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Ye H, Ye L, Hu L, Yang Y, Ge Y, Chen R, Wang S, Jin B, Ming W, Wang Z, Xu S, Xu C, Wang Y, Ding Y, Zhu J, Ding M, Chen Z, Wang S, Chen C. Widespread slow oscillations support interictal epileptiform discharge networks in focal epilepsy. Neurobiol Dis 2024; 191:106409. [PMID: 38218457 DOI: 10.1016/j.nbd.2024.106409] [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: 09/24/2023] [Revised: 01/01/2024] [Accepted: 01/09/2024] [Indexed: 01/15/2024] Open
Abstract
Interictal epileptiform discharges (IEDs) often co-occur across spatially-separated cortical regions, forming IED networks. However, the factors prompting IED propagation remain unelucidated. We hypothesized that slow oscillations (SOs) might facilitate IED propagation. Here, the amplitude and phase synchronization of SOs preceding propagating and non-propagating IEDs were compared in 22 patients with focal epilepsy undergoing intracranial electroencephalography (EEG) evaluation. Intracranial channels were categorized into the irritative zone (IZ) and normal zone (NOZ) regarding the presence of IEDs. During wakefulness, we found that pre-IED SOs within the IZ exhibited higher amplitudes for propagating IEDs than non-propagating IEDs (delta band: p = 0.001, theta band: p < 0.001). This increase in SOs was also concurrently observed in the NOZ (delta band: p = 0.04). Similarly, the inter-channel phase synchronization of SOs prior to propagating IEDs was higher than those preceding non-propagating IEDs in the IZ (delta band: p = 0.04). Through sliding window analysis, we observed that SOs preceding propagating IEDs progressively increased in amplitude and phase synchronization, while those preceding non-propagating IEDs remained relatively stable. Significant differences in amplitude occurred approximately 1150 ms before IEDs. During non-rapid eye movement (NREM) sleep, SOs on scalp recordings also showed higher amplitudes before intracranial propagating IEDs than before non-propagating IEDs (delta band: p = 0.006). Furthermore, the analysis of IED density around sleep SOs revealed that only high-amplitude sleep SOs demonstrated correlation with IED propagation. Overall, our study highlights that transient but widely distributed SOs are associated with IED propagation as well as generation in focal epilepsy during sleep and wakefulness, providing new insight into the EEG substrate supporting IED networks.
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Affiliation(s)
- Hongyi Ye
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Nanhu Brain-computer Interface Institute, Hangzhou, China
| | - Lingqi Ye
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lingli Hu
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yuyu Yang
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Ge
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Ruotong Chen
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shan Wang
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Bo Jin
- Department of Neurology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Wenjie Ming
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhongjin Wang
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Sha Xu
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Cenglin Xu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yi Wang
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yao Ding
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Junming Zhu
- Department of Neurosurgery and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Meiping Ding
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhong Chen
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Shuang Wang
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Nanhu Brain-computer Interface Institute, Hangzhou, China.
| | - Cong Chen
- Department of Neurology and Epilepsy Center, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
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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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3
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Silva AB, Leonard MK, Oganian Y, D’Esopo E, Krish D, Kopald B, Tran EB, Chang EF, Kleen JK. Interictal epileptiform discharges contribute to word-finding difficulty in epilepsy through multiple cognitive mechanisms. Epilepsia 2023; 64:3266-3278. [PMID: 37753856 PMCID: PMC10841419 DOI: 10.1111/epi.17781] [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: 04/25/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 09/28/2023]
Abstract
OBJECTIVE Cognitive impairment often impacts quality of life in epilepsy even if seizures are controlled. Word-finding difficulty is particularly prevalent and often attributed to etiological (static, baseline) circuit alterations. We sought to determine whether interictal discharges convey significant superimposed contributions to word-finding difficulty in patients, and if so, through which cognitive mechanism(s). METHODS Twenty-three patients undergoing intracranial monitoring for drug-resistant epilepsy participated in multiple tasks involving word production (auditory naming, short-term verbal free recall, repetition) to probe word-finding difficulty across different cognitive domains. We compared behavioral performance between trials with versus without interictal discharges across six major brain areas and adjusted for intersubject differences using mixed-effects models. We also evaluated for subjective word-finding difficulties through retrospective chart review. RESULTS Subjective word-finding difficulty was reported by the majority (79%) of studied patients preoperatively. During intracranial recordings, interictal epileptiform discharges (IEDs) in the medial temporal lobe were associated with long-term lexicosemantic memory impairments as indexed by auditory naming (p = .009), in addition to their established impact on short-term verbal memory as indexed by free recall (p = .004). Interictal discharges involving the lateral temporal cortex and lateral frontal cortex were associated with delayed reaction time in the auditory naming task (p = .016 and p = .018), as well as phonological working memory impairments as indexed by repetition reaction time (p = .002). Effects of IEDs across anatomical regions were strongly dependent on their precise timing within the task. SIGNIFICANCE IEDs appear to act through multiple cognitive mechanisms to form a convergent basis for the debilitating clinical word-finding difficulty reported by patients with epilepsy. This was particularly notable for medial temporal spikes, which are quite common in adult focal epilepsy. In parallel with the treatment of seizures, the modulation of interictal discharges through emerging pharmacological means and neurostimulation approaches may be an opportunity to help address devastating memory and language impairments in epilepsy.
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Affiliation(s)
- Alexander B. Silva
- Department of Neurosurgery, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
- Medical Scientist Training Program, University of California, San Francisco, CA, USA
- University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, USA
| | - Matthew K. Leonard
- Department of Neurosurgery, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | | | - Emma D’Esopo
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Devon Krish
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Brandon Kopald
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Edwina B. Tran
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Edward F. Chang
- Department of Neurosurgery, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
- University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, USA
| | - Jonathan K. Kleen
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
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Matarrese MAG, Loppini A, Fabbri L, Tamilia E, Perry MS, Madsen JR, Bolton J, Stone SSD, Pearl PL, Filippi S, Papadelis C. Spike propagation mapping reveals effective connectivity and predicts surgical outcome in epilepsy. Brain 2023; 146:3898-3912. [PMID: 37018068 PMCID: PMC10473571 DOI: 10.1093/brain/awad118] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/14/2023] [Accepted: 03/23/2023] [Indexed: 04/06/2023] Open
Abstract
Neurosurgical intervention is the best available treatment for selected patients with drug resistant epilepsy. For these patients, surgical planning requires biomarkers that delineate the epileptogenic zone, the brain area that is indispensable for the generation of seizures. Interictal spikes recorded with electrophysiological techniques are considered key biomarkers of epilepsy. Yet, they lack specificity, mostly because they propagate across brain areas forming networks. Understanding the relationship between interictal spike propagation and functional connections among the involved brain areas may help develop novel biomarkers that can delineate the epileptogenic zone with high precision. Here, we reveal the relationship between spike propagation and effective connectivity among onset and areas of spread and assess the prognostic value of resecting these areas. We analysed intracranial EEG data from 43 children with drug resistant epilepsy who underwent invasive monitoring for neurosurgical planning. Using electric source imaging, we mapped spike propagation in the source domain and identified three zones: onset, early-spread and late-spread. For each zone, we calculated the overlap and distance from surgical resection. We then estimated a virtual sensor for each zone and the direction of information flow among them via Granger causality. Finally, we compared the prognostic value of resecting these zones, the clinically-defined seizure onset zone and the spike onset on intracranial EEG channels by estimating their overlap with resection. We observed a spike propagation in source space for 37 patients with a median duration of 95 ms (interquartile range: 34-206), a spatial displacement of 14 cm (7.5-22 cm) and a velocity of 0.5 m/s (0.3-0.8 m/s). In patients with good surgical outcome (25 patients, Engel I), the onset had higher overlap with resection [96% (40-100%)] than early-spread [86% (34-100%), P = 0.01] and late-spread [59% (12-100%), P = 0.002], and it was also closer to resection than late-spread [5 mm versus 9 mm, P = 0.007]. We found an information flow from onset to early-spread in 66% of patients with good outcomes, and from early-spread to onset in 50% of patients with poor outcome. Finally, resection of spike onset, but not area of spike spread or the seizure onset zone, predicted outcome with positive predictive value of 79% and negative predictive value of 56% (P = 0.04). Spatiotemporal mapping of spike propagation reveals information flow from onset to areas of spread in epilepsy brain. Surgical resection of the spike onset disrupts the epileptogenic network and may render patients with drug resistant epilepsy seizure-free without having to wait for a seizure to occur during intracranial monitoring.
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Affiliation(s)
- Margherita A G Matarrese
- Jane and John Justin Institute for Mind Health Neurosciences Center, Cook Children’s Health Care System, Fort Worth, TX, USA
- Laboratory of Nonlinear Physics and Mathematical Modeling, Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
- Department of Bioengineering, The University of Texas at Arlington, Arlington, TX, USA
| | - Alessandro Loppini
- Laboratory of Nonlinear Physics and Mathematical Modeling, Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Lorenzo Fabbri
- Jane and John Justin Institute for Mind Health Neurosciences Center, Cook Children’s Health Care System, Fort Worth, TX, USA
- Department of Bioengineering, The University of Texas at Arlington, Arlington, TX, USA
| | - Eleonora Tamilia
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - M Scott Perry
- Jane and John Justin Institute for Mind Health Neurosciences Center, Cook Children’s Health Care System, Fort Worth, TX, USA
| | - Joseph R Madsen
- Division of Epilepsy Surgery, Department of Neurosurgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Jeffrey Bolton
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Scellig S D Stone
- Division of Epilepsy Surgery, Department of Neurosurgery, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Phillip L Pearl
- Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Simonetta Filippi
- Laboratory of Nonlinear Physics and Mathematical Modeling, Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Christos Papadelis
- Jane and John Justin Institute for Mind Health Neurosciences Center, Cook Children’s Health Care System, Fort Worth, TX, USA
- Department of Bioengineering, The University of Texas at Arlington, Arlington, TX, USA
- School of Medicine, Texas Christian University, Fort Worth, TX, USA
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5
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Poprelka K, Patrikelis P, Takousi M, Messinis L, Fasilis T, Margariti S, Ntinopoulou E, Verentzioti A, Stefanatou M, Alexoudi A, Korfias S, Zalonis I, Gatzonis S. Arousal deregulation in the co-shaping of neuropsychological dysfunction in frontal and mesial temporal lobe epilepsy. Epilepsy Res 2023; 194:107189. [PMID: 37421714 DOI: 10.1016/j.eplepsyres.2023.107189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 06/27/2023] [Accepted: 07/03/2023] [Indexed: 07/10/2023]
Abstract
OBJECTIVE Our work aims to investigate the role of physiological arousal in the expression of neuropsychological deficits in frontal lobe epilepsy (FLE) and mesial temporal lobe epilepsy (mTLE), by drawing on the Lurian theory of brain function. METHODS For this study a total of 43 patients with focal onset epilepsy has been taken; twenty-four patients with FLE, 19 patients with mTLE and 26 healthy controls, all matched for age and education. Participants underwent a comprehensive neuropsychological assessment including various cognitive domains, such as attention, episodic memory, speed of information processing, response inhibition and mental flexibility, working memory, verbal fluency (phonological & semantic). RESULTS There were no significant differences between FLE and mTLE patients in terms of neuropsychological performance. However, both FLE and mTLE patients showed significantly worse performance in several cognitive domains than HCs. The results seem to support our hypothesis that aberrant physiological arousal, as reflected in patients' worse performance in vigilance and attention, response inhibition, and processing speed, along with other disease-specific variables, may co-determine neuropsychological dysfunction and/or impairment in both FLE and mTLE. CONCLUSION Identifying a differential arousal-related neuropsychological affection in FLE and mTLE, among the known deleterious effects of the functional deficit zone and other disease-related variables, may further our understanding of the underlying cognitive-pathophysiological mechanisms in focal epilepsy syndromes.
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Affiliation(s)
- Katerina Poprelka
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece.
| | - Panayiotis Patrikelis
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece; Laboratory of Cognitive Neuroscience, Department of Psychology, Aristotle University of Thessaloniki, Greece
| | - Maria Takousi
- School of Health Sciences, Metropolitan College, Athens, Greece
| | - Lambros Messinis
- Laboratory of Cognitive Neuroscience, Department of Psychology, Aristotle University of Thessaloniki, Greece
| | - Theodoros Fasilis
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
| | - Sofia Margariti
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
| | - Evniki Ntinopoulou
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
| | - Anastasia Verentzioti
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
| | - Maria Stefanatou
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
| | - Athanasia Alexoudi
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
| | - Stefanos Korfias
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
| | - Ioannis Zalonis
- Aeginition Hospital, Medical School, National & Kapodistrian University of Athens, Neuropsychological Laboratory, 1st Department of Neurology, Greece
| | - Stylianos Gatzonis
- 1st Department of Neurosurgery, National & Kapodistrian University of Athens, Greece
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Diamond JM, Withers CP, Chapeton JI, Rahman S, Inati SK, Zaghloul KA. Interictal discharges in the human brain are travelling waves arising from an epileptogenic source. Brain 2023; 146:1903-1915. [PMID: 36729683 PMCID: PMC10411927 DOI: 10.1093/brain/awad015] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/27/2022] [Accepted: 01/08/2023] [Indexed: 02/03/2023] Open
Abstract
While seizure activity may be electrographically widespread, increasing evidence has suggested that ictal discharges may in fact represent travelling waves propagated from a focal seizure source. Interictal epileptiform discharges (IEDs) are an electrographic manifestation of excessive hypersynchronization of cortical activity that occur between seizures and are considered a marker of potentially epileptogenic tissue. The precise relationship between brain regions demonstrating IEDs and those involved in seizure onset, however, remains poorly understood. Here, we hypothesize that IEDs likewise reflect the receipt of travelling waves propagated from the same regions which give rise to seizures. Forty patients from our institution who underwent invasive monitoring for epilepsy, proceeded to surgery and had at least one year of follow-up were included in our study. Interictal epileptiform discharges were detected using custom software, validated by a clinical epileptologist. We show that IEDs reach electrodes in sequences with a consistent temporal ordering, and this ordering matches the timing of receipt of ictal discharges, suggesting that both types of discharges spread as travelling waves. We use a novel approach for localization of ictal discharges, in which time differences of discharge receipt at nearby electrodes are used to compute source location; similar algorithms have been used in acoustics and geophysics. We find that interictal discharges co-localize with ictal discharges. Moreover, interictal discharges tend to localize to the resection territory in patients with good surgical outcome and outside of the resection territory in patients with poor outcome. The seizure source may originate at, and also travel to, spatially distinct IED foci. Our data provide evidence that interictal discharges may represent travelling waves of pathological activity that are similar to their ictal counterparts, and that both ictal and interictal discharges emerge from common epileptogenic brain regions. Our findings have important clinical implications, as they suggest that seizure source localizations may be derived from interictal discharges, which are much more frequent than seizures.
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Affiliation(s)
- Joshua M Diamond
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - C Price Withers
- Clinical Epilepsy Section, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Julio I Chapeton
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shareena Rahman
- Office of the Clinical Director, NINDS, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sara K Inati
- 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
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7
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Pellegrino G, Hedrich T, Sziklas V, Lina J, Grova C, Kobayashi E. How cerebral cortex protects itself from interictal spikes: The alpha/beta inhibition mechanism. Hum Brain Mapp 2021; 42:3352-3365. [PMID: 34002916 PMCID: PMC8249896 DOI: 10.1002/hbm.25422] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 03/05/2021] [Indexed: 11/10/2022] Open
Abstract
Interactions between interictal epileptiform discharges (IEDs) and distant cortical regions subserve potential effects on cognition of patients with focal epilepsy. We hypothesize that "healthy" brain areas at a distance from the epileptic focus may respond to the interference of IEDs by generating inhibitory alpha and beta oscillations. We predict that more prominent alpha-beta oscillations can be found in patients with less impaired neurocognitive profile. We performed a source imaging magnetoencephalography study, including 41 focal epilepsy patients: 21 with frontal lobe epilepsy (FLE) and 20 with mesial temporal lobe epilepsy. We investigated the effect of anterior (i.e., frontal and temporal) IEDs on the oscillatory pattern over posterior head regions. We compared cortical oscillations (5-80 Hz) temporally linked to 3,749 IEDs (1,945 frontal and 1,803 temporal) versus an equal number of IED-free segments. We correlated results from IED triggered oscillations to global neurocognitive performance. Only frontal IEDs triggered alpha-beta oscillations over posterior head regions. IEDs with higher amplitude triggered alpha-beta oscillations of higher magnitude. The intensity of posterior head region alpha-beta oscillations significantly correlated with a better neuropsychological profile. Our study demonstrated that cerebral cortex protects itself from IEDs with generation of inhibitory alpha-beta oscillations at distant cortical regions. The association of more prominent oscillations with a better cognitive status suggests that this mechanism might play a role in determining the cognitive resilience in patients with FLE.
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Affiliation(s)
- Giovanni Pellegrino
- Department of Neurology and Neurosurgery, Montreal Neurological InstituteMcGill UniversityMontrealQuebecCanada
| | - Tanguy Hedrich
- Department of Biomedical Engineering, Multimodal Functional Imaging LabMcGill UniversityMontrealQuebecCanada
| | - Viviane Sziklas
- Department of Neurology and Neurosurgery, Montreal Neurological InstituteMcGill UniversityMontrealQuebecCanada
| | - Jean‐Marc Lina
- Departement de Genie ElectriqueEcole de Technologie SuperieureMontrealQuebecCanada
- Centre De Recherches En MathematiquesMontrealQuebecCanada
| | - Christophe Grova
- Department of Neurology and Neurosurgery, Montreal Neurological InstituteMcGill UniversityMontrealQuebecCanada
- Department of Biomedical Engineering, Multimodal Functional Imaging LabMcGill UniversityMontrealQuebecCanada
- Centre De Recherches En MathematiquesMontrealQuebecCanada
- Department of Physics and PERFORM CentreConcordia UniversityMontrealQuebecCanada
| | - Eliane Kobayashi
- Department of Neurology and Neurosurgery, Montreal Neurological InstituteMcGill UniversityMontrealQuebecCanada
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8
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Nair S, Szaflarski JP. Neuroimaging of memory in frontal lobe epilepsy. Epilepsy Behav 2020; 103:106857. [PMID: 31937510 DOI: 10.1016/j.yebeh.2019.106857] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/04/2019] [Accepted: 12/13/2019] [Indexed: 10/25/2022]
Abstract
In a large percentage of epilepsies, seizures have focal onset. These epilepsies are associated with a wide range of behavioral and cognitive deficits sometimes limited to the functions encompassed within the ictal onset zone but, more frequently, expanding beyond it. The presence of impairments associated with neuroanatomical areas outside of the ictal onset zone suggests distal propagation of epileptic activity via brain networks and interconnected whole-brain neural circuitry. In patients with frontal lobe epilepsy (FLE), using functional magnetic resonance imaging (fMRI) to identify deficits in working, semantic, and episodic memory may provide a lens through which to understand typical and atypical network organization. A network approach to focal epilepsy is relevant in these patients because of the frequently noted early age of seizure onset. Early seizure-related disruption in healthy brain development may result in a significant brain reorganization, development of compensation-related mechanisms of dealing with function abnormalities and disruptions, and the propagation of epileptic activity from the focus to widespread brain areas (functional deficit zones). Benefits of a network approach in the study of focal epilepsy are discussed along with considerations for future neuroimaging studies of patients with FLE.
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Affiliation(s)
- Sangeeta Nair
- Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, USA.
| | - Jerzy P Szaflarski
- Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Neurosurgery, University of Alabama at Birmingham, Birmingham, AL, USA
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9
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Cotter R, Winnik S, Singer A, Aaron G. Effects of Small Temperature Differences Detected in Callosal Circuits of the Anterior Cingulate Cortex. Neuroscience 2020; 428:154-164. [PMID: 31918013 DOI: 10.1016/j.neuroscience.2019.12.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 11/25/2022]
Abstract
We measured the sensitivity of cortical circuit activity to small differences in local cortical environments by studying how temperature affects the trajectory of epileptiform events (EEs). EEs evoked via blockade of GABA-A receptors were recorded extracellularly from mouse coronal brain slices containing both hemispheres of anterior cingulate cortex synaptically connected by corpus callosum axons. Preferentially illuminating one hemisphere with the microscope condenser produced temperature differences of 0.1 °C between the hemispheres. The relatively warmer hemisphere typically initiated the EEs that then propagated to the contralateral side, demonstrating temperature directed propagation. Severing the callosum following one hour of EEs showed that the warmer hemisphere possessed a higher rate of EE generation. Further experiments implied that intact callosal circuits were required for the increased EE generation in the warmer hemisphere. We propose a hypothesis whereby callosal circuits can amplify differences in respective hemispheric activity, promoting this directionality in seizure propagation.
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Affiliation(s)
- R Cotter
- Wesleyan University, Middletown, CT 06459, United States
| | - S Winnik
- Wesleyan University, Middletown, CT 06459, United States
| | - A Singer
- Wesleyan University, Middletown, CT 06459, United States
| | - G Aaron
- Wesleyan University, Middletown, CT 06459, United States.
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Diamond JM, Chapeton JI, Theodore WH, Inati SK, Zaghloul KA. The seizure onset zone drives state-dependent epileptiform activity in susceptible brain regions. Clin Neurophysiol 2019; 130:1628-1641. [PMID: 31325676 DOI: 10.1016/j.clinph.2019.05.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 04/05/2019] [Accepted: 05/14/2019] [Indexed: 01/14/2023]
Abstract
OBJECTIVE Due to variability in the patterns of propagation of interictal epileptiform discharges (IEDs), qualitative definition of the irritative zone has been challenging. Here, we introduce a quantitative approach toward exploration of the dynamics of IED propagation within the irritative zone. METHODS We examined intracranial EEG (iEEG) in nine participants undergoing invasive monitoring for seizure localization. We used an automated IED detector and a community detection algorithm to identify populations of electrodes exhibiting IED activity that co-occur in time, and to group these electrodes into communities. RESULTS Within our algorithmically-identified communities, IED activity in the seizure onset zone (SOZ) tended to lead IED activity in other functionally coupled brain regions. The tendency of pathological activity to arise in the SOZ, and to spread to non-SOZ tissues, was greater in the asleep state. CONCLUSIONS IED activity, and, by extension, the variability observed between the asleep and awake states, is propagated from a core seizure focus to nearby less pathological brain regions. SIGNIFICANCE Using an unsupervised, computational approach, we show that the spread of IED activity through the epilepsy network varies with physiologic state.
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Affiliation(s)
- Joshua M Diamond
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, United States
| | - Julio I Chapeton
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, United States
| | - William H Theodore
- Clinical Epilepsy Section, NINDS, National Institutes of Health, Bethesda, MD 20892, United States
| | - Sara K Inati
- Epilepsy Service and EEG Section, NINDS, National Institutes of Health, Bethesda, MD 20892, United States.
| | - Kareem A Zaghloul
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, MD 20892, United States.
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Schevon CA, Tobochnik S, Eissa T, Merricks E, Gill B, Parrish RR, Bateman LM, McKhann GM, Emerson RG, Trevelyan AJ. Multiscale recordings reveal the dynamic spatial structure of human seizures. Neurobiol Dis 2019; 127:303-311. [PMID: 30898669 PMCID: PMC6588430 DOI: 10.1016/j.nbd.2019.03.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/11/2019] [Accepted: 03/15/2019] [Indexed: 02/07/2023] Open
Abstract
The cellular activity underlying human focal seizures, and its relationship to key signatures in the EEG recordings used for therapeutic purposes, has not been well characterized despite many years of investigation both in laboratory and clinical settings. The increasing use of microelectrodes in epilepsy surgery patients has made it possible to apply principles derived from laboratory research to the problem of mapping the spatiotemporal structure of human focal seizures, and characterizing the corresponding EEG signatures. In this review, we describe results from human microelectrode studies, discuss some data interpretation pitfalls, and explain the current understanding of the key mechanisms of ictogenesis and seizure spread.
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Affiliation(s)
- Catherine A Schevon
- Department of Neurology, Columbia University Medical Center, New York, NY, USA.
| | - Steven Tobochnik
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Tahra Eissa
- Department of Applied Mathematics, University of Colorado at Boulder, Boulder, CO, USA
| | - Edward Merricks
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Brian Gill
- Department of Neurological Surgery, Columbia University Medical Center, New York, NY, USA
| | - R Ryley Parrish
- Institute for Aging, Newcastle University, Newcastle-Upon-Tyne, UK
| | - Lisa M Bateman
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University Medical Center, New York, NY, USA
| | - Ronald G Emerson
- Department of Neurology, Weill Cornell Medical Center, New York, NY, USA
| | - Andrew J Trevelyan
- Department of Neurology, Columbia University Medical Center, New York, NY, USA; Institute for Aging, Newcastle University, Newcastle-Upon-Tyne, UK
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Hamberger MJ, MacAllister WS, Seidel WT, Busch RM, Salinas CM, Klaas P, Smith ML. Noninvasive identification of seizure lateralization in children: Name that thing. Neurology 2019; 92:e1-e8. [PMID: 30518557 PMCID: PMC6336167 DOI: 10.1212/wnl.0000000000006691] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 08/16/2018] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE With this prospective, observational study, we aimed to determine whether noninvasive language tasks, developed specifically for children, could reliably identify the hemisphere of seizure onset in pediatric epilepsy. METHODS Seventy-eight children with unilateral epilepsy (44 left), aged 6-15 years (mean age = 11.8, SD = 2.6), completed the Children's Auditory Naming and Visual Naming Tests, the Boston Naming Test, and other verbal and nonverbal tasks. Multivariate analysis of variance was used to compare test performance between left and right hemisphere epilepsy groups, and χ2 analyses and odds ratios were used to examine classification of left vs right hemisphere epilepsy for individual patients based on test performance. RESULTS Group comparisons revealed poorer auditory naming in children with left hemisphere epilepsy (p = 0.02), yet no significant differences on measures of visual naming, general intelligence, or other cognitive functions. Moreover, χ2 analyses using auditory naming cutoff scores to define intact vs impaired performance correctly classified seizure laterality in a significant proportion of children (p = 0.004). The odds of left hemisphere epilepsy were 4.2 times higher (95% confidence interval 1.4-11.7) than the odds of right hemisphere epilepsy with poor auditory naming performance. In the subset of patients with temporal lobe epilepsy (TLE), the odds of left TLE were 11.3 times higher (95% confidence interval 2.00-63.17) than the odds of right TLE with poor auditory naming performance. CONCLUSION Contrary to previous findings, naming performance can lateralize hemisphere of seizure onset in children with epilepsy, thereby assisting in the preoperative workup for pediatric epilepsy surgery.
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Affiliation(s)
- Marla J Hamberger
- From the Department of Neurology (M.J.H.), Columbia University, New York; New York University (W.S.M.), NY; Tris Pharma, Inc. (W.T.S.), Monmouth Junction, NJ; Epilepsy Center (R.M.B.), and Department of Psychiatry and Psychology (P.K.), Cleveland Clinic, OH; Department of Psychology (C.M.S.), University of Florida Hospital for Children, Orlando; and Department of Psychology (M.L.S.), University of Toronto, Mississauga, Canada. W.S.M. is currently at Alberta Children's Hospital Research Institute, Canada. C.M.S. is currently at Space Coast Neuropsychology Center, Melbourne, FL.
| | - William S MacAllister
- From the Department of Neurology (M.J.H.), Columbia University, New York; New York University (W.S.M.), NY; Tris Pharma, Inc. (W.T.S.), Monmouth Junction, NJ; Epilepsy Center (R.M.B.), and Department of Psychiatry and Psychology (P.K.), Cleveland Clinic, OH; Department of Psychology (C.M.S.), University of Florida Hospital for Children, Orlando; and Department of Psychology (M.L.S.), University of Toronto, Mississauga, Canada. W.S.M. is currently at Alberta Children's Hospital Research Institute, Canada. C.M.S. is currently at Space Coast Neuropsychology Center, Melbourne, FL
| | - William T Seidel
- From the Department of Neurology (M.J.H.), Columbia University, New York; New York University (W.S.M.), NY; Tris Pharma, Inc. (W.T.S.), Monmouth Junction, NJ; Epilepsy Center (R.M.B.), and Department of Psychiatry and Psychology (P.K.), Cleveland Clinic, OH; Department of Psychology (C.M.S.), University of Florida Hospital for Children, Orlando; and Department of Psychology (M.L.S.), University of Toronto, Mississauga, Canada. W.S.M. is currently at Alberta Children's Hospital Research Institute, Canada. C.M.S. is currently at Space Coast Neuropsychology Center, Melbourne, FL
| | - Robyn M Busch
- From the Department of Neurology (M.J.H.), Columbia University, New York; New York University (W.S.M.), NY; Tris Pharma, Inc. (W.T.S.), Monmouth Junction, NJ; Epilepsy Center (R.M.B.), and Department of Psychiatry and Psychology (P.K.), Cleveland Clinic, OH; Department of Psychology (C.M.S.), University of Florida Hospital for Children, Orlando; and Department of Psychology (M.L.S.), University of Toronto, Mississauga, Canada. W.S.M. is currently at Alberta Children's Hospital Research Institute, Canada. C.M.S. is currently at Space Coast Neuropsychology Center, Melbourne, FL
| | - Christine M Salinas
- From the Department of Neurology (M.J.H.), Columbia University, New York; New York University (W.S.M.), NY; Tris Pharma, Inc. (W.T.S.), Monmouth Junction, NJ; Epilepsy Center (R.M.B.), and Department of Psychiatry and Psychology (P.K.), Cleveland Clinic, OH; Department of Psychology (C.M.S.), University of Florida Hospital for Children, Orlando; and Department of Psychology (M.L.S.), University of Toronto, Mississauga, Canada. W.S.M. is currently at Alberta Children's Hospital Research Institute, Canada. C.M.S. is currently at Space Coast Neuropsychology Center, Melbourne, FL
| | - Patricia Klaas
- From the Department of Neurology (M.J.H.), Columbia University, New York; New York University (W.S.M.), NY; Tris Pharma, Inc. (W.T.S.), Monmouth Junction, NJ; Epilepsy Center (R.M.B.), and Department of Psychiatry and Psychology (P.K.), Cleveland Clinic, OH; Department of Psychology (C.M.S.), University of Florida Hospital for Children, Orlando; and Department of Psychology (M.L.S.), University of Toronto, Mississauga, Canada. W.S.M. is currently at Alberta Children's Hospital Research Institute, Canada. C.M.S. is currently at Space Coast Neuropsychology Center, Melbourne, FL
| | - Mary Lou Smith
- From the Department of Neurology (M.J.H.), Columbia University, New York; New York University (W.S.M.), NY; Tris Pharma, Inc. (W.T.S.), Monmouth Junction, NJ; Epilepsy Center (R.M.B.), and Department of Psychiatry and Psychology (P.K.), Cleveland Clinic, OH; Department of Psychology (C.M.S.), University of Florida Hospital for Children, Orlando; and Department of Psychology (M.L.S.), University of Toronto, Mississauga, Canada. W.S.M. is currently at Alberta Children's Hospital Research Institute, Canada. C.M.S. is currently at Space Coast Neuropsychology Center, Melbourne, FL
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Ofer I, LeRose C, Mast H, LeVan P, Metternich B, Egger K, Urbach H, Schulze-Bonhage A, Wagner K. Association between seizure freedom and default mode network reorganization in patients with unilateral temporal lobe epilepsy. Epilepsy Behav 2019; 90:238-246. [PMID: 30538081 DOI: 10.1016/j.yebeh.2018.10.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 10/19/2018] [Accepted: 10/21/2018] [Indexed: 01/10/2023]
Abstract
RATIONALE The spontaneous synchronized activity and intrinsic organization of the Default Mode Network (DMN) has been found to be altered because of epileptic activity of temporal lobe origin. Thus, the aim of the present study was to compare DMN's topological properties in patients with seizure-free (SF) and not seizure-free (NSF) temporal lobe epilepsy (TLE). METHODS Functional connectivity within the DMN was determined from an 8-minute resting state functional magnetic resonance imaging (fMRI) in 27 patients with TLE (12 SF, 15 NSF) and 15 healthy controls (HC). The DMN regions of interest were extracted according to the automated anatomical labeling (AAL) atlas. Network properties were assessed using standard graph-theoretical measures. RESULTS Analyses revealed, irrespectively of focus lateralization, borderline significance for longer paths (p = 0.049) and in trend reduced local efficiency within the DMN of SF when compared with that of NSF (p = 0.075). The SF and NSF patients did not differ in global network topology from HC (p > 0.05). At the nodal network level, the degree of central hubs was significantly reduced in SF when compared with that in NSF (0.002 ≤ p ≤ 0.080) and HC (0.001 ≤ p ≤ 0.066) while simultaneously, right anterior superior temporal gyrus revealed significantly higher degree in SF than in NSF (p = 0.005) and HC (p = 0.016). CONCLUSION Seizure freedom seems to be associated with hub redistributions that may underlie longer paths and (in trend) reduced local efficiency of the network. An associated slower system response might reduce the probability of a rapid spread of epileptic discharges over the whole network and may help to prevent hypersynchronous neuronal activity in brain networks that may result in epileptic seizures.
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Affiliation(s)
- Isabell Ofer
- Epilepsy Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany; Freiburg Brain Imaging Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany.
| | | | - Hansjoerg Mast
- Faculty of Medicine, University of Freiburg, Germany; Department of Neuroradiology, Medical Center - Faculty of Medicine, University of Freiburg, Germany; Freiburg Brain Imaging Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany
| | - Pierre LeVan
- Faculty of Medicine, University of Freiburg, Germany; Department of Radiology, Medical Physics, Medical Center - University of Freiburg, Germany
| | - Birgitta Metternich
- Epilepsy Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany; Freiburg Brain Imaging Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany
| | - Karl Egger
- Faculty of Medicine, University of Freiburg, Germany; Department of Neuroradiology, Medical Center - Faculty of Medicine, University of Freiburg, Germany; Freiburg Brain Imaging Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany
| | - Horst Urbach
- Faculty of Medicine, University of Freiburg, Germany; Department of Neuroradiology, Medical Center - Faculty of Medicine, University of Freiburg, Germany; Freiburg Brain Imaging Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany
| | - Andreas Schulze-Bonhage
- Epilepsy Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany; Freiburg Brain Imaging Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany
| | - Kathrin Wagner
- Epilepsy Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany; Faculty of Medicine, University of Freiburg, Germany; Freiburg Brain Imaging Center, Medical Center - Faculty of Medicine, University of Freiburg, Germany
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Audrain S, McAndrews MP. Cognitive and functional correlates of accelerated long-term forgetting in temporal lobe epilepsy. Cortex 2019; 110:101-114. [DOI: 10.1016/j.cortex.2018.03.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 12/24/2017] [Accepted: 03/19/2018] [Indexed: 02/07/2023]
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Liou JY, Smith EH, Bateman LM, McKhann GM, Goodman RR, Greger B, Davis TS, Kellis SS, House PA, Schevon CA. Multivariate regression methods for estimating velocity of ictal discharges from human microelectrode recordings. J Neural Eng 2018; 14:044001. [PMID: 28332484 DOI: 10.1088/1741-2552/aa68a6] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Epileptiform discharges, an electrophysiological hallmark of seizures, can propagate across cortical tissue in a manner similar to traveling waves. Recent work has focused attention on the origination and propagation patterns of these discharges, yielding important clues to their source location and mechanism of travel. However, systematic studies of methods for measuring propagation are lacking. APPROACH We analyzed epileptiform discharges in microelectrode array recordings of human seizures. The array records multiunit activity and local field potentials at 400 micron spatial resolution, from a small cortical site free of obstructions. We evaluated several computationally efficient statistical methods for calculating traveling wave velocity, benchmarking them to analyses of associated neuronal burst firing. MAIN RESULTS Over 90% of discharges met statistical criteria for propagation across the sampled cortical territory. Detection rate, direction and speed estimates derived from a multiunit estimator were compared to four field potential-based estimators: negative peak, maximum descent, high gamma power, and cross-correlation. Interestingly, the methods that were computationally simplest and most efficient (negative peak and maximal descent) offer non-inferior results in predicting neuronal traveling wave velocities compared to the other two, more complex methods. Moreover, the negative peak and maximal descent methods proved to be more robust against reduced spatial sampling challenges. Using least absolute deviation in place of least squares error minimized the impact of outliers, and reduced the discrepancies between local field potential-based and multiunit estimators. SIGNIFICANCE Our findings suggest that ictal epileptiform discharges typically take the form of exceptionally strong, rapidly traveling waves, with propagation detectable across millimeter distances. The sequential activation of neurons in space can be inferred from clinically-observable EEG data, with a variety of straightforward computation methods available. This opens possibilities for systematic assessments of ictal discharge propagation in clinical and research settings.
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Affiliation(s)
- Jyun-You Liou
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY 10032, United States of America
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Abstract
Focal epileptic seizures have long been considered to arise from a small susceptible brain area and spread through uninvolved regions. In the past decade, the idea that focal seizures instead arise from coordinated activity across large-scale epileptic networks has become widely accepted. Understanding the network model's applicability is critical, due to its increasing influence on clinical research and surgical treatment paradigms. In this review, we examine the origins of the concept of epileptic networks as the nidus for recurring seizures. We summarize analytical and methodological elements of epileptic network studies and discuss findings from recent detailed electrophysiological investigations. Our review highlights the strengths and limitations of the epileptic network theory as a metaphor for the complex interactions that occur during seizures. We present lines of investigation that may usefully probe these interactions and thus serve to advance our understanding of the long-range effects of epileptiform activity.
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Affiliation(s)
- Elliot H Smith
- Department of Neurological Surgery, Columbia University Medical Center, New York, NY, 10032, USA
| | - Catherine A Schevon
- Department of Neurology, Columbia University Medical Center, New York, NY, 10032, USA.
- Neurological Institute, 710 West 168th Street, New York, NY, 10032, USA.
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Spatiotemporal propagation patterns of generalized ictal spikes in childhood absence epilepsy. Clin Neurophysiol 2017; 128:1553-1562. [PMID: 28709121 DOI: 10.1016/j.clinph.2017.05.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 04/29/2017] [Accepted: 05/31/2017] [Indexed: 11/23/2022]
Abstract
OBJECTIVE This work investigates the spatial distribution in time of generalized ictal spikes in the typical absences of childhood absence epilepsy (CAE). METHODS We studied twelve children with CAE, who had more than two typical absences during their routine video-EEG. Seizures were identified, and ictal spikes were marked over the maximum electronegative peak, clustered, waveform-averaged and spatiotemporaly analyzed in 2D electrode space. RESULTS Consistency of spatiotemporal patterns of ictal spikes was high between the absences of the same child, but low between children. Three main discharge patterns were identified: of anterio-posterior propagation, of posterio-anterior propagation and confined to the frontal/prefrontal regions. In 4 patients, the propagation patterns transformed during the seizure into either a lateralized diminished or a non-lateralized reverse direction form. Most spikes originated fronto-temporaly, all maximized over the frontal/prefrontal electrodes and mostly decayed prefrontaly. In 4 patients, lateralized propagation patterns were identified. CONCLUSIONS Ictal spike propagation patterns suggest that epileptogenic CAE networks are personalized, interconnect distal areas in the brain - not the entire cortex - with a tendency to generate bilateral symmetrical discharges, sometimes unsuccessfully. The transformation of propagation patterns during the seizure indicates the existence of dynamic interplay within epileptogenic networks. SIGNIFICANCE Our results support the revised concept of ictogenesis of ILAE definition in genetic (also known as idiopathic) generalized epilepsies. Understanding the focal features in CAE avoids misdiagnosis as focal epilepsy and inappropriate treatment.
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18
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Magnetoencephalography with temporal spread imaging to visualize propagation of epileptic activity. Clin Neurophysiol 2017; 128:734-743. [DOI: 10.1016/j.clinph.2017.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 12/11/2016] [Accepted: 01/04/2017] [Indexed: 11/18/2022]
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Hassan M, Merlet I, Mheich A, Kabbara A, Biraben A, Nica A, Wendling F. Identification of Interictal Epileptic Networks from Dense-EEG. Brain Topogr 2016; 30:60-76. [PMID: 27549639 DOI: 10.1007/s10548-016-0517-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 08/16/2016] [Indexed: 01/09/2023]
Abstract
Epilepsy is a network disease. The epileptic network usually involves spatially distributed brain regions. In this context, noninvasive M/EEG source connectivity is an emerging technique to identify functional brain networks at cortical level from noninvasive recordings. In this paper, we analyze the effect of the two key factors involved in EEG source connectivity processing: (i) the algorithm used in the solution of the EEG inverse problem and (ii) the method used in the estimation of the functional connectivity. We evaluate four inverse solutions algorithms (dSPM, wMNE, sLORETA and cMEM) and four connectivity measures (r 2, h 2, PLV, and MI) on data simulated from a combined biophysical/physiological model to generate realistic interictal epileptic spikes reflected in scalp EEG. We use a new network-based similarity index to compare between the network identified by each of the inverse/connectivity combination and the original network generated in the model. The method will be also applied on real data recorded from one epileptic patient who underwent a full presurgical evaluation for drug-resistant focal epilepsy. In simulated data, results revealed that the selection of the inverse/connectivity combination has a significant impact on the identified networks. Results suggested that nonlinear methods (nonlinear correlation coefficient, phase synchronization and mutual information) for measuring the connectivity are more efficient than the linear one (the cross correlation coefficient). The wMNE inverse solution showed higher performance than dSPM, cMEM and sLORETA. In real data, the combination (wMNE/PLV) led to a very good matching between the interictal epileptic network identified from noninvasive EEG recordings and the network obtained from connectivity analysis of intracerebral EEG recordings. These results suggest that source connectivity method, when appropriately configured, is able to extract highly relevant diagnostic information about networks involved in interictal epileptic spikes from non-invasive dense-EEG data.
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Affiliation(s)
- Mahmoud Hassan
- INSERM, U1099, Rennes, 35000, France.
- LTSI, Université de Rennes 1, Rennes, 35000, France.
| | - Isabelle Merlet
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
| | - Ahmad Mheich
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
- AZM Center-EDST, Lebanese University, Tripoli, Lebanon
| | - Aya Kabbara
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
- AZM Center-EDST, Lebanese University, Tripoli, Lebanon
| | - Arnaud Biraben
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
- Neurology Department, CHU, Rennes, 35000, France
| | - Anca Nica
- Neurology Department, CHU, Rennes, 35000, France
| | - Fabrice Wendling
- INSERM, U1099, Rennes, 35000, France
- LTSI, Université de Rennes 1, Rennes, 35000, France
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Hamberger MJ, Miozzo M, Schevon CA, Morrison C, Carlson C, Mehta AD, Klein GE, McKhann GM, Williams AC. Functional differences among stimulation-identified cortical naming sites in the temporal region. Epilepsy Behav 2016; 60:124-129. [PMID: 27206230 PMCID: PMC4912888 DOI: 10.1016/j.yebeh.2016.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 11/16/2022]
Abstract
To preserve postoperative language, electrical stimulation mapping is often conducted prior to surgery involving the language-dominant hemisphere. Object naming is the task most widely used to identify language cortex, and sites where stimulation elicits naming difficulty are typically spared from resection. In clinical practice, sites classified as positive undergo no further testing regarding the underlying cause of naming failure. Word production is a complex function involving multiple mechanisms that culminate in the identification of the target word. Two main mechanisms, i.e., semantic and phonological, underlie the retrieval of stored information regarding word meaning and word sounds, and naming can be hampered by disrupting either of these. These two mechanisms are likely mediated by different brain areas, and therefore, stimulation-identified naming sites might not be functionally equivalent. We investigated whether further testing at stimulation-identified naming sites would reveal an anatomical dissociation between these two mechanisms. In 16 patients with refractory temporal lobe epilepsy (TLE) with implanted subdural electrodes, we tested whether, despite inability to produce an item name, patients could reliably access semantic or phonological information regarding objects during cortical stimulation. We found that stimulation at naming sites in superior temporal cortex tended to impair phonological processing yet spared access to semantic information. By contrast, stimulation of inferior temporal naming sites revealed a greater proportion of sites where semantic access was impaired and a dissociation between sites where stimulation spared or disrupted semantic or phonological processing. These functional-anatomical dissociations reveal the more specific contribution to naming provided by these cortical areas and shed light on the often profound, interictal word-finding deficit observed in temporal lobe epilepsy. Additionally, these techniques potentially lay the groundwork for future studies to determine whether particular naming sites that fall within the margins of the desired clinical resection might be resected without significant risk of decline.
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Affiliation(s)
- Marla J Hamberger
- Department of Neurology, Columbia University Medical Center, New York, NY, United States.
| | - Michele Miozzo
- Department of Neurology, Columbia University Medical Center, New York, NY, United States
| | - Catherine A Schevon
- Department of Neurology, Columbia University Medical Center, New York, NY, United States
| | - Chris Morrison
- Department of Neurology, New York University Medical Center, New York, NY, United States
| | - Chad Carlson
- Department of Neurology, New York University Medical Center, New York, NY, United States
| | - Ashesh D Mehta
- Department of Neurological Surgery, North Shore LIJ Medical Center, New Hyde Park, NY, United States
| | - Gad E Klein
- Department of Neurological Surgery, North Shore LIJ Medical Center, New Hyde Park, NY, United States
| | - Guy M McKhann
- Department of Neurological Surgery, Columbia University Medical Center, New York, NY, United States
| | - Alicia C Williams
- Department of Neurology, Columbia University Medical Center, New York, NY, United States
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Mălîia MD, Meritam P, Scherg M, Fabricius M, Rubboli G, Mîndruţă I, Beniczky S. Epileptiform discharge propagation: Analyzing spikes from the onset to the peak. Clin Neurophysiol 2016; 127:2127-33. [DOI: 10.1016/j.clinph.2015.12.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/22/2015] [Accepted: 12/31/2015] [Indexed: 11/30/2022]
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The ictal wavefront is the spatiotemporal source of discharges during spontaneous human seizures. Nat Commun 2016; 7:11098. [PMID: 27020798 PMCID: PMC4820627 DOI: 10.1038/ncomms11098] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 02/19/2016] [Indexed: 11/26/2022] Open
Abstract
The extensive distribution and simultaneous termination of seizures across cortical areas has led to the hypothesis that seizures are caused by large-scale coordinated networks spanning these areas. This view, however, is difficult to reconcile with most proposed mechanisms of seizure spread and termination, which operate on a cellular scale. We hypothesize that seizures evolve into self-organized structures wherein a small seizing territory projects high-intensity electrical signals over a broad cortical area. Here we investigate human seizures on both small and large electrophysiological scales. We show that the migrating edge of the seizing territory is the source of travelling waves of synaptic activity into adjacent cortical areas. As the seizure progresses, slow dynamics in induced activity from these waves indicate a weakening and eventual failure of their source. These observations support a parsimonious theory for how large-scale evolution and termination of seizures are driven from a small, migrating cortical area. Epileptic brains display inhibitory restraint as manifested by the spread of synchronized activities being delayed in timing. Here, Elliot Smith and colleagues show fast-moving traveling wave that originates from the edge of ictal wavefront with subsequent depolarization and multiunit firing in the seizing brain regions in epileptic patients.
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What is the concordance between the seizure onset zone and the irritative zone? A SEEG quantified study. Clin Neurophysiol 2016; 127:1157-1162. [DOI: 10.1016/j.clinph.2015.10.029] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 09/30/2015] [Accepted: 10/03/2015] [Indexed: 11/15/2022]
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MEG-EEG Information Fusion and Electromagnetic Source Imaging: From Theory to Clinical Application in Epilepsy. Brain Topogr 2015; 28:785-812. [PMID: 26016950 PMCID: PMC4600479 DOI: 10.1007/s10548-015-0437-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 05/04/2015] [Indexed: 11/26/2022]
Abstract
The purpose of this study is to develop and quantitatively assess whether fusion of EEG and MEG (MEEG) data within the maximum entropy on the mean (MEM) framework increases the spatial accuracy of source localization, by yielding better recovery of the spatial extent and propagation pathway of the underlying generators of inter-ictal epileptic discharges (IEDs). The key element in this study is the integration of the complementary information from EEG and MEG data within the MEM framework. MEEG was compared with EEG and MEG when localizing single transient IEDs. The fusion approach was evaluated using realistic simulation models involving one or two spatially extended sources mimicking propagation patterns of IEDs. We also assessed the impact of the number of EEG electrodes required for an efficient EEG–MEG fusion. MEM was compared with minimum norm estimate, dynamic statistical parametric mapping, and standardized low-resolution electromagnetic tomography. The fusion approach was finally assessed on real epileptic data recorded from two patients showing IEDs simultaneously in EEG and MEG. Overall the localization of MEEG data using MEM provided better recovery of the source spatial extent, more sensitivity to the source depth and more accurate detection of the onset and propagation of IEDs than EEG or MEG alone. MEM was more accurate than the other methods. MEEG proved more robust than EEG and MEG for single IED localization in low signal-to-noise ratio conditions. We also showed that only few EEG electrodes are required to bring additional relevant information to MEG during MEM fusion.
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Object naming in epilepsy and epilepsy surgery. Epilepsy Behav 2015; 46:27-33. [PMID: 25599985 DOI: 10.1016/j.yebeh.2014.12.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 12/15/2014] [Accepted: 12/16/2014] [Indexed: 11/22/2022]
Abstract
The ability to express oneself verbally is critical for success in academic, occupational, and social domains. Unfortunately, word-finding or "naming" difficulty is the most common cognitive complaint among individuals with temporal lobe epilepsy (TLE), and a substantial body of work over the past several decades has documented naming impairment in left (language-dominant) TLE, with further risk to naming ability following left temporal lobe resection for seizure control. With these findings well established, this paper reviews more recent work that has aimed to identify the neuroanatomical substrates of naming, understand how adverse structural and functional effects of TLE might impinge upon these brain regions, predict and potentially reduce the risk of postoperative naming decline, and begin to understand naming difficulty in TLE from a developmental perspective. Factors that have confounded interpretation and hindrances to progress are discussed, and suggestions are provided for improved empirical investigation and directions for future research.
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Coito A, Plomp G, Genetti M, Abela E, Wiest R, Seeck M, Michel CM, Vulliemoz S. Dynamic directed interictal connectivity in left and right temporal lobe epilepsy. Epilepsia 2015; 56:207-17. [PMID: 25599821 DOI: 10.1111/epi.12904] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2014] [Indexed: 11/27/2022]
Abstract
OBJECTIVE There is increasing evidence that epileptic activity involves widespread brain networks rather than single sources and that these networks contribute to interictal brain dysfunction. We investigated the fast-varying behavior of epileptic networks during interictal spikes in right and left temporal lobe epilepsy (RTLE and LTLE) at a whole-brain scale using directed connectivity. METHODS In 16 patients, 8 with LTLE and 8 with RTLE, we estimated the electrical source activity in 82 cortical regions of interest (ROIs) using high-density electroencephalography (EEG), individual head models, and a distributed linear inverse solution. A multivariate, time-varying, and frequency-resolved Granger-causal modeling (weighted Partial Directed Coherence) was applied to the source signal of all ROIs. A nonparametric statistical test assessed differences between spike and baseline epochs. Connectivity results between RTLE and LTLE were compared between RTLE and LTLE and with neuropsychological impairments. RESULTS Ipsilateral anterior temporal structures were identified as key drivers for both groups, concordant with the epileptogenic zone estimated invasively. We observed an increase in outflow from the key driver already before the spike. There were also important temporal and extratemporal ipsilateral drivers in both conditions, and contralateral only in RTLE. A different network pattern between LTLE and RTLE was found: in RTLE there was a much more prominent ipsilateral to contralateral pattern than in LTLE. Half of the RTLE patients but none of the LTLE patients had neuropsychological deficits consistent with contralateral temporal lobe dysfunction, suggesting a relationship between connectivity changes and cognitive deficits. SIGNIFICANCE The different patterns of time-varying connectivity in LTLE and RTLE suggest that they are not symmetrical entities, in line with our neuropsychological results. The highest outflow region was concordant with invasive validation of the epileptogenic zone. This enhanced characterization of dynamic connectivity patterns could better explain cognitive deficits and help the management of epilepsy surgery candidates.
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Affiliation(s)
- Ana Coito
- Functional Brain Mapping Lab, Department of Fundamental Neurosciences, University of Geneva, Geneva, Switzerland
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Miozzo M, Hamberger MJ. Preserved meaning in the context of impaired naming in temporal lobe epilepsy. Neuropsychology 2014; 29:274-281. [PMID: 24933490 DOI: 10.1037/neu0000097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
OBJECTIVE Word-finding difficulties are a common complaint among individuals with left (domain) temporal lobe epilepsy (TLE). We tested the hypothesis that these difficulties stem from a deficit in semantic processing. METHOD We tested and compared semantic processing in left and right TLE patients and healthy controls. To avoid the confound of word retrieval, we used two semantic tasks (semantic priming and picture-matching) that did not require spoken word production. In addition to accuracy, we recorded response time in an effort to achieve a sensitive assessment of semantic processing. RESULTS Semantic priming was in all respects comparable between left TLE patients with documented word-finding difficulty and right TLE patients without word-finding difficulty. Likewise, performances were comparable between groups on picture matching, which demanded knowledge of detailed semantic features for decisions regarding subtle differences in semantic relatedness. CONCLUSIONS Overall, these results, which demonstrate a relative preservation of semantic processing in left TLE, suggest that the probable cause of word-finding difficulty in this group relates to processes that follow semantic retrieval in word production, involving the retrieval of lexical/phonological information. In addition to clinical implications for remediation, these results refine our understanding of the neurocognitive organization of temporal mechanisms supporting spoken word production.
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Khan S, Lefèvre J, Baillet S, Michmizos KP, Ganesan S, Kitzbichler MG, Zetino M, Hämäläinen MS, Papadelis C, Kenet T. Encoding cortical dynamics in sparse features. Front Hum Neurosci 2014; 8:338. [PMID: 24904377 PMCID: PMC4033054 DOI: 10.3389/fnhum.2014.00338] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 05/05/2014] [Indexed: 11/16/2022] Open
Abstract
Distributed cortical solutions of magnetoencephalography (MEG) and electroencephalography (EEG) exhibit complex spatial and temporal dynamics. The extraction of patterns of interest and dynamic features from these cortical signals has so far relied on the expertise of investigators. There is a definite need in both clinical and neuroscience research for a method that will extract critical features from high-dimensional neuroimaging data in an automatic fashion. We have previously demonstrated the use of optical flow techniques for evaluating the kinematic properties of motion field projected on non-flat manifolds like in a cortical surface. We have further extended this framework to automatically detect features in the optical flow vector field by using the modified and extended 2-Riemannian Helmholtz–Hodge decomposition (HHD). Here, we applied these mathematical models on simulation and MEG data recorded from a healthy individual during a somatosensory experiment and an epilepsy pediatric patient during sleep. We tested whether our technique can automatically extract salient dynamical features of cortical activity. Simulation results indicated that we can precisely reproduce the simulated cortical dynamics with HHD; encode them in sparse features and represent the propagation of brain activity between distinct cortical areas. Using HHD, we decoded the somatosensory N20 component into two HHD features and represented the dynamics of brain activity as a traveling source between two primary somatosensory regions. In the epilepsy patient, we displayed the propagation of the epileptic activity around the margins of a brain lesion. Our findings indicate that HHD measures computed from cortical dynamics can: (i) quantitatively access the cortical dynamics in both healthy and disease brain in terms of sparse features and dynamic brain activity propagation between distinct cortical areas, and (ii) facilitate a reproducible, automated analysis of experimental and clinical MEG/EEG source imaging data.
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Affiliation(s)
- Sheraz Khan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School/Massachusetts Institute of Technology , Charlestown, MA , USA ; McGovern Institute, Massachusetts Institute of Technology , Cambridge, MA , USA ; Department of Neurology, Massachusetts General Hospital, Harvard Medical School , Boston, MA , USA
| | - Julien Lefèvre
- Aix Marseille Université, CNRS, ENSAM, Université de Toulon, LSIS UMR 7296 , Marseille , France
| | - Sylvain Baillet
- Montreal Neurological Institute, McGill University , Montreal, QC , Canada
| | - Konstantinos P Michmizos
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School/Massachusetts Institute of Technology , Charlestown, MA , USA ; McGovern Institute, Massachusetts Institute of Technology , Cambridge, MA , USA ; Department of Neurology, Massachusetts General Hospital, Harvard Medical School , Boston, MA , USA
| | - Santosh Ganesan
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School/Massachusetts Institute of Technology , Charlestown, MA , USA ; Department of Neurology, Massachusetts General Hospital, Harvard Medical School , Boston, MA , USA
| | - Manfred G Kitzbichler
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School/Massachusetts Institute of Technology , Charlestown, MA , USA ; Department of Neurology, Massachusetts General Hospital, Harvard Medical School , Boston, MA , USA ; Behavioural and Clinical Neuroscience Institute, University of Cambridge , Cambridge , UK
| | - Manuel Zetino
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School/Massachusetts Institute of Technology , Charlestown, MA , USA ; Department of Neurology, Massachusetts General Hospital, Harvard Medical School , Boston, MA , USA
| | - Matti S Hämäläinen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School/Massachusetts Institute of Technology , Charlestown, MA , USA
| | - Christos Papadelis
- BabyMEG Facility, Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, Harvard Medical School , Boston, MA , USA ; Division of Newborn Medicine, Boston Children's Hospital, Harvard Medical School , Boston, MA , USA
| | - Tal Kenet
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School/Massachusetts Institute of Technology , Charlestown, MA , USA ; Department of Neurology, Massachusetts General Hospital, Harvard Medical School , Boston, MA , USA
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Gaspard N, Alkawadri R, Farooque P, Goncharova II, Zaveri HP. Automatic detection of prominent interictal spikes in intracranial EEG: validation of an algorithm and relationsip to the seizure onset zone. Clin Neurophysiol 2013; 125:1095-103. [PMID: 24269092 DOI: 10.1016/j.clinph.2013.10.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 10/21/2013] [Accepted: 10/27/2013] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To develop an algorithm for the automatic quantitative description and detection of spikes in the intracranial EEG and quantify the relationship between prominent spikes and the seizure onset zone. METHODS An algorithm was developed for the quantification of time-frequency properties of spikes (upslope, instantaneous energy, downslope) and their statistical representation in a univariate generalized extreme value distribution. Its performance was evaluated in comparison to expert detection of spikes in intracranial EEG recordings from 10 patients. It was subsequently used in 18 patients to detect prominent spikes and quantify their spatial relationship to the seizure onset area. RESULTS The algorithm displayed an average sensitivity of 63.4% with a false detection rate of 3.2 per minute for the detection of individual spikes and an average sensitivity of 88.6% with a false detection rate of 1.4% for the detection of intracranial EEG contacts containing the most prominent spikes. Prominent spikes occurred closer to the seizure onset area than less prominent spikes but they overlapped with it only in a minority of cases (3/18). CONCLUSIONS Automatic detection and quantification of the morphology of spikes increases their utility to localize the seizure onset area. Prominent spikes tend to originate mostly from contacts located in the close vicinity of the seizure onset area rather than from within it. SIGNIFICANCE Quantitative analysis of time-frequency characteristics and spatial distribution of intracranial spikes provides complementary information that may be useful for the localization of the seizure-onset zone.
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Affiliation(s)
- Nicolas Gaspard
- Comprehensive Epilepsy Center and Computational Neurophysiology Laboratory, Dept. of Neurology, School of Medicine, Yale University, Yale-New Haven Hospital, New Haven, CT, USA.
| | - Rafeed Alkawadri
- Comprehensive Epilepsy Center and Computational Neurophysiology Laboratory, Dept. of Neurology, School of Medicine, Yale University, Yale-New Haven Hospital, New Haven, CT, USA
| | - Pue Farooque
- Comprehensive Epilepsy Center and Computational Neurophysiology Laboratory, Dept. of Neurology, School of Medicine, Yale University, Yale-New Haven Hospital, New Haven, CT, USA
| | - Irina I Goncharova
- Comprehensive Epilepsy Center and Computational Neurophysiology Laboratory, Dept. of Neurology, School of Medicine, Yale University, Yale-New Haven Hospital, New Haven, CT, USA
| | - Hitten P Zaveri
- Comprehensive Epilepsy Center and Computational Neurophysiology Laboratory, Dept. of Neurology, School of Medicine, Yale University, Yale-New Haven Hospital, New Haven, CT, USA
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Evidence of an inhibitory restraint of seizure activity in humans. Nat Commun 2013; 3:1060. [PMID: 22968706 PMCID: PMC3658011 DOI: 10.1038/ncomms2056] [Citation(s) in RCA: 304] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 08/09/2012] [Indexed: 12/04/2022] Open
Abstract
The location and trajectory of seizure activity is of great importance, yet our ability to map such activity remains primitive. Recently, the development of multi-electrode arrays for use in humans has provided new levels of temporal and spatial resolution for recording seizures. Here, we show that there is a sharp delineation between areas showing intense, hypersynchronous firing indicative of recruitment to the seizure, and adjacent territories where there is only low-level, unstructured firing. Thus, there is a core territory of recruited neurons and a surrounding 'ictal penumbra'. The defining feature of the 'ictal penumbra' is the contrast between the large amplitude EEG signals and the low-level firing there. Our human recordings bear striking similarities with animal studies of an inhibitory restraint, indicating that they can be readily understood in terms of this mechanism. These findings have important implications for how we localize seizure activity and map its spread. Seizure activity in the brain is characterized by the recruitment of cortical neuronal activity. Schevon and colleagues study seizure activity in human subjects and find that the recruitment of neurons is hypersynchronous and that there is an intrinsic restraint on the propagation of this activity.
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O’Muircheartaigh J, Richardson MP. Epilepsy and the frontal lobes. Cortex 2012; 48:144-55. [DOI: 10.1016/j.cortex.2011.11.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 03/19/2011] [Accepted: 06/27/2011] [Indexed: 10/15/2022]
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Gottlieb L, Zelko FA, Kim DS, Nordli DR. Cognitive proficiency in pediatric epilepsy. Epilepsy Behav 2012; 23:146-51. [PMID: 22227594 DOI: 10.1016/j.yebeh.2011.10.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 10/20/2011] [Accepted: 10/24/2011] [Indexed: 11/24/2022]
Abstract
Cognitive proficiency (CP) is a sensitive gauge of neurological status, but it is not typically viewed in relation to focal cerebral function. We examined CP and its relationship to general intellectual ability and seizure focus in 90 patients with pediatric epilepsy. CP was significantly lower than general ability (GA) in the overall sample. In particular, it was more deficient than GA in patients with right- than left-lateralized epilepsy onset, and in patients with frontal- than temporal-onset epilepsy. The discrepancy between CP and GA varied with participants' overall intelligence, being more pronounced (i.e., GA-CP difference larger) in individuals of lower overall ability. Deficits in CP are a defining characteristic of pediatric epilepsy and serve as an important marker of neurocognitive status, especially when seizures originate from a primary epileptogenic focus within the right hemisphere or the frontal lobe.
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Affiliation(s)
- Lev Gottlieb
- Department of Child and Adolescent Psychiatry, Children's Memorial Hospital, Feinberg School of Medicine, Northwestern University, Chicago, IL 60614, USA
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Umeoka SC, Lüders HO, Turnbull JP, Koubeissi MZ, Maciunas RJ. Requirement of longitudinal synchrony of epileptiform discharges in the hippocampus for seizure generation: a pilot study. J Neurosurg 2011; 116:513-24. [PMID: 22175726 DOI: 10.3171/2011.10.jns11261] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The goal in this study was to assess the role of longitudinal hippocampal circuits in the generation of interictal and ictal activity in temporal lobe epilepsy (TLE) and to evaluate the effects of multiple hippocampal transections (MHT). METHODS In 6 patients with TLE, the authors evaluated the synchrony of hippocampal interictal and ictal epileptiform discharges by using a cross-correlation analysis, and the effect of MHT on hippocampal interictal spikes was studied. Five of the 6 patients were studied with depth electrodes, and epilepsy surgery was performed in 4 patients (anterior temporal lobectomy in 1 and MHT in 3). RESULTS Four hundred eighty-two (95.1%) of 507 hippocampal spikes showed an anterior-to-posterior propagation within the hippocampus, with a fixed peak-to-peak interval. During seizures, a significant increase of synchronization between different hippocampal regions and between the hippocampus and the ipsilateral anterior parahippocampal gyrus was observed in all seizures. An ictal increase in synchronization between the hippocampus and ipsilateral amygdala was seen in only 24.1% of the seizures. No changes in synchronization were noticed during seizures between the hippocampi and the amygdala on either side. The structure leading the epileptic seizures varied over time during a given seizure and also from one seizure to another. Spike analysis during MHT demonstrated that there were two spike populations that reacted differently to this procedure--namely, 1) spikes that showed maximum amplitude at the head of the hippocampus (type H); and 2) spikes that showed the highest amplitude at the hippocampal body (type B). A striking decrease in amplitude and frequency of type B spikes was noticed in all 3 patients after transections at the head or anterior portion of the hippocampal body. Type H spikes were seen in 2 cases and did not change in amplitude and frequency throughout MHT. Type B spikes showed constantly high cross-correlation values in different derivations and a relatively fixed peak-to-peak interval before MHT. This fixed interpeak delay disappeared after the first transection, although high cross-correlation values persisted unchanged. All patients who underwent MHT remained seizure free for more than 2 years. CONCLUSIONS These data suggest that synchronized discharges involving the complete anterior-posterior axis of the hippocampal/parahippocampal (H/P) formation underlie the spread of epileptiform discharges outside the H/P structures and, therefore, for the generation of epileptic seizures originating in the H/P structures. This conclusion is supported by the following observations. 1) Hippocampal spikes are consistently synchronized in the whole hippocampal structures, with a fixed delay between the different hippocampal areas. 2) One or two transections between the head and body of the hippocampal formation are sufficient to abolish hippocampal spikes that are synchronized along the anterior-posterior axis of the hippocampus. 3) Treatment with MHT leads to seizure freedom in patients with H/P epilepsy.
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Affiliation(s)
- Shuichi C Umeoka
- Epilepsy Center, University Hospitals Neurological Institute, Case Medical Center, 11100 Euclid Avenue, Cleveland, Ohio 44106-5040, USA
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Brodbeck V, Spinelli L, Lascano AM, Wissmeier M, Vargas MI, Vulliemoz S, Pollo C, Schaller K, Michel CM, Seeck M. Electroencephalographic source imaging: a prospective study of 152 operated epileptic patients. Brain 2011; 134:2887-97. [PMID: 21975586 PMCID: PMC3187544 DOI: 10.1093/brain/awr243] [Citation(s) in RCA: 282] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Electroencephalography is mandatory to determine the epilepsy syndrome. However, for the precise localization of the irritative zone in patients with focal epilepsy, costly and sometimes cumbersome imaging techniques are used. Recent small studies using electric source imaging suggest that electroencephalography itself could be used to localize the focus. However, a large prospective validation study is missing. This study presents a cohort of 152 operated patients where electric source imaging was applied as part of the pre-surgical work-up allowing a comparison with the results from other methods. Patients (n = 152) with >1 year postoperative follow-up were studied prospectively. The sensitivity and specificity of each imaging method was defined by comparing the localization of the source maximum with the resected zone and surgical outcome. Electric source imaging had a sensitivity of 84% and a specificity of 88% if the electroencephalogram was recorded with a large number of electrodes (128–256 channels) and the individual magnetic resonance image was used as head model. These values compared favourably with those of structural magnetic resonance imaging (76% sensitivity, 53% specificity), positron emission tomography (69% sensitivity, 44% specificity) and ictal/interictal single-photon emission-computed tomography (58% sensitivity, 47% specificity). The sensitivity and specificity of electric source imaging decreased to 57% and 59%, respectively, with low number of electrodes (<32 channels) and a template head model. This study demonstrated the validity and clinical utility of electric source imaging in a large prospective study. Given the low cost and high flexibility of electroencephalographic systems even with high channel counts, we conclude that electric source imaging is a highly valuable tool in pre-surgical epilepsy evaluation.
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Affiliation(s)
- Verena Brodbeck
- Department of Basic and Clinical Neurosciences, University of Geneva, 1211 Geneva, Switzerland
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Mohamed IS, Otsubo H, Ferrari P, Ochi A, Snead OC, Cheyne D. Neuromagnetic cerebellar activation during seizures arising from the motor cortex. Epilepsy Res 2011; 96:283-7. [DOI: 10.1016/j.eplepsyres.2011.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Accepted: 06/05/2011] [Indexed: 11/17/2022]
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Hamberger MJ, Cole J. Language organization and reorganization in epilepsy. Neuropsychol Rev 2011; 21:240-51. [PMID: 21842185 PMCID: PMC3193181 DOI: 10.1007/s11065-011-9180-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 07/31/2011] [Indexed: 10/17/2022]
Abstract
The vast majority of healthy individuals are left hemisphere dominant for language; however, individuals with left hemisphere epilepsy have a higher likelihood of atypical language organization. The cerebral organization of language in epilepsy has been studied with invasive procedures such as Wada testing and electrical cortical stimulation mapping (ESM), and more recently, with noninvasive neuroimaging techniques such as functional magnetic resonance imaging (fMRI). Investigators have used these techniques to explore the influence of unique clinical features inherent in epilepsy that might contribute to the reorganization of language, such as location of seizure onset, age of seizure onset, and extent of interictal epileptiform activity. In this paper, we review the contribution of these and other clinical variables to the lateralization and localization of language in epilepsy, and how these patient-related variables affect the results from these three different, yet complementary methodologies. Unlike the abrupt language changes that occur following acute brain injury with disruption of established language circuits, converging evidence suggests that the chronic nature of epileptic activity can result in a developmental shift of language from the left to the right hemisphere or re-routing of language pathways from traditional to non-traditional areas within the dominant left hemisphere. Clinical variables have been shown to contribute to cerebral language reorganization in the setting of chronic seizure disorders, yet such factors have not been reliable predictors of altered language networks in individual patients, underscoring the need for language lateralization and localization procedures when definitive identification of language cortex is necessary for clinical care.
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Affiliation(s)
- Marla J Hamberger
- The Neurological Institute, Columbia University Medical Center, 710 West 168th Street, 7th floor, New York, NY 10032, USA.
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Pittau F, Levan P, Moeller F, Gholipour T, Haegelen C, Zelmann R, Dubeau F, Gotman J. Changes preceding interictal epileptic EEG abnormalities: comparison between EEG/fMRI and intracerebral EEG. Epilepsia 2011; 52:1120-9. [PMID: 21671923 DOI: 10.1111/j.1528-1167.2011.03072.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE In simultaneous scalp electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), blood oxygen level dependent (BOLD) changes occurring before the spike have been sometimes described but could not be explained. To characterize the origin of this prespike BOLD signal change, we looked for electrographic changes in stereo-EEG (SEEG) possibly preceding the scalp spike in patients that showed early BOLD response in EEG/fMRI. METHODS We studied four patients with drug-resistant focal epilepsy who underwent EEG/fMRI, showed a prespike BOLD response, and were then studied with depth electrodes for presurgical localization of the epileptic generator. Early BOLD responses in the region of the spike field were analyzed using models with hemodynamic response functions (HRFs) peaking from -9 to +9 s around the spike. SEEG recordings in the period and location corresponding to the early HRF responses were analyzed to detect if electrographic changes were present in the SEEG before the scalp abnormality. KEY FINDINGS One of the four patients presented a SEEG interictal discharge in the period corresponding to the early BOLD response. In the other three, no electrographic changes were detected in the SEEG in the period corresponding to early BOLD changes. SIGNIFICANCE Although the early BOLD activity may sometimes be explained by a synchronized neural discharge detectable with SEEG but not visible on the scalp EEG, in most cases the early BOLD response reflects a metabolic phenomenon that does not appear to result from a synchronized neuronal discharge. Prespike metabolic responses can result from synchronized or nonsynchronized neuronal activity, or from nonneuronal mechanisms including glia.
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Affiliation(s)
- Francesca Pittau
- Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
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38
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Abstract
Microseizures are highly focal low-frequency epileptiform-appearing events recorded from the neocortex of epilepsy patients. Because of their tiny, often submillimeter distribution, they may be regarded as a high-resolution window into the epileptic process, providing an excellent opportunity to study the fine temporal structure of their origin and spread. A 16 mm² 96-microelectrode array with 400-μm interelectrode spacing was implanted in seven patients undergoing invasive EEG monitoring for medically refractory epilepsy. Seven microdischarge populations were tested for a substantial contribution by volume conduction to the observed waveform amplitudes. Single-unit activity was examined for specific evidence of neural activity at multiple sites within the microdischarge fields. We found that microdischarges appear to originate at a highly focal source location, likely within a single cortical macrocolumn, and spread to local and more distant sites via neural propagation.
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Protzner AB, McAndrews MP. Network alterations supporting word retrieval in patients with medial temporal lobe epilepsy. J Cogn Neurosci 2010; 23:2605-19. [PMID: 20964592 DOI: 10.1162/jocn.2010.21599] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Although the hippocampus is not considered a key structure in semantic memory, patients with medial-temporal lobe epilepsy (mTLE) have deficits in semantic access on some word retrieval tasks. We hypothesized that these deficits reflect the negative impact of focal epilepsy on remote cerebral structures. Thus, we expected that the networks that support word retrieval tasks would be altered in left mTLE patients. We measured brain activity with fMRI while participants (13 controls, 13 left mTLE, and 13 right mTLE) performed a verb generation task. We examined functional connectivity during this task in relation to language performance on an off-line clinical test of lexical access (Boston Naming Test, BNT). Using task-seed-behavior partial least squares, we identified a canonical language network that was more active during verb generation than the baseline condition, but this network did not correlate with variability in BNT performance in either controls or patients. Instead, additional networks were identified for each group, with more anterior temporal and prefrontal regions recruited for controls and more posterior temporal regions for both left and right mTLE patients. Our findings go beyond the literature emphasizing differences in laterality of language processes in mTLE patients and, critically, highlight how network changes can be used to account for performance variation among patients on clinically relevant measures. This strategy of correlating network changes and off-line behavior may provide a powerful tool for predicting a postoperative decline in language performance.
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Affiliation(s)
- Andrea B Protzner
- Department of Neuropsychology, Krembil Neuroscience Centre, University Health Network, 399 Bathurst St., Toronto, ON, Canada.
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40
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Larsson PG, Eeg-Olofsson O, Michel CM, Seeck M, Lantz G. Decrease in propagation of interictal epileptiform activity after introduction of levetiracetam visualized with electric source imaging. Brain Topogr 2010; 23:269-78. [PMID: 20574764 DOI: 10.1007/s10548-010-0150-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 05/29/2010] [Indexed: 11/29/2022]
Abstract
Different neuroimaging techniques (fMRI, spectroscopy, PET) are being used to evaluate candidate drugs in pharmacological development. In patients with epilepsy fast propagation of the epileptiform activity between different brain areas occurs. Electric Source Imaging (ESI), in contrast to the aforementioned techniques, has a millisecond time resolution, allowing visualization of this fast propagation. The purpose of the current project was to use ESI to investigate whether introduction of an antiepileptic drug (levetiracetam, LEV) would change the propagation patterns of the interictal epileptiform activity. Thirty patients with epilepsy were subject to an EEG recording before (pre-LEV) and after (in-LEV) introduction of LEV. Interictal spikes with similar topographic distribution were averaged within each subject, and a distributed source model was used to localize the EEG sources of the epileptiform activity. The temporal development of the activity within 20 regions of interest (ROIs) was determined, and source propagation between different regions was compared between the pre-LEV and in-LEV recordings. Patients with epileptic seizures showed propagation in 22/24 identified spike types in the pre-LEV recordings. In the in-LEV recordings only 7/15 spike types showed propagation, and six of these seven propagating spikes were recorded in patients with poor effect of treatment. Also in patients without seizures LEV tended to suppress propagation. We conclude that the observed suppression of source propagation can be considered as an indicator of effective antiepileptic treatment. ESI might thus become a useful tool in the early clinical evaluation of new candidate drugs in pharmacological development.
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Affiliation(s)
- Pål G Larsson
- Department of Neurosurgery, Oslo University Hospital, Oslo, 0027, Norway
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41
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Tanaka N, Hämäläinen MS, Ahlfors SP, Liu H, Madsen JR, Bourgeois BF, Lee JW, Dworetzky BA, Belliveau JW, Stufflebeam SM. Propagation of epileptic spikes reconstructed from spatiotemporal magnetoencephalographic and electroencephalographic source analysis. Neuroimage 2009; 50:217-22. [PMID: 20006721 DOI: 10.1016/j.neuroimage.2009.12.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 11/25/2009] [Accepted: 12/05/2009] [Indexed: 10/20/2022] Open
Abstract
The purpose of this study is to assess the accuracy of spatiotemporal source analysis of magnetoencephalography (MEG) and scalp electroencephalography (EEG) for representing the propagation of frontotemporal spikes in patients with partial epilepsy. This study focuses on frontotemporal spikes, which are typically characterized by a preceding anterior temporal peak followed by an ipsilateral inferior frontal peak. Ten patients with frontotemporal spikes on MEG/EEG were studied. We analyzed the propagation of temporal to frontal epileptic spikes on both MEG and EEG independently by using a cortically constrained minimum norm estimate (MNE). Spatiotemporal source distribution of each spike was obtained on the cortical surface derived from the patient's MRI. All patients underwent an extraoperative intracranial EEG (IEEG) recording covering temporal and frontal lobes after presurgical evaluation. We extracted source waveforms of MEG and EEG from the source distribution of interictal spikes at the sites corresponding to the location of intracranial electrodes. The time differences of the ipsilateral temporal and frontal peaks as obtained by MEG, EEG and IEEG were statistically compared in each patient. In all patients, MEG and IEEG showed similar time differences between temporal and frontal peaks. The time differences of EEG spikes were significantly smaller than those of IEEG in nine of ten patients. Spatiotemporal analysis of MEG spikes models the time course of frontotemporal spikes as observed on IEEG more adequately than EEG in our patients. Spatiotemporal source analysis may be useful for planning epilepsy surgery, by predicting the pattern of IEEG spikes.
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Affiliation(s)
- Naoaki Tanaka
- Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA.
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42
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Estimating short-run and long-run interaction mechanisms in interictal state. J Comput Neurosci 2009; 28:177-92. [PMID: 19902345 DOI: 10.1007/s10827-009-0198-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 10/07/2009] [Accepted: 10/13/2009] [Indexed: 10/20/2022]
Abstract
We address the issue of analyzing electroencephalogram (EEG) from seizure patients in order to test, model and determine the statistical properties that distinguish between EEG states (interictal, pre-ictal, ictal) by introducing a new class of time series analysis methods. In the present study: firstly, we employ statistical methods to determine the non-stationary behavior of focal interictal epileptiform series within very short time intervals; secondly, for such intervals that are deemed non-stationary we suggest the concept of Autoregressive Integrated Moving Average (ARIMA) process modelling, well known in time series analysis. We finally address the queries of causal relationships between epileptic states and between brain areas during epileptiform activity. We estimate the interaction between different EEG series (channels) in short time intervals by performing Granger-causality analysis and also estimate such interaction in long time intervals by employing Cointegration analysis, both analysis methods are well-known in econometrics. Here we find: first, that the causal relationship between neuronal assemblies can be identified according to the duration and the direction of their possible mutual influences; second, that although the estimated bidirectional causality in short time intervals yields that the neuronal ensembles positively affect each other, in long time intervals neither of them is affected (increasing amplitudes) from this relationship. Moreover, Cointegration analysis of the EEG series enables us to identify whether there is a causal link from the interictal state to ictal state.
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Schevon CA, Trevelyan AJ, Schroeder CE, Goodman RR, McKhann G, Emerson RG. Spatial characterization of interictal high frequency oscillations in epileptic neocortex. Brain 2009; 132:3047-59. [PMID: 19745024 PMCID: PMC2768661 DOI: 10.1093/brain/awp222] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Interictal high frequency oscillations (HFOs), in particular those with frequency components in excess of 200 Hz, have been proposed as important biomarkers of epileptic cortex as well as the genesis of seizures. We investigated the spatial extent, classification and distribution of HFOs using a dense 4 × 4 mm2 two dimensional microelectrode array implanted in the neocortex of four patients undergoing epilepsy surgery. The majority (97%) of oscillations detected included fast ripples and were concentrated in relatively few recording sites. While most HFOs were limited to single channels, ∼10% occurred on a larger spatial scale with simultaneous but morphologically distinct detections in multiple channels. Eighty per cent of these large-scale events were associated with interictal epileptiform discharges. We propose that large-scale HFOs, rather than the more frequent highly focal events, are the substrates of the HFOs detected by clinical depth electrodes. This feature was prominent in three patients but rarely seen in only one patient recorded outside epileptogenic cortex. Additionally, we found that HFOs were commonly associated with widespread interictal epileptiform discharges but not with locally generated ‘microdischarges’. Our observations raise the possibility that, rather than being initiators of epileptiform activity, fast ripples may be markers of a secondary local response.
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Abstract
Naming is generally considered a left-hemisphere function without precise localization. However, recent cortical stimulation studies demonstrate a modality-related anatomical dissociation, in that anterior temporal stimulation disrupts auditory description naming ("auditory naming") but not visual object naming ("visual naming"), whereas posterior temporal stimulation disrupts naming on both tasks. We hypothesized that patients with anterior temporal abnormalities would exhibit impaired auditory naming, yet normal range visual naming, whereas patients with posterior temporal abnormalities would exhibit impaired performance on both tasks. Thirty-four patients with documented anterior temporal abnormalities and 14 patients with documented posterior temporal abnormalities received both naming tests. As hypothesized, patients with anterior temporal abnormalities demonstrated impaired auditory naming, yet normal range visual naming performance. Patients with posterior temporal abnormalities were impaired in visual naming; however, auditory naming scores were intact. Although these group patterns were statistically significant, on an individual basis, auditory-visual naming asymmetries better predicted whether individual patients had anterior or posterior temporal abnormalities. These behavioral findings are generally consistent with stimulation results, suggesting that modality specificity is inherent in the organization of language, with predictable neuroanatomical correlates. Results also carry clinical implications regarding localizing dysfunction, identifying and characterizing naming deficits, and potentially, in treating neurologically based language disorders.
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Affiliation(s)
- Marla J Hamberger
- Department of Neurology, College of Physicians and Surgeons, Columbia University, 710 West 168th Street, Box 100, New York, New York 10032, USA.
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45
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Agirre-Arrizubieta Z, Huiskamp GJM, Ferrier CH, van Huffelen AC, Leijten FSS. Interictal magnetoencephalography and the irritative zone in the electrocorticogram. Brain 2009; 132:3060-71. [DOI: 10.1093/brain/awp137] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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46
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Hemodynamic changes preceding the interictal EEG spike in patients with focal epilepsy investigated using simultaneous EEG-fMRI. Neuroimage 2009; 45:1220-31. [DOI: 10.1016/j.neuroimage.2009.01.014] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2008] [Revised: 01/05/2009] [Accepted: 01/08/2009] [Indexed: 11/24/2022] Open
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47
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Subthalamic role on the generation of spikes in temporal epilepsy. Epilepsy Res 2008; 83:257-60. [PMID: 19056246 DOI: 10.1016/j.eplepsyres.2008.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 10/07/2008] [Accepted: 10/17/2008] [Indexed: 11/21/2022]
Abstract
SUMMARY We report the electrophysiological findings in an unusual patient with temporal lobe epilepsy and subthalamic stimulators implanted to treat Parkinson's disease. Temporal and frontotemporal spikes were observed in the EEG. Temporal spikes spread to the STN in a 40% of cases, involving simultaneously all contacts. Frontotemporal spikes showed more frequent STN propagation (70%), shorter delays, and progressive spread from ventral to dorsal contacts than temporal spikes. These results suggest that a direct fronto-subthalamic pathway might account for the fast propagation of the frontotemporal spikes to the ventral STN.
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Schevon CA, Ng SK, Cappell J, Goodman RR, McKhann G, Waziri A, Branner A, Sosunov A, Schroeder CE, Emerson RG. Microphysiology of epileptiform activity in human neocortex. J Clin Neurophysiol 2008; 25:321-30. [PMID: 18997628 PMCID: PMC2967462 DOI: 10.1097/wnp.0b013e31818e8010] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The authors report the use of dense two-dimensional microelectrode array recordings to characterize fine resolution electrocortical activity ("microEEG") in epileptogenic human cortex. A 16-mm(2) 96 microelectrode array with 400-mum interelectrode spacing was implanted in five patients undergoing invasive EEG monitoring for medically refractory epilepsy. High spatial resolution data from the array were analyzed in conjunction with simultaneously acquired data from standard intracranial electrode grids and strips. microEEG recorded from within the epileptogenic zone demonstrates discharges resembling both interictal epileptiform activity ("microdischarges") and electrographic seizures ("microseizures") but confined to cortical regions as small as 200 microm(2). In two patients, this activity appeared to be involved in the initiation or propagation of electrographic seizures. The authors hypothesize that microdischarges and microseizures are generated by small cortical domains that form the substrate of epileptogenic cortex and play important roles in seizure initiation and propagation.
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Lai Y, van Drongelen W, Hecox K, Frim D, Kohrman M, He B. Cortical activation mapping of epileptiform activity derived from interictal ECoG spikes. Epilepsia 2007; 48:305-14. [PMID: 17295624 DOI: 10.1111/j.1528-1167.2006.00936.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE To develop and evaluate a new cortical activation mapping (CAM) method to obtain the neuronal activation sequences from the cortical potential distributions. METHODS Interictal electrocorticogram (ECoG) recordings were analyzed for eight pediatric epilepsy patients to find the cortical activation maps, which were compared with the patients' seizure-onset zones identified from ictal ECoG recordings. Various relations between the local activation time and cortical potential were assumed. The most effective relation was determined by accessing their capability to predict the seizure-onset zone. Computer simulations using a moving dipole source model were also conducted to test the present approach in imaging the propagated cortical activity. RESULTS In both clinical data analysis and computer simulations, the maximal amplitude proved to be the most effective criterion with which to determine the local cortical activation time. The present method successfully predicted the seizure-onset zone in seven of eight patients by the CAM analysis of ECoG-recorded interictal spikes (IISs). For patients with multiple seizure foci, each focus can be revealed by analyzing IISs with different spatial patterns. CONCLUSIONS The time difference between spike peaks of the interictal events in the leading channel and other channels can be effectively defined as the local cortical activation time. The cortical activation mapping method based on this time latency can be used to predict the seizure-onset zones, suggesting that the present CAM method is useful to assist the presurgical evaluation for the epilepsy patients.
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Affiliation(s)
- Yuan Lai
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA
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50
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Hawco CS, Bagshaw AP, Lu Y, Dubeau F, Gotman J. BOLD changes occur prior to epileptic spikes seen on scalp EEG. Neuroimage 2007; 35:1450-8. [PMID: 17399999 DOI: 10.1016/j.neuroimage.2006.12.042] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 11/30/2006] [Accepted: 12/05/2006] [Indexed: 11/22/2022] Open
Abstract
This study examined BOLD changes prior to interictal discharges in the EEG of patients with epilepsy. From a database of 143 EEG-fMRI studies, we selected the 16 data sets that showed both strong fMRI activation in the original analysis and only a single spike type in the EEG. Scans were then analyzed using seven model HRFs, peaking 3 or 1 s before the event, or 1, 3, 5, 7, or 9 s after it. An HRF was calculated using a deconvolution method for all activations seen in each analysis. The results showed that seven data sets had HRFs that peaked 1 s after the event or earlier, indicating a BOLD change starting prior to the spike seen on the scalp EEG. This is surprising since the BOLD change is expected to result from the spike. For most of the data sets with early peaking HRFs, the maximum activation in all of the statistical maps was when the model HRF peaked 1 s after the event, suggesting that the early activation was at least as important as any later activation. We suggest that this early activity is the result of neuronal changes occurring several seconds prior to a surface EEG event, but that these changes are not visible on the scalp. This is the first report of a BOLD response occurring several seconds prior to an interictal event seen on the scalp and could have important implications for our understanding of the generation of epileptic discharges.
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Affiliation(s)
- Colin S Hawco
- Montreal Neurological Institute and Hospital, McGill University, 3801 University Street, Montreal, Quebec, Canada H3A 2B4
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