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Beamforming Seizures from the Temporal Lobe Using Magnetoencephalography. Can J Neurol Sci 2023; 50:201-213. [PMID: 35022091 DOI: 10.1017/cjn.2022.1] [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: 11/06/2022]
Abstract
BACKGROUND Surgical treatment of drug-resistant temporal lobe epilepsy (TLE) depends on proper identification of the seizure onset zone (SOZ) and differentiation of mesial, temporolimbic seizure onsets from temporal neocortical seizure onsets. Noninvasive source imaging using electroencephalography (EEG) and magnetoencephalography (MEG) can provide accurate information on interictal spike localization; however, EEG and MEG have low sensitivity for epileptiform activity restricted to deep temporolimbic structures. Moreover, in mesial temporal lobe epilepsy (MTLE), interictal spikes frequently arise in neocortical foci distant from the SOZ, rendering interictal spike localization potentially misleading for presurgical planning. METHODS In this study, we used two different beamformer techniques applied to the MEG signal of ictal events acquired during EEG-MEG recordings in six patients with TLE (three neocortical, three MTLE) in whom the ictal source localization results could be compared to ground truth SOZ localizations determined from intracranial EEG and/or clinical, neuroimaging, and postsurgical outcome evidence. RESULTS Beamformer analysis proved to be highly accurate in all cases and was able to identify focal SOZs in mesial, temporolimbic structures. In three patients, interictal spikes were absent, too complex for dipole modeling, or localized to anterolateral temporal neocortex distant to a mesial temporal SOZ, and thus unhelpful in presurgical investigation. CONCLUSIONS MEG beamformer source reconstruction is suitable for analysis of ictal events in TLE and can complement or supersede the traditional analysis of interictal spikes. The method outlined is applicable to any type of epileptiform event, expanding the information value of MEG and broadening its utility for presurgical recording in epilepsy.
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Epilepsy Surgery is a Viable Treatment for Lennox Gastaut Syndrome. Semin Pediatr Neurol 2021; 38:100894. [PMID: 34183143 DOI: 10.1016/j.spen.2021.100894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/09/2021] [Accepted: 04/10/2021] [Indexed: 11/21/2022]
Abstract
Lennox Gastaut Syndrome (LGS) is a severe developmental epileptic encephalopathy with onset in childhood characterized by multiple seizure types and characteristic electroencephalogram findings. The majority of patients develop drug resistant epilepsy, defined as failure of 2 appropriate anti-seizure medications used at adequate doses. Epilepsy surgery can reduce seizure burden, in some cases leading to seizure freedom, and improve neuro-developmental outcomes and quality of life. Epilepsy surgery should be considered for all patients with drug resistant LGS. Herein, we review current surgical treatment options for patients with LGS, both definitive and palliative, including: focal cortical resection, vagus nerve stimulation and corpus callosotomy. Newer neuromodulation techniques will be explored, as well as the concept of LGS as a secondary network disorder.
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Warren AE, Harvey AS, Vogrin SJ, Bailey C, Davidson A, Jackson GD, Abbott DF, Archer JS. The epileptic network of Lennox-Gastaut syndrome. Neurology 2019; 93:e215-e226. [DOI: 10.1212/wnl.0000000000007775] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 03/08/2019] [Indexed: 02/07/2023] Open
Abstract
ObjectiveTo identify brain regions underlying interictal generalized paroxysmal fast activity (GPFA), and their causal interactions, in children and adults with Lennox-Gastaut syndrome (LGS).MethodsConcurrent scalp EEG-fMRI was performed in 2 separately analyzed patient groups with LGS: 10 children (mean age 8.9 years) scanned under isoflurane-remifentanil anesthesia and 15 older patients (mean age 31.7 years) scanned without anesthesia. Whole-brain event-related analysis determined GPFA-related activation in each group. Results were used as priors in a dynamic causal modeling (DCM) analysis comparing evidence for different neuronal hypotheses describing initiation and propagation of GPFA between cortex, thalamus, and brainstem.ResultsA total of 1,045 GPFA events were analyzed (cumulative duration 1,433 seconds). In both pediatric and older groups, activation occurred in distributed association cortical areas, as well as the thalamus and brainstem (p < 0.05, corrected for family-wise error). Activation was similar across individual patients with structural, genetic, and unknown etiologies of epilepsy, particularly in frontoparietal cortex. In both groups, DCM revealed that GPFA was most likely driven by prefrontal cortex, with propagation occurring first to the brainstem and then from brainstem to thalamus.ConclusionsWe show reproducible evidence of a cortically driven process within the epileptic network of LGS. This network is present early (in children) and late (in older patients) in the course of the syndrome and across diverse etiologies of epilepsy, suggesting that LGS reflects shared “secondary network” involvement. A cortical-to-subcortical hierarchy is postulated whereby GPFA rapidly propagates from prefrontal cortex to the brainstem via extrapyramidal corticoreticular pathways, whereas the thalamus is engaged secondarily.
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Yang D, Du Q, Huang Z, Li L, Zhang Z, Zhang L, Zhao X, Zhao X, Li T, Lin Y, Wang Y. Transcranial Direct Current Stimulation for Patients With Pharmacoresistant Epileptic Spasms: A Pilot Study. Front Neurol 2019; 10:50. [PMID: 30804872 PMCID: PMC6370643 DOI: 10.3389/fneur.2019.00050] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/15/2019] [Indexed: 01/29/2023] Open
Abstract
Background: Epileptic spasms (ES) is a severe seizure type and lack of adequate methods for controlling of clinical attacks. Previous studies have indicated that cathodal transcranial direct current stimulation (tDCS) reduces seizure frequency for patients with epilepsy. ES are proposed to have a focal cortical origin. We hypothesized that patients with ES exhibit hyperactive network hubs in the parietal lobe, and that cathodal tDCS targeting the bilateral parietal region can reduce seizure frequency in patients with pharmacoresistant ES. Materials and Methods: The present study consisted of three basic phases: (a) a pre-treatment monitoring period for 14 days; (b) a consecutive 14-day treatment period during which patients were treated with 1 or 2 mA cathode tDCS for 40 min once per day; (c) and a follow-up period for at least 28 days. During the first 20 min of treatment, the cathode was placed over the right parietal lobe (P4) with the reference electrode over the contralateral supra-orbital area. In the second 20 min, the cathode was placed over the left parietal lobe (P3), with the reference electrode over the contralateral supra-orbital area. All patients received active tDCS treatment, and some patients underwent more than one treatment block. Patients maintained a seizure diary throughout the study. Antiepileptic drug therapy remained unchanged throughout the study. K-related samples Friedman tests and two-related samples tests were used to analyze data from all patients. Results: Seven patients with pharmacoresistant ES were included, receiving a total of eighteen 14-day blocks of tDCS treatment. We observed a significant difference in seizure frequency at the second month (p = 0.028, unadjusted), as well as a trend toward decreased seizure frequency at the fourth month (p = 0.068, unadjusted) of the first follow-up, relative to baseline. Three of seven patients (42.9%) exhibited sustained seizure reduction, while one (14.3%) experienced a short-term reduction in seizure frequency following cathodal tDCS treatment. Treatment was well tolerated in all patients. Conclusions: Repeated tDCS with the cathode placed over the bilateral parietal region is safe and may be effective for reducing seizure frequency in a subgroup of patients with pharmacoresistant ES.
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Affiliation(s)
- Dongju Yang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China
| | - Qiaoyi Du
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China
| | - Zhaoyang Huang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China
| | - Liping Li
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China
| | - Zhang Zhang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China
| | - Liping Zhang
- Department of Pediatric, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Xin Zhao
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China
| | - Xuan Zhao
- Department of Pediatric, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Ting Li
- Department of Pediatric, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yicong Lin
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China
| | - Yuping Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Neuromodulation, Beijing, China.,Department of Pediatric, Xuanwu Hospital, Capital Medical University, Beijing, China.,Center of Epilepsy, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
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Jeong W, Kim JS, Chung CK. Usefulness of multiple frequency band source localizations in ictal MEG. Clin Neurophysiol 2015; 127:1049-1056. [PMID: 26235699 DOI: 10.1016/j.clinph.2015.07.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 06/24/2015] [Accepted: 07/15/2015] [Indexed: 12/13/2022]
Abstract
OBJECTIVE We evaluated the diagnostic value of multiple frequency band MEG source localization within a wide time window during the preictal period. METHODS Data for 13 epilepsy patients who showed an ictal event during MEG were analyzed. Several seconds of preictal data were localized in the theta, alpha, beta, and gamma bands by using wavelet transformation and the sLORETA algorithm. The same analysis was performed with narrow time and frequency band. Localization concordances to the surgically resected area were compared. RESULTS Source localization in the gamma band for a 10s window before ictal onset showed best concordance to the resection cavity. Eight of 13 patients showed sub-lobar concordance in the 10s gamma band localization, whereas 3 showed concordance in the narrow time and frequency analysis. Four of 7 patients with focal cortical dysplasia (FCD) achieved seizure-free outcome, and all 4 showed sub-lobar concordance. CONCLUSIONS A 10s time window gamma source localization method can be used to delineate the epileptogenic zone. SIGNIFICANCE The use of a long period during preictal gamma source localization has the potential to become a localizing biomarker of the epileptogenic zone in candidates for surgical intervention, especially in MRI-suspected FCD.
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Affiliation(s)
- Woorim Jeong
- Department of Neurosurgery, Seoul National University Hospital, Seoul, South Korea; Interdisciplinary Program in Neuroscience, Seoul National University College of Natural Science, Seoul, South Korea.
| | - June Sic Kim
- Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, South Korea.
| | - Chun Kee Chung
- Department of Neurosurgery, Seoul National University Hospital, Seoul, South Korea; Interdisciplinary Program in Neuroscience, Seoul National University College of Natural Science, Seoul, South Korea; Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, South Korea; Neuroscience Research Institute, Seoul National University Medical Research Center, Seoul, South Korea.
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Asymmetrical generalized paroxysmal fast activities in children with intractable localization-related epilepsy. Brain Dev 2015; 37:59-65. [PMID: 24809226 DOI: 10.1016/j.braindev.2014.03.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 03/12/2014] [Accepted: 03/13/2014] [Indexed: 11/22/2022]
Abstract
BACKGROUND Generalized paroxysmal fast activity (GPFA) consists of burst of generalized rhythmic discharges; 100-200 μV; 1-9s; 8-26 Hz; with frontal predominance; appearing during NREM sleep. GPFA was originally described as an electrographic feature of Lennox-Gastaut Syndrome (LGS). We analyzed GPFA on scalp video EEG (VEEG) in children to evaluate that GPFA presents in patients with intractable localization-related epilepsy. METHODS We collected cases with GPFA with intractable localization-related epilepsy who underwent scalp VEEG, MRI, and magnetoencephalography (MEG) prior to intracranial video EEG (IVEEG) and surgical resection. We collected 50 epochs of GPFA per patient during the first night during scalp VEEG. We analyzed amplitude, duration and frequency of GPFA over the bilateral frontal region between surgical resection side with grid placement and non-resection side. RESULTS We identified 14 (14%) patients with GPFA on scalp VEEG. The mean amplitude ranged from 145 to 589 μV (mean 293 μV). The mean duration ranged from 1.18 to 2.31s (mean 1.6s). The mean frequencies ranged from 9.3 to 14.7 Hz (mean 11.1 Hz). The amplitude (307 ± 156 μV) and duration (1.62 ± 0.8s) of GPFAs in all the patients over the resection side were significantly higher than those (279 ± 141 μV, 1.58 ± 0.8s) of the non-resection side (p<0.001). All nine patients who showed significant duration differences between two hemispheres (p<0.05) had longer duration of GPFA over the resection side. Eight of 12 patients who showed significant amplitude differences between two hemispheres (p<0.05) had higher amplitude of GPFA over the resection side. Four of six patients who showed significant frequency differences between two hemispheres (p<0.05) had higher frequency of GPFA over the resection side. Nine (64%) patients became seizure free after surgical resection including multilobar resections in eight patients. CONCLUSIONS GPFA can exist in localization-related epilepsy with secondary bilateral synchrony. Although EEG shows GPFA on scalp VEEG, the precise localization of the epileptogenic zone using IVEEG could achieve the successful surgical resection.
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Archer JS, Warren AEL, Jackson GD, Abbott DF. Conceptualizing lennox-gastaut syndrome as a secondary network epilepsy. Front Neurol 2014; 5:225. [PMID: 25400619 PMCID: PMC4214194 DOI: 10.3389/fneur.2014.00225] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 10/15/2014] [Indexed: 12/22/2022] Open
Abstract
Lennox–Gastaut Syndrome (LGS) is a category of severe, disabling epilepsy, characterized by frequent, treatment-resistant seizures, and cognitive impairment. Electroencephalography (EEG) shows characteristic generalized epileptic activity that is similar in those with lesional, genetic, or unknown causes, suggesting a common underlying mechanism. The condition typically begins in young children, leaving many severely disabled with recurring seizures throughout their adult life. Scalp EEG of the tonic seizures of LGS is characterized by a diffuse high-voltage slow transient evolving into generalized low-voltage fast activity, likely reflecting sustained fast neuronal firing over a wide cortical area. The typical interictal discharges (runs of slow spike-and-wave and bursts of generalized paroxysmal fast activity) also have a “generalized” electrical field, suggesting widespread cortical involvement. Recent brain mapping studies have begun to reveal which cortical and subcortical regions are active during these “generalized” discharges. In this critical review, we examine findings from neuroimaging studies of LGS and place these in the context of the electrical and clinical features of the syndrome. We suggest that LGS can be conceptualized as “secondary network epilepsy,” where the epileptic activity is expressed through large-scale brain networks, particularly the attention and default-mode networks. Cortical lesions, when present, appear to chronically interact with these networks to produce network instability rather than triggering each individual epileptic discharge. LGS can be considered as “secondary” network epilepsy because the epileptic manifestations of the disorder reflect the networks being driven, rather than the specific initiating process. In this review, we begin with a summation of the clinical manifestations of LGS and what this has revealed about the underlying etiology of the condition. We then undertake a systematic review of the functional neuroimaging literature in LGS, which leads us to conclude that LGS can best be conceptualized as “secondary network epilepsy.”
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Affiliation(s)
- John S Archer
- Department of Medicine, Austin Health, The University of Melbourne , Heidelberg, VIC , Australia ; Florey Institute of Neuroscience and Mental Health , Heidelberg, VIC , Australia ; Department Neurology, Austin Health , Heidelberg, VIC , Australia
| | - Aaron E L Warren
- Department of Medicine, Austin Health, The University of Melbourne , Heidelberg, VIC , Australia
| | - Graeme D Jackson
- Department of Medicine, Austin Health, The University of Melbourne , Heidelberg, VIC , Australia ; Florey Institute of Neuroscience and Mental Health , Heidelberg, VIC , Australia ; Department Neurology, Austin Health , Heidelberg, VIC , Australia
| | - David F Abbott
- Department of Medicine, Austin Health, The University of Melbourne , Heidelberg, VIC , Australia ; Florey Institute of Neuroscience and Mental Health , Heidelberg, VIC , Australia
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Douglass LM, Salpekar J. Surgical options for patients with Lennox-Gastaut syndrome. Epilepsia 2014; 55 Suppl 4:21-8. [DOI: 10.1111/epi.12742] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2014] [Indexed: 01/30/2023]
Affiliation(s)
- Laurie M. Douglass
- Boston Medical Center; Boston University School of Medicine; Boston Massachusetts U.S.A
| | - Jay Salpekar
- Kennedy Krieger Institute; Baltimore Maryland U.S.A
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