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Yao Y, Wang X, Zhao B, Mo J, Guo Z, Yang B, Li Z, Fan X, Cai D, Sang L, Zheng Z, Shao X, Ai L, Hu W, Zhang C, Zhang K. Hypometabolic patterns are related to post-surgical seizure outcomes in focal cortical dysplasia: A semi-quantitative study. Epilepsia Open 2024; 9:653-664. [PMID: 38265725 PMCID: PMC10984320 DOI: 10.1002/epi4.12903] [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: 05/11/2023] [Revised: 12/25/2023] [Accepted: 01/06/2024] [Indexed: 01/25/2024] Open
Abstract
OBJECTIVE Fluorine-18-fluorodeoxyglucose-positron emission tomography (FDG-PET) is routinely used for presurgical evaluation in many epilepsy centers. Hypometabolic characteristics have been extensively examined in prior studies, but the metabolic patterns associated with specific pathological types of drug-resistant epilepsy remain to be fully defined. This study was developed to explore the relationship between metabolic patterns or characteristics and surgical outcomes in type I and II focal cortical dysplasia (FCD) patients based on results from a large cohort. METHODS Data from individuals who underwent epilepsy surgery from 2014 to 2019 with a follow-up duration of over 3 years and a pathological classification of type I or II FCD in our hospital were retrospectively analyzed. Hypometabolic patterns were quantitatively identified via statistical parametric mapping (SPM) and qualitatively analyzed via visual examination of PET-MRI co-registration images. Univariate analyses were used to explore the relationship between metabolic patterns and surgical outcomes. RESULTS In total, this study included data from 210 patients. Following SPM calculations, four hypometabolic patterns were defined including unilobar, multi-lobar, and remote patterns as well as cases where no pattern was evident. In type II FCD patients, the unilobar pattern was associated with the best surgical outcomes (p = 0.014). In visual analysis, single gyrus (p = 0.032) and Clear-cut hypometabolism edge (p = 0.040) patterns exhibited better surgery outcomes in the type II FCD group. CONCLUSIONS PET metabolic patterns are well-correlated with the prognosis of type II FCD patients. However, similar correlations were not observed in type I FCD, potentially owing to the complex distribution of the epileptogenic region. PLAIN LANGUAGE SUMMARY In this study, we demonstrated that FDG-PET was a crucial examination for patients with FCD, which was a common cause of epilepsy. We compared the surgical prognosis for patients with different hypometabolism distribution patterns and found that clear and focal abnormal region in PET was correlated with good surgical outcome in type II FCD patients.
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Affiliation(s)
- Yuan Yao
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Xiu Wang
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Baotian Zhao
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Jiajie Mo
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Zhihao Guo
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Bowen Yang
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Zilin Li
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Xiuliang Fan
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Du Cai
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Lin Sang
- Department of NeurosurgeryBeijing FengTai HospitalBeijingChina
| | - Zhong Zheng
- Department of NeurosurgeryBeijing FengTai HospitalBeijingChina
| | - Xiaoqiu Shao
- Department of NeurologyBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Lin Ai
- Department of Nuclear MedicineBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Wenhan Hu
- Beijing Neurosurgical InstituteCapital Medical UniversityBeijingChina
| | - Chao Zhang
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
| | - Kai Zhang
- Department of NeurosurgeryBeijing TianTan Hospital, Capital Medical UniversityBeijingChina
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Miao Y, Suzuki H, Sugano H, Ueda T, Iimura Y, Matsui R, Tanaka T. Causal Connectivity Network Analysis of Ictal Electrocorticogram With Temporal Lobe Epilepsy Based on Dynamic Phase Transfer Entropy. IEEE Trans Biomed Eng 2024; 71:531-541. [PMID: 37624716 DOI: 10.1109/tbme.2023.3308616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/27/2023]
Abstract
Temporallobe epilepsy (TLE) has been conceptualized as a brain network disease, which generates brain connectivity dynamics within and beyond the temporal lobe structures in seizures. The hippocampus is a representative epileptogenic focus in TLE. Understanding the causal connectivity in terms of brain network during seizures is crucial in revealing the triggering mechanism of epileptic seizures originating from the hippocampus (HPC) spread to the lateral temporal cortex (LTC) by ictal electrocorticogram (ECoG), particularly in high-frequency oscillations (HFOs) bands. In this study, we proposed the unified-epoch dynamic causality analysis method to investigate the causal influence dynamics between two brain regions (HPC and LTC) at interictal and ictal phases in the frequency range of 1-500 Hz by introducing the phase transfer entropy (PTE) out/in-ratio and sliding window. We also proposed PTE-based machine learning algorithms to identify epileptogenic zone (EZ). Nine patients with a total of 26 seizures were included in this study. We hypothesized that: 1) HPC is the focus with the stronger causal connectivity than that in LTC in the ictal state at gamma and HFOs bands. 2) Causal connectivity in the ictal phase shows significant changes compared to that in the interictal phase. 3) The PTE out/in-ratio in the HFOs band can identify the EZ with the best prediction performance.
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Withers CP, Diamond JM, Yang B, Snyder K, Abdollahi S, Sarlls J, Chapeton JI, Theodore WH, Zaghloul KA, Inati SK. Identifying sources of human interictal discharges with travelling wave and white matter propagation. Brain 2023; 146:5168-5181. [PMID: 37527460 PMCID: PMC11046055 DOI: 10.1093/brain/awad259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/30/2023] [Accepted: 07/19/2023] [Indexed: 08/03/2023] Open
Abstract
Interictal epileptiform discharges have been shown to propagate from focal epileptogenic sources as travelling waves or through more rapid white matter conduction. We hypothesize that both modes of propagation are necessary to explain interictal discharge timing delays. We propose a method that, for the first time, incorporates both propagation modes to identify unique potential sources of interictal activity. We retrospectively analysed 38 focal epilepsy patients who underwent intracranial EEG recordings and diffusion-weighted imaging for epilepsy surgery evaluation. Interictal discharges were detected and localized to the most likely source based on relative delays in time of arrival across electrodes, incorporating travelling waves and white matter propagation. We assessed the influence of white matter propagation on distance of spread, timing and clinical interpretation of interictal activity. To evaluate accuracy, we compared our source localization results to earliest spiking regions to predict seizure outcomes. White matter propagation helps to explain the timing delays observed in interictal discharge sequences, underlying rapid and distant propagation. Sources identified based on differences in time of receipt of interictal discharges are often distinct from the leading electrode location. Receipt of activity propagating rapidly via white matter can occur earlier than more local activity propagating via slower cortical travelling waves. In our cohort, our source localization approach was more accurate in predicting seizure outcomes than the leading electrode location. Inclusion of white matter in addition to travelling wave propagation in our model of discharge spread did not improve overall accuracy but allowed for identification of unique and at times distant potential sources of activity, particularly in patients with persistent postoperative seizures. Since distant white matter propagation can occur more rapidly than local travelling wave propagation, combined modes of propagation within an interictal discharge sequence can decouple the commonly assumed relationship between spike timing and distance from the source. Our findings thus highlight the clinical importance of recognizing the presence of dual modes of propagation during interictal discharges, as this may be a cause of clinical mislocalization.
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Affiliation(s)
- C Price Withers
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joshua M Diamond
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Braden Yang
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kathryn Snyder
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shervin Abdollahi
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joelle Sarlls
- NIH MRI Research Facility, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Julio I Chapeton
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - William H Theodore
- Clinical Epilepsy Section, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kareem A Zaghloul
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sara K Inati
- Neurophysiology of Epilepsy Unit, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
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Aiello G, Ledergerber D, Dubcek T, Stieglitz L, Baumann C, Polanìa R, Imbach L. Functional network dynamics between the anterior thalamus and the cortex in deep brain stimulation for epilepsy. Brain 2023; 146:4717-4735. [PMID: 37343140 DOI: 10.1093/brain/awad211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 05/10/2023] [Accepted: 06/08/2023] [Indexed: 06/23/2023] Open
Abstract
Owing to its unique connectivity profile with cortical brain regions, and its suggested role in the subcortical propagation of seizures, the anterior nucleus of the thalamus (ANT) has been proposed as a key deep brain stimulation (DBS) target in drug-resistant epilepsy. However, the spatio-temporal interaction dynamics of this brain structure, and the functional mechanisms underlying ANT DBS in epilepsy remain unknown. Here, we study how the ANT interacts with the neocortex in vivo in humans and provide a detailed neurofunctional characterization of mechanisms underlying the effectiveness of ANT DBS, aiming at defining intraoperative neural biomarkers of responsiveness to therapy, assessed at 6 months post-implantation as the reduction in seizure frequency. A cohort of 15 patients with drug-resistant epilepsy (n = 6 males, age = 41.6 ± 13.79 years) underwent bilateral ANT DBS implantation. Using intraoperative cortical and ANT simultaneous electrophysiological recordings, we found that the ANT is characterized by high amplitude θ (4-8 Hz) oscillations, mostly in its superior part. The strongest functional connectivity between the ANT and the scalp EEG was also found in the θ band in ipsilateral centro-frontal regions. Upon intraoperative stimulation in the ANT, we found a decrease in higher EEG frequencies (20-70 Hz) and a generalized increase in scalp-to-scalp connectivity. Crucially, we observed that responders to ANT DBS treatment were characterized by higher EEG θ oscillations, higher θ power in the ANT, and stronger ANT-to-scalp θ connectivity, highlighting the crucial role of θ oscillations in the dynamical network characterization of these structures. Our study provides a comprehensive characterization of the interaction dynamic between the ANT and the cortex, delivering crucial information to optimize and predict clinical DBS response in patients with drug-resistant epilepsy.
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Affiliation(s)
- Giovanna Aiello
- Decision Neuroscience Lab, Department of Health Sciences and Technology, ETH Zurich, 8092 Zurich, Switzerland
- Swiss Epilepsy Center (Klinik Lengg), 8008 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, 8057 Zurich, Switzerland
| | - Debora Ledergerber
- Swiss Epilepsy Center (Klinik Lengg), 8008 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, 8057 Zurich, Switzerland
| | - Tena Dubcek
- Decision Neuroscience Lab, Department of Health Sciences and Technology, ETH Zurich, 8092 Zurich, Switzerland
- Swiss Epilepsy Center (Klinik Lengg), 8008 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, 8057 Zurich, Switzerland
| | - Lennart Stieglitz
- Department of Neurosurgery, University Hospital Zurich, 8091 Zurich, Switzerland
| | - Christian Baumann
- Department of Neurology, University Hospital Zurich, 8091 Zurich, Switzerland
| | - Rafael Polanìa
- Decision Neuroscience Lab, Department of Health Sciences and Technology, ETH Zurich, 8092 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, 8057 Zurich, Switzerland
| | - Lukas Imbach
- Swiss Epilepsy Center (Klinik Lengg), 8008 Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, 8057 Zurich, Switzerland
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Guo J, Guo M, Liu R, Kong Y, Hu X, Yao L, Lv S, Lv J, Wang X, Kong QX. Seizure Outcome After Surgery for Refractory Epilepsy Diagnosed by 18F-fluorodeoxyglucose positron emission tomography ( 18F-FDG PET/MRI): A Systematic Review and Meta-Analysis. World Neurosurg 2023; 173:34-43. [PMID: 36746239 DOI: 10.1016/j.wneu.2023.01.114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Accepted: 01/30/2023] [Indexed: 02/05/2023]
Abstract
OBJECTIVE When magnetic resonance imaging (MRI) fails to detect an underlying epileptogenic lesion, the odds of a good outcome after epilepsy surgery are significantly lower (20%-65% compared with 60%-90% if a lesion is detected). We investigated the possible effects of introducing hybrid 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET)/MRI into the decision algorithm for patients with lesioned and nonlesioned drug-resistant epilepsy. METHODS Three databases were searched from January 1990 to October 2022. We registered the protocol with International Platform of Registered Systematic Review and Meta-analysis Protocols. Studies in which 18F-FDG PET/MRI was conducted with ≥12 months of postsurgical follow-up in patients with refractory epilepsy. Random-effects meta-analysis was used to calculate the proportion of patients with good outcomes. Metaregression was used to investigate sources of heterogeneity. RESULTS We identified 8105 studies, of which 23 (1292 patients in total) were included. The overall good postoperative outcome rate was 71% (95% confidence interval 63.6-74.9). Good outcome was associated with the location of the refractory epileptic lesion (temporal lobe or extratemporal; risk ratio 1.27 [95% confidence interval 1.01-1.52], P = 0.009); Length of postoperative follow-up ≥40 months included in the same study accounted for 0.6% of the observed heterogeneity. CONCLUSIONS Seventy-one percent of patients with refractory epilepsy and 18F-FDG PET/MRI epileptogenic lesion features had a good outcome of epilepsy after surgery. Our findings can be incorporated into routine preoperative consultations and emphasize the importance of the complete resection of the temporal lobe epileptogenic zone for 18F-FDG PET/MRI detection when safe and feasible.
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Affiliation(s)
- Jia Guo
- Clinical Medical College, Jining Medical University, Jining, China
| | - Mujie Guo
- Department of Imaging, Affiliated Hospital of Jining Medical University, Jining, China
| | - Ruihan Liu
- Department of Pediatrics, Affiliated Hospital of Jining Medical University, Jining, China; Postdoctoral Mobile Station of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Yu Kong
- Department of Imaging, Affiliated Hospital of Jining Medical University, Jining, China
| | - Xibin Hu
- Department of Imaging, Affiliated Hospital of Jining Medical University, Jining, China
| | - Lei Yao
- Clinical Medical College, Jining Medical University, Jining, China
| | - Shaomin Lv
- Clinical Medical College, Jining Medical University, Jining, China
| | - Jiahua Lv
- Clinical Medical College, Jining Medical University, Jining, China
| | - Xinyu Wang
- Clinical Medical College, Jining Medical University, Jining, China
| | - Qing-Xia Kong
- Department of Neurology, Affiliated Hospital of Jining Medical University, Jining, China.
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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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Sumsky S, Greenfield LJ. Network analysis of preictal iEEG reveals changes in network structure preceding seizure onset. Sci Rep 2022; 12:12526. [PMID: 35869236 PMCID: PMC9307526 DOI: 10.1038/s41598-022-16877-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 07/18/2022] [Indexed: 12/05/2022] Open
Abstract
Seizures likely result from aberrant network activity and synchronization. Changes in brain network connectivity may underlie seizure onset. We used a novel method of rapid network model estimation from intracranial electroencephalography (iEEG) data to characterize pre-ictal changes in network structure prior to seizure onset. We analyzed iEEG data from 20 patients from the iEEG.org database. Using 10 s epochs sliding by 1 s intervals, a multiple input, single output (MISO) state space model was estimated for each output channel and time point with all other channels as inputs, generating sequential directed network graphs of channel connectivity. These networks were assessed using degree and betweenness centrality. Both degree and betweenness increased at seizure onset zone (SOZ) channels 37.0 ± 2.8 s before seizure onset. Degree rose in all channels 8.2 ± 2.2 s prior to seizure onset, with increasing connections between the SOZ and surrounding channels. Interictal networks showed low and stable connectivity. A novel MISO model-based network estimation method identified changes in brain network structure just prior to seizure onset. Increased connectivity was initially isolated within the SOZ and spread to non-SOZ channels before electrographic seizure onset. Such models could help confirm localization of SOZ regions.
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Li X, Zhang H, Lai H, Wang J, Wang W, Yang X. High-Frequency Oscillations and Epileptogenic Network. Curr Neuropharmacol 2022; 20:1687-1703. [PMID: 34503414 PMCID: PMC9881061 DOI: 10.2174/1570159x19666210908165641] [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: 05/11/2021] [Revised: 08/26/2021] [Accepted: 08/31/2021] [Indexed: 11/22/2022] Open
Abstract
Epilepsy is a network disease caused by aberrant neocortical large-scale connectivity spanning regions on the scale of several centimeters. High-frequency oscillations, characterized by the 80-600 Hz signals in electroencephalography, have been proven to be a promising biomarker of epilepsy that can be used in assessing the severity and susceptibility of epilepsy as well as the location of the epileptogenic zone. However, the presence of a high-frequency oscillation network remains a topic of debate as high-frequency oscillations have been previously thought to be incapable of propagation, and the relationship between high-frequency oscillations and the epileptogenic network has rarely been discussed. Some recent studies reported that high-frequency oscillations may behave like networks that are closely relevant to the epileptogenic network. Pathological highfrequency oscillations are network-driven phenomena and elucidate epileptogenic network development; high-frequency oscillations show different characteristics coincident with the epileptogenic network dynamics, and cross-frequency coupling between high-frequency oscillations and other signals may mediate the generation and propagation of abnormal discharges across the network.
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Affiliation(s)
- Xiaonan Li
- Bioland Laboratory, Guangzhou, China; ,Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
| | | | | | - Jiaoyang Wang
- Bioland Laboratory, Guangzhou, China; ,Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
| | - Wei Wang
- Bioland Laboratory, Guangzhou, China; ,Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China
| | - Xiaofeng Yang
- Bioland Laboratory, Guangzhou, China; ,Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China,Address correspondence to this author at the Bioland Laboratory, Guangzhou, China; Tel: 86+ 18515855127; E-mail:
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Multimodal Presurgical Evaluation of Medically Refractory Focal Epilepsy in Adults: An Update for Radiologists. AJR Am J Roentgenol 2022; 219:488-500. [PMID: 35441531 DOI: 10.2214/ajr.22.27588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Surgery is a potentially curative treatment option for patients with medically refractory focal epilepsy. Advanced neuroimaging modalities often improve surgical outcomes by contributing key information during the highly individualized surgical planning process and intraoperative localization. Hence, neuroradiologists play an integral role as part of the multidisciplinary management team. In this review, we initially present the conceptual background and practical framework of the presurgical evaluation process, including a description of the surgical treatment approaches in medically refractory focal epilepsy in adults. This background is followed by an overview of the advanced modalities commonly used during the presurgical workup at level IV epilepsy centers including diffusion imaging techniques, blood oxygen level dependent (BOLD) functional MRI (fMRI), PET, SPECT, and subtraction ictal SPECT, as well as by introductions to 7-T MRI and electrophysiologic techniques including electroencephalography (EEG) and magnetoencephalography (MEG). We also provide illustrative case examples of multimodal neuroimaging including PET/MRI, PET/MRI-DTI, subtraction ictal SPECT, and image-guided stereotactic planning with fMRI-DTI.
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Cao M, Vogrin SJ, Peterson ADH, Woods W, Cook MJ, Plummer C. Dynamical Network Models From EEG and MEG for Epilepsy Surgery—A Quantitative Approach. Front Neurol 2022; 13:837893. [PMID: 35422755 PMCID: PMC9001937 DOI: 10.3389/fneur.2022.837893] [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: 12/17/2021] [Accepted: 03/01/2022] [Indexed: 11/16/2022] Open
Abstract
There is an urgent need for more informative quantitative techniques that non-invasively and objectively assess strategies for epilepsy surgery. Invasive intracranial electroencephalography (iEEG) remains the clinical gold standard to investigate the nature of the epileptogenic zone (EZ) before surgical resection. However, there are major limitations of iEEG, such as the limited spatial sampling and the degree of subjectivity inherent in the analysis and clinical interpretation of iEEG data. Recent advances in network analysis and dynamical network modeling provide a novel aspect toward a more objective assessment of the EZ. The advantage of such approaches is that they are data-driven and require less or no human input. Multiple studies have demonstrated success using these approaches when applied to iEEG data in characterizing the EZ and predicting surgical outcomes. However, the limitations of iEEG recordings equally apply to these studies—limited spatial sampling and the implicit assumption that iEEG electrodes, whether strip, grid, depth or stereo EEG (sEEG) arrays, are placed in the correct location. Therefore, it is of interest to clinicians and scientists to see whether the same analysis and modeling techniques can be applied to whole-brain, non-invasive neuroimaging data (from MRI-based techniques) and neurophysiological data (from MEG and scalp EEG recordings), thus removing the limitation of spatial sampling, while safely and objectively characterizing the EZ. This review aims to summarize current state of the art non-invasive methods that inform epilepsy surgery using network analysis and dynamical network models. We also present perspectives on future directions and clinical applications of these promising approaches.
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Affiliation(s)
- Miao Cao
- Center for MRI Research, Peking University, Beijing, China
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
- Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, VIC, Australia
| | - Simon J. Vogrin
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
- Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, VIC, Australia
- School of Health Sciences, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Andre D. H. Peterson
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
- Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, VIC, Australia
| | - William Woods
- School of Health Sciences, Swinburne University of Technology, Melbourne, VIC, Australia
| | - Mark J. Cook
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
- Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, VIC, Australia
| | - Chris Plummer
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
- Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, VIC, Australia
- School of Health Sciences, Swinburne University of Technology, Melbourne, VIC, Australia
- *Correspondence: Chris Plummer
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Comparison of Qualitative and Quantitative Analyses of MR-Arterial Spin Labeling Perfusion Data for the Assessment of Pediatric Patients with Focal Epilepsies. Diagnostics (Basel) 2022; 12:diagnostics12040811. [PMID: 35453858 PMCID: PMC9032819 DOI: 10.3390/diagnostics12040811] [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: 02/17/2022] [Revised: 03/17/2022] [Accepted: 03/23/2022] [Indexed: 12/07/2022] Open
Abstract
The role of MR Arterial-Spin-Labeling Cerebral Blood Flow maps (ASL-CBF) in the assessment of pediatric focal epilepsy is still debated. We aim to compare the Seizure Onset Zone (SOZ) detection rate of three methods of evaluation of ASL-CBF: 1) qualitative visual (qCBF), 2) z-score voxel-based quantitative analysis of index of asymmetry (AI-CBF), and 3) z-score voxel-based cluster analysis of the quantitative difference of patient’s CBF from the normative data of an age-matched healthy population (cCBF). Interictal ASL-CBF were acquired in 65 pediatric patients with focal epilepsy: 26 with focal brain lesions and 39 with a normal MRI. All hypoperfusion areas visible in at least 3 contiguous images of qCBF analysis were identified. In the quantitative evaluations, clusters with a significant z-score AI-CBF ≤ −1.64 and areas with a z-score cCBF ≤ −1.64 were considered potentially related to the SOZ. These areas were compared with the SOZ defined by the anatomo-electro-clinical data. In patients with a positive MRI, SOZ was correctly identified in 27% of patients using qCBF, 73% using AI-CBF, and 77% using cCBF. In negative MRI patients, SOZ was identified in 18% of patients using qCBF, in 46% using AI-CBF, and in 64% using cCBF (p < 0.001). Quantitative analyses of ASL-CBF maps increase the detection rate of SOZ compared to the qualitative method, principally in negative MRI patients.
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12
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Cao M, Galvis D, Vogrin SJ, Woods WP, Vogrin S, Wang F, Woldman W, Terry JR, Peterson A, Plummer C, Cook MJ. Virtual intracranial EEG signals reconstructed from MEG with potential for epilepsy surgery. Nat Commun 2022; 13:994. [PMID: 35194035 PMCID: PMC8863890 DOI: 10.1038/s41467-022-28640-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 01/28/2022] [Indexed: 12/17/2022] Open
Abstract
Modelling the interactions that arise from neural dynamics in seizure genesis is challenging but important in the effort to improve the success of epilepsy surgery. Dynamical network models developed from physiological evidence offer insights into rapidly evolving brain networks in the epileptic seizure. A limitation of previous studies in this field is the dependence on invasive cortical recordings with constrained spatial sampling of brain regions that might be involved in seizure dynamics. Here, we propose virtual intracranial electroencephalography (ViEEG), which combines non-invasive ictal magnetoencephalographic imaging (MEG), dynamical network models and a virtual resection technique. In this proof-of-concept study, we show that ViEEG signals reconstructed from MEG alone preserve critical temporospatial characteristics for dynamical approaches to identify brain areas involved in seizure generation. We show the non-invasive ViEEG approach may have some advantage over intracranial electroencephalography (iEEG). Future work may be designed to test the potential of the virtual iEEG approach for use in surgical management of epilepsy.
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Affiliation(s)
- Miao Cao
- Department of Medicine St Vincent's Hospital, The University of Melbourne, Melbourne, Australia.,Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, Australia
| | - Daniel Galvis
- Translational Research Exchange at Exeter, University of Exeter, Exeter, UK.,Living Systems Institute, University of Exeter, Exeter, UK.,Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, UK.,Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - Simon J Vogrin
- Department of Medicine St Vincent's Hospital, The University of Melbourne, Melbourne, Australia.,Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, Australia.,Faculty of Health, Art and Design, Swinburne University of Technology, Melbourne, Australia
| | - William P Woods
- Faculty of Health, Art and Design, Swinburne University of Technology, Melbourne, Australia
| | - Sara Vogrin
- Department of Medicine St Vincent's Hospital, The University of Melbourne, Melbourne, Australia.,Department of Medicine Western Health, The University of Melbourne, Melbourne, Australia
| | - Fan Wang
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,CAS Centre for Excellence in Brain Science and Intelligence Technology, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Wessel Woldman
- Translational Research Exchange at Exeter, University of Exeter, Exeter, UK.,Living Systems Institute, University of Exeter, Exeter, UK.,Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, UK.,Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - John R Terry
- Translational Research Exchange at Exeter, University of Exeter, Exeter, UK.,Living Systems Institute, University of Exeter, Exeter, UK.,Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, UK.,Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - Andre Peterson
- Department of Medicine St Vincent's Hospital, The University of Melbourne, Melbourne, Australia.,Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, Australia.,Department of Biomedical Engineering, The University of Melbourne, Melbourne, Australia
| | - Chris Plummer
- Department of Medicine St Vincent's Hospital, The University of Melbourne, Melbourne, Australia. .,Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, Australia. .,Faculty of Health, Art and Design, Swinburne University of Technology, Melbourne, Australia.
| | - Mark J Cook
- Department of Medicine St Vincent's Hospital, The University of Melbourne, Melbourne, Australia.,Centre for Clinical Neurosciences and Neurological Research, St Vincent's Hospital Melbourne, Melbourne, Australia.,Department of Biomedical Engineering, The University of Melbourne, Melbourne, Australia
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13
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Zhang L, Zhou H, Zhang W, Ling X, Zeng C, Tang Y, Gan J, Tan Q, Hu X, Li H, Cheng B, Xu H, Guo Q. Electroclinical and Multimodality Neuroimaging Characteristics and Predictors of Post-Surgical Outcome in Focal Cortical Dysplasia Type IIIa. Front Bioeng Biotechnol 2022; 9:810897. [PMID: 35083208 PMCID: PMC8784525 DOI: 10.3389/fbioe.2021.810897] [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: 11/08/2021] [Accepted: 11/26/2021] [Indexed: 11/18/2022] Open
Abstract
Focal cortical dysplasia (FCD) type IIIa is an easily ignored cause of intractable temporal lobe epilepsy. This study aimed to analyze the clinical, electrophysiological, and imaging characteristics in FCD type IIIa and to search for predictors associated with postoperative outcome in order to identify potential candidates for epilepsy surgery. We performed a retrospective review including sixty-six patients with FCD type IIIa who underwent resection for drug-resistant epilepsy. We evaluated the clinical, electrophysiological, and neuroimaging features for potential association with seizure outcome. Univariate and multivariate analyses were conducted to explore their predictive role on the seizure outcome. We demonstrated that thirty-nine (59.1%) patients had seizure freedom outcomes (Engel class Ia) with a median postsurgical follow-up lasting 29.5 months. By univariate analysis, duration of epilepsy (less than 12 years) (p = 0.044), absence of contralateral insular lobe hypometabolism on PET/MRI (pLog-rank = 0.025), and complete resection of epileptogenic area (pLog-rank = 0.004) were associated with seizure outcome. The incomplete resection of the epileptogenic area (hazard ratio = 2.977, 95% CI 1.218–7.277, p = 0.017) was the only independent predictor for seizure recurrence after surgery by multivariate analysis. The results of past history, semiology, electrophysiological, and MRI were not associated with seizure outcomes. Carefully included patients with FCD type IIIa through a comprehensive evaluation of their clinical, electrophysiological, and neuroimaging characteristics can be good candidates for resection. Several preoperative factors appear to be predictive of the postoperative outcome and may help in optimizing the selection of ideal candidates to benefit from epilepsy surgery.
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Affiliation(s)
- Lingling Zhang
- Department of Nuclear Medicine, PET/CT-MRI Center, Center of Cyclotron and PET Radiopharmaceuticals, The First Affiliated Hospital of Jinan University, Guangzhou, China.,Department of Neurology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Zhejiang, China
| | - Hailing Zhou
- Department of Nuclear Medicine, PET/CT-MRI Center, Center of Cyclotron and PET Radiopharmaceuticals, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Wei Zhang
- Epilepsy Center, Guangdong 999 Brain Hospital, Guangzhou, China
| | - Xueying Ling
- Department of Nuclear Medicine, PET/CT-MRI Center, Center of Cyclotron and PET Radiopharmaceuticals, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Chunyuan Zeng
- Department of Nuclear Medicine, PET/CT-MRI Center, Center of Cyclotron and PET Radiopharmaceuticals, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Yongjin Tang
- Department of Nuclear Medicine, PET/CT-MRI Center, Center of Cyclotron and PET Radiopharmaceuticals, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Jiefeng Gan
- Department of Nuclear Medicine, PET/CT-MRI Center, Center of Cyclotron and PET Radiopharmaceuticals, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Qinghua Tan
- Epilepsy Center, Guangdong 999 Brain Hospital, Guangzhou, China
| | - Xiangshu Hu
- Epilepsy Center, Guangdong 999 Brain Hospital, Guangzhou, China
| | - Hainan Li
- Department of Pathology, Guangdong 999 Brain Hospital, Guangzhou, China
| | - Baijie Cheng
- Department of Pathology, Guangdong 999 Brain Hospital, Guangzhou, China
| | - Hao Xu
- Department of Nuclear Medicine, PET/CT-MRI Center, Center of Cyclotron and PET Radiopharmaceuticals, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Qiang Guo
- Epilepsy Center, Guangdong 999 Brain Hospital, Guangzhou, China
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14
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Zhang F, Yang Y, Zheng Y, Zhu J, Wang P, Xu K. Combination of Matching Responsive Stimulations of Hippocampus and Subiculum for Effective Seizure Suppression in Temporal Lobe Epilepsy. Front Neurol 2021; 12:638795. [PMID: 34512497 PMCID: PMC8426572 DOI: 10.3389/fneur.2021.638795] [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: 12/07/2020] [Accepted: 06/22/2021] [Indexed: 11/13/2022] Open
Abstract
Responsive neural stimulation (RNS) is considered a promising neural modulation therapy for refractory epilepsy. Combined stimulation on different targets may hold great promise for improving the efficacy of seizure control since neural activity changed dynamically within associated brain targets in the epileptic network. Three major issues need to be further explored to achieve better efficacy of combined stimulation: (1) which nodes within the epileptogenic network should be chosen as stimulation targets? (2) What stimulus frequency should be delivered to different targets? and (3) Could the efficacy of RNS for seizure control be optimized by combined different stimulation targets together? In our current study, Granger causality (GC) method was applied to analyze epileptogenic networks for finding key targets of RNS. Single target stimulation (100 μA amplitude, 300 μs pulse width, 5s duration, biphasic, charge-balanced) with high frequency (130 Hz, HFS) or low frequency (5 Hz, LFS) was firstly delivered by our lab designed RNS systems to CA3, CA1, subiculum (SUB) of hippocampi, and anterior nucleus of thalamus (ANT). The efficacy of combined stimulation with different groups of frequencies was finally assessed to find out better combined key targets with optimal stimulus frequency. Our results showed that stimulation individually delivered to SUB and CA1 could shorten the average duration of seizures. Different stimulation frequencies impacted the efficacy of seizure control, as HFS delivered to CA1 and LFS delivered to SUB, respectively, were more effective for shortening the average duration of electrographic seizure in Sprague-Dawley rats (n = 3). Moreover, the synchronous stimulation of HFS in CA1 combined with LFS in SUB reduced the duration of discharge significantly in rats (n = 6). The combination of responsive stimulation at different targets may be an inspiration to optimize stimulation therapy for epilepsy.
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Affiliation(s)
- Fang Zhang
- Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou, China.,Key Laboratory of Biomedical Engineering of Education Ministry, Department of Biomedical Engineering Zhejiang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
| | - Yufang Yang
- Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou, China.,Key Laboratory of Biomedical Engineering of Education Ministry, Department of Biomedical Engineering Zhejiang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
| | - Yongte Zheng
- Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou, China.,Key Laboratory of Biomedical Engineering of Education Ministry, Department of Biomedical Engineering Zhejiang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
| | - Junming Zhu
- Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China.,Department of Neurosurgery, Second Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Ping Wang
- Key Laboratory of Biomedical Engineering of Education Ministry, Department of Biomedical Engineering Zhejiang University, Hangzhou, China
| | - Kedi Xu
- Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou, China.,Key Laboratory of Biomedical Engineering of Education Ministry, Department of Biomedical Engineering Zhejiang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou, China
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15
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Elsherif M, Esmael A. Hippocampal atrophy and quantitative EEG markers in mild cognitive impairment in temporal lobe epilepsy versus extra-temporal lobe epilepsy. Neurol Sci 2021; 43:1975-1986. [PMID: 34406537 DOI: 10.1007/s10072-021-05540-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 07/26/2021] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Cognitive impairment in temporal lobe epilepsy is widely acknowledged as one of the most well-known comorbidities. This study aimed to explore cognitive impairment and to determine the potential clinical, radiological, and quantitative electroencephalography markers for cognitive impairment in temporal lobe epilepsy patients versus extra-temporal lobe epilepsy. METHODS Forty-five patients with temporal lobe epilepsy and forty-five patients with extra-temporal lobe epilepsy were recruited for an administered digit span test, verbal fluency test, mini-mental state examination, digital symbol test, and Montreal cognitive assessment. Also, they were subjected to magnetic resonance imaging assessment for hippocampal atrophy and a quantitative electroencephalography assessment for electroencephalography markers (median frequency, peak frequency, and the alpha-to-theta ratio). RESULTS Patients with extra-temporal lobe epilepsy showed non-significant higher epilepsy durations and a higher frequency of seizures. Temporal lobe epilepsy patients showed a more statistically significant family history of epilepsy (37.7%), more history of febrile convulsions (13.3%), higher hippocampal atrophy (17.8%), and lower cognitive scales, especially mini-mental state examination and Montreal cognitive assessment; lower digital symbol test, verbal fluency test, and backward memory of digit span test. Also, temporal lobe epilepsy patients had a strong negative correlation with electroencephalography markers: median frequency, peak frequency, and the alpha-to-theta ratio (r = - 0.68, P < 0.005 and r = - 0.64, P < 0.005 and r = - 0.66, P < 0.005 respectively). CONCLUSION Cognitive impairment in patients with temporal lobe epilepsy was correlated with hippocampal atrophy and quantitative electroencephalography abnormalities, especially peak frequency, median frequency, and alpha-to-theta ratio that could be used alone for the identification of early cognitive impairment. TRIAL REGISTRATION Clinicaltrials.gov: NCT04376671.
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Affiliation(s)
- Mohammed Elsherif
- Department of Neurology, Mansoura Faculty of Medicine, Mansoura University, Mansoura, 35516, Dakahlia, Egypt.
| | - Ahmed Esmael
- Department of Neurology, Mansoura Faculty of Medicine, Mansoura University, Mansoura, 35516, Dakahlia, Egypt
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16
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Iannotti GR, Preti MG, Grouiller F, Carboni M, De Stefano P, Pittau F, Momjian S, Carmichael D, Centeno M, Seeck M, Korff CM, Schaller K, De Ville DV, Vulliemoz S. Modulation of epileptic networks by transient interictal epileptic activity: A dynamic approach to simultaneous EEG-fMRI. NEUROIMAGE-CLINICAL 2020; 28:102467. [PMID: 33395963 PMCID: PMC7645285 DOI: 10.1016/j.nicl.2020.102467] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 09/15/2020] [Accepted: 10/09/2020] [Indexed: 12/27/2022]
Abstract
EEG-fMRI has been instrumental in characterizing brain networks in epilepsy. Its value is documented in the pre-surgical assessment of drug-resistant epilepsy. The delineation of brain areas to resect is fundamental for the post-surgical outcome. Standard EEG-fMRI in epilepsy assesses static functional connectivity of the network. EEG-fMRI dynamic connectivity identifies transitory features of specific connections. We integrate dynamic fMRI connectivity and dynamic patterns of simultaneous scalp EEG. This allows to better characterize the spatiotemporal aspects of epileptic networks. This may help in more efficiently target the surgical intervention.
Epileptic networks, defined as brain regions involved in epileptic brain activity, have been mapped by functional connectivity in simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) recordings. This technique allows to define brain hemodynamic changes, measured by the Blood Oxygen Level Dependent (BOLD) signal, associated to the interictal epileptic discharges (IED), which together with ictal events constitute a signature of epileptic disease. Given the highly time-varying nature of epileptic activity, a dynamic functional connectivity (dFC) analysis of EEG-fMRI data appears particularly suitable, having the potential to identify transitory features of specific connections in epileptic networks. In the present study, we propose a novel method, defined dFC-EEG, that integrates dFC assessed by fMRI with the information recorded by simultaneous scalp EEG, in order to identify the connections characterised by a dynamic profile correlated with the occurrence of IED, forming the dynamic epileptic subnetwork. Ten patients with drug-resistant focal epilepsy were included, with different aetiology and showing a widespread (or multilobar) BOLD activation, defined as involving at least two distinct clusters, located in two different lobes and/or extended to the hemisphere contralateral to the epileptic focus. The epileptic focus was defined from the IED-related BOLD map. Regions involved in the occurrence of interictal epileptic activity; i.e., forming the epileptic network, were identified by a general linear model considering the timecourse of the fMRI-defined focus as main regressor. dFC between these regions was assessed with a sliding-window approach. dFC timecourses were then correlated with the sliding-window variance of the IED signal (VarIED), to identify connections whose dynamics related to the epileptic activity; i.e., the dynamic epileptic subnetwork. As expected, given the very different clinical picture of each individual, the extent of this subnetwork was highly variable across patients, but was but was reduced of at least 30% with respect to the initially identified epileptic network in 9/10 patients. The connections of the dynamic subnetwork were most commonly close to the epileptic focus, as reflected by the laterality index of the subnetwork connections, reported higher than the one within the original epileptic network. Moreover, the correlation between dFC timecourses and VarIED was predominantly positive, suggesting a strengthening of the dynamic subnetwork associated to the occurrence of IED. The integration of dFC and scalp IED offers a more specific description of the epileptic network, identifying connections strongly influenced by IED. These findings could be relevant in the pre-surgical evaluation for the resection or disconnection of the epileptogenic zone and help in reaching a better post-surgical outcome. This would be particularly important for patients characterised by a widespread pathological brain activity which challenges the surgical intervention.
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Affiliation(s)
- G R Iannotti
- EEG and Epilepsy, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland; Functional Brain Mapping Lab, Department of Fundamental Neurosciences, University of Geneva, Switzerland; Neurosurgery, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland.
| | - M G Preti
- Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland; Department of Radiology and Medical Informatics, University of Geneva, Geneva, Switzerland
| | - F Grouiller
- Swiss Center for Affective Sciences, University of Geneva, Switzerland; Laboratory of Behavioral Neurology and Imaging of Cognition, Department of Fundamental Neurosciences, University of Geneva, Switzerland
| | - M Carboni
- EEG and Epilepsy, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland; Functional Brain Mapping Lab, Department of Fundamental Neurosciences, University of Geneva, Switzerland
| | - P De Stefano
- EEG and Epilepsy, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland
| | - F Pittau
- EEG and Epilepsy, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland; Epilepsy Unit, Institution de Lavigny, Switzerland
| | - S Momjian
- Neurosurgery, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland
| | - D Carmichael
- Biomedical Engineering Department, Kings College London, United Kingdom; Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - M Centeno
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London, United Kingdom; Epilepsy Unit, Neurology Department, Clinica Universidad de Pamplona, Navarra, Spain
| | - M Seeck
- EEG and Epilepsy, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland
| | - C M Korff
- Pediatric Neurology Unit, University Hospitals of Geneva, Geneva, Switzerland
| | - K Schaller
- Neurosurgery, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland
| | - D Van De Ville
- Institute of Bioengineering, Center for Neuroprosthetics, Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland; Department of Radiology and Medical Informatics, University of Geneva, Geneva, Switzerland
| | - S Vulliemoz
- EEG and Epilepsy, Clinical Neuroscience Department, University Hospital and Faculty of Medicine of Geneva, Switzerland
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17
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Conrad EC, Tomlinson SB, Wong JN, Oechsel KF, Shinohara RT, Litt B, Davis KA, Marsh ED. Spatial distribution of interictal spikes fluctuates over time and localizes seizure onset. Brain 2020; 143:554-569. [PMID: 31860064 DOI: 10.1093/brain/awz386] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 10/15/2019] [Accepted: 10/25/2019] [Indexed: 12/21/2022] Open
Abstract
The location of interictal spikes is used to aid surgical planning in patients with medically refractory epilepsy; however, their spatial and temporal dynamics are poorly understood. In this study, we analysed the spatial distribution of interictal spikes over time in 20 adult and paediatric patients (12 females, mean age = 34.5 years, range = 5-58) who underwent intracranial EEG evaluation for epilepsy surgery. Interictal spikes were detected in the 24 h surrounding each seizure and spikes were clustered based on spatial location. The temporal dynamics of spike spatial distribution were calculated for each patient and the effects of sleep and seizures on these dynamics were evaluated. Finally, spike location was assessed in relation to seizure onset location. We found that spike spatial distribution fluctuated significantly over time in 14/20 patients (with a significant aggregate effect across patients, Fisher's method: P < 0.001). A median of 12 sequential hours were required to capture 80% of the variability in spike spatial distribution. Sleep and postictal state affected the spike spatial distribution in 8/20 and 4/20 patients, respectively, with a significant aggregate effect (Fisher's method: P < 0.001 for each). There was no evidence of pre-ictal change in the spike spatial distribution for any patient or in aggregate (Fisher's method: P = 0.99). The electrode with the highest spike frequency and the electrode with the largest area of downstream spike propagation both localized the seizure onset zone better than predicted by chance (Wilcoxon signed-rank test: P = 0.005 and P = 0.002, respectively). In conclusion, spikes localize seizure onset. However, temporal fluctuations in spike spatial distribution, particularly in relation to sleep and post-ictal state, can confound localization. An adequate duration of intracranial recording-ideally at least 12 sequential hours-capturing both sleep and wakefulness should be obtained to sufficiently sample the interictal network.
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Affiliation(s)
- Erin C Conrad
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Samuel B Tomlinson
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.,School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY, USA
| | - Jeremy N Wong
- Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kelly F Oechsel
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Russell T Shinohara
- Penn Statistics in Imaging and Visualization Center, Department of Biostatistics, Epidemiology and Informatics and Center for Biomedical Image Computing and Analytics, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian Litt
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Kathryn A Davis
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Eric D Marsh
- Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA.,Division of Child Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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18
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Mégevand P, Seeck M. Electric source imaging for presurgical epilepsy evaluation: current status and future prospects. Expert Rev Med Devices 2020; 17:405-412. [DOI: 10.1080/17434440.2020.1748008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Pierre Mégevand
- Epilepsy Unit, Neurology Division, Clinical Neuroscience Department, Geneva University Hospitals, Genève, Switzerland
- Basic Neuroscience Department, Faculty of Medicine, University of Geneva, Genève, Switzerland
| | - Margitta Seeck
- Epilepsy Unit, Neurology Division, Clinical Neuroscience Department, Geneva University Hospitals, Genève, Switzerland
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19
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Shi Q, Zhang T, Miao A, Sun J, Sun Y, Chen Q, Hu Z, Xiang J, Wang X. Differences Between Interictal and Ictal Generalized Spike-Wave Discharges in Childhood Absence Epilepsy: A MEG Study. Front Neurol 2020; 10:1359. [PMID: 32038453 PMCID: PMC6992575 DOI: 10.3389/fneur.2019.01359] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 12/09/2019] [Indexed: 12/05/2022] Open
Abstract
Purpose: To investigate the differences between interictal and ictal generalized spike-wave discharges (GSWDs) for insights on how epileptic activity propagates and the physiopathological mechanisms underlying childhood absence epilepsy (CAE). Methods: Twenty-five patients with CAE were studied using magnetoencephalography (MEG). MEG data were digitized at 6,000 Hz during the interictal and ictal GSWDs. GSWDs were analyzed at both neural magnetic source levels and functional connectivity (FC) in multifrequency bands: delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta (12–30 Hz), gamma (30–80 Hz), ripple (80–250 Hz), and fast ripple (250–500 Hz). Brain FC was studied with the posterior cingulate cortex/precuneus (PCC/pC) as the seed region. Results: The magnetic source of interictal GSWDs mainly locates in the PCC/pC region at 4–8 and 8–12 Hz, while that of ictal GSWDs mainly locates in the medial frontal cortex (MFC) at 80–250 Hz. There were statistically significant differences between interictal and ictal GSWDs (p < 0.05). The FC network involving the PCC/pC showed strong connections in the anterior-posterior pathways (mainly with the frontal cortex) at 80–250 Hz during ictal GSWDs, while the interictal GSWDs FC were mostly limited to the posterior cortex region. There was no significant difference in the magnetic source strength among interictal and ictal GSWDs at all bandwidths. Conclusions: There are significant disparities in the source localization and FC between interictal and ictal GSWDs. Low-frequency activation in the PCC/pC during inhibition of seizures possibly relates to the maintenance of consciousness during interictal GSWDs. High-frequency oscillations (HFOs) of the MFC during CAE may associate with the inducing or occurrence of GSWDs. Weakened network connections may be in favor of preventing overexcitability and relates to the termination of GSWDs.
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Affiliation(s)
- Qi Shi
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Tingting Zhang
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Ailiang Miao
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Jintao Sun
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Yulei Sun
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
| | - Qiqi Chen
- MEG Center, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, China
| | - Zheng Hu
- Department of Neurology, Nanjing Children's Hospital, Nanjing, China
| | - Jing Xiang
- Division of Neurology, MEG Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Xiaoshan Wang
- Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China
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20
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Gil F, Padilla N, Soria-Pastor S, Setoain X, Boget T, Rumiá J, Roldán P, Reyes D, Bargalló N, Conde E, Pintor L, Vernet O, Manzanares I, Ådén U, Carreño M, Donaire A. Beyond the Epileptic Focus: Functional Epileptic Networks in Focal Epilepsy. Cereb Cortex 2019; 30:2338-2357. [DOI: 10.1093/cercor/bhz243] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Abstract
Focal epilepsy can be conceptualized as a network disorder, and the functional epileptic network can be described as a complex system of multiple brain areas that interact dynamically to generate epileptic activity. However, we still do not fully understand the functional architecture of epileptic networks. We studied a cohort of 21 patients with extratemporal focal epilepsy. We used independent component analysis of functional magnetic resonance imaging (fMRI) data. In order to identify the epilepsy-related components, we examined the general linear model-derived electroencephalography-fMRI (EEG–fMRI) time courses associated with interictal epileptic activity as intrinsic hemodynamic epileptic biomarkers. Independent component analysis revealed components related to the epileptic time courses in all 21 patients. Each epilepsy-related component described a network of spatially distributed brain areas that corresponded to the specific epileptic network in each patient. We also provided evidence for the interaction between the epileptic activity generated at the epileptic network and the physiological resting state networks. Our findings suggest that independent component analysis, guided by EEG–fMRI epileptic time courses, have the potential to define the functional architecture of the epileptic network in a noninvasive way. These data could be useful in planning invasive EEG electrode placement, guiding surgical resections, and more effective therapeutic interventions.
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Affiliation(s)
- Francisco Gil
- Epilepsy Program, Department of Neurology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - Nelly Padilla
- Department of Women’s and Children’s Health, Karolinska Institutet, Stockholm, Sweden
| | - Sara Soria-Pastor
- Department of Psychiatry, Consorci Sanitari del Maresme, Hospital of Mataro, CP 08304, Mataro, Spain
| | - Xavier Setoain
- Epilepsy Program, Department of Nuclear Medicine, Hospital Clínic, CDIC, CP 08036, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Clinical and Experimental Neuroscience, Clinical Neurophysiology, CP 08036, Barcelona, Spain
- Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), University of Barcelona, CP 08036, Barcelona, Spain
| | - Teresa Boget
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Clinical and Experimental Neuroscience, Clinical Neurophysiology, CP 08036, Barcelona, Spain
- Epilepsy Program, Department of Neuropsychology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - Jordi Rumiá
- Epilepsy Program, Department of Neurosurgery, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - Pedro Roldán
- Epilepsy Program, Department of Neurosurgery, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - David Reyes
- Epilepsy Program, Department of Neurology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - Núria Bargalló
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Clinical and Experimental Neuroscience, Clinical Neurophysiology, CP 08036, Barcelona, Spain
- Epilepsy Program, Department of Radiology, Hospital Clínic, CDIC, CP 08036, Barcelona, Spain
| | - Estefanía Conde
- Epilepsy Program, Department of Neurology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - Luis Pintor
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Clinical and Experimental Neuroscience, Clinical Neurophysiology, CP 08036, Barcelona, Spain
- Epilepsy Program, Department of Psychiatry, Hospital Clínic, CDIC, CP 08036, Barcelona, Spain
| | - Oriol Vernet
- Epilepsy Program, Department of Neurology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - Isabel Manzanares
- Epilepsy Program, Department of Neurology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
| | - Ulrika Ådén
- Department of Women’s and Children’s Health, Karolinska Institutet, Stockholm, Sweden
| | - Mar Carreño
- Epilepsy Program, Department of Neurology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Clinical and Experimental Neuroscience, Clinical Neurophysiology, CP 08036, Barcelona, Spain
| | - Antonio Donaire
- Epilepsy Program, Department of Neurology, Hospital Clínic, Neuroscience Institute, CP 08036, Barcelona, Spain
- Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Clinical and Experimental Neuroscience, Clinical Neurophysiology, CP 08036, Barcelona, Spain
- Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), University of Barcelona, CP 08036, Barcelona, Spain
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21
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Shamshiri EA, Sheybani L, Vulliemoz S. The Role of EEG-fMRI in Studying Cognitive Network Alterations in Epilepsy. Front Neurol 2019; 10:1033. [PMID: 31608007 PMCID: PMC6771300 DOI: 10.3389/fneur.2019.01033] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 09/11/2019] [Indexed: 02/01/2023] Open
Abstract
Brain functions do not arise from isolated brain regions, but from interactions in widespread networks necessary for both normal and pathological conditions. These Intrinsic Connectivity Networks (ICNs) support cognitive processes such as language, memory, or executive functions, but can be disrupted by epileptic activity. Simultaneous EEG-fMRI can help explore the hemodynamic changes associated with focal or generalized epileptic discharges, thus providing information about both transient and non-transient impairment of cognitive networks related to spatio-temporal overlap with epileptic activity. In the following review, we discuss the importance of interictal discharges and their impact on cognition in different epilepsy syndromes. We explore the cognitive impact of interictal activity in both animal models and human connectivity networks in order to confirm that this effect could have a possible clinical impact for prescribing medication and characterizing post-surgical outcome. Future work is needed to further investigate electrophysiological changes, such as amplitude/latency of single evoked responses or spontaneous epileptic activity in either scalp or intracranial EEG and determine its relative change in hemodynamic response with subsequent network modifications.
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Affiliation(s)
- Elhum A Shamshiri
- EEG and Epilepsy Unit, Neurology Department, University Hospitals and Faculty of Medicine of Geneva, Geneva, Switzerland
| | - Laurent Sheybani
- Neurology Clinic, University Hospitals and Faculty of Medicine of Geneva, Geneva, Switzerland
| | - Serge Vulliemoz
- EEG and Epilepsy Unit, Neurology Department, University Hospitals and Faculty of Medicine of Geneva, Geneva, Switzerland.,Neurology Clinic, University Hospitals and Faculty of Medicine of Geneva, Geneva, Switzerland
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22
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Jayalakshmi S, Nanda SK, Vooturi S, Vadapalli R, Sudhakar P, Madigubba S, Panigrahi M. Focal Cortical Dysplasia and Refractory Epilepsy: Role of Multimodality Imaging and Outcome of Surgery. AJNR Am J Neuroradiol 2019; 40:892-898. [PMID: 31000525 DOI: 10.3174/ajnr.a6041] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/12/2019] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND PURPOSE Focal cortical dysplasia (FCD) is one of the most common causes of drug resistant epilepsy. Our aim was to evaluate the role of presurgical noninvasive multimodality imaging techniques in selecting patients with refractory epilepsy and focal cortical dysplasia for epilepsy surgery and the influence of the imaging modalities on long-term seizure freedom. MATERIALS AND METHODS We performed a retrospective analysis of data of 188 consecutive patients with FCD and refractory epilepsy with at least 2 years of postsurgery follow-up. Predictors of seizure freedom and the sensitivity of neuroimaging modalities were analyzed. RESULTS MR imaging showed clear-cut FCD in 136 (72.3%) patients. Interictal FDG-PET showed focal hypo-/hypermetabolism in 144 (76.6%); in 110 patients in whom ictal SPECT was performed, focal hyperperfusion was noted in 77 (70.3%). Focal resection was the most common surgery performed in 112 (59.6%). Histopathology revealed FCD type I in 102 (54.3%) patients. At last follow-up, 124 (66.0%) were seizure-free. Complete resection of FCD and type II FCD were predictors of seizure freedom. Localization of FCD on either MR imaging or PET or ictal SPECT had the highest sensitivity for seizure freedom at 97.5%. Among individual modalities, FDG-PET had the highest sensitivity (78.2%), followed by MR imaging (75.8%) and ictal SPECT (71.8%). The sensitivity of MR imaging to localize type I FCD (60.8%) was significantly lower than that for type II FCD (84.8%, P < .001). Among 37 patients with subtle MR imaging findings and a focal FDG-PET pattern, 30 patients had type I FCD. CONCLUSIONS During presurgical multimodality evaluation, localization of the extent of the epileptogenic zone in at least 2 imaging modalities helps achieve seizure freedom in about two-thirds of patients with refractory epilepsy due to FCD. FDG-PET is the most sensitive imaging modality for seizure freedom, especially in patients with type I FCD.
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Affiliation(s)
- S Jayalakshmi
- From the Departments of Neurology (S.J., S.K.N., S.V.)
| | - S K Nanda
- From the Departments of Neurology (S.J., S.K.N., S.V.)
| | - S Vooturi
- From the Departments of Neurology (S.J., S.K.N., S.V.)
| | | | | | | | - M Panigrahi
- Neurosurgery (M.P.), Krishna Institute of Medical Sciences, Secunderabad, India
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23
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Electroencephalography, magnetoencephalography and source localization: their value in epilepsy. Curr Opin Neurol 2019; 31:176-183. [PMID: 29432218 DOI: 10.1097/wco.0000000000000545] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
PURPOSE OF REVIEW Source localization of cerebral activity using electroencephalography (EEG) or magnetoencephalography (MEG) can reveal noninvasively the generators of the abnormal signals recorded in epilepsy, such as interictal epileptic discharges (IEDs) and seizures. Here, we review recent progress showcasing the usefulness of these techniques in treating patients with drug-resistant epilepsy. RECENT FINDINGS The source localization of IEDs by high-density EEG and MEG has now been proved in large patient cohorts to be accurate and clinically relevant, with positive and negative predictive values rivaling those of structural MRI. Localizing seizure onsets is an emerging technique that seems to perform similarly well to the localization of interictal spikes, although there remain questions regarding the processing of signals for reliable results. The localization of somatosensory cortex using EEG/MEG is well established. The localization of language cortex is less reliable, although progress has been made regarding hemispheric lateralization. Source localization is also able to reveal how epilepsy alters the dynamics of neuronal activity in the large-scale networks that underlie cerebral function. SUMMARY Given the high performance of EEG/MEG source localization, these tools should find a place similar to that of established techniques like MRI in the assessment of patients for epilepsy surgery.
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24
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Lee SM, Kwon S, Lee YJ. Diagnostic usefulness of arterial spin labeling in MR negative children with new onset seizures. Seizure 2019; 65:151-158. [PMID: 30718217 DOI: 10.1016/j.seizure.2019.01.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/25/2018] [Accepted: 01/25/2019] [Indexed: 01/18/2023] Open
Abstract
PURPOSE Arterial spine labeling (ASL) magnetic resonance imaging (MRI) is the non-invasive measurement of cerebral blood flow that can localize the seizure focus in patients with epilepsy. The aim of this study was to identify its utility for localizing the seizure focus in children with no structural lesion on MRI. METHODS Forty-three consecutive children who underwent electroencephalography (EEG) and structural MRI, along with ASL for evaluation of newly developed seizures, were included. ASL abnormalities were classified as hypo/hyperperfusion, based on visual assessment, and compared with the seizure focus determined by clinical information and EEG. RESULTS Among the 43 patients (M 17: F 26, mean age, 6.3 ± 3.3 years), the seizure type was focal in 36 patients and generalized in seven patients. Twenty-five (58.1%) patients showed perfusion change. Out of 36 patients with focal seizure, 24 (66.7%) showed ASL abnormalities, and 19 (52.8%) showed concordance between ASL and clinical focus. Out of seven patients with generalized seizure, only one patient showed ASL abnormalities. The overall concordance revealed moderate agreement (k = 0.542). ASL acquisition within one day from seizure onset was the only significant associating factor with the concordance between the two (p = 0. 014). CONCLUSION To our knowledge, this is the first study to assess the usefulness of ASL MRI to assist in localizing the seizure focus in MR-negative children with new onset seizures. The combined use of ASL with EEG and structural MRI may play an important role in the evaluation of pediatric epilepsy.
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Affiliation(s)
- So Mi Lee
- Department of Radiology, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, Daegu, South Korea
| | - Soonhak Kwon
- Department of Pediatric, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, Daegu, South Korea
| | - Yun Jeong Lee
- Department of Pediatric, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, Daegu, South Korea.
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25
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Kuo CC, Tucker DM, Luu P, Jenson K, Tsai JJ, Ojemann JG, Holmes MD. EEG source imaging of epileptic activity at seizure onset. Epilepsy Res 2018; 146:160-171. [DOI: 10.1016/j.eplepsyres.2018.07.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 07/06/2018] [Accepted: 07/16/2018] [Indexed: 01/16/2023]
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26
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Youssofzadeh V, Agler W, Tenney JR, Kadis DS. Whole-brain MEG connectivity-based analyses reveals critical hubs in childhood absence epilepsy. Epilepsy Res 2018; 145:102-109. [PMID: 29936300 DOI: 10.1016/j.eplepsyres.2018.06.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 03/21/2018] [Accepted: 06/03/2018] [Indexed: 01/01/2023]
Abstract
Absence seizures are thought to be linked to abnormal interplays between regions of a thalamocortical network. However, the complexity of this widespread network makes characterizing the functional interactions among various brain regions challenging. Using whole-brain functional connectivity and network analysis of magnetoencephalography (MEG) data, we explored pre-treatment brain hubs ("highly connected nodes") of patients aged 6 to 12 years with childhood absence epilepsy. We analyzed ictal MEG data of 74 seizures from 16 patients. We employed a time-domain beamformer technique to estimate MEG sources in broadband (1-40 Hz) where the greatest power changes between ictal and preictal periods were identified. A phase synchrony measure, phase locking value, and a graph theory metric, eigenvector centrality (EVC), were utilized to quantify voxel-level connectivity and network hubs of ictal > preictal periods, respectively. A volumetric atlas containing 116 regions of interests (ROIs) was utilized to summarize the network measures. ROIs with EVC (z-score) > 1.96 were reported as critical hubs. ROIs analysis revealed functional-anatomical hubs in a widespread network containing bilateral precuneus (right/left, z = 2.39, 2.18), left thalamus (z = 2.28), and three anterior cerebellar subunits of lobule "IV-V" (z = 3.9), vermis "IV-V" (z = 3.57), and lobule "III" (z = 2.03). Findings suggest that highly connected brain areas or hubs are present in focal cortical, subcortical, and cerebellar regions during absence seizures. Hubs in thalami, precuneus and cingulate cortex generally support a theory of rapidly engaging and bilaterally distributed networks of cortical and subcortical regions responsible for seizures generation, whereas hubs in anterior cerebellar regions may be linked to terminating motor automatisms frequently seen during typical absence seizures. Whole-brain network connectivity is a powerful analytic tool to reveal focal components of absence seizures in MEG. Our investigations can lead to a better understanding of the pathophysiology of CAE.
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Affiliation(s)
- Vahab Youssofzadeh
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, USA; Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, USA; Pediatric Neuroimaging Research Consortium (PNRC), Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA; Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
| | - William Agler
- Pediatric Neuroimaging Research Consortium (PNRC), Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA; Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
| | - Jeffrey R Tenney
- Pediatric Neuroimaging Research Consortium (PNRC), Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA; Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; College of Medicine, Department of Pediatrics, University of Cincinnati, Cincinnati OH, USA.
| | - Darren S Kadis
- Pediatric Neuroimaging Research Consortium (PNRC), Cincinnati Children's Hospital Medical Center, Cincinnati OH, USA; Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; College of Medicine, Department of Pediatrics, University of Cincinnati, Cincinnati OH, USA.
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27
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Janca R, Krsek P, Jezdik P, Cmejla R, Tomasek M, Komarek V, Marusic P, Jiruska P. The Sub-Regional Functional Organization of Neocortical Irritative Epileptic Networks in Pediatric Epilepsy. Front Neurol 2018; 9:184. [PMID: 29628910 PMCID: PMC5876241 DOI: 10.3389/fneur.2018.00184] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/09/2018] [Indexed: 11/13/2022] Open
Abstract
Between seizures, irritative network generates frequent brief synchronous activity, which manifests on the EEG as interictal epileptiform discharges (IEDs). Recent insights into the mechanism of IEDs at the microscopic level have demonstrated a high variance in the recruitment of neuronal populations generating IEDs and a high variability in the trajectories through which IEDs propagate across the brain. These phenomena represent one of the major constraints for precise characterization of network organization and for the utilization of IEDs during presurgical evaluations. We have developed a new approach to dissect human neocortical irritative networks and quantify their properties. We have demonstrated that irritative network has modular nature and it is composed of multiple independent sub-regions, each with specific IED propagation trajectories and differing in the extent of IED activity generated. The global activity of the irritative network is determined by long-term and circadian fluctuations in sub-region spatiotemporal properties. Also, the most active sub-region co-localizes with the seizure onset zone in 12/14 cases. This study demonstrates that principles of recruitment variability and propagation are conserved at the macroscopic level and that they determine irritative network properties in humans. Functional stratification of the irritative network increases the diagnostic yield of intracranial investigations with the potential to improve the outcomes of surgical treatment of neocortical epilepsy.
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Affiliation(s)
- Radek Janca
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Pavel Krsek
- Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Petr Jezdik
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Roman Cmejla
- Department of Circuit Theory, Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czechia
| | - Martin Tomasek
- Department of Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Vladimir Komarek
- Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Petr Marusic
- Department of Neurology, 2nd Faculty of Medicine, Charles University, Motol University Hospital, Prague, Czechia
| | - Premysl Jiruska
- Department of Developmental Epileptology, Institute of Physiology, The Czech Academy of Sciences, Prague, Czechia
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28
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Exploring the origins of EEG motion artefacts during simultaneous fMRI acquisition: Implications for motion artefact correction. Neuroimage 2018; 173:188-198. [PMID: 29486322 PMCID: PMC5929889 DOI: 10.1016/j.neuroimage.2018.02.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 02/16/2018] [Indexed: 11/24/2022] Open
Abstract
Motion artefacts (MAs) are induced within EEG data collected simultaneously with fMRI when the subject's head rotates relative to the magnetic field. The effects of these artefacts have generally been ameliorated by removing periods of data during which large artefact voltages appear in the EEG traces. However, even when combined with other standard post-processing methods, this strategy does not remove smaller MAs which can dominate the neuronal signals of interest. A number of methods are therefore being developed to characterise the MA by measuring reference signals and then using these in artefact correction. These methods generally assume that the head and EEG cap, plus any attached sensors, form a rigid body which can be characterised by a standard set of six motion parameters. Here we investigate the motion of the head/EEG cap system to provide a better understanding of MAs. We focus on the reference layer artefact subtraction (RLAS) approach, as this allows measurement of a separate reference signal for each electrode that is being used to measure brain activity. Through a series of experiments on phantoms and subjects, we find that movement of the EEG cap relative to the phantom and skin on the forehead is relatively small and that this non-rigid body movement does not appear to cause considerable discrepancy in artefacts between the scalp and reference signals. However, differences in the amplitude of these signals is observed which may be due to differences in geometry of the system from which the reference signals are measured compared with the brain signals. In addition, we find that there is non-rigid body movement of the skull and skin which produces an additional MA component for a head shake, which is not present for a head nod. This results in a large discrepancy in the amplitude and temporal profile of the MA measured on the scalp and reference layer, reducing the efficacy of MA correction based on the reference signals. Together our data suggest that the efficacy of the correction of MA using any reference-based system is likely to differ for different types of head movement with head shake being the hardest to correct. This provides new information to inform the development of hardware and post-processing methods for removing MAs from EEG data acquired simultaneously with fMRI data.
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29
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Mikulan E, Hesse E, Sedeño L, Bekinschtein T, Sigman M, García MDC, Silva W, Ciraolo C, García AM, Ibáñez A. Intracranial high-γ connectivity distinguishes wakefulness from sleep. Neuroimage 2017; 169:265-277. [PMID: 29225064 DOI: 10.1016/j.neuroimage.2017.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 11/21/2017] [Accepted: 12/06/2017] [Indexed: 12/27/2022] Open
Abstract
Neural synchrony in the γ-band is considered a fundamental process in cortical computation and communication and it has also been proposed as a crucial correlate of consciousness. However, the latter claim remains inconclusive, mainly due to methodological limitations, such as the spectral constraints of scalp-level electroencephalographic recordings or volume-conduction confounds. Here, we circumvented these caveats by comparing γ-band connectivity between two global states of consciousness via intracranial electroencephalography (iEEG), which provides the most reliable measurements of high-frequency activity in the human brain. Non-REM Sleep recordings were compared to passive-wakefulness recordings of the same duration in three subjects with surgically implanted electrodes. Signals were analyzed through the weighted Phase Lag Index connectivity measure and relevant graph theory metrics. We found that connectivity in the high-γ range (90-120 Hz), as well as relevant graph theory properties, were higher during wakefulness than during sleep and discriminated between conditions better than any other canonical frequency band. Our results constitute the first report of iEEG differences between wakefulness and sleep in the high-γ range at both local and distant sites, highlighting the utility of this technique in the search for the neural correlates of global states of consciousness.
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Affiliation(s)
- Ezequiel Mikulan
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, UK.
| | - Eugenia Hesse
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Instituto de Ingeniería Biomédica, Facultad de Ingeniería, Universidad de Buenos Aires, Argentina
| | - Lucas Sedeño
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Tristán Bekinschtein
- Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, UK
| | | | - María Del Carmen García
- Programa de Cirugía de Epilepsia, Hospital Italiano de Buenos Asires, Buenos Aires, Argentina
| | - Walter Silva
- Programa de Cirugía de Epilepsia, Hospital Italiano de Buenos Asires, Buenos Aires, Argentina
| | - Carlos Ciraolo
- Programa de Cirugía de Epilepsia, Hospital Italiano de Buenos Asires, Buenos Aires, Argentina
| | - Adolfo M García
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Faculty of Education, National University of Cuyo (UNCuyo), Mendoza, Argentina
| | - Agustín Ibáñez
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Universidad Autónoma del Caribe, Barranquilla, Colombia; Center for Social and Cognitive Neuroscience (CSCN), School of Psychology, Universidad Adolfo Ibañez, Santiago de Chile, Chile; Australian Research Council Centre of Excellence in Cognition and its Disorders, Sydney, Australia.
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30
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Tousseyn S, Krishnan B, Wang ZI, Wongwiangjunt S, Nayak CS, Mosher JC, Wu G, Van Paesschen W, Leahy RM, Gonzalez-Martinez JA, Bulacio J, Najm IM, Alexopoulos AV, Nair DR. Connectivity in ictal single photon emission computed tomography perfusion: a cortico-cortical evoked potential study. Brain 2017; 140:1872-1884. [PMID: 28582473 DOI: 10.1093/brain/awx123] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 04/14/2017] [Indexed: 11/13/2022] Open
Abstract
Subtraction ictal and interictal single photon emission computed tomography can demonstrate complex ictal perfusion patterns. Regions with ictal hyperperfusion are suggested to reflect seizure onset and propagation pathways. The significance of ictal hypoperfusion is not well understood. The aim of this study was to verify whether ictal perfusion changes, both hyper- and hypoperfusion, correspond to electrically connected brain networks. A total of 36 subtraction ictal and interictal perfusion studies were analysed in 31 consecutive medically refractory focal epilepsy patients, evaluated by stereo-electroencephalography that demonstrated a single focal onset. Cortico-cortical evoked potential studies were performed after repetitive electrical stimulation of the ictal onset zone. Evoked responses at electrode contacts outside the stimulation site were used as a measure of connectivity. The evoked responses at these electrodes were compared to ictal perfusion values noted at these locations. In 67% of studies, evoked responses were significantly larger in hyperperfused compared to baseline-perfused areas. The majority of hyperperfused contacts also had significantly increased evoked responses relative to pre-stimulus electroencephalogram. In contrast, baseline-perfused and hypoperfused contacts mainly demonstrated non-significant evoked responses. Finally, positive significant correlations (P < 0.05) were found between perfusion scores and evoked responses in 61% of studies. When the stimulated ictal onset area was hyperperfused, 82% of studies demonstrated positive significant correlations. Following stimulation of hyperperfused areas outside seizure onset, positive significant correlations between perfusion changes and evoked responses could be seen, suggesting bidirectional connectivity. We conclude that strong connectivity was demonstrated between the ictal onset zone and hyperperfused regions, while connectivity was weaker in the direction of baseline-perfused or hypoperfused areas. In trying to understand a patient's epilepsy, one should consider the contribution of all hyperperfused regions, as these are likely not random, but represent an electrically connected epileptic network.
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Affiliation(s)
- Simon Tousseyn
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA.,Academic Center for Epileptology, Kempenhaeghe and Maastricht UMC+, Heeze, The Netherlands
| | - Balu Krishnan
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Zhong I Wang
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
| | | | - Chetan S Nayak
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - John C Mosher
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Guiyun Wu
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
| | | | | | | | - Juan Bulacio
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Imad M Najm
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
| | | | - Dileep R Nair
- Epilepsy Center, Cleveland Clinic Foundation, Cleveland, OH, USA
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31
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Sonoda M, Masuda H, Shirozu H, Ito Y, Akazawa K, Asano E, Kameyama S. Predictors of cognitive function in patients with hypothalamic hamartoma following stereotactic radiofrequency thermocoagulation surgery. Epilepsia 2017; 58:1556-1565. [DOI: 10.1111/epi.13838] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2017] [Indexed: 01/04/2023]
Affiliation(s)
- Masaki Sonoda
- Hypothalamic Hamartoma Center; Department of Functional Neurosurgery; Nishi-Niigata Chuo National Hospital; Niigata Japan
- Department of Neurosurgery; Graduate School of Medicine; Yokohama City University; Yokohama Kanagawa Japan
| | - Hiroshi Masuda
- Hypothalamic Hamartoma Center; Department of Functional Neurosurgery; Nishi-Niigata Chuo National Hospital; Niigata Japan
| | - Hiroshi Shirozu
- Hypothalamic Hamartoma Center; Department of Functional Neurosurgery; Nishi-Niigata Chuo National Hospital; Niigata Japan
| | - Yosuke Ito
- Hypothalamic Hamartoma Center; Department of Functional Neurosurgery; Nishi-Niigata Chuo National Hospital; Niigata Japan
| | - Kohei Akazawa
- Department of Medical Informatics; Niigata University Medical and Dental Hospital; Niigata Japan
| | - Eishi Asano
- Department of Pediatrics; Children's Hospital of Michigan; Detroit Medical Center; Wayne State University; Detroit Michigan U.S.A
- Department of Neurology; Children's Hospital of Michigan; Detroit Medical Center; Wayne State University; Detroit Michigan U.S.A
| | - Shigeki Kameyama
- Hypothalamic Hamartoma Center; Department of Functional Neurosurgery; Nishi-Niigata Chuo National Hospital; Niigata Japan
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Höller Y, Butz K, Thomschewski A, Schmid E, Uhl A, Bathke AC, Zimmermann G, Tomasi SO, Nardone R, Staffen W, Höller P, Leitinger M, Höfler J, Kalss G, Taylor AC, Kuchukhidze G, Trinka E. Reliability of EEG Interactions Differs between Measures and Is Specific for Neurological Diseases. Front Hum Neurosci 2017; 11:350. [PMID: 28725190 PMCID: PMC5496950 DOI: 10.3389/fnhum.2017.00350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 06/20/2017] [Indexed: 11/21/2022] Open
Abstract
Alterations of interaction (connectivity) of the EEG reflect pathological processes in patients with neurologic disorders. Nevertheless, it is questionable whether these patterns are reliable over time in different measures of interaction and whether this reliability of the measures is the same across different patient populations. In order to address this topic we examined 22 patients with mild cognitive impairment, five patients with subjective cognitive complaints, six patients with right-lateralized temporal lobe epilepsy, seven patients with left lateralized temporal lobe epilepsy, and 20 healthy controls. We calculated 14 measures of interaction from two EEG-recordings separated by 2 weeks. In order to characterize test-retest reliability, we correlated these measures for each group and compared the correlations between measures and between groups. We found that both measures of interaction as well as groups differed from each other in terms of reliability. The strongest correlation coefficients were found for spectrum, coherence, and full frequency directed transfer function (average rho > 0.9). In the delta (2–4 Hz) range, reliability was lower for mild cognitive impairment compared to healthy controls and left lateralized temporal lobe epilepsy. In the beta (13–30 Hz), gamma (31–80 Hz), and high gamma (81–125 Hz) frequency ranges we found decreased reliability in subjective cognitive complaints compared to mild cognitive impairment. In the gamma and high gamma range we found increased reliability in left lateralized temporal lobe epilepsy patients compared to healthy controls. Our results emphasize the importance of documenting reliability of measures of interaction, which may vary considerably between measures, but also between patient populations. We suggest that studies claiming clinical usefulness of measures of interaction should provide information on the reliability of the results. In addition, differences between patient groups in reliability of interactions in the EEG indicate the potential of reliability to serve as a new biomarker for pathological memory decline as well as for epilepsy. While the brain concert of information flow is generally variable, high reliability, and thus, low variability may reflect abnormal firing patterns.
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Affiliation(s)
- Yvonne Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Kevin Butz
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Aljoscha Thomschewski
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria.,Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical UniversitySalzburg, Austria
| | - Elisabeth Schmid
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria.,Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical UniversitySalzburg, Austria
| | - Andreas Uhl
- Department of Computer Sciences, Paris Lodron University of SalzburgSalzburg, Austria
| | - Arne C Bathke
- Department of Mathematics, Paris Lodron University of SalzburgSalzburg, Austria
| | - Georg Zimmermann
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria.,Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical UniversitySalzburg, Austria.,Department of Mathematics, Paris Lodron University of SalzburgSalzburg, Austria
| | - Santino O Tomasi
- Department of Neurosurgery, Christian Doppler Medical Centre, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Raffaele Nardone
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria.,Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical UniversitySalzburg, Austria.,Department of Neurology, Franz Tappeiner HospitalMerano, Italy
| | - Wolfgang Staffen
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Peter Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria.,Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical UniversitySalzburg, Austria
| | - Markus Leitinger
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Julia Höfler
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Gudrun Kalss
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Alexandra C Taylor
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Giorgi Kuchukhidze
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University SalzburgSalzburg, Austria.,Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical UniversitySalzburg, Austria
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Safety and EEG data quality of concurrent high-density EEG and high-speed fMRI at 3 Tesla. PLoS One 2017; 12:e0178409. [PMID: 28552957 PMCID: PMC5446172 DOI: 10.1371/journal.pone.0178409] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 05/13/2017] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Concurrent EEG and fMRI is increasingly used to characterize the spatial-temporal dynamics of brain activity. However, most studies to date have been limited to conventional echo-planar imaging (EPI). There is considerable interest in integrating recently developed high-speed fMRI methods with high-density EEG to increase temporal resolution and sensitivity for task-based and resting state fMRI, and for detecting interictal spikes in epilepsy. In the present study using concurrent high-density EEG and recently developed high-speed fMRI methods, we investigate safety of radiofrequency (RF) related heating, the effect of EEG on cortical signal-to-noise ratio (SNR) in fMRI, and assess EEG data quality. MATERIALS AND METHODS The study compared EPI, multi-echo EPI, multi-band EPI and multi-slab echo-volumar imaging pulse sequences, using clinical 3 Tesla MR scanners from two different vendors that were equipped with 64- and 256-channel MR-compatible EEG systems, respectively, and receive only array head coils. Data were collected in 11 healthy controls (3 males, age range 18-70 years) and 13 patients with epilepsy (8 males, age range 21-67 years). Three of the healthy controls were scanned with the 256-channel EEG system, the other subjects were scanned with the 64-channel EEG system. Scalp surface temperature, SNR in occipital cortex and head movement were measured with and without the EEG cap. The degree of artifacts and the ability to identify background activity was assessed by visual analysis by a trained expert in the 64 channel EEG data (7 healthy controls, 13 patients). RESULTS RF induced heating at the surface of the EEG electrodes during a 30-minute scan period with stable temperature prior to scanning did not exceed 1.0° C with either EEG system and any of the pulse sequences used in this study. There was no significant decrease in cortical SNR due to the presence of the EEG cap (p > 0.05). No significant differences in the visually analyzed EEG data quality were found between EEG recorded during high-speed fMRI and during conventional EPI (p = 0.78). Residual ballistocardiographic artifacts resulted in 58% of EEG data being rated as poor quality. CONCLUSION This study demonstrates that high-density EEG can be safely implemented in conjunction with high-speed fMRI and that high-speed fMRI does not adversely affect EEG data quality. However, the deterioration of the EEG quality due to residual ballistocardiographic artifacts remains a significant constraint for routine clinical applications of concurrent EEG-fMRI.
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Bartolomei F, Lagarde S, Wendling F, McGonigal A, Jirsa V, Guye M, Bénar C. Defining epileptogenic networks: Contribution of SEEG and signal analysis. Epilepsia 2017; 58:1131-1147. [DOI: 10.1111/epi.13791] [Citation(s) in RCA: 262] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Fabrice Bartolomei
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
- AP-HM; Service de Neurophysiologie Clinique; Hôpital de la Timone; Marseille France
| | - Stanislas Lagarde
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
- AP-HM; Service de Neurophysiologie Clinique; Hôpital de la Timone; Marseille France
| | - Fabrice Wendling
- U1099; INSERM; Rennes France
- Laboratoire de Traitement du Signal et de l'Image; Université de Rennes 1; Rennes France
| | - Aileen McGonigal
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
- AP-HM; Service de Neurophysiologie Clinique; Hôpital de la Timone; Marseille France
| | - Viktor Jirsa
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
| | - Maxime Guye
- Centre d'Exploration Métabolique par Résonance Magnétique (CEMEREM); APHM; Hôpitaux de la Timone; Marseille France
| | - Christian Bénar
- Institut de Neurosciences des Systèmes; Aix Marseille University; Marseille France
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Coppola G, Piccorossi A, Operto FF, Verrotti A. Anticonvulsant drugs for generalized tonic-clonic epilepsy. Expert Opin Pharmacother 2017; 18:925-936. [DOI: 10.1080/14656566.2017.1328499] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Giangennaro Coppola
- Child and Adolescent Neuropsychiatry, Department of Medicine and Surgery, University of Salerno, Salerno, Italy
| | | | - Francesca Felicia Operto
- Child and Adolescent Neuropsychiatry, Department of Medicine and Surgery, University of Salerno, Salerno, Italy
| | - Alberto Verrotti
- Department of Pediatrics, University of L’Aquila, L’Aquila, Italy
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36
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Martinez-Vargas JD, Strobbe G, Vonck K, van Mierlo P, Castellanos-Dominguez G. Improved Localization of Seizure Onset Zones Using Spatiotemporal Constraints and Time-Varying Source Connectivity. Front Neurosci 2017; 11:156. [PMID: 28428738 PMCID: PMC5382162 DOI: 10.3389/fnins.2017.00156] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 03/10/2017] [Indexed: 11/30/2022] Open
Abstract
Presurgical evaluation of brain neural activity is commonly carried out in refractory epilepsy patients to delineate as accurately as possible the seizure onset zone (SOZ) before epilepsy surgery. In practice, any subjective interpretation of electroencephalographic (EEG) recordings is hindered mainly because of the highly stochastic behavior of the epileptic activity. We propose a new method for dynamic source connectivity analysis that aims to accurately localize the seizure onset zones by explicitly including temporal, spectral, and spatial information of the brain neural activity extracted from EEG recordings. In particular, we encode the source nonstationarities in three critical stages of processing: Inverse problem solution, estimation of the time courses extracted from the regions of interest, and connectivity assessment. With the aim to correctly encode all temporal dynamics of the seizure-related neural network, a directed functional connectivity measure is employed to quantify the information flow variations over the time window of interest. Obtained results on simulated and real EEG data confirm that the proposed approach improves the accuracy of SOZ localization.
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Affiliation(s)
- Juan D Martinez-Vargas
- Signal Processing and Recognition Group, Universidad Nacional de ColombiaManizales, Colombia
| | - Gregor Strobbe
- Medical Image and Signal Processing Group, iMinds Medical IT Department, Ghent UniversityGhent, Belgium
| | - Kristl Vonck
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Ghent University HospitalGhent, Belgium
| | - Pieter van Mierlo
- Medical Image and Signal Processing Group, iMinds Medical IT Department, Ghent UniversityGhent, Belgium
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Pittau F, Ferri L, Fahoum F, Dubeau F, Gotman J. Contributions of EEG-fMRI to Assessing the Epileptogenicity of Focal Cortical Dysplasia. Front Comput Neurosci 2017; 11:8. [PMID: 28265244 PMCID: PMC5316536 DOI: 10.3389/fncom.2017.00008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 02/02/2017] [Indexed: 12/16/2022] Open
Abstract
Purpose: To examine the ability of the BOLD response to EEG spikes to assess the epileptogenicity of the lesion in patients with focal cortical dysplasia (FCD). Method: Patients with focal epilepsy and FCD who underwent 3T EEG-fMRI from 2006 to 2010 were included. Diagnosis of FCD was based on neuroradiology (MRI+), or histopathology in MRI-negative cases (MRI−). Patients underwent 120 min EEG-fMRI recording session. Spikes similar to those recorded outside the scanner were marked in the filtered EEG. The lesion (in MRI+) or the removed cortex (in MRI−) was marked on the anatomical T1 sequence, blindly to the BOLD response, after reviewing the FLAIR images. For each BOLD response we assessed the concordance with the spike field and with the lesion in MRI+ or the removed cortex in MRI−. BOLD responses were considered “concordant” if the maximal t-value was inside the marking. Follow-up after resection was used as gold-standard. Results: Twenty patients were included (13 MRI+, 7 MRI−), but in seven the EEG was not active or there were artifacts during acquisition. In all 13 studied patients, at least one BOLD response was concordant with the spike field; in 9/13 (69%) at least one BOLD response was concordant with the lesion: in 6/7 (86%) MRI+ and in 3/6 (50%) MRI− patients. Conclusions: Our study shows a high level of concordance between FCD and BOLD response. This data could provide useful information especially for MRI negative patients. Moreover, it shows in almost all FCD patients, a metabolic involvement of remote cortical or subcortical structures, corroborating the concept of epileptic network.
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Affiliation(s)
- Francesca Pittau
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill UniversityQuébec, QC, Canada; Neurology Department, Geneva University HospitalsGeneva, Switzerland
| | - Lorenzo Ferri
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University Québec, QC, Canada
| | - Firas Fahoum
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University Québec, QC, Canada
| | - François Dubeau
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University Québec, QC, Canada
| | - Jean Gotman
- Department of Neurology and Neurosurgery, Montreal Neurological Institute and Hospital, McGill University Québec, QC, Canada
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38
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Sousa K, Decker N, Pires TR, Papke DKM, Coelho VR, Pflüger P, Pereira P, Picada JN. Neurobehavioral effects of vigabatrin and its ability to induce DNA damage in brain cells after acute treatment in rats. Psychopharmacology (Berl) 2017; 234:129-136. [PMID: 27678549 DOI: 10.1007/s00213-016-4446-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 09/19/2016] [Indexed: 12/29/2022]
Abstract
RATIONALE Vigabatrin (VGB) is a drug indicated mostly for the treatment of spasms in childhood and West's syndrome patients. This drug inhibits irreversibly the enzyme GABA-transaminase (GABA-T), increasing GABA concentrations and enhancing GABAergic neurotransmission in the brain, which is known to induce behavioral changes. OBJECTIVES The aims of this study were to evaluate the effects of VGB in the short-term memory (STM), long-term memory (LTM), motivation, locomotion, and exploratory behavior tests and to detect deleterious or protective effects on DNA in target tissues of the drug. METHODS Male Wistar rats were treated with a single dose of VGB (100, 250, or 500 mg/kg) or saline solution before the inhibitory avoidance and open-field tasks. DNA damage was evaluated using the alkaline comet assay in peripheral blood, cerebral cortex, and hippocampus after behavioral testing. RESULTS There was no significant difference in the inhibitory avoidance task between the treated groups and the saline group. In all tested doses, VGB reduced the number of rearings in the open-field task. Besides, VGB 500 mg/kg affected locomotion, though it was not able to induce any DNA damage. CONCLUSIONS VGB did not affect STM and LTM, but the drug impaired the exploration and locomotion likely associated with its sedative effect. In addition, no DNA damage in cortex and hippocampus was detected after behavioral testing, when brain GABA levels are already increased.
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Affiliation(s)
- Karen Sousa
- Laboratory of Toxicological Genetics, Lutheran University of Brazil (ULBRA), Farroupilha Avenue, 8001, Canoas, RS, 2425-900, Brazil
| | - Natalia Decker
- Laboratory of Toxicological Genetics, Lutheran University of Brazil (ULBRA), Farroupilha Avenue, 8001, Canoas, RS, 2425-900, Brazil
| | - Thienne Rocha Pires
- Laboratory of Toxicological Genetics, Lutheran University of Brazil (ULBRA), Farroupilha Avenue, 8001, Canoas, RS, 2425-900, Brazil
| | - Débora Kuck Mausolff Papke
- Laboratory of Toxicological Genetics, Lutheran University of Brazil (ULBRA), Farroupilha Avenue, 8001, Canoas, RS, 2425-900, Brazil
| | - Vanessa Rodrigues Coelho
- Laboratory of Neuropharmacology and Pre-Clinical Toxicology. Pharmacology Department, Institute for Basic Health Sciences, Federal University of Rio Grande do Sul (UFRGS), Sarmento Leite Street, 500/305, Porto Alegre, RS, 90050-170, Brazil
| | - Pricila Pflüger
- Laboratory of Neuropharmacology and Pre-Clinical Toxicology. Pharmacology Department, Institute for Basic Health Sciences, Federal University of Rio Grande do Sul (UFRGS), Sarmento Leite Street, 500/305, Porto Alegre, RS, 90050-170, Brazil
| | - Patrícia Pereira
- Laboratory of Neuropharmacology and Pre-Clinical Toxicology. Pharmacology Department, Institute for Basic Health Sciences, Federal University of Rio Grande do Sul (UFRGS), Sarmento Leite Street, 500/305, Porto Alegre, RS, 90050-170, Brazil
| | - Jaqueline Nascimento Picada
- Laboratory of Toxicological Genetics, Lutheran University of Brazil (ULBRA), Farroupilha Avenue, 8001, Canoas, RS, 2425-900, Brazil.
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Amtul Z, Aziz AA. Microbial Proteins as Novel Industrial Biotechnology Hosts to Treat Epilepsy. Mol Neurobiol 2016; 54:8211-8224. [PMID: 27905012 DOI: 10.1007/s12035-016-0279-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/31/2016] [Indexed: 12/16/2022]
Abstract
Epilepsy is characterized by the hyperexcitability of various neuronal circuits that results due to the imbalance between glutamate-mediated excitation of voltage-gated cation channels and γ-amino butyric acid (GABA)-mediated inhibition of anion channels leading to aberrant, sporadic oscillations or fluctuations in neuronal electrical activity. Epilepsy with a risk of mortality and around 65 million sufferers of all ages all over the world is limited therapeutically with high rates of adverse reactions, lack of complete seizure control, and over 30% patients with refractory epilepsy. The only alternative to medicines is to identify and surgically remove the seizure foci in the brain or to abort the seizures just as they begin using an implanted cerebral electrode. However, these alternatives are unable to precisely aim aberrant neuronal circuits while leaving others unaltered. Epilepsy animal models also constitute the identical constraint. Thus, a better target-specific approach is needed to study and treat epilepsy. Unicellular green algae Chlamydomonas reinhardtii expresses a channelrhodopsin-2 (ChR2) sodium ion channel protein that controls the phototaxis movement of algae in response to blue light. Similarly, archaeon Natronomonas pharaonis (NpHR) expresses a monovalent Cl- channel protein halorhodopsin that responds to yellow light. These features of ChR2 and NpHR proteins can be used in optogenetic techniques to manipulate the bi-directional firing pattern of neuronal circuits in an attempt to better understand the pathophysiology of epileptic seizures as well as to discover novel potential drugs to treat epilepsy.
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Affiliation(s)
- Zareen Amtul
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan.
| | - Amal A Aziz
- Sir Wilfrid Laurier Secondary School, Thames Valley District School Board, N6C 4W7, London, ON, Canada
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40
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Dynamic causal modelling of seizure activity in a rat model. Neuroimage 2016; 146:518-532. [PMID: 27639356 DOI: 10.1016/j.neuroimage.2016.08.062] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 07/27/2016] [Accepted: 08/30/2016] [Indexed: 11/22/2022] Open
Abstract
This paper presents a physiological account of seizure activity and its evolution over time using a rat model of induced epilepsy. We analyse spectral activity recorded in the hippocampi of three rats who received kainic acid injections in the right hippocampus. We use dynamic causal modelling of seizure activity and Bayesian model reduction to identify the key synaptic and connectivity parameters that underlie seizure onset. Using recent advances in hierarchical modelling (parametric empirical Bayes), we characterise seizure onset in terms of slow fluctuations in synaptic excitability of specific neuronal populations. Our results suggest differences in the pathophysiology - of seizure activity in the lesioned versus the non-lesioned hippocampus - with pronounced changes in excitation-inhibition balance and temporal summation on the lesioned side. In particular, our analyses suggest that marked reductions in the synaptic time constant of the deep pyramidal cells and the self-inhibition of inhibitory interneurons (in the lesioned hippocampus) are sufficient to explain changes in spectral activity. Although these synaptic changes are consistent over rats, the resulting electrophysiological phenotype can be quite diverse.
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41
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Sperdin HF, Schaer M. Aberrant Development of Speech Processing in Young Children with Autism: New Insights from Neuroimaging Biomarkers. Front Neurosci 2016; 10:393. [PMID: 27610073 PMCID: PMC4997090 DOI: 10.3389/fnins.2016.00393] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/10/2016] [Indexed: 12/13/2022] Open
Abstract
From the time of birth, a newborn is continuously exposed and naturally attracted to human voices, and as he grows, he becomes increasingly responsive to these speech stimuli, which are strong drivers for his language development and knowledge acquisition about the world. In contrast, young children with autism spectrum disorder (ASD) are often insensitive to human voices, failing to orient and respond to them. Failure to attend to speech in turn results in altered development of language and social-communication skills. Here, we review the critical role of orienting to speech in ASD, as well as the neural substrates of human voice processing. Recent functional neuroimaging and electroencephalography studies demonstrate that aberrant voice processing could be a promising marker to identify ASD very early on. With the advent of refined brain imaging methods, coupled with the possibility of screening infants and toddlers, predictive brain function biomarkers are actively being examined and are starting to emerge. Their timely identification might not only help to differentiate between phenotypes, but also guide the clinicians in setting up appropriate therapies, and better predicting or quantifying long-term outcome.
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Affiliation(s)
- Holger F. Sperdin
- Office Médico-Pédagogique, Department of Psychiatry, University of Geneva School of MedicineGeneva, Switzerland
| | - Marie Schaer
- Office Médico-Pédagogique, Department of Psychiatry, University of Geneva School of MedicineGeneva, Switzerland
- Stanford Cognitive & Systems Neuroscience Laboratory, Stanford University School of MedicinePalo Alto, CA, USA
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Englot DJ, Konrad PE, Morgan VL. Regional and global connectivity disturbances in focal epilepsy, related neurocognitive sequelae, and potential mechanistic underpinnings. Epilepsia 2016; 57:1546-1557. [PMID: 27554793 DOI: 10.1111/epi.13510] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2016] [Indexed: 12/19/2022]
Abstract
Epilepsy is among the most common brain network disorders, and it is associated with substantial morbidity and increased mortality. Although focal epilepsy was traditionally considered a regional brain disorder, growing evidence has demonstrated widespread network alterations in this disorder that extend beyond the epileptogenic zone from which seizures originate. The goal of this review is to summarize recent investigations examining functional and structural connectivity alterations in focal epilepsy, including neuroimaging and electrophysiologic studies utilizing model-based or data-driven analytic methods. A significant subset of studies in both mesial temporal lobe epilepsy and focal neocortical epilepsy have demonstrated patterns of increased connectivity related to the epileptogenic zone, coupled with decreased connectivity in widespread distal networks. Connectivity patterns appear to be related to the duration and severity of disease, suggesting progressive connectivity reorganization in the setting of recurrent seizures over time. Global resting-state connectivity disturbances in focal epilepsy have been linked to neurocognitive problems, including memory and language disturbances. Although it is possible that increased connectivity in a particular brain region may enhance the propensity for seizure generation, it is not clear if global reductions in connectivity represent the damaging consequences of recurrent seizures, or an adaptive mechanism to prevent seizure propagation away from the epileptogenic zone. Overall, studying the connectome in focal epilepsy is a critical endeavor that may lead to improved strategies for epileptogenic-zone localization, surgical outcome prediction, and a better understanding of the neuropsychological implications of recurrent seizures.
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Affiliation(s)
- Dario J Englot
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, U.S.A..
| | - Peter E Konrad
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, U.S.A
| | - Victoria L Morgan
- Department of Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, U.S.A
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Ahl M, Avdic U, Skoug C, Ali I, Chugh D, Johansson UE, Ekdahl CT. Immune response in the eye following epileptic seizures. J Neuroinflammation 2016; 13:155. [PMID: 27346214 PMCID: PMC4922060 DOI: 10.1186/s12974-016-0618-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 06/08/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Epileptic seizures are associated with an immune response in the brain. However, it is not known whether it can extend to remote areas of the brain, such as the eyes. Hence, we investigated whether epileptic seizures induce inflammation in the retina. METHODS Adult rats underwent electrically induced temporal status epilepticus, and the eyes were studied 6 h, 1, and 7 weeks later with biochemical and immunohistochemical analyses. An additional group of animals received CX3CR1 antibody intracerebroventricularly for 6 weeks after status epilepticus. RESULTS Biochemical analyses and immunohistochemistry revealed no increased cell death and unaltered expression of several immune-related cytokines and chemokines as well as no microglial activation, 6 h post-status epilepticus compared to non-stimulated controls. At 1 week, again, retinal cytoarchitecture appeared normal and there was no cell death or micro- or macroglial reaction, apart from a small decrease in interleukin-10. However, at 7 weeks, even if the cytoarchitecture remained normal and no ongoing cell death was detected, the numbers of microglia were increased ipsi- and contralateral to the epileptic focus. The microglia remained within the synaptic layers but often in clusters and with more processes extending into the outer nuclear layer. Morphological analyses revealed a decrease in surveying and an increase in activated microglia. In addition, increased levels of the chemokine KC/GRO and cytokine interleukin-1β were found. Furthermore, macroglial activation was noted in the inner retina. No alterations in numbers of phagocytic cells, infiltrating macrophages, or vascular pericytes were observed. Post-synaptic density-95 cluster intensity was reduced in the outer nuclear layer, reflecting seizure-induced synaptic changes without disrupted cytoarchitecture in areas with increased microglial activation. The retinal gliosis was decreased by a CX3CR1 immune modulation known to reduce gliosis within epileptic foci, suggesting a common immunological reaction. CONCLUSIONS Our results are the first evidence that epileptic seizures induce an immune response in the retina. It has a potential to become a novel non-invasive tool for detecting brain inflammation through the eyes.
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Affiliation(s)
- Matilda Ahl
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Una Avdic
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Cecilia Skoug
- Division of Ophthalmology, Department of Clinical Sciences, Lund University, SE-221 85, Lund, Sweden
| | - Idrish Ali
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Deepti Chugh
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Ulrica Englund Johansson
- Division of Ophthalmology, Department of Clinical Sciences, Lund University, SE-221 85, Lund, Sweden
| | - Christine T Ekdahl
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden. .,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden.
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Iannotti GR, Grouiller F, Centeno M, Carmichael DW, Abela E, Wiest R, Korff C, Seeck M, Michel C, Pittau F, Vulliemoz S. Epileptic networks are strongly connected with and without the effects of interictal discharges. Epilepsia 2016; 57:1086-96. [PMID: 27153929 DOI: 10.1111/epi.13400] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2016] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Epilepsy is increasingly considered as the dysfunction of a pathologic neuronal network (epileptic network) rather than a single focal source. We aimed to assess the interactions between the regions that comprise the epileptic network and to investigate their dependence on the occurrence of interictal epileptiform discharges (IEDs). METHODS We analyzed resting state simultaneous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) recordings in 10 patients with drug-resistant focal epilepsy with multifocal IED-related blood oxygen level-dependent (BOLD) responses and a maximum t-value in the IED field. We computed functional connectivity (FC) maps of the epileptic network using two types of seed: (1) a 10-mm diameter sphere centered in the global maximum of IED-related BOLD map, and (2) the independent component with highest correlation to the IED-related BOLD map, named epileptic component. For both approaches, we compared FC maps before and after regressing out the effect of IEDs in terms of maximum and mean t-values and percentage of map overlap. RESULTS Maximum and mean FC maps t-values were significantly lower after regressing out IEDs at the group level (p < 0.01). Overlap extent was 85% ± 12% and 87% ± 12% when the seed was the 10-mm diameter sphere and the epileptic component, respectively. SIGNIFICANCE Regions involved in a specific epileptic network show coherent BOLD fluctuations independent of scalp EEG IEDs. FC topography and strength is largely preserved by removing the IED effect. This could represent a signature of a sustained pathologic network with contribution from epileptic activity invisible to the scalp EEG.
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Affiliation(s)
- Giannina R Iannotti
- Functional Brain Mapping Lab, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Frédéric Grouiller
- Department of Radiology and Medical Informatics, University Hospital of Geneva, Geneva, Switzerland
| | - Maria Centeno
- Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom
| | - David W Carmichael
- Developmental Imaging and Biophysics Section, UCL Institute of Child Health, London, United Kingdom
| | - Eugenio Abela
- Support Center of Advanced Neuroimaging (SCAN), Institute for Diagnostic and Interventional Neuroradiology, University Hospital Inselspital, Bern, Switzerland
| | - Roland Wiest
- Support Center of Advanced Neuroimaging (SCAN), Institute for Diagnostic and Interventional Neuroradiology, University Hospital Inselspital, Bern, Switzerland
| | - Christian Korff
- Pediatric Neurology, Child and Adolescent Department, University Hospitals and Faculty of Medicine of Geneva, Geneva, Switzerland
| | - Margitta Seeck
- Neurology Clinic, University Hospital and Faculty of Medicine of Geneva, Geneva, Switzerland
| | - Christoph Michel
- Functional Brain Mapping Lab, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Francesca Pittau
- Neurology Clinic, University Hospital and Faculty of Medicine of Geneva, Geneva, Switzerland
| | - Serge Vulliemoz
- Neurology Clinic, University Hospital and Faculty of Medicine of Geneva, Geneva, Switzerland
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