco, CA, United States.,Department of Psychiatry, University of California, San Francisco, San Francisco, CA, United States.,Sierra Pacific Mental Illness Research Education and Clinical Centers, San Francisco, CA, United States
| | - Maria Centeno
- Epilepsy Unit, Neurology Department, Hospital Clinic, Barcelona, Spain
| | - Xiaosong He
- Department of Psychology, University of Science and Technology of China, Hefei, China
| | - Mark P Richardson
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry Psychology and Neuroscience, King's College London, London, United Kingdom
| | - Martin M Tisdall
- Department of Neurosurgery, Great Ormond Street Hospital for Children, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - David W Carmichael
- Wellcome EPSRC Centre for Medical Imaging, Department of Biomedical Engineering, King's College London, London, United Kingdom
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15
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Welch WP, Hect JL, Abel TJ. Case Report: Responsive Neurostimulation of the Centromedian Thalamic Nucleus for the Detection and Treatment of Seizures in Pediatric Primary Generalized Epilepsy. Front Neurol 2021; 12:656585. [PMID: 33995254 PMCID: PMC8113700 DOI: 10.3389/fneur.2021.656585] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Up to 20% of pediatric patients with primary generalized epilepsy (PGE) will not respond effectively to medication for seizure control. Responsive neurostimulation (RNS) is a promising therapy for pediatric patients with drug-resistant epilepsy and has been shown to be an effective therapy for reducing seizure frequency and severity in adult patients. RNS of the centromedian nucleus of the thalamus may help to prevent loss of awareness during seizure activity in PGE patients with absence seizures. Here we present a 16-year-old male, with drug-resistant PGE with absence seizures, characterized by 3 Hz spike-and-slow-wave discharges on EEG, who achieved a 75% reduction in seizure frequency following bilateral RNS of the centromedian nuclei. At 6-months post-implant, this patient reported complete resolution of the baseline daily absence seizure activity, and decrease from 3-4 generalized convulsive seizures per month to 1 per month. RNS recordings showed well-formed 3 Hz spike-wave discharges in bilateral CM nuclei, further supporting the notion that clinically relevant ictal discharges in PGE can be detected in CM. This report demonstrates that CM RNS can detect PGE-related seizures in the CM nucleus and deliver therapeutic stimulation.
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Affiliation(s)
- William P Welch
- Division of Pediatric Neurology, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Jasmine L Hect
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Taylor J Abel
- Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.,Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA, United States
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16
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Brodovskaya A, Shiono S, Kapur J. Activation of the basal ganglia and indirect pathway neurons during frontal lobe seizures. Brain 2021; 144:2074-2091. [PMID: 33730155 DOI: 10.1093/brain/awab119] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 12/12/2020] [Accepted: 01/04/2021] [Indexed: 12/27/2022] Open
Abstract
There are no detailed descriptions of neuronal circuit active during frontal lobe motor seizures. Using activity reporter mice, local field potential recordings, tissue clearing, viral tracing, and super-resolution microscopy, we found neuronal activation after focal motor to bilateral tonic-clonic seizures in the striatum, globus pallidus externus, subthalamic nucleus, substantia nigra pars reticulata and neurons of the indirect pathway. Seizures preferentially activated dopamine D2 receptor-expressing neurons over D1 in the striatum, which have different projections. Furthermore, the D2 receptor agonist infused into the striatum exerted an anticonvulsant effect. Seizures activate structures via short and long latency loops, and anatomical connections of the seizure focus determine the seizure circuit. These studies, for the first time, show activation of neurons in the striatum, globus pallidus, subthalamic nucleus, and substantia nigra during frontal lobe motor seizures on the cellular level, revealing a complex neuronal activation circuit subject to modulation by the basal ganglia.
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Affiliation(s)
- Anastasia Brodovskaya
- Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Shinnosuke Shiono
- Department of Neurology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, Virginia 22908, USA.,UVA Brain Institute, University of Virginia, Charlottesville, Virginia 22908, USA
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17
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Characterization of the Expression of the ATP-Gated P2X7 Receptor Following Status Epilepticus and during Epilepsy Using a P2X7-EGFP Reporter Mouse. Neurosci Bull 2020; 36:1242-1258. [PMID: 32895896 DOI: 10.1007/s12264-020-00573-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 07/08/2020] [Indexed: 12/18/2022] Open
Abstract
Mounting evidence suggests that the ATP-gated P2X7 receptor contributes to increased hyperexcitability in the brain. While increased expression of P2X7 in the hippocampus and cortex following status epilepticus and during epilepsy has been repeatedly demonstrated, the cell type-specific expression of P2X7 and its expression in extra-hippocampal brain structures remains incompletely explored. In this study, P2X7 expression was visualized by using a transgenic mouse model overexpressing P2X7 fused to the fluorescent protein EGFP. The results showed increased P2X7-EGFP expression after status epilepticus induced by intra-amygdala kainic acid and during epilepsy in different brain regions including the hippocampus, cortex, striatum, thalamus and cerebellum, and this was most evident in microglia and oligodendrocytes. Co-localization of P2X7-EGFP with cell type-specific markers was not detected in neurons or astrocytes. These data suggest that P2X7 activation is a common pathological hallmark across different brain structures, possibly contributing to brain inflammation and neurodegeneration following acute seizures and during epilepsy.
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18
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He X, Chaitanya G, Asma B, Caciagli L, Bassett DS, Tracy JI, Sperling MR. Disrupted basal ganglia-thalamocortical loops in focal to bilateral tonic-clonic seizures. Brain 2020; 143:175-190. [PMID: 31860076 DOI: 10.1093/brain/awz361] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 08/16/2019] [Accepted: 09/24/2019] [Indexed: 02/07/2023] Open
Abstract
Focal to bilateral tonic-clonic seizures are associated with lower quality of life, higher risk of seizure-related injuries, increased chance of sudden unexpected death, and unfavourable treatment outcomes. Achieving greater understanding of their underlying circuitry offers better opportunity to control these seizures. Towards this goal, we provide a network science perspective of the interactive pathways among basal ganglia, thalamus and cortex, to explore the imprinting of secondary seizure generalization on the mesoscale brain network in temporal lobe epilepsy. Specifically, we parameterized the functional organization of both the thalamocortical network and the basal ganglia-thalamus network with resting state functional MRI in three groups of patients with different focal to bilateral tonic-clonic seizure histories. Using the participation coefficient to describe the pattern of thalamocortical connections among different cortical networks, we showed that, compared to patients with no previous history, those with positive histories of focal to bilateral tonic-clonic seizures, including both remote (none for >1 year) and current (within the past year) histories, presented more uniform distribution patterns of thalamocortical connections in the ipsilateral medial-dorsal thalamic nuclei. As a sign of greater thalamus-mediated cortico-cortical communication, this result comports with greater susceptibility to secondary seizure generalization from the epileptogenic temporal lobe to broader brain networks in these patients. Using interregional integration to characterize the functional interaction between basal ganglia and thalamus, we demonstrated that patients with current history presented increased interaction between putamen and globus pallidus internus, and decreased interaction between the latter and the thalamus, compared to the other two patient groups. Importantly, through a series of 'disconnection' simulations, we showed that these changes in interactive profiles of the basal ganglia-thalamus network in the current history group mainly depended upon the direct but not the indirect basal ganglia pathway. It is intuitively plausible that such disruption in the striatum-modulated tonic inhibition of the thalamus from the globus pallidus internus could lead to an under-suppressed thalamus, which in turn may account for their greater vulnerability to secondary seizure generalization. Collectively, these findings suggest that the broken balance between basal ganglia inhibition and thalamus synchronization can inform the presence and effective control of focal to bilateral tonic-clonic seizures. The mechanistic underpinnings we uncover may shed light on the development of new treatment strategies for patients with temporal lobe epilepsy.
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Affiliation(s)
- Xiaosong He
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ganne Chaitanya
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Burcu Asma
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Lorenzo Caciagli
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London, UK
| | - Danielle S Bassett
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Santa Fe Institute, Santa Fe, New Mexico, USA
| | - Joseph I Tracy
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Michael R Sperling
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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19
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Quantitative characteristics of spike-wave paroxysms in genetic generalized epilepsy. Clin Neurophysiol 2020; 131:1230-1240. [DOI: 10.1016/j.clinph.2020.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/17/2020] [Accepted: 03/12/2020] [Indexed: 11/20/2022]
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20
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Weng Y, Larivière S, Caciagli L, Vos de Wael R, Rodríguez-Cruces R, Royer J, Xu Q, Bernasconi N, Bernasconi A, Thomas Yeo BT, Lu G, Zhang Z, Bernhardt BC. Macroscale and microcircuit dissociation of focal and generalized human epilepsies. Commun Biol 2020; 3:244. [PMID: 32424317 PMCID: PMC7234993 DOI: 10.1038/s42003-020-0958-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 04/15/2020] [Indexed: 01/01/2023] Open
Abstract
Thalamo-cortical pathology plays key roles in both generalized and focal epilepsies, but there is little work directly comparing these syndromes at the level of whole-brain mechanisms. Using multimodal imaging, connectomics, and computational simulations, we examined thalamo-cortical and cortico-cortical signatures and underlying microcircuits in 96 genetic generalized (GE) and 107 temporal lobe epilepsy (TLE) patients, along with 65 healthy controls. Structural and functional network profiling highlighted extensive atrophy, microstructural disruptions and decreased thalamo-cortical connectivity in TLE, while GE showed only subtle structural anomalies paralleled by enhanced thalamo-cortical connectivity. Connectome-informed biophysical simulations indicated modest increases in subcortical drive contributing to cortical dynamics in GE, while TLE presented with reduced subcortical drive and imbalanced excitation-inhibition within limbic and somatomotor microcircuits. Multiple sensitivity analyses supported robustness. Our multiscale analyses differentiate human focal and generalized epilepsy at the systems-level, showing paradoxically more severe microcircuit and macroscale imbalances in the former.
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Affiliation(s)
- Yifei Weng
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Sara Larivière
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Lorenzo Caciagli
- University College London Queen Square Institute of Neurology, London, United Kingdom
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Reinder Vos de Wael
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Raúl Rodríguez-Cruces
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Jessica Royer
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Qiang Xu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Neda Bernasconi
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - Andrea Bernasconi
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada
| | - B T Thomas Yeo
- Department of Electrical and Computer Engineering, Centre for Sleep and Cognition, Clinical Imaging Research Centre and N.1 Institute for Health, National University of Singapore, Singapore, Singapore
| | - Guangming Lu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Zhiqiang Zhang
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.
| | - Boris C Bernhardt
- McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, QC, H3A2B4, Canada.
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21
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Tukker JJ, Beed P, Schmitz D, Larkum ME, Sachdev RNS. Up and Down States and Memory Consolidation Across Somatosensory, Entorhinal, and Hippocampal Cortices. Front Syst Neurosci 2020; 14:22. [PMID: 32457582 PMCID: PMC7227438 DOI: 10.3389/fnsys.2020.00022] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/03/2020] [Indexed: 01/01/2023] Open
Abstract
In the course of a day, brain states fluctuate, from conscious awake information-acquiring states to sleep states, during which previously acquired information is further processed and stored as memories. One hypothesis is that memories are consolidated and stored during "offline" states such as sleep, a process thought to involve transfer of information from the hippocampus to other cortical areas. Up and Down states (UDS), patterns of activity that occur under anesthesia and sleep states, are likely to play a role in this process, although the nature of this role remains unclear. Here we review what is currently known about these mechanisms in three anatomically distinct but interconnected cortical areas: somatosensory cortex, entorhinal cortex, and the hippocampus. In doing so, we consider the role of this activity in the coordination of "replay" during sleep states, particularly during hippocampal sharp-wave ripples. We conclude that understanding the generation and propagation of UDS may provide key insights into the cortico-hippocampal dialogue linking archi- and neocortical areas during memory formation.
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Affiliation(s)
- John J Tukker
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Neuroscience Research Center, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Prateep Beed
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Neuroscience Research Center, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Neuroscience Research Center, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Berlin Institute of Health, Berlin, Germany.,Cluster of Excellence NeuroCure, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany
| | - Matthew E Larkum
- Cluster of Excellence NeuroCure, Berlin, Germany.,Einstein Center for Neurosciences Berlin, Berlin, Germany.,Institut für Biologie, Humboldt Universität, Berlin, Germany
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Şanlıdağ B, Köken ÖY, Temel EÜ, Arhan E, Aydın K, Serdaroğlu A. Benign epilepsy with centrotemporal spikes: Is there a thalamocortical network dysfunction present? Seizure 2020; 79:44-48. [PMID: 32416566 DOI: 10.1016/j.seizure.2020.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 04/10/2020] [Accepted: 04/12/2020] [Indexed: 10/24/2022] Open
Abstract
INTRODUCTION Benign epilepsy of childhood with centrotemporal spikes (BECTS) is one of the most frequently seen epileptic syndromes in childhood. It is characterized by centrotemporal spikes (CTS) on electroencephalography (EEG) that are typically activated by drowsiness and stage N2 sleep. The location, frequency, and amplitude of the spikes may vary in different EEG records of the same patient, supporting the presence of a global pathology rather than a focal one. Despite the well-known relation between BECTS and stage N2 sleep, the results of sleep studies have been diverse and have mainly focused on sleep cycles. The characteristics of sleep spindles in the interictal periods have not been studied well. METHODS A retrospective study involving patients with BECTS who were admitted to the Gazi University, Faculty of Medicine, Department of Pediatric Neurology from January 2017 to October 2018 was conducted herein. Patients with BECTS and age-matched controls who had stage N2 sleep records of 10 min were enrolled for spindle amplitude (peak-to-peak difference in spindle voltage), frequency (number of waveforms per second), and duration and density (number of spindle bursts/minute of stage N2 sleep). RESULTS A total of 30 children with BECTS and 20 age-matched healthy peers were enrolled in the study. There were no significant differences between the age and sex of the patients. Statistically significant lower mean values of the amplitude, and duration and density of the spindle activity were observed in patients with BECTS when compared to the controls (P: 0.034, P: 0.016, and 0.020, respectively). Additionally, the risk of epilepsy was found to increase by 1.9 %, by the decrease of the mean amplitude of the spindles by 1 mV when compared to control group. CONCLUSION The interictal records of stage N2 sleep differed in the patients with BECTS when compared to the controls. Findings related to the stage N2 sleep of the present study may suggest a network problem involving the thalamus and thalamocortical pathways in patients with BECTS.
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Affiliation(s)
- Burçin Şanlıdağ
- Department of Pediatric Neurology, Medical Faculty of Near East University, Nicosia, Cyprus.
| | - Özlem Yayıcı Köken
- Department of Pediatric Neurology, SBU, Dr. Sami Ulus Research and Training Hospital, Ankara, Turkey.
| | - Esra Ülgen Temel
- Department of Pediatric Neurology, Medical Faculty of Gazi University, Ankara, Turkey.
| | - Ebru Arhan
- Department of Pediatric Neurology, Medical Faculty of Gazi University, Ankara, Turkey.
| | - Kürşad Aydın
- Department of Pediatric Neurology, Medical Faculty of Medipol University, İstanbul, Turkey.
| | - Ayşe Serdaroğlu
- Department of Pediatric Neurology, Medical Faculty of Gazi University, Ankara, Turkey.
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23
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Williams MS, Lecas S, Charpier S, Mahon S. Phase-dependent modulation of cortical and thalamic sensory responses during spike-and-wave discharges. Epilepsia 2020; 61:330-341. [PMID: 31912497 DOI: 10.1111/epi.16422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 12/14/2019] [Accepted: 12/16/2019] [Indexed: 12/29/2022]
Abstract
OBJECTIVE The neuronal underpinnings of impaired consciousness during absence seizures remain largely unknown. Spike-and-wave (SW) activity associated with absences imposes two extremely different states in cortical neurons, which transition from suprathreshold synaptic depolarizations during spike phases to membrane hyperpolarization and electrical silence during wave phases. To investigate whether this rhythmic alternation of neuronal states affects the processing of sensory information during seizures, we examined cortical and thalamic responsiveness to brief sensory stimuli in the different phases of the epileptic cycle. METHODS Electrocorticographic (ECoG) monitoring from the primary somatosensory cortex combined with intracellular recordings of subjacent pyramidal neurons, or extracellular recordings of somatosensory thalamic neurons, were performed in the Genetic Absence Epilepsy Rat From Strasbourg. Sensory stimuli consisted of pulses of compressed air applied to the contralateral whiskers. RESULTS Whisker stimuli delivered during spike phases evoked smaller depolarizing synaptic potentials and fewer action potentials in cortical neurons compared to stimuli occurring during wave phases. This spike-related attenuation of cortical responsiveness was accompanied by a reduced neuronal membrane resistance, likely due to the large increase in synaptic conductance. Sensory-evoked firing in thalamocortical neurons was also decreased during ECoG spikes as compared to wave phases, indicating that time-to-time changes in the thalamocortical volley may also contribute to the variability of cortical responses during seizures. SIGNIFICANCE These findings demonstrate that thalamocortical sensory processing during absence seizures is nonstationary and strongly suggest that the cortical impact of a given environmental stimulus is conditioned by its exact timing relative to the SW cycle. The lack of stability of thalamic and cortical responses along seizures may contribute to impaired conscious sensory perception during absences.
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Affiliation(s)
- Mark S Williams
- Brain and Spine Institute, National Institute of Health and Medical Research Mixed Unit of Research 1127, National Center for Scientific Research Mixed Unit of Research 7225, Pitié-Salpêtrière Hospital, Paris, France
| | - Sarah Lecas
- Brain and Spine Institute, National Institute of Health and Medical Research Mixed Unit of Research 1127, National Center for Scientific Research Mixed Unit of Research 7225, Pitié-Salpêtrière Hospital, Paris, France.,Sorbonne University, Pierre and Marie Curie University, Paris, France
| | - Stéphane Charpier
- Brain and Spine Institute, National Institute of Health and Medical Research Mixed Unit of Research 1127, National Center for Scientific Research Mixed Unit of Research 7225, Pitié-Salpêtrière Hospital, Paris, France.,Sorbonne University, Pierre and Marie Curie University, Paris, France
| | - Séverine Mahon
- Brain and Spine Institute, National Institute of Health and Medical Research Mixed Unit of Research 1127, National Center for Scientific Research Mixed Unit of Research 7225, Pitié-Salpêtrière Hospital, Paris, France
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24
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González HFJ, Chakravorti S, Goodale SE, Gupta K, Claassen DO, Dawant B, Morgan VL, Englot DJ. Thalamic arousal network disturbances in temporal lobe epilepsy and improvement after surgery. J Neurol Neurosurg Psychiatry 2019; 90:1109-1116. [PMID: 31123139 PMCID: PMC6744309 DOI: 10.1136/jnnp-2019-320748] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/19/2019] [Accepted: 04/26/2019] [Indexed: 12/23/2022]
Abstract
OBJECTIVE The effects of temporal lobe epilepsy (TLE) on subcortical arousal structures remain incompletely understood. Here, we evaluate thalamic arousal network functional connectivity in TLE and examine changes after epilepsy surgery. METHODS We examined 26 adult patients with TLE and 26 matched control participants and used resting-state functional MRI (fMRI) to measure functional connectivity between the thalamus (entire thalamus and 19 bilateral thalamic nuclei) and both neocortex and brainstem ascending reticular activating system (ARAS) nuclei. Postoperative imaging was completed for 19 patients >1 year after surgery and compared with preoperative baseline. RESULTS Before surgery, patients with TLE demonstrated abnormal thalamo-occipital functional connectivity, losing the normal negative fMRI correlation between the intralaminar central lateral (CL) nucleus and medial occipital lobe seen in controls (p < 0.001, paired t-test). Patients also had abnormal connectivity between ARAS and CL, lower ipsilateral intrathalamic connectivity, and smaller ipsilateral thalamic volume compared with controls (p < 0.05 for each, paired t-tests). Abnormal brainstem-thalamic connectivity was associated with impaired visuospatial attention (ρ = -0.50, p = 0.02, Spearman's rho) while lower intrathalamic connectivity and volume were related to higher frequency of consciousness-sparing seizures (p < 0.02, Spearman's rho). After epilepsy surgery, patients with improved seizures showed partial recovery of thalamo-occipital and brainstem-thalamic connectivity, with values more closely resembling controls (p < 0.01 for each, analysis of variance). CONCLUSIONS Overall, patients with TLE demonstrate impaired connectivity in thalamic arousal networks that may be involved in visuospatial attention, but these disturbances may partially recover after successful epilepsy surgery. Thalamic arousal network dysfunction may contribute to morbidity in TLE.
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Affiliation(s)
- Hernán F J González
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA .,Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Srijata Chakravorti
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Sarah E Goodale
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Kanupriya Gupta
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Daniel O Claassen
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Benoit Dawant
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - Victoria L Morgan
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Dario J Englot
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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25
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Ranjan M, Boutet A, Bhatia S, Wilfong A, Hader W, Lee MR, Rezai AR, Adelson PD. Neuromodulation beyond neurostimulation for epilepsy: scope for focused ultrasound. Expert Rev Neurother 2019; 19:937-943. [PMID: 31232614 DOI: 10.1080/14737175.2019.1635013] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Introduction: Epilepsy is one of the most common neurological disorders and is often difficult to control with medication. Intractable epilepsy often results in compromised quality of life (QOL), neurologic morbidity and even mortality. In carefully selected cases, resective surgery offers the best potential for cure or seizure control. However, a large proportion of patients are not suitable for resective epilepsy surgery. Neuromodulation techniques are increasingly being used to treat such refractory cases. Recently, the FDA approved Magnetic Resonance-guided Focused Ultrasound (MRgFUS) for essential tremor and this novel technology is also being explored in several other neuropsychiatric conditions and neurological disorders, including epilepsy. Area covered: While the literature is scant and scattered, the pertinent literature of the MRgFUS is reviewed with an emphasis on research relevant to its application for epilepsy. Expert opinion: Limited preliminary clinical experiences and research studies with MRgFUS ablation or neuromodulation for epilepsy have shown promising results; however, this procedure remains experimental requiring further investigations. Safe and reversible opening of the blood-brain barrier (BBB) with MRgFUS adds an additional therapeutic avenue by allowing targeted delivery of neurotherapeutics in neurological disorders, potentially including epilepsy. Ongoing clinical trials and research coupled with technological advancements contribute to strengthening the MRgFUS epilepsy field. MRgFUS could be the future technology of choice for 'ablation' or 'sononeuromodulation', and/or a 'targeted therapeutics' for epilepsy.
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Affiliation(s)
- Manish Ranjan
- Department of Neurosurgery, West Virginia University , Morgantown , WV , USA.,Neurosurgery, Rockefeller Neuroscience Institute , Morgantown , WV , USA
| | - Alexandre Boutet
- Joint Department of Medical Imaging, University of Toronto , Toronto , ON , Canada
| | - Sanjiv Bhatia
- Division of Pediatric Neurological Surgery, Nicklaus Children's Hospital Brain Institute, University of Miami , Miami , FL , USA
| | - Angus Wilfong
- Division of Neurology, BARROW Neurological Institute at Phoenix Children's Hospital , Phoenix , AZ , USA
| | - Walter Hader
- Division of Pediatric Neurosurgery, Department of clinical neurosciences, University of Calgary , Calgary , AB , Canada
| | - Mark R Lee
- Department of Neurosurgery, West Virginia University , Morgantown , WV , USA.,Neurosurgery, Rockefeller Neuroscience Institute , Morgantown , WV , USA
| | - Ali R Rezai
- Department of Neurosurgery, West Virginia University , Morgantown , WV , USA.,Neurosurgery, Rockefeller Neuroscience Institute , Morgantown , WV , USA
| | - P David Adelson
- Division of Pediatric Neurosurgery, BARROW Neurological Institute at Phoenix Children's Hospital , Phoenix , AZ , USA
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26
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Sinha N, Wang Y, Dauwels J, Kaiser M, Thesen T, Forsyth R, Taylor PN. Computer modelling of connectivity change suggests epileptogenesis mechanisms in idiopathic generalised epilepsy. NEUROIMAGE-CLINICAL 2019; 21:101655. [PMID: 30685702 PMCID: PMC6356007 DOI: 10.1016/j.nicl.2019.101655] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 12/21/2018] [Accepted: 01/03/2019] [Indexed: 12/14/2022]
Abstract
Patients with idiopathic generalised epilepsy (IGE) typically have normal conventional magnetic resonance imaging (MRI), hence diagnosis based on MRI is challenging. Anatomical abnormalities underlying brain dysfunctions in IGE are unclear and their relation to the pathomechanisms of epileptogenesis is poorly understood. In this study, we applied connectometry, an advanced quantitative neuroimaging technique for investigating localised changes in white-matter tissues in vivo. Analysing white matter structures of 32 subjects we incorporated our in vivo findings in a computational model of seizure dynamics to suggest a plausible mechanism of epileptogenesis. Patients with IGE have significant bilateral alterations in major white-matter fascicles. In the cingulum, fornix, and superior longitudinal fasciculus, tract integrity is compromised, whereas in specific parts of tracts between thalamus and the precentral gyrus, tract integrity is enhanced in patients. Combining these alterations in a logistic regression model, we computed the decision boundary that discriminated patients and controls. The computational model, informed with the findings on the tract abnormalities, specifically highlighted the importance of enhanced cortico-reticular connections along with impaired cortico-cortical connections in inducing pathological seizure-like dynamics. We emphasise taking directionality of brain connectivity into consideration towards understanding the pathological mechanisms; this is possible by combining neuroimaging and computational modelling. Our imaging evidence of structural alterations suggest the loss of cortico-cortical and enhancement of cortico-thalamic fibre integrity in IGE. We further suggest that impaired connectivity from cortical regions to the thalamic reticular nucleus offers a therapeutic target for selectively modifying the brain circuit for reversing the mechanisms leading to epileptogenesis. Significant focal alterations along major white-matter fascicles in IGE patients are characterised. Increased white matter integrity found in thalamo-cortical connections. Decreased white matter integrity found in cortico-cortical connections. Disease mechanism is investigated by combining the neuroimaging findings with a dynamical model of seizure activity. Model implicates cortical projections to the thalamic reticular nucleus in IGE.
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Affiliation(s)
- Nishant Sinha
- Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK; Interdisciplinary Computing and Complex BioSystems Group, School of Computing, Newcastle University, Newcastle upon Tyne, UK.
| | - Yujiang Wang
- Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK; Interdisciplinary Computing and Complex BioSystems Group, School of Computing, Newcastle University, Newcastle upon Tyne, UK; Institute of Neurology, University College London, UK
| | - Justin Dauwels
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore
| | - Marcus Kaiser
- Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK; Interdisciplinary Computing and Complex BioSystems Group, School of Computing, Newcastle University, Newcastle upon Tyne, UK
| | - Thomas Thesen
- Department of Neurology, School of Medicine, New York University, NY, USA; Department of Physiology and Neuroscience, St. Georges University, Grenada, West Indies
| | - Rob Forsyth
- Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Peter Neal Taylor
- Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK; Interdisciplinary Computing and Complex BioSystems Group, School of Computing, Newcastle University, Newcastle upon Tyne, UK; Institute of Neurology, University College London, UK.
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27
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He X, Doucet GE, Pustina D, Sperling MR, Sharan AD, Tracy JI. Presurgical thalamic "hubness" predicts surgical outcome in temporal lobe epilepsy. Neurology 2017; 88:2285-2293. [PMID: 28515267 DOI: 10.1212/wnl.0000000000004035] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/14/2017] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE To characterize the presurgical brain functional architecture presented in patients with temporal lobe epilepsy (TLE) using graph theoretical measures of resting-state fMRI data and to test its association with surgical outcome. METHODS Fifty-six unilateral patients with TLE, who subsequently underwent anterior temporal lobectomy and were classified as obtaining a seizure-free (Engel class I, n = 35) vs not seizure-free (Engel classes II-IV, n = 21) outcome at 1 year after surgery, and 28 matched healthy controls were enrolled. On the basis of their presurgical resting-state functional connectivity, network properties, including nodal hubness (importance of a node to the network; degree, betweenness, and eigenvector centralities) and integration (global efficiency), were estimated and compared across our experimental groups. Cross-validations with support vector machine (SVM) were used to examine whether selective nodal hubness exceeded standard clinical characteristics in outcome prediction. RESULTS Compared to the seizure-free patients and healthy controls, the not seizure-free patients displayed a specific increase in nodal hubness (degree and eigenvector centralities) involving both the ipsilateral and contralateral thalami, contributed by an increase in the number of connections to regions distributed mostly in the contralateral hemisphere. Simulating removal of thalamus reduced network integration more dramatically in not seizure-free patients. Lastly, SVM models built on these thalamic hubness measures produced 76% prediction accuracy, while models built with standard clinical variables yielded only 58% accuracy (both were cross-validated). CONCLUSIONS A thalamic network associated with seizure recurrence may already be established presurgically. Thalamic hubness can serve as a potential biomarker of surgical outcome, outperforming the clinical characteristics commonly used in epilepsy surgery centers.
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Affiliation(s)
- Xiaosong He
- From the Departments of Neurology (X.H., M.R.S., J.I.T.) and Neurosurgery (A.D.S.), Thomas Jefferson University, Philadelphia, PA; Department of Psychiatry (G.E.D.), Icahn School of Medicine at Mount Sinai, New York, NY; and Departments of Neurology and Radiology (D.P.), University of Pennsylvania, Philadelphia
| | - Gaelle E Doucet
- From the Departments of Neurology (X.H., M.R.S., J.I.T.) and Neurosurgery (A.D.S.), Thomas Jefferson University, Philadelphia, PA; Department of Psychiatry (G.E.D.), Icahn School of Medicine at Mount Sinai, New York, NY; and Departments of Neurology and Radiology (D.P.), University of Pennsylvania, Philadelphia
| | - Dorian Pustina
- From the Departments of Neurology (X.H., M.R.S., J.I.T.) and Neurosurgery (A.D.S.), Thomas Jefferson University, Philadelphia, PA; Department of Psychiatry (G.E.D.), Icahn School of Medicine at Mount Sinai, New York, NY; and Departments of Neurology and Radiology (D.P.), University of Pennsylvania, Philadelphia
| | - Michael R Sperling
- From the Departments of Neurology (X.H., M.R.S., J.I.T.) and Neurosurgery (A.D.S.), Thomas Jefferson University, Philadelphia, PA; Department of Psychiatry (G.E.D.), Icahn School of Medicine at Mount Sinai, New York, NY; and Departments of Neurology and Radiology (D.P.), University of Pennsylvania, Philadelphia
| | - Ashwini D Sharan
- From the Departments of Neurology (X.H., M.R.S., J.I.T.) and Neurosurgery (A.D.S.), Thomas Jefferson University, Philadelphia, PA; Department of Psychiatry (G.E.D.), Icahn School of Medicine at Mount Sinai, New York, NY; and Departments of Neurology and Radiology (D.P.), University of Pennsylvania, Philadelphia
| | - Joseph I Tracy
- From the Departments of Neurology (X.H., M.R.S., J.I.T.) and Neurosurgery (A.D.S.), Thomas Jefferson University, Philadelphia, PA; Department of Psychiatry (G.E.D.), Icahn School of Medicine at Mount Sinai, New York, NY; and Departments of Neurology and Radiology (D.P.), University of Pennsylvania, Philadelphia.
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28
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Haridas NJ, Kalayil RV, Tharayil HM, Rappai MP. Organic Mood Disorder Following Left Anterior Temporal Lobectomy with Amygdalohippocampectomy. Indian J Psychol Med 2015; 37:441-2. [PMID: 26702178 PMCID: PMC4676212 DOI: 10.4103/0253-7176.168590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
One third of patients with antiepileptic-resistant temporal lobe epilepsy (TLE) will have to undergo surgery for a better seizure control. Anterior temporal lobectomy (ATL) is done for mesial temporal sclerosis that is the most common histopathological lesion associated with TLE. Psychiatric manifestations following ATL are not uncommon with depressive symptoms more common with left ATL and manic symptoms following right ATL. Mr. A is a 42-year-old left cerebral dominant (Confirmed by WADA test) male with no past history of psychiatric illness who had undergone anterior temporal lobectomy with amygdalohippocampectomy. He started having manic episodes post operatively which subsided with antipsychotics. He had multiple such episodes over the next 13 years with minimal inter episodic symptoms. This is a rare instance of manic symptoms following left-sided ATL that emphasizes the need for better understanding of the cerebral laterality of affective symptoms.
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Affiliation(s)
- Nishanth J Haridas
- Department of Psychiatry, Government Medical College, Kozhikode, Kerala, India
| | - Rajeesh V Kalayil
- Department of Psychiatry, Government Medical College, Kozhikode, Kerala, India
| | - Harish M Tharayil
- Department of Psychiatry, Government Medical College, Kozhikode, Kerala, India
| | - Mary P Rappai
- Comprehensive Center For Sleep Disorders, Sri Chitra Tirunal Institute of Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
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29
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He X, Doucet GE, Sperling M, Sharan A, Tracy JI. Reduced thalamocortical functional connectivity in temporal lobe epilepsy. Epilepsia 2015; 56:1571-9. [PMID: 26193910 DOI: 10.1111/epi.13085] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2015] [Indexed: 01/06/2023]
Abstract
OBJECTIVE In temporal lobe epilepsy (TLE), the thalamus is well known for its role in the propagation and spread of epileptiform activity. However, the integrity of thalamocortical functional connectivity (FC) in TLE and its relation to specific seizure patterns have not yet been determined. We address these issues with resting-state functional magnetic resonance imaging (fMRI). METHODS Resting-state fMRI was performed on two groups of unilateral TLE patients: those with focal seizures only (16 left TLE, 16 right TLE) and those with additional generalized seizures (16 left TLE, 10 right TLE), and 16 matched controls. A thalamic parcellation based on FC between five nonoverlapping cortical seeds (prefrontal, motor, somatosensory, parietal-occipital, and temporal) and the ipsilateral thalamus was carried out to parcel each thalamus into five corresponding segments. FCs between each segment and its ipsilateral cortical seed were extracted and compared across groups using analyses of variance (ANOVAs). RESULTS Compared to healthy controls, patients with TLE displayed decreased thalamocortical FC in multiple posterior and ventromedial thalamic segments of both the ictal and nonictal hemispheres. Our parcellation analysis revealed that these thalamic regions were functionally connected to the parietal/occipital and temporal lobes. In patients with TLE with focal seizures these regional thalamocortical FC decreases were limited to the ictal hemisphere. In contrast, TLE patients with both focal and generalized epileptiform activity displayed FC decreases in both the ictal and nonictal thalamus involving the dorsolateral pulvinar, a region preferentially connected to the parietal and occipital lobes. SIGNIFICANCE Our data provide the first evidence of regional specific thalamocortical FC decreases in patients with unilateral TLE. Furthermore, our results demonstrate that patients with different seizure types present different thalamoparietal/occipital FC decrease patterns. While patients with focal seizures present thalamocortical FC decreases in the ictal hemisphere only, patients with additional generalized seizure activity also show thalamocortical FC decreases involving the thalamus in the nonictal hemisphere.
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Affiliation(s)
- Xiaosong He
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Gaelle E Doucet
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Michael Sperling
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Ashwini Sharan
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Joseph I Tracy
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
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30
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Zhang Z, Xu Q, Liao W, Wang Z, Li Q, Yang F, Zhang Z, Liu Y, Lu G. Pathological uncoupling between amplitude and connectivity of brain fluctuations in epilepsy. Hum Brain Mapp 2015; 36:2756-66. [PMID: 25879781 DOI: 10.1002/hbm.22805] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 03/23/2015] [Accepted: 03/23/2015] [Indexed: 11/11/2022] Open
Abstract
Amplitude and functional connectivity are two fundamental parameters for describing the spontaneous brain fluctuations. These two parameters present close coupling in physiological state, and present different alteration patterns in epilepsy revealed by functional MRI (fMRI). We hypothesized that the alteration of coupling between these two imaging parameters may be underpinned by specific pathological factors of epilepsy, and can be employed to improve the capability for epileptic focus detection. Forty-seven patients (26 left- and 21 right-sided) with mesial temporal lobe epilepsy (mTLE) and 32 healthy controls underwent resting-state fMRI scans. All patients were detected to have interictal epileptic discharges on simultaneous electroencephalograph (EEG) recordings. Amplitude-connectivity coupling was calculated by correlating amplitude and functional connectivity density of low-frequency brain fluctuations. We observed reduced amplitude-connectivity coupling associated with epileptic discharges in the mesial temporal regions in both groups of patients, and increased coupling associated with epilepsy durations in the posterior regions of the default-mode network in the right-sided patients. Moreover, we proposed a new index of amplitude subtracting connectivity, which elevated imaging contrast for differentiating the patients from the controls. The findings indicated that epileptic discharges and chronic damaging effect of epilepsy might both contribute to alterations of amplitude-connectivity coupling in different pivotal regions in mTLE. Investigation on imaging coupling provides synergistic approach for describing brain functional changing features in epilepsy.
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Affiliation(s)
- Zhiqiang Zhang
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.,State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing, China
| | - Qiang Xu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Wei Liao
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.,Center for Cognition and Brain Disorders, Affiliated Hospital of Hangzhou Normal University, Hangzhou, China
| | - Zhengge Wang
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Qian Li
- Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Fang Yang
- Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Zongjun Zhang
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Yijun Liu
- Department of Psychiatry and Neuroscience, University of Florida, Gainesville, Florida
| | - Guangming Lu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.,State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing, China
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31
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Carney PW, Jackson GD. Insights into the mechanisms of absence seizure generation provided by EEG with functional MRI. Front Neurol 2014; 5:162. [PMID: 25225491 PMCID: PMC4150362 DOI: 10.3389/fneur.2014.00162] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 08/14/2014] [Indexed: 11/20/2022] Open
Abstract
Absence seizures (AS) are brief epileptic events characterized by loss of awareness with subtle motor features. They may be very frequent, and impact on attention, learning, and memory. A number of pathophysiological models have been developed to explain the mechanism of absence seizure generation, which relies heavily on observations from animal studies. Studying the structural and functional relationships between large-scale brain networks in humans is only practical with non-invasive whole brain techniques. EEG with functional MRI (EEG-fMRI) is one such technique that provides an opportunity to explore the interactions between brain structures involved in AS generation. A number of fMRI techniques including event-related analysis, time-course analysis, and functional connectivity (FC) have identified a common network of structures involved in AS. This network comprises the thalamus, midline, and lateral parietal cortex [the default mode network (DMN)], caudate nuclei, and the reticular structures of the pons. The main component displaying an increase in blood oxygen level dependent (BOLD) signal relative to the resting state, in group studies, is the thalamus while the most consistent cortical change is reduced BOLD signal in the DMN. Time-course analysis shows that, rather than some structures being activated or inactivated during AS, there appears to be increase in activity across components of the network preceding or following the electro-clinical onset of the seizure. The earliest change in BOLD signal occurs in the DMN, prior to the onset of epileptiform events. This region also shows altered FC in patients with AS. Hence, it appears that engagement of this network is central to AS. In this review, we will explore the insights of EEG-fMRI studies into the mechanisms of AS and consider how the DMN is likely to be the major large-scale brain network central to both seizure generation and seizure manifestations.
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Affiliation(s)
- Patrick W Carney
- The Florey Institute for Neuroscience and Mental Health , Heidelberg, VIC , Australia ; The University of Melbourne , Parkville, VIC , Australia ; Austin Health , Heidelberg, VIC , Australia
| | - Graeme D Jackson
- The Florey Institute for Neuroscience and Mental Health , Heidelberg, VIC , Australia ; The University of Melbourne , Parkville, VIC , Australia ; Austin Health , Heidelberg, VIC , Australia
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Kay B, Szaflarski JP. EEG/fMRI contributions to our understanding of genetic generalized epilepsies. Epilepsy Behav 2014; 34:129-35. [PMID: 24679893 PMCID: PMC4008674 DOI: 10.1016/j.yebeh.2014.02.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Accepted: 02/26/2014] [Indexed: 12/26/2022]
Abstract
The first reports of combined EEG and fMRI used for evaluation of epileptic spikes date back to the mid-90s. At that time, the technique was called EEG-triggered fMRI--the "triggered" corresponded to an epilepsy specialist reviewing live EEG while the patient was located in the scanner; after the spike was identified, a scan was initiated to collect the data. Since then major progress has been made in combined EEG/fMRI data collection and analyses. These advances allow studying the electrophysiology of genetic generalized epilepsies (GGEs) in vivo in greater detail than ever. In addition to continuous data collection, we now have better methods for removing physiologic and fMRI-related artifacts, more advanced understanding of the hemodynamic response functions, and better computational methods to address the questions regarding the origins of the epileptiform discharge generators in patients with GGEs. These advances have allowed us to examine numerous cohorts of children and adults with GGEs while not only looking for spike and wave generators but also examining specific types of GGEs (e.g., juvenile myoclonic epilepsy or childhood absence epilepsy), drug-naïve patients, effects of medication resistance, or effects of epileptiform abnormalities and/or seizures on brain connectivity. While the discussion is ongoing, the prevailing thought is that the GGEs as a group are a network disorder with participation from multiple nodes including the thalami and cortex with the clinical presentation depending on which node of the participating network is affected by the disease process. This review discusses the contributions of EEG/fMRI to our understanding of GGEs.
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Affiliation(s)
- Benjamin Kay
- Graduate Program in Neuroscience, University of Cincinnati Academic Health Center, Cincinnati, OH, USA,Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, OH, USA
| | - Jerzy P. Szaflarski
- Department of Neurology, University of Cincinnati Academic Health Center, Cincinnati, OH, USA,Department of Neurology and the University of Alabama at Birmingham (UAB) Epilepsy Center, UAB, Birmingham, AL, USA
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Kay BP, Holland SK, Privitera MD, Szaflarski JP. Differences in paracingulate connectivity associated with epileptiform discharges and uncontrolled seizures in genetic generalized epilepsy. Epilepsia 2014; 55:256-63. [PMID: 24447031 DOI: 10.1111/epi.12486] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2013] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Patients with genetic generalized epilepsy (GGE) frequently continue to have seizures despite appropriate clinical management. GGE is associated with changes in the resting-state networks modulated by clinical factors such as duration of disease and response to treatment. However, the effect of generalized spike and wave discharges (GSWDs) and/or seizures on resting-state functional connectivity (RSFC) is not well understood. METHODS We investigated the effects of GSWD frequency (in GGE patients), GGE (patients vs. healthy controls), and seizures (uncontrolled vs. controlled) on RSFC using seed-based voxel correlation in simultaneous electroencephalography (EEG) and resting-state functional magnetic resonance imaging (fMRI) (EEG/fMRI) data from 72 GGE patients (23 with uncontrolled seizures) and 38 healthy controls. We used seeds in paracingulate cortex, thalamus, cerebellum, and posterior cingulate cortex to examine changes in cortical-subcortical resting-state networks and the default mode network (DMN). We excluded from analyses time points surrounding GSWDs to avoid possible contamination of the resting state. RESULTS (1) Higher frequency of GSWDs was associated with an increase in seed-based voxel correlation with cortical and subcortical brain regions associated with executive function, attention, and the DMN; (2) RSFC in patients with GGE, when compared to healthy controls, was increased between paracingulate cortex and anterior, but not posterior, thalamus; and (3) GGE patients with uncontrolled seizures exhibited decreased cerebellar RSFC. SIGNIFICANCE Our findings in this large sample of patients with GGE (1) demonstrate an effect of interictal GSWDs on resting-state networks, (2) provide evidence that different thalamic nuclei may be affected differently by GGE, and (3) suggest that cerebellum is a modulator of ictogenic circuits.
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Affiliation(s)
- Benjamin P Kay
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, Ohio, U.S.A; Pediatric Neuroimaging Research Consortium, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, U.S.A
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The involvement of limbic structures in typical and atypical absence epilepsy. Epilepsy Res 2013; 103:111-23. [DOI: 10.1016/j.eplepsyres.2012.08.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 08/15/2012] [Accepted: 08/22/2012] [Indexed: 11/21/2022]
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Szaflarski JP, Kay B, Gotman J, Privitera MD, Holland SK. The relationship between the localization of the generalized spike and wave discharge generators and the response to valproate. Epilepsia 2013; 54:471-80. [PMID: 23294001 DOI: 10.1111/epi.12062] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2012] [Indexed: 11/29/2022]
Abstract
PURPOSE Up to 30% of patients with idiopathic generalized epilepsy (IGE) have seizures that are refractory to medication despite appropriate therapy that commonly includes valproate (VPA). The aim of this study was to compare patients with VPA-refractory and VPA-responsive IGE in order to determine whether there are group differences in generalized spike and wave discharge (GSWD) generators that may be associated with VPA resistance. METHODS Of 89 IGE patients who underwent electroencephalography (EEG) combined with functional magnetic resonance imaging (fMRI; EEG/fMRI), 25 with GSWDs identified in EEG/fMRI data were included. Simultaneous acquisition of 64 channels of EEG data at 10 kHz was performed using an MRI-compatible EEG cap and amplifier at 4T. VPA resistance was defined as lack of seizure control despite therapeutic dose of VPA. KEY FINDINGS The fMRI blood oxygen-level dependent (BOLD) correlates of GSWD in the entire group involved midline thalamus, frontal regions comprising Brodmann areas 6, 24, and 32, and temporal lobes diffusely. When VPA-responsive and VPA-resistant patients were compared, BOLD signal increases were noted in the VPA-resistant patients in medial frontal cortex, along the paracingulate gyrus (Montreal Neurological Institute; MNI x = 2, y = 13.6, z = 45.9), and anterior insula bilaterally (right MNI x = 37.6, y = 7.8, z = 0.6, left MNI x = -35.3, y = 13.6, z = -5.3). SIGNIFICANCE Our findings support the hypothesis that VPA-resistant and VPA-responsive patients may have different GSWD generators. Furthermore, we hypothesize that these differences in GSWD generators may be the reason for different responses to VPA.
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Affiliation(s)
- Jerzy P Szaflarski
- Department of Neurology and Cincinnati Epilepsy Center, University of Cincinnati, Cincinnati, Ohio, USA.
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Lew SM, Matthews AE, Hartman AL, Haranhalli N. Posthemispherectomy hydrocephalus: results of a comprehensive, multiinstitutional review. Epilepsia 2012; 54:383-9. [PMID: 23106378 DOI: 10.1111/epi.12010] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Hemispherectomy surgery for medically intractable epilepsy is known to cause hydrocephalus in a subset of patients. Existing data regarding the incidence of, and risk factors for, developing posthemispherectomy hydrocephalus have been limited by the relatively small number of cases performed by any single center. Our goal was to better understand this phenomenon and to identify risk factors that may predispose patients to developing hydrocephalus after hemispherectomy surgery. METHODS Fifteen pediatric epilepsy centers participated in this study. A retrospective chart review was performed on all available patients who had hemispherectomy surgery. Data collected included surgical techniques, etiology of seizures, prior brain surgery, symptoms and signs of hydrocephalus, timing of shunt placement, and basic demographics. KEY FINDINGS Data were collected from 736 patients who underwent hemispherectomy surgery between 1986 and 2011. Forty-six patients had preexisting shunted hydrocephalus and were excluded from analysis, yielding 690 patients for this study. One hundred sixty-two patients (23%) required hydrocephalus treatment. The timing of hydrocephalus ranged from the immediate postoperative period to 8.5 years after surgery, with 43 patients (27%) receiving shunts >90 days after surgery. Multivariate regression analysis revealed anatomic hemispherectomies (odds ratio [OR] 4.1, p < 0.0001) and previous brain surgery (OR 1.7, p = 0.04) as independent significant risk factors for developing hydrocephalus. There was a trend toward significance for the use of hemostatic agents (OR 2.2, p = 0.07) and the involvement of basal ganglia or thalamus in the resection (OR 2.2, p = 0.08) as risk factors. SIGNIFICANCE Hydrocephalus is a common sequela of hemispherectomy surgery. Surgical technique and prior brain surgery influence the occurrence of posthemispherectomy hydrocephalus. A significant portion of patients develop hydrocephalus on a delayed basis, indicating the need for long-term surveillance.
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Affiliation(s)
- Sean M Lew
- Department of Neurosurgery, Children's Hospital of Wisconsin, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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Berman R, Negishi M, Vestal M, Spann M, Chung MH, Bai X, Purcaro M, Motelow JE, Danielson N, Dix-Cooper L, Enev M, Novotny EJ, Constable RT, Blumenfeld H. Simultaneous EEG, fMRI, and behavior in typical childhood absence seizures. Epilepsia 2010; 51:2011-22. [PMID: 20608963 DOI: 10.1111/j.1528-1167.2010.02652.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
PURPOSE Absence seizures cause transient impairment of consciousness. Typical absence seizures occur in children, and are accompanied by 3-4-Hz spike-wave discharges (SWDs) on electroencephalography (EEG). Prior EEG-functional magnetic resonance imaging (fMRI) studies of SWDs have shown a network of cortical and subcortical changes during these electrical events. However, fMRI during typical childhood absence seizures with confirmed impaired consciousness has not been previously investigated. METHODS We performed EEG-fMRI with simultaneous behavioral testing in 37 children with typical childhood absence epilepsy (CAE). Attentional vigilance was evaluated by a continuous performance task (CPT), and simpler motor performance was evaluated by a repetitive tapping task (RTT). RESULTS SWD episodes were obtained during fMRI scanning from 9 patients among the 37 studied. fMRI signal increases during SWDs were observed in the thalamus, frontal cortex, primary visual, auditory, somatosensory, and motor cortex, and fMRI decreases were seen in the lateral and medial parietal cortex, cingulate gyrus, and basal ganglia. Omission error rate (missed targets) with SWDs during fMRI was 81% on CPT and 39% on RTT. For those seizure epochs during which CPT performance was impaired, fMRI changes were seen in cortical and subcortical structures typically involved in SWDs, whereas minimal changes were observed for the few epochs during which performance was spared. DISCUSSION These findings suggest that typical absence seizures involve a network of cortical-subcortical areas necessary for normal attention and primary information processing. Identification of this network may improve understanding of cognitive impairments in CAE, and may help guide development of new therapies for this disorder.
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Affiliation(s)
- Rachel Berman
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA
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Szaflarski JP, DiFrancesco M, Hirschauer T, Banks C, Privitera MD, Gotman J, Holland SK. Cortical and subcortical contributions to absence seizure onset examined with EEG/fMRI. Epilepsy Behav 2010; 18:404-13. [PMID: 20580319 PMCID: PMC2922486 DOI: 10.1016/j.yebeh.2010.05.009] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2009] [Revised: 05/10/2010] [Accepted: 05/13/2010] [Indexed: 10/19/2022]
Abstract
In patients with idiopathic generalized epilepsies (IGEs), bursts of generalized spike and wave discharges (GSWDs) lasting > or =2 seconds are considered absence seizures. The location of the absence seizures generators in IGEs is thought to involve interplay between various components of thalamocortical circuits; we have recently postulated that medication resistance may, in part, be related to the location of the GSWD generators [Szaflarski JP, Lindsell CJ, Zakaria T, Banks C, Privitera MD. Epilepsy Behav. 2010;17:525-30]. In the present study we hypothesized that patients with medication-refractory IGE (R-IGE) and continued absence seizures may have GSWD generators in locations other than the thalamus, as typically seen in patients with IGE. Hence, the objective of this study was to determine the location of the GSWD generators in patients with R-IGE using EEG/fMRI. Eighty-three patients with IGE received concurrent EEG/fMRI at 4 T. Nine of them (aged 15-55) experienced absence seizures during EEG/fMRI and were included; all were diagnosed with R-IGE. Subjects participated in up to three 20-minute EEG/fMRI sessions (400 volumes, TR=3 seconds) performed at 4 T. After removal of fMRI and ballistocardiographic artifacts, 36 absence seizures were identified. Statistical parametric maps were generated for each of these sessions correlating seizures to BOLD response. Timing differences between brain regions were tested using statistical parametric maps generated by modeling seizures with onset times shifted relative to the GSWD onsets. Although thalamic BOLD responses peaked approximately 6 seconds after the onset of absence seizures, other areas including the prefrontal and dorsolateral cortices showed brief and nonsustained peaks occurring approximately 2 seconds prior to the maximum of the thalamic peak. Temporal lobe peaks occurred at the same time as the thalamic peak, with a cerebellar peak occurring approximately 1 second later. Confirmatory analysis averaging cross-correlation between cortical and thalamic regions of interest across seizures corroborated these findings. Finally, Granger causality analysis showed effective connectivity directed from frontal lobe to thalamus, supporting the notion of earlier frontal than thalamic involvement. The results of this study support our original hypothesis and indicate that in the patients with R-IGE studied, absence seizures may be initiated by widespread cortical (frontal and parietal) areas and sustained in subcortical (thalamic) regions, suggesting that the examined patients have cortical onset epilepsy with propagation to thalamus.
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Affiliation(s)
- Jerzy P. Szaflarski
- Department of Neurology, University of Cincinnati Medical Center, Cincinnati, OH, USA, Department of Neuroscience, University of Cincinnati Medical Center, Cincinnati, OH, USA, Center for Imaging Research at the University of Cincinnati Medical Center, Cincinnati, OH, USA, Imaging Research Center at the Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA,Address for Correspondence: Jerzy P. Szaflarski, MD, PhD, Department of Neurology, University of Cincinnati College of Medicine, 260 Stetson Street, Cincinnati, OH 45267-0525, Phone: 513.558.5440,
| | - Mark DiFrancesco
- Imaging Research Center at the Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA, Department of Radiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Thomas Hirschauer
- Imaging Research Center at the Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Christi Banks
- Department of Neurology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Michael D. Privitera
- Department of Neurology, University of Cincinnati Medical Center, Cincinnati, OH, USA
| | - Jean Gotman
- Montreal Neurological Institute at the McGill University, Montreal, CA
| | - Scott K. Holland
- Department of Neuroscience, University of Cincinnati Medical Center, Cincinnati, OH, USA, Imaging Research Center at the Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA, Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, OH, USA, Department of Radiology, University of Cincinnati Medical Center, Cincinnati, OH, USA
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Sitnikova E. Thalamo-cortical mechanisms of sleep spindles and spike–wave discharges in rat model of absence epilepsy (a review). Epilepsy Res 2010; 89:17-26. [DOI: 10.1016/j.eplepsyres.2009.09.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 08/26/2009] [Accepted: 09/07/2009] [Indexed: 11/29/2022]
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Millett D. Chapter 26: a history of seizures and epilepsies: from the falling disease to dysrhythmias of the brain. HANDBOOK OF CLINICAL NEUROLOGY 2010; 95:387-400. [PMID: 19892129 DOI: 10.1016/s0072-9752(08)02126-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- David Millett
- Department of Neurology, Keck School of Medicine at USC, Los Angeles, CA 90033, USA.
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Glykys J, Dzhala VI, Kuchibhotla KV, Feng G, Kuner T, Augustine G, Bacskai BJ, Staley KJ. Differences in cortical versus subcortical GABAergic signaling: a candidate mechanism of electroclinical uncoupling of neonatal seizures. Neuron 2009; 63:657-72. [PMID: 19755108 DOI: 10.1016/j.neuron.2009.08.022] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 08/19/2009] [Accepted: 08/19/2009] [Indexed: 01/24/2023]
Abstract
Electroclinical uncoupling of neonatal seizures refers to electrographic seizure activity that is not clinically manifest. Uncoupling increases after treatment with Phenobarbital, which enhances the GABA(A) receptor (GABA(A)R) conductance. The effects of GABA(A)R activation depend on the intracellular Cl(-) concentration ([Cl(-)](i)) that is determined by the inward Cl(-) transporter NKCC1 and the outward Cl(-) transporter KCC2. Differential maturation of Cl(-) transport observed in cortical versus subcortical regions should alter the efficacy of GABA-mediated inhibition. In perinatal rat pups, most thalamic neurons maintained low [Cl(-)](i) and were inhibited by GABA. Phenobarbital suppressed thalamic seizure activity. Most neocortical neurons maintained higher [Cl(-)](i), and were excited by GABA(A)R activation. Phenobarbital had insignificant anticonvulsant responses in the neocortex until NKCC1 was blocked. Regional differences in the ontogeny of Cl(-) transport may thus explain why seizure activity in the cortex is not suppressed by anticonvulsants that block the transmission of seizure activity through subcortical networks.
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Affiliation(s)
- Joseph Glykys
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02144, USA
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Westmijse I, Ossenblok P, Gunning B, van Luijtelaar G. Onset and propagation of spike and slow wave discharges in human absence epilepsy: A MEG study. Epilepsia 2009; 50:2538-48. [PMID: 19519798 DOI: 10.1111/j.1528-1167.2009.02162.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE A nonlinear association and a source localization technique were used to describe the onset and propagation of spike-and-slow-wave discharges (SWDs) in children with absence seizures. Previous studies have emphasized a leading cortical role in the generation of absence seizures in genetic epileptic rats. METHODS Synchronization between all magnetoencephalography (MEG) sensor-couples before and during SWDs in five patients was investigated over time. A source localization [beamformer, SAM(g(2))] technique was used to find brain regions associated with the origin of the spikes of the SWDs. RESULTS The onset of SWDs was characterized by high associations at left and right frontal regions. An alternating pattern of high synchronization was found during trains of SWDs: generalized during the wave and localized during the spike; the origin of the spike was different from the onset of SWDs, more frontal lateral and medial parietal. The localization of this latter region was confirmed with SAM(g(2)). DISCUSSION The outcome of the nonlinear association techniques demonstrated that SWDs have a local cortical onset, whereas the association and beamformer technique support a local or even a focal cortical involvement in the occurrence of the spike in a train of SWDs. In all, the cortex contains local frontal and parietal sites relevant before the onset of the generalized pattern of SWDs and other ones that might contain the driving force behind the spike in trains of 3-4 Hz SWDs.
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Affiliation(s)
- Inge Westmijse
- Donders Centre for Cognition, Radboud University Nijmegen, The Netherlands
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Blumenfeld H, Varghese GI, Purcaro MJ, Motelow JE, Enev M, McNally KA, Levin AR, Hirsch LJ, Tikofsky R, Zubal IG, Paige AL, Spencer SS. Cortical and subcortical networks in human secondarily generalized tonic-clonic seizures. ACTA ACUST UNITED AC 2009; 132:999-1012. [PMID: 19339252 DOI: 10.1093/brain/awp028] [Citation(s) in RCA: 229] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Generalized tonic-clonic seizures are among the most dramatic physiological events in the nervous system. The brain regions involved during partial seizures with secondary generalization have not been thoroughly investigated in humans. We used single photon emission computed tomography (SPECT) to image cerebral blood flow (CBF) changes in 59 secondarily generalized seizures from 53 patients. Images were analysed using statistical parametric mapping to detect cortical and subcortical regions most commonly affected in three different time periods: (i) during the partial seizure phase prior to generalization; (ii) during the generalization period; and (iii) post-ictally. We found that in the pre-generalization period, there were focal CBF increases in the temporal lobe on group analysis, reflecting the most common region of partial seizure onset. During generalization, individual patients had focal CBF increases in variable regions of the cerebral cortex. Group analysis during generalization revealed that the most consistent increase occurred in the superior medial cerebellum, thalamus and basal ganglia. Post-ictally, there was a marked progressive CBF increase in the cerebellum which spread to involve the bilateral lateral cerebellar hemispheres, as well as CBF increases in the midbrain and basal ganglia. CBF decreases were seen in the fronto-parietal association cortex, precuneus and cingulate gyrus during and following seizures, similar to the 'default mode' regions reported previously to show decreased activity in seizures and in normal behavioural tasks. Analysis of patient behaviour during and following seizures showed impaired consciousness at the time of SPECT tracer injections. Correlation analysis across patients demonstrated that cerebellar CBF increases were related to increases in the upper brainstem and thalamus, and to decreases in the fronto-parietal association cortex. These results reveal a network of cortical and subcortical structures that are most consistently involved in secondarily generalized tonic-clonic seizures. Abnormal increased activity in subcortical structures (cerebellum, basal ganglia, brainstem and thalamus), along with decreased activity in the association cortex may be crucial for motor manifestations and for impaired consciousness in tonic-clonic seizures. Understanding the networks involved in generalized tonic-clonic seizures can provide insights into mechanisms of behavioural changes, and may elucidate targets for improved therapies.
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Affiliation(s)
- H Blumenfeld
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8018, USA.
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Abstract
Generalized spike-wave seizures are typically brief events associated with dynamic changes in brain physiology, metabolism, and behavior. Functional magnetic resonance imaging (fMRI) provides a relatively high spatiotemporal resolution method for imaging cortical-subcortical network activity during spike-wave seizures. Patients with spike-wave seizures often have episodes of staring and unresponsiveness which interfere with normal behavior. Results from human fMRI studies suggest that spike-wave seizures disrupt specific networks in the thalamus and frontoparietal association cortex which are critical for normal attentive consciousness. However, the neuronal activity underlying imaging changes seen during fMRI is not well understood, particularly in abnormal conditions such as seizures. Animal models have begun to provide important fundamental insights into the neuronal basis for fMRI changes during spike-wave activity. Work from these models including both fMRI and direct neuronal recordings suggest that, in humans, specific cortical-subcortical networks are involved in spike-wave, while other regions are spared. Regions showing fMRI increases demonstrate correlated increases in neuronal activity in animal models. The mechanisms of fMRI decreases in spike-wave will require further investigation. A better understanding of the specific brain regions involved in generating spike-wave seizures may help guide efforts to develop targeted therapies aimed at preventing or reversing abnormal excitability in these brain regions, ultimately leading to a cure for this disorder.
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Affiliation(s)
- Joshua E. Motelow
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
| | - Hal Blumenfeld
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
- Department of Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
- QNMR, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
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Sitnikova E, Dikanev T, Smirnov D, Bezruchko B, van Luijtelaar G. Granger causality: cortico-thalamic interdependencies during absence seizures in WAG/Rij rats. J Neurosci Methods 2008; 170:245-54. [PMID: 18313761 DOI: 10.1016/j.jneumeth.2008.01.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 12/14/2007] [Accepted: 01/18/2008] [Indexed: 11/18/2022]
Abstract
Linear Granger causality was used to identify the coupling strength and directionality of information transport between frontal cortex and thalamus during spontaneous absence seizures in a genetic model, the WAG/Rij rats. Electroencephalograms were recorded at the cortical surface and from the specific thalamus. Granger coupling strength was measured before, during and after the occurrence of spike-wave discharges (SWD). Before the onset of SWD, coupling strength was low, but associations from thalamus-to-cortex were stronger than vice versa. The onset of SWD was associated with a rapid and significant increase of coupling strength in both directions. There were no changes in Granger causalities before the onset of SWD. The strength of thalamus-to-cortex coupling remained constantly high during the seizures. The strength of cortex-to-thalamus coupling gradually diminished shortly after the onset of SWD and returned to the pre-SWD level when SWD stopped. In contrast, the strength of thalamus-to-cortex coupling remained elevated even after cessation of SWD. The strong and sustained influence of thalamus-to-cortex may facilitate propagation and maintenance of seizure activity, while rapid reduction of cortex-to-thalamus coupling strength may prompt the cessation of SWD. However, the linear estimation of Granger coupling strength does not seem to be sufficient for predicting episodes with absence epilepsy.
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Affiliation(s)
- Evgenia Sitnikova
- Department of Neuroontogenesis, Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova Str. 5A, 117485 Moscow, Russia.
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Sitnikova E, van Luijtelaar G. Electroencephalographic Characterization of Spike-Wave Discharges in Cortex and Thalamus in WAG/Rij Rats. Epilepsia 2007. [DOI: 10.1111/j.1528-1167.2007.01250.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Takebayashi S, Hashizume K, Tanaka T, Hodozuka A. The effect of electrical stimulation and lesioning of the anterior thalamic nucleus on kainic acid-induced focal cortical seizure status in rats. Epilepsia 2007; 48:348-58. [PMID: 17295630 DOI: 10.1111/j.1528-1167.2006.00948.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE The present study aimed to clarify the effect of electrical stimulation and lesioning of the anterior nucleus of the thalamus (ANT) on kainic acid (KA)-induced focal cortical seizures in a rat model. To address the mechanism underlying these anticonvulsant actions, cerebral glucose metabolism after ANT electrical stimulation and lesioning was also examined. METHODS Wistar rats were divided into five major groups: control (n = 9), unilateral (n = 9), and bilateral (n = 9) ANT electrical stimulation, and unilateral (n = 9) and bilateral (n = 9) ANT lesioning. After KA injection, average clinical-seizure frequencies in each group were measured. Electrical stimulation of ANT was introduced after induction of seizure status epilepticus. Stimulation was on for 30 min and off for 30 min per 60-min cycle. Local cerebral glucose utilization (LCGU) was also measured by using [(14)C] 2-deoxyglucose autoradiography in three groups of rats: control (n = 7), bilateral ANT stimulation (n = 7), and bilateral ANT lesioning (n = 7). RESULTS Unilateral ANT electrical stimulation and lesioning significantly reduced clinical seizure frequency, compared with control animals. Strikingly, no animals treated with bilateral ANT procedures demonstrated any clinical seizure. LCGU was markedly increased in the sensorimotor cortex, striatum, thalamus, mammillary body, and midbrain tegmentum of control group rats after KA injection, but no increase in LCGU was noted in rats treated with bilateral ANT lesioning or stimulation. CONCLUSIONS The electrical stimulation and lesioning of ANT suppressed focal cortical clinical seizures induced by KA injection. Additionally, an analysis of cerebral metabolic changes indicated that these procedures might suppress the function as amplifier and synchronizer of seizure activity.
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Affiliation(s)
- Seiji Takebayashi
- Department of Neurosurgery, Asahikawa Medical College, Asahikawa, Japan.
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Abstract
The idiopathic generalized epilepsies encompass a class of epileptic seizure types that exhibit a polygenic and heritable etiology. Advances in molecular biology and genetics have implicated defects in certain types of voltage-gated calcium channels and their ancillary subunits as important players in this form of epilepsy. Both T-type and P/Q-type channels appear to mediate important contributions to seizure genesis, modulation of network activity, and genetic seizure susceptibility. Here, we provide a comprehensive overview of the roles of these channels and associated subunits in normal and pathological brain activity within the context of idiopathic generalized epilepsy.
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Affiliation(s)
- Houman Khosravani
- Department of Physiology and Biophysics, Hotchkiss Brain Institute, University of Calgary, Canada
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Abstract
Spike-wave seizures are often considered a relatively "pure" form of epilepsy, with a uniform defect present in all patients and involvement of the whole brain homogeneously. Here, we present evidence against these common misconceptions. Rather than a uniform disorder, spike-wave rhythms arise from the normal inherent network properties of brain excitatory and inhibitory circuits, where they can be provoked by many different insults in several different brain networks. Here we discuss several different cellular and molecular mechanisms that may contribute to the generation of spike-wave seizures, particularly in idiopathic generalized epilepsy. In addition, we discuss growing evidence that electrical, neuroimaging, and molecular changes in spike-wave seizures do not involve the entire brain homogeneously. Rather, spike-wave discharges occur selectively in some thalamocortical networks, while sparing others. It is hoped that improved understanding of the heterogeneous defects and selective brain regions involved will ultimately lead to more effective treatments for spike-wave seizures.
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Affiliation(s)
- Hal Blumenfeld
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA.
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