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Přibylová L, Ševčík J, Eclerová V, Klimeš P, Brázdil M, Meijer HGE. Weak coupling of neurons enables very high-frequency and ultra-fast oscillations through the interplay of synchronized phase shifts. Netw Neurosci 2024; 8:293-318. [PMID: 38562290 PMCID: PMC10954350 DOI: 10.1162/netn_a_00351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 11/21/2023] [Indexed: 04/04/2024] Open
Abstract
Recently, in the past decade, high-frequency oscillations (HFOs), very high-frequency oscillations (VHFOs), and ultra-fast oscillations (UFOs) were reported in epileptic patients with drug-resistant epilepsy. However, to this day, the physiological origin of these events has yet to be understood. Our study establishes a mathematical framework based on bifurcation theory for investigating the occurrence of VHFOs and UFOs in depth EEG signals of patients with focal epilepsy, focusing on the potential role of reduced connection strength between neurons in an epileptic focus. We demonstrate that synchronization of a weakly coupled network can generate very and ultra high-frequency signals detectable by nearby microelectrodes. In particular, we show that a bistability region enables the persistence of phase-shift synchronized clusters of neurons. This phenomenon is observed for different hippocampal neuron models, including Morris-Lecar, Destexhe-Paré, and an interneuron model. The mechanism seems to be robust for small coupling, and it also persists with random noise affecting the external current. Our findings suggest that weakened neuronal connections could contribute to the production of oscillations with frequencies above 1000 Hz, which could advance our understanding of epilepsy pathology and potentially improve treatment strategies. However, further exploration of various coupling types and complex network models is needed.
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Affiliation(s)
- Lenka Přibylová
- Department of Mathematics and Statistics, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Jan Ševčík
- Department of Mathematics and Statistics, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Veronika Eclerová
- Department of Mathematics and Statistics, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Petr Klimeš
- Institute of Scientific Instruments, The Czech Academy of Sciences, Brno, Czech Republic
| | - Milan Brázdil
- Brno Epilepsy Center, Dept. of Neurology, St. Anne’s Univ. Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic, member of the ERN EpiCARE
- Behavioral and Social Neuroscience Research Group, Central European Institute of Technology, Masaryk University, Brno, Czech Republic
| | - Hil G. E. Meijer
- Department of Applied Mathematics, Techmed Centre, University of Twente, Enschede, The Netherlands
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Shamas M, Yeh HJ, Fried I, Engel J, Staba RJ. High-rate leading spikes in propagating spike sequences predict seizure outcome in surgical patients with temporal lobe epilepsy. Brain Commun 2023; 5:fcad289. [PMID: 37953846 PMCID: PMC10636565 DOI: 10.1093/braincomms/fcad289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 08/14/2023] [Accepted: 10/23/2023] [Indexed: 11/14/2023] Open
Abstract
Inter-ictal spikes aid in the diagnosis of epilepsy and in planning surgery of medication-resistant epilepsy. However, the localizing information from spikes can be unreliable because spikes can propagate, and the burden of spikes, often assessed as a rate, does not always correlate with the seizure onset zone or seizure outcome. Recent work indicates identifying where spikes regularly emerge and spread could localize the seizure network. Thus, the current study sought to better understand where and how rates of single and coupled spikes, and especially brain regions with high-rate and leading spike of a propagating sequence, informs the extent of the seizure network. In 37 patients with medication-resistant temporal lobe seizures, who had surgery to treat their seizure disorder, an algorithm detected spikes in the pre-surgical depth inter-ictal EEG. A separate algorithm detected spike propagation sequences and identified the location of leading and downstream spikes in each sequence. We analysed the rate and power of single spikes on each electrode and coupled spikes between pairs of electrodes, and the proportion of sites with high-rate, leading spikes in relation to the seizure onset zone of patients seizure free (n = 19) and those with continuing seizures (n = 18). We found increased rates of single spikes in mesial temporal seizure onset zone (ANOVA, P < 0.001, η2 = 0.138), and increased rates of coupled spikes within, but not between, mesial-, lateral- and extra-temporal seizure onset zone of patients with continuing seizures (P < 0.001; η2 = 0.195, 0.113 and 0.102, respectively). In these same patients, there was a higher proportion of brain regions with high-rate leaders, and each sequence contained a greater number of spikes that propagated with a higher efficiency over a longer distance outside the seizure onset zone than patients seizure free (Wilcoxon, P = 0.0172). The proportion of high-rate leaders in and outside the seizure onset zone could predict seizure outcome with area under curve = 0.699, but not rates of single or coupled spikes (0.514 and 0.566). Rates of coupled spikes to a greater extent than single spikes localize the seizure onset zone and provide evidence for inter-ictal functional segregation, which could be an adaptation to avert seizures. Spike rates, however, have little value in predicting seizure outcome. High-rate spike sites leading propagation could represent sources of spikes that are important components of an efficient seizure network beyond the clinical seizure onset zone, and like the seizure onset zone these, too, need to be removed, disconnected or stimulated to increase the likelihood for seizure control.
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Affiliation(s)
- Mohamad Shamas
- David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Hsiang J Yeh
- David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Itzhak Fried
- David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Jerome Engel
- David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Richard J Staba
- David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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Granado M, Collavini S, Baravalle R, Martinez N, Montemurro MA, Rosso OA, Montani F. High-frequency oscillations in the ripple bands and amplitude information coding: Toward a biomarker of maximum entropy in the preictal signals. CHAOS (WOODBURY, N.Y.) 2022; 32:093151. [PMID: 36182366 DOI: 10.1063/5.0101220] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/29/2022] [Indexed: 06/16/2023]
Abstract
Intracranial electroencephalography (iEEG) can directly record local field potentials (LFPs) from a large set of neurons in the vicinity of the electrode. To search for possible epileptic biomarkers and to determine the epileptogenic zone that gives rise to seizures, we investigated the dynamics of basal and preictal signals. For this purpose, we explored the dynamics of the recorded time series for different frequency bands considering high-frequency oscillations (HFO) up to 240 Hz. We apply a Hilbert transform to study the amplitude and phase of the signals. The dynamics of the different frequency bands in the time causal entropy-complexity plane, H × C, is characterized by comparing the dynamical evolution of the basal and preictal time series. As the preictal states evolve closer to the time in which the epileptic seizure starts, the, H × C, dynamics changes for the higher frequency bands. The complexity evolves to very low values and the entropy becomes nearer to its maximal value. These quasi-stable states converge to equiprobable states when the entropy is maximal, and the complexity is zero. We could, therefore, speculate that in this case, it corresponds to the minimization of Gibbs free energy. In this case, the maximum entropy is equivalent to the principle of minimum consumption of resources in the system. We can interpret this as the nature of the system evolving temporally in the preictal state in such a way that the consumption of resources by the system is minimal for the amplitude in frequencies between 220-230 and 230-240 Hz.
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Affiliation(s)
- Mauro Granado
- Instituto de Física de La Plata (IFLP), Universidad Nacional de La Plata, CONICET CCT-La Plata, Diagonal 113 entre 63 y 64, La Plata 1900, Buenos Aires, Argentina
| | - Santiago Collavini
- Instituto de Electrónica Industrial, Control y Procesamiento de Se nales (LEICI), Facultad de Ingeniería, Universidad Nacional de La Plata (UNLP-CONICET), La Plata 1900, Buenos Aires, Argentina
| | - Roman Baravalle
- Instituto de Física de La Plata (IFLP), Universidad Nacional de La Plata, CONICET CCT-La Plata, Diagonal 113 entre 63 y 64, La Plata 1900, Buenos Aires, Argentina
| | - Nataniel Martinez
- Instituto de Física de Mar del Plata, Universidad Nacional de Mar del Plata & CONICET, Mar del Plata 7600, Buenos Aires, Argentina
| | - Marcelo A Montemurro
- School of Mathematics & Statistics, Faculty of Science, Technology, Engineering & Mathematics, The Open University, Walton Hall, Milton Keynes MK7 6AA, United Kingdom
| | - Osvaldo A Rosso
- Instituto de Física de La Plata (IFLP), Universidad Nacional de La Plata, CONICET CCT-La Plata, Diagonal 113 entre 63 y 64, La Plata 1900, Buenos Aires, Argentina
| | - Fernando Montani
- Instituto de Física de La Plata (IFLP), Universidad Nacional de La Plata, CONICET CCT-La Plata, Diagonal 113 entre 63 y 64, La Plata 1900, Buenos Aires, Argentina
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El Idrissi A, Alonso ADC. Pathological Human Tau Induces Alterations in the Brain Insulin Signaling Cascade. Front Neurosci 2022; 16:805046. [PMID: 35264925 PMCID: PMC8899662 DOI: 10.3389/fnins.2022.805046] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/17/2022] [Indexed: 11/25/2022] Open
Abstract
The process of neurodegeneration in Alzheimer's disease has been associated with a disruption of insulin signaling cascade in neurons, and to insulin resistance. T2DM correlates with Alzheimer's disease, but mechanisms of interaction are unknown. We have developed a mouse model of tau induced neurodegeneration expressing pseudo-phosphorylated tau [Pathological Human Tau (PH-Tau)] in neurons. This model (PH-Tau-Tg) recapitulated cognitive decline and neurodegeneration observed in AD. In this study we examined if expression of PH-Tau could affect neuronal excitability and insulin receptor signaling. Neuronal excitability was investigated using intracerebral recordings of extracellular field potentials from prefrontal cortex after insulin and kainic acid (KA) injection. Analysis of baseline recordings indicated an increased excitability of PH-Tau-Tg as evidenced by higher spectrum densities (PSDs) of high frequencies brain waves. Injection of insulin (1IU, s.c) led to a decrease of fast ripples PSDs, more pronounced in PH-Tau-Tg mice than controls. Subsequent injection of kainic acid (KA, 5 mg/kg, s.c) led to significant increase in firing rate, amplitude of extracellular field potentials and PSDs of high frequency brain waves in control mice only. To further investigate the role of insulin in PH-Tau-Tg mice, we subjected mice to a glucose tolerance test. We found that PH-Tau-Tg mice were significantly hyperglycemic prior to glucose injection. Interestingly, the PH-Tau-Tg mice showed a moderate increase at 30 min due to the higher baseline, indicating a low sensitivity of insulin receptor in these mice. This is consistent with increased levels of activated insulin receptors in the brain and the inhibitory effect of insulin on ictal activity post KA injection in PH-Tau-Tg mice. We suggest that these mice have reduced insulin sensitivity (hyperglycemia) and as a compensatory mechanism there is overactivation/expression of insulin receptor in the brain rendering neuronal circuits resistant to seizure induction after injection of insulin. These data indicate that insulin signal transduction pathway is altered in PH-Tau-Tg mice, and that injection of exogenous insulin reduces hypersynchronous bursting activity of field potentials recorded from cortical neuronal circuits. We propose that the appearance of abnormal tau might potentiate the toxic environment by interfering with the insulin signaling cascade in the brain of patients with Alzheimer's disease.
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Affiliation(s)
- Abdeslem El Idrissi
- Department of Biology and Center for Developmental Neuroscience, College of Staten Island, The City University of New York, New York, NY, United States,Biology Program, The Graduate Center, The City University of New York, New York, NY, United States,*Correspondence: Abdeslem El Idrissi,
| | - Alejandra del Carmen Alonso
- Department of Biology and Center for Developmental Neuroscience, College of Staten Island, The City University of New York, New York, NY, United States,Biology Program, The Graduate Center, The City University of New York, New York, NY, United States,Alejandra del Carmen Alonso,
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5
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Swarnalingam E, Jacobs J. The missing link: Epileptic brain ripples, is neuroinflammation the culprit? Clin Neurophysiol 2021; 133:154-156. [PMID: 34810103 DOI: 10.1016/j.clinph.2021.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 11/01/2021] [Indexed: 11/26/2022]
Affiliation(s)
- Eroshini Swarnalingam
- Department of Pediatrics, Alberta Children's Hospital Research Institute & Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, AB, Canada
| | - Julia Jacobs
- Department of Pediatrics, Alberta Children's Hospital Research Institute & Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, AB, Canada.
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Wang W, Li H, Yan J, Zhang H, Li X, Zheng S, Wang J, Xing Y, Cheng L, Li D, Lai H, Qu J, Loh HH, Fang F, Yang X. Automatic detection of interictal ripples on scalp EEG to evaluate the effect and prognosis of ACTH therapy in patients with infantile spasms. Epilepsia 2021; 62:2240-2251. [PMID: 34309835 DOI: 10.1111/epi.17018] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 12/22/2022]
Abstract
OBJECTIVE We aimed to explore the feasibility of using scalp-recorded high-frequency oscillations (HFOs) to evaluate the efficacy and prognosis of adrenocorticotropic hormone (ACTH) treatment in patients with infantile spasms. METHODS Thirty-nine children with infantile spasms were enrolled and divided into seizure-free and non-seizure-free groups after ACTH treatment. Patients who were seizure-free were further divided into relapse and non-relapse subgroups based on the observations made during a 6-month follow-up period. Scalp ripples were detected and compared during the interictal periods before and after 2 weeks of treatment. RESULTS After ACTH treatment, the number and channels of ripples were significantly lower, whereas the percentage decrease in the number, spectral power, and channels of ripples was significantly higher in the seizure-free group than in the non-seizure-free group. In addition, the relapse subgroup showed higher number and spectral power and wider distribution of ripples than did the non-relapse subgroup. Changes in HFOs in terms of number, spectral power, and channel of ripples were closely related to the severity of epilepsy and can indicate disease susceptibility. SIGNIFICANCE Scalp HFOs can be used as an effective biomarker to monitor the effect and evaluate the prognosis of ACTH therapy in patients with infantile spasms.
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Affiliation(s)
- Wei Wang
- Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.,Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Hua Li
- Department of Neurology, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Jiaqing Yan
- College of Electrical and Control Engineering, North China University of Technology, Beijing, China
| | - Herui Zhang
- Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Xiaonan Li
- Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.,Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Su Zheng
- Department of Neurology, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Jiaoyang Wang
- Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.,Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Yue Xing
- Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Lipeng Cheng
- Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.,Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Donghong Li
- The Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Huanling Lai
- Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Junda Qu
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Horace H Loh
- Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Fang Fang
- Department of Neurology, National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
| | - Xiaofeng Yang
- Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.,Bioland Laboratory Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
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7
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Agudelo Valencia P, van Klink NEC, van 't Klooster MA, Zweiphenning WJEM, Swampillai B, van Eijsden P, Gebbink T, van Zandvoort MJE, Zijlmans M. Are HFOs in the Intra-operative ECoG Related to Hippocampal Sclerosis, Volume and IQ? Front Neurol 2021; 12:645925. [PMID: 33841312 PMCID: PMC8024640 DOI: 10.3389/fneur.2021.645925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 03/02/2021] [Indexed: 11/13/2022] Open
Abstract
Temporal lobe epilepsy (TLE) is the most common form of refractory focal epilepsy and is often associated with hippocampal sclerosis (HS) and cognitive disturbances. Over the last decade, high frequency oscillations (HFOs) in the intraoperative electrocorticography (ioECoG) have been proposed to be biomarkers for the delineation of epileptic tissue but hippocampal ripples have also been associated with memory consolidation. Healthy hippocampi can show prolonged ripple activity in stereo- EEG. We aimed to identify how the HFO rates [ripples (80–250 Hz, fast ripples (250–500 Hz); prolonged ripples (80–250 Hz, 200–500 ms)] in the pre-resection ioECoG over subtemporal area (hippocampus) and lateral temporal neocortex relate to presence of hippocampal sclerosis, the hippocampal volume quantified on MRI and the severity of cognitive impairment in TLE patients. Volumetric measurement of hippocampal subregions was performed in 47 patients with TLE, who underwent ioECoG. Ripples, prolonged ripples, and fast ripples were visually marked and rates of HFOs were calculated. The intellectual quotient (IQ) before resection was determined. There was a trend toward higher rates of ripples and fast ripples in subtemporal electrodes vs. the lateral neocortex (ripples: 2.1 vs. 1.3/min; fast ripples: 0.9 vs. 0.2/min). Patients with HS showed higher rates of subtemporal fast ripples than other patients (Z = −2.51, p = 0.012). Prolonged ripples were only found in the lateral temporal neocortex. The normalized ratio (smallest/largest) of hippocampal volume was correlated to pre-resection IQ (r = 0.45, p = 0.015). There was no correlation between HFO rates and hippocampal volumes or HFO rates and IQ. To conclude, intra-operative fast ripples were a marker for HS, but ripples and fast ripples were not linearly correlated with either the amount of hippocampal atrophy, nor for pre-surgical IQ.
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Affiliation(s)
- Paula Agudelo Valencia
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Nicole E C van Klink
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Maryse A van 't Klooster
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Willemiek J E M Zweiphenning
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Banu Swampillai
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Pieter van Eijsden
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Tineke Gebbink
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Martine J E van Zandvoort
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands
| | - Maeike Zijlmans
- Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, University Utrecht, Utrecht, Netherlands.,Stiching Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
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Jacobs J, Zijlmans M. HFO to Measure Seizure Propensity and Improve Prognostication in Patients With Epilepsy. Epilepsy Curr 2020; 20:338-347. [PMID: 33081501 PMCID: PMC7818207 DOI: 10.1177/1535759720957308] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The study of high frequency oscillations (HFO) in the electroencephalogram (EEG)
as biomarkers of epileptic activity has merely focused on their spatial location
and relationship to the epileptogenic zone. It has been suggested in several
ways that the amount of HFO at a certain point in time may reflect the disease
activity or severity. This could be clinically useful in several ways,
especially as noninvasive recording of HFO appears feasible. We grouped the
potential hypotheses into 4 categories: (1) HFO as biomarkers to predict the
development of epilepsy; (2) HFO as biomarkers to predict the occurrence of
seizures; (3) HFO as biomarkers linked to the severity of epilepsy, and (4) HFO
as biomarkers to evaluate outcome of treatment. We will review the literature
that addresses these 4 hypotheses and see to what extent HFO can be used to
measure seizure propensity and help determine prognosis of this unpredictable
disease.
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Affiliation(s)
- Julia Jacobs
- 157744Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Maeike Zijlmans
- 36512UMC Utrecht Brain Center Rudolf Magnus, Utrecht, the Netherlands
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9
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Gerner N, Thomschewski A, Marcu A, Trinka E, Höller Y. Pitfalls in Scalp High-Frequency Oscillation Detection From Long-Term EEG Monitoring. Front Neurol 2020; 11:432. [PMID: 32582002 PMCID: PMC7280487 DOI: 10.3389/fneur.2020.00432] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 04/23/2020] [Indexed: 11/17/2022] Open
Abstract
Aims: Intracranially recorded high-frequency oscillations (>80 Hz) are considered a candidate epilepsy biomarker. Recent studies claimed their detectability on the scalp surface. We aimed to investigate the applicability of high-frequency oscillation analysis to routine surface EEG obtained at an epilepsy monitoring unit. Methods: We retrospectively analyzed surface EEGs of 18 patients with focal epilepsy and six controls, recorded during sleep under maximal medication withdrawal. As a proof of principle, the occurrence of motor task-related events during wakefulness was analyzed in a subsample of six patients with seizure- or syncope-related motor symptoms. Ripples (80-250 Hz) and fast ripples (>250 Hz) were identified by semi-automatic detection. Using semi-parametric statistics, differences in spontaneous and task-related occurrence rates were examined within subjects and between diagnostic groups considering the factors diagnosis, brain region, ripple type, and task condition. Results: We detected high-frequency oscillations in 17 out of 18 patients and in four out of six controls. Results did not show statistically significant differences in the mean rates of event occurrences, neither regarding the laterality of the epileptic focus, nor with respect to active and inactive task conditions, or the moving hand laterality. Significant differences in general spontaneous incidence [WTS(1) = 9.594; p = 0.005] that indicated higher rates of fast ripples compared to ripples, notably in patients with epilepsy compared to the control group, may be explained by variations in data quality. Conclusion: The current analysis methods are prone to biases. A common agreement on a standard operating procedure is needed to ensure reliable and economic detection of high-frequency oscillations.
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Affiliation(s)
- Nathalie Gerner
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria,Department of Mathematics, Paris-Lodron University of Salzburg, Salzburg, Austria
| | - Aljoscha Thomschewski
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria,Department of Mathematics, Paris-Lodron University of Salzburg, Salzburg, Austria,*Correspondence: Aljoscha Thomschewski
| | - Adrian Marcu
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria
| | - Eugen Trinka
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria
| | - Yvonne Höller
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria,Department of Psychology, University of Akureyri, Akureyri, Iceland
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10
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Job AS, David O, Minotti L, Bartolomei F, Chabardès S, Kahane P. Epileptogenicity Maps of Intracerebral Fast Activities (60-100 Hz) at Seizure Onset in Epilepsy Surgery Candidates. Front Neurol 2019; 10:1263. [PMID: 31849823 PMCID: PMC6892969 DOI: 10.3389/fneur.2019.01263] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 11/13/2019] [Indexed: 11/13/2022] Open
Abstract
Fast activities (FA) at seizure onset have been increasingly described as a useful signature of the epileptogenic zone (EZ) in patients undergoing intracranial EEG recordings. Different computer-based signal analysis methods have thus been developed for objectively quantifying ictal FA. Whether these methods detect FA in all forms of focal epilepsies, whether they provide similar information than visual analysis (VA), and whether they might help for the surgical decision remain crucial issues. We thus conducted a retrospective study in 21 consecutive patients suffering from drug-resistant seizures studied by SEEG recordings. Ictal FA were quantified using the Epileptogenicity Maps (EM) method that we recently developed and which generates, by adopting a neuroimaging approach, statistical parametric maps of FA ranging from 60 to 100 Hz (FA60−100). Ictal FA were analyzed blindly using VA and EM, and the prognostic significance of removing areas exhibiting FA60−100 at seizure onset was evaluated. A significant ictal FA60−100 activation was found in all patients, and in 92.6% of all the 68 seizures recorded, whatever the epilepsy type. The overlap ratio (OR) between VA and EM was significantly better for defining the regions spared at seizure onset than those from which seizure arose (p < 0.001), especially in temporal or temporal “plus” epilepsies. EM and VA were much more discordant to define the EZ, with a mean number of electrode contacts involved at seizure onset significantly higher with EM than with VA (p = <0.0001). Seizure outcome correlated with the resection ratio for FA60−100, which was significantly higher in seizure-free (Engel's class Ia) than in non seizure-free patients (class Ic-IV) (p = 0.048). The quantification of FA at seizure onset can bring information additional to clinical expertise that might contribute to define accurately the cortical region to be resected.
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Affiliation(s)
- Anne-Sophie Job
- Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Université Grenoble Alpes, Grenoble, France
| | - Olivier David
- Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Université Grenoble Alpes, Grenoble, France.,INS, Inserm, U1106, Marseille, France
| | - Lorella Minotti
- Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Université Grenoble Alpes, Grenoble, France
| | - Fabrice Bartolomei
- INS, Inserm, U1106, Marseille, France.,Neurophysiology Departement, La Timone Hospital, Marseille, France
| | - Stephan Chabardès
- Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Université Grenoble Alpes, Grenoble, France
| | - Philippe Kahane
- Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neurosciences, Université Grenoble Alpes, Grenoble, France
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Boran E, Ramantani G, Krayenbühl N, Schreiber M, König K, Fedele T, Sarnthein J. High-density ECoG improves the detection of high frequency oscillations that predict seizure outcome. Clin Neurophysiol 2019; 130:1882-1888. [DOI: 10.1016/j.clinph.2019.07.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 05/31/2019] [Accepted: 07/06/2019] [Indexed: 01/11/2023]
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12
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Cimbalnik J, Brinkmann B, Kremen V, Jurak P, Berry B, Gompel JV, Stead M, Worrell G. Physiological and pathological high frequency oscillations in focal epilepsy. Ann Clin Transl Neurol 2018; 5:1062-1076. [PMID: 30250863 PMCID: PMC6144446 DOI: 10.1002/acn3.618] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 06/08/2018] [Accepted: 06/11/2018] [Indexed: 11/19/2022] Open
Abstract
Objective This study investigates high‐frequency oscillations (HFOs; 65–600 Hz) as a biomarker of epileptogenic brain and explores three barriers to their clinical translation: (1) Distinguishing pathological HFOs (pathHFO) from physiological HFOs (physHFO). (2) Classifying tissue under individual electrodes as epileptogenic (3) Reproducing results across laboratories. Methods We recorded HFOs using intracranial EEG (iEEG) in 90 patients with focal epilepsy and 11 patients without epilepsy. In nine patients with epilepsy putative physHFOs were induced by cognitive or motor tasks. HFOs were identified using validated detectors. A support vector machine (SVM) using HFO features was developed to classify tissue under individual electrodes as normal or epileptogenic. Results There was significant overlap in the amplitude, frequency, and duration distributions for spontaneous physHFO, task induced physHFO, and pathHFO, but the amplitudes of the pathHFO were higher (P < 0.0001). High gamma pathHFO had the strongest association with seizure onset zone (SOZ), and were elevated on SOZ electrodes in 70% of epilepsy patients (P < 0.0001). Failure to resect tissue generating high gamma pathHFO was associated with poor outcomes (P < 0.0001). A SVM classified individual electrodes as epileptogenic with 63.9% sensitivity and 73.7% specificity using SOZ as the target. Interpretation A broader range of interictal pathHFO (65–600 Hz) than previously recognized are biomarkers of epileptogenic brain, and are associated with SOZ and surgical outcome. Classification of HFOs into physiological or pathological remains challenging. Classification of tissue under individual electrodes was demonstrated to be feasible. The open source data and algorithms provide a resource for future studies.
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Affiliation(s)
- Jan Cimbalnik
- Mayo Systems Electrophysiology Laboratory Department of Neurology Mayo Clinic 200 First St SW Rochester Minnesota 55905.,International Clinical Research Center St. Anne's University Hospital Brno Czech Republic
| | - Benjamin Brinkmann
- Mayo Systems Electrophysiology Laboratory Department of Neurology Mayo Clinic 200 First St SW Rochester Minnesota 55905.,Department of Physiology and Biomedical Engineering Mayo Clinic 200 First St SW Rochester Minnesota 55905
| | - Vaclav Kremen
- Mayo Systems Electrophysiology Laboratory Department of Neurology Mayo Clinic 200 First St SW Rochester Minnesota 55905.,Department of Physiology and Biomedical Engineering Mayo Clinic 200 First St SW Rochester Minnesota 55905.,Czech Institute of Informatics, Robotics, and Cybernetics Czech Technical University in Prague Prague Czech Republic
| | - Pavel Jurak
- International Clinical Research Center St. Anne's University Hospital Brno Czech Republic.,Institute of Scientific Instruments The Czech Academy of Sciences Brno Czech Republic
| | - Brent Berry
- Mayo Systems Electrophysiology Laboratory Department of Neurology Mayo Clinic 200 First St SW Rochester Minnesota 55905.,Department of Neurology University of Minnesota Minneapolis Minnesota 55455
| | - Jamie Van Gompel
- Department of Neurosurgery Mayo Clinic 200 First St SW Rochester Minnesota 55905
| | - Matt Stead
- Mayo Systems Electrophysiology Laboratory Department of Neurology Mayo Clinic 200 First St SW Rochester Minnesota 55905.,Department of Physiology and Biomedical Engineering Mayo Clinic 200 First St SW Rochester Minnesota 55905
| | - Greg Worrell
- Mayo Systems Electrophysiology Laboratory Department of Neurology Mayo Clinic 200 First St SW Rochester Minnesota 55905.,Department of Physiology and Biomedical Engineering Mayo Clinic 200 First St SW Rochester Minnesota 55905
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Höller P, Trinka E, Höller Y. High-Frequency Oscillations in the Scalp Electroencephalogram: Mission Impossible without Computational Intelligence. COMPUTATIONAL INTELLIGENCE AND NEUROSCIENCE 2018; 2018:1638097. [PMID: 30158959 PMCID: PMC6109569 DOI: 10.1155/2018/1638097] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/20/2018] [Accepted: 07/12/2018] [Indexed: 01/22/2023]
Abstract
High-frequency oscillations (HFOs) in the electroencephalogram (EEG) are thought to be a promising marker for epileptogenicity. A number of automated detection algorithms have been developed for reliable analysis of invasively recorded HFOs. However, invasive recordings are not widely applicable since they bear risks and costs, and the harm of the surgical intervention of implantation needs to be weighted against the informational benefits of the invasive examination. In contrast, scalp EEG is widely available at low costs and does not bear any risks. However, the detection of HFOs on the scalp represents a challenge that was taken on so far mostly via visual detection. Visual detection of HFOs is, in turn, highly time-consuming and subjective. In this review, we discuss that automated detection algorithms for detection of HFOs on the scalp are highly warranted because the available algorithms were all developed for invasively recorded EEG and do not perform satisfactorily in scalp EEG because of the low signal-to-noise ratio and numerous artefacts as well as physiological activity that obscures the tiny phenomena in the high-frequency range.
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Affiliation(s)
- Peter Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
| | - Yvonne Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
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Spring AM, Pittman DJ, Aghakhani Y, Jirsch J, Pillay N, Bello-Espinosa LE, Josephson C, Federico P. Generalizability of High Frequency Oscillation Evaluations in the Ripple Band. Front Neurol 2018; 9:510. [PMID: 30002645 PMCID: PMC6031752 DOI: 10.3389/fneur.2018.00510] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 06/11/2018] [Indexed: 11/29/2022] Open
Abstract
Objective: We examined the interrater reliability and generalizability of high-frequency oscillation (HFO) visual evaluations in the ripple (80–250 Hz) band, and established a framework for the transition of HFO analysis to routine clinical care. We were interested in the interrater reliability or epoch generalizability to describe how similar the evaluations were between reviewers, and in the reviewer generalizability to represent the consistency of the internal threshold each individual reviewer. Methods: We studied 41 adult epilepsy patients (mean age: 35.6 years) who underwent intracranial electroencephalography. A morphology detector was designed and used to detect candidate HFO events, lower-threshold events, and distractor events. These events were subsequently presented to six expert reviewers, who visually evaluated events for the presence of HFOs. Generalizability theory was used to characterize the epoch generalizability (interrater reliability) and reviewer generalizability (internal threshold consistency) of visual evaluations, as well as to project the numbers of epochs, reviewers, and datasets required to achieve strong generalizability (threshold of 0.8). Results: The reviewer generalizability was almost perfect (0.983), indicating there were sufficient evaluations to determine the internal threshold of each reviewer. However, the interrater reliability for 6 reviewers (0.588) and pairwise interrater reliability (0.322) were both poor, indicating that the agreement of 6 reviewers is insufficient to reliably establish the presence or absence of individual HFOs. Strong interrater reliability (≥0.8) was projected as requiring a minimum of 17 reviewers, while strong reviewer generalizability could be achieved with <30 epoch evaluations per reviewer. Significance: This study reaffirms the poor reliability of using small numbers of reviewers to identify HFOs, and projects the number of reviewers required to overcome this limitation. It also provides a set of tools which may be used for training reviewers, tracking changes to interrater reliability, and for constructing a benchmark set of epochs that can serve as a generalizable gold standard, against which other HFO detection algorithms may be compared. This study represents an important step toward the reconciliation of important but discordant findings from HFO studies undertaken with different sets of HFOs, and ultimately toward transitioning HFO analysis into a meaningful part of the clinical epilepsy workup.
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Affiliation(s)
- Aaron M Spring
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada
| | - Daniel J Pittman
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada
| | - Yahya Aghakhani
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
| | - Jeffrey Jirsch
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Neelan Pillay
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
| | - Luis E Bello-Espinosa
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada.,Department of Paediatrics, University of Calgary, Calgary, AB, Canada
| | - Colin Josephson
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada
| | - Paolo Federico
- Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada.,Department of Radiology, University of Calgary, Calgary, AB, Canada
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15
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Guragain H, Cimbalnik J, Stead M, Groppe DM, Berry BM, Kremen V, Kenney-Jung D, Britton J, Worrell GA, Brinkmann BH. Spatial variation in high-frequency oscillation rates and amplitudes in intracranial EEG. Neurology 2018; 90:e639-e646. [PMID: 29367441 PMCID: PMC5818159 DOI: 10.1212/wnl.0000000000004998] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 11/02/2017] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To assess the variation in baseline and seizure onset zone interictal high-frequency oscillation (HFO) rates and amplitudes across different anatomic brain regions in a large cohort of patients. METHODS Seventy patients who had wide-bandwidth (5 kHz) intracranial EEG (iEEG) recordings during surgical evaluation for drug-resistant epilepsy between 2005 and 2014 who had high-resolution MRI and CT imaging were identified. Discrete HFOs were identified in 2-hour segments of high-quality interictal iEEG data with an automated detector. Electrode locations were determined by coregistering the patient's preoperative MRI with an X-ray CT scan acquired immediately after electrode implantation and correcting electrode locations for postimplant brain shift. The anatomic locations of electrodes were determined using the Desikan-Killiany brain atlas via FreeSurfer. HFO rates and mean amplitudes were measured in seizure onset zone (SOZ) and non-SOZ electrodes, as determined by the clinical iEEG seizure recordings. To promote reproducible research, imaging and iEEG data are made freely available (msel.mayo.edu). RESULTS Baseline (non-SOZ) HFO rates and amplitudes vary significantly in different brain structures, and between homologous structures in left and right hemispheres. While HFO rates and amplitudes were significantly higher in SOZ than non-SOZ electrodes when analyzed regardless of contact location, SOZ and non-SOZ HFO rates and amplitudes were not separable in some lobes and structures (e.g., frontal and temporal neocortex). CONCLUSIONS The anatomic variation in SOZ and non-SOZ HFO rates and amplitudes suggests the need to assess interictal HFO activity relative to anatomically accurate normative standards when using HFOs for presurgical planning.
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Affiliation(s)
- Hari Guragain
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Jan Cimbalnik
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Matt Stead
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - David M Groppe
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Brent M Berry
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Vaclav Kremen
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Daniel Kenney-Jung
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Jeffrey Britton
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Gregory A Worrell
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic
| | - Benjamin H Brinkmann
- From Mayo Systems Electrophysiology Laboratory, Department of Neurology (H.G., M.S., B.M.B., V.K., D.K.-J., J.B., G.A.W., B.H.B.), and Department of Physiology & Biomedical Engineering (B.M.B., V.K., G.A.W., B.H.B.), Mayo Clinic, Rochester, MN; International Clinical Research Center (J.C.), St. Anne's University Hospital, Brno, Czech Republic; The Krembil Neuroscience Centre (D.M.G.), Toronto, Canada; and Czech Institute of Informatics, Robotics, and Cybernetics (V.K.), Czech Technical University in Prague, Czech Republic.
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16
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Frauscher B, Bartolomei F, Kobayashi K, Cimbalnik J, van 't Klooster MA, Rampp S, Otsubo H, Höller Y, Wu JY, Asano E, Engel J, Kahane P, Jacobs J, Gotman J. High-frequency oscillations: The state of clinical research. Epilepsia 2017; 58:1316-1329. [PMID: 28666056 DOI: 10.1111/epi.13829] [Citation(s) in RCA: 209] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/25/2017] [Indexed: 01/03/2023]
Abstract
Modern electroencephalographic (EEG) technology contributed to the appreciation that the EEG signal outside the classical Berger frequency band contains important information. In epilepsy, research of the past decade focused particularly on interictal high-frequency oscillations (HFOs) > 80 Hz. The first large application of HFOs was in the context of epilepsy surgery. This is now followed by other applications such as assessment of epilepsy severity and monitoring of antiepileptic therapy. This article reviews the evidence on the clinical use of HFOs in epilepsy with an emphasis on the latest developments. It highlights the growing literature on the association between HFOs and postsurgical seizure outcome. A recent meta-analysis confirmed a higher resection ratio for HFOs in seizure-free versus non-seizure-free patients. Residual HFOs in the postoperative electrocorticogram were shown to predict epilepsy surgery outcome better than preoperative HFO rates. The review further discusses the different attempts to separate physiological from epileptic HFOs, as this might increase the specificity of HFOs. As an example, analysis of sleep microstructure demonstrated a different coupling between HFOs inside and outside the epileptogenic zone. Moreover, there is increasing evidence that HFOs are useful to measure disease activity and assess treatment response using noninvasive EEG and magnetoencephalography. This approach is particularly promising in children, because they show high scalp HFO rates. HFO rates in West syndrome decrease after adrenocorticotropic hormone treatment. Presence of HFOs at the time of rolandic spikes correlates with seizure frequency. The time-consuming visual assessment of HFOs, which prevented their clinical application in the past, is now overcome by validated computer-assisted algorithms. HFO research has considerably advanced over the past decade, and use of noninvasive methods will make HFOs accessible to large numbers of patients. Prospective multicenter trials are awaited to gather information over long recording periods in large patient samples.
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Affiliation(s)
- Birgit Frauscher
- Department of Medicine and Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - Fabrice Bartolomei
- National Institute of Health and Medical Research, Institute of Neurosciences of Systems, Aix Marseille University, Marseille, France
| | - Katsuhiro Kobayashi
- Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hospital, Kita-ku, Okayama, Japan
| | - Jan Cimbalnik
- International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic
| | - Maryse A van 't Klooster
- Department of Neurology and Neurosurgery, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Stefan Rampp
- Department of Neurosurgery, University Hospital Erlangen, Erlangen, Germany
| | - Hiroshi Otsubo
- Division of Neurology, Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Yvonne Höller
- Department of Neurology, Christian Doppler Medical Center and Center for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Joyce Y Wu
- Division of Pediatric Neurology, Mattel Children's Hospital at UCLA, Los Angeles, California, U.S.A
| | - Eishi Asano
- Departments of Pediatrics and Neurology, Detroit Medical Center, Children's Hospital of Michigan, Wayne State University, Detroit, Michigan, U.S.A
| | - Jerome Engel
- Departments of Neurology, Neurobiology, and Psychiatry, Brain Research Institute, University of California, Los Angeles, Los Angeles, California, U.S.A
| | - Philippe Kahane
- Department of Neurology, Grenoble-Alpes University Hospital and Grenoble-Alpes University, Grenoble, France
| | - Julia Jacobs
- Department of Neuropediatrics and Muscular Diseases, University Medical Center Freiburg, Freiburg, Germany
| | - Jean Gotman
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
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Medina-Ceja L, García-Barba C. The glutamate receptor antagonists CNQX and MPEP decrease fast ripple events in rats treated with kainic acid. Neurosci Lett 2017; 655:137-142. [PMID: 28673833 DOI: 10.1016/j.neulet.2017.06.056] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 06/06/2017] [Accepted: 06/29/2017] [Indexed: 12/17/2022]
Abstract
Fast ripples (FR) are high frequency oscillations (250-600Hz) that have been associated with epilepsy. FR are assumed to be generated in small areas of the hippocampus (1mm3) that contain pathologically interconnected glutamate pyramidal cell clusters. Additionally, a relation between glutamate neurotransmission and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainite (AMPA/KA) and metabotropic mGluR5 receptors is well established. Therefore, we hypothesized that antagonism of these glutamate receptors would decrease FR activity. For this propose, we induced status epilepticus with a kainic acid injection in the posterior right hippocampus and performed intracranial EEG recordings to detect and evaluate the presence of FR 15days after the injection. The glutamate AMPA/KA receptor antagonist CNQX (10mg/kg) and the mGluR5 antagonist MPEP (20mg/kg) were administered intraperitoneally, and the effects of the drugs were evaluated for a period of three hours after their administration. The results show a decrease in the number of FR in the first hour after drug administration in both cases (CNQX, p=0.0125; MPEP, p=0.0132) and a return to basal values in the third hour of the experiment, but not significant differences in the number of oscillations per event of FR, and the frequency and duration of each event of FR. We therefore conclude that blockade of AMPA/KA and mGluR5 receptors transiently decreases the generation of FR; however, the mechanisms by which this effect is achieved are to be further analyzed in future experiments.
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Affiliation(s)
- Laura Medina-Ceja
- Laboratory of Neurophysiology, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Jalisco, Mexico.
| | - Carla García-Barba
- Laboratory of Neurophysiology, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Jalisco, Mexico
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18
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Interrater reliability of visually evaluated high frequency oscillations. Clin Neurophysiol 2017; 128:433-441. [DOI: 10.1016/j.clinph.2016.12.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 11/13/2016] [Accepted: 12/15/2016] [Indexed: 02/01/2023]
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Abstract
PURPOSE OF REVIEW Localization of focal epileptic brain is critical for successful epilepsy surgery and focal brain stimulation. Despite significant progress, roughly half of all patients undergoing focal surgical resection, and most patients receiving focal electrical stimulation, are not seizure free. There is intense interest in high-frequency oscillations (HFOs) recorded with intracranial electroencephalography as potential biomarkers to improve epileptogenic brain localization, resective surgery, and focal electrical stimulation. The present review examines the evidence that HFOs are clinically useful biomarkers. RECENT FINDINGS Performing the PubMed search 'High-Frequency Oscillations and Epilepsy' for 2013-2015 identifies 308 articles exploring HFO characteristics, physiological significance, and potential clinical applications. SUMMARY There is strong evidence that HFOs are spatially associated with epileptic brain. There remain, however, significant challenges for clinical translation of HFOs as epileptogenic brain biomarkers: Differentiating true HFO from the high-frequency power changes associated with increased neuronal firing and bandpass filtering sharp transients. Distinguishing pathological HFO from normal physiological HFO. Classifying tissue under individual electrodes as normal or pathological. Sharing data and algorithms so research results can be reproduced across laboratories. Multicenter prospective trials to provide definitive evidence of clinical utility.
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Abstract
Pathological high-frequency oscillations (HFOs) (80-800 Hz) are considered biomarkers of epileptogenic tissue, but the underlying complex neuronal events are not well understood. Here, we identify and discuss several outstanding issues or conundrums in regards to the recording, analysis, and interpretation of HFOs in the epileptic brain to critically highlight what is known and what is not about these enigmatic events. High-frequency oscillations reflect a range of neuronal processes contributing to overlapping frequencies from the lower 80 Hz to the very fast spectral frequency bands. Given their complex neuronal nature, HFOs are extremely sensitive to recording conditions and analytical approaches. We provide a list of recommendations that could help to obtain comparable HFO signals in clinical and basic epilepsy research. Adopting basic standards will facilitate data sharing and interpretation that collectively will aid in understanding the role of HFOs in health and disease for translational purpose.
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Shiri Z, Manseau F, Lévesque M, Williams S, Avoli M. Activation of specific neuronal networks leads to different seizure onset types. Ann Neurol 2016; 79:354-65. [PMID: 26605509 DOI: 10.1002/ana.24570] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/12/2015] [Accepted: 11/15/2015] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Ictal events occurring in temporal lobe epilepsy patients and in experimental models mimicking this neurological disorder can be classified, based on their onset pattern, into low-voltage, fast versus hypersynchronous onset seizures. It has been suggested that the low-voltage, fast onset pattern is mainly contributed by interneuronal (γ-aminobutyric acidergic) signaling, whereas the hypersynchronous onset involves the activation of principal (glutamatergic) cells. METHODS Here, we tested this hypothesis using the optogenetic control of parvalbumin-positive or somatostatin-positive interneurons and of calmodulin-dependent, protein kinase-positive, principal cells in the mouse entorhinal cortex in the in vitro 4-aminopyridine model of epileptiform synchronization. RESULTS We found that during 4-aminopyridine application, both spontaneous seizure-like events and those induced by optogenetic activation of interneurons displayed low-voltage, fast onset patterns that were associated with a higher occurrence of ripples than of fast ripples. In contrast, seizures induced by the optogenetic activation of principal cells had a hypersynchronous onset pattern with fast ripple rates that were higher than those of ripples. INTERPRETATION Our results firmly establish that under a similar experimental condition (ie, bath application of 4-aminopyridine), the initiation of low-voltage, fast and of hypersynchronous onset seizures in the entorhinal cortex depends on the preponderant involvement of interneuronal and principal cell networks, respectively.
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Affiliation(s)
- Zahra Shiri
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Frédéric Manseau
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
| | - Maxime Lévesque
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Sylvain Williams
- Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
| | - Massimo Avoli
- Montreal Neurological Institute, Department of Neurology and Neurosurgery, and Department of Physiology, McGill University, Montreal, Quebec, Canada
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Jacobs J, Vogt C, LeVan P, Zelmann R, Gotman J, Kobayashi K. The identification of distinct high-frequency oscillations during spikes delineates the seizure onset zone better than high-frequency spectral power changes. Clin Neurophysiol 2016; 127:129-142. [DOI: 10.1016/j.clinph.2015.04.053] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 03/12/2015] [Accepted: 04/04/2015] [Indexed: 10/23/2022]
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Höller Y, Kutil R, Klaffenböck L, Thomschewski A, Höller PM, Bathke AC, Jacobs J, Taylor AC, Nardone R, Trinka E. High-frequency oscillations in epilepsy and surgical outcome. A meta-analysis. Front Hum Neurosci 2015; 9:574. [PMID: 26539097 PMCID: PMC4611152 DOI: 10.3389/fnhum.2015.00574] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 10/02/2015] [Indexed: 01/14/2023] Open
Abstract
High frequency oscillations (HFOs) are estimated as a potential marker for epileptogenicity. Current research strives for valid evidence that these HFOs could aid the delineation of the to-be resected area in patients with refractory epilepsy and improve surgical outcomes. In the present meta-analysis, we evaluated the relation between resection of regions from which HFOs can be detected and outcome after epilepsy surgery. We conducted a systematic review of all studies that related the resection of HFO-generating areas to postsurgical outcome. We related the outcome (seizure freedom) to resection ratio, that is, the ratio between the number of channels on which HFOs were detected and, among these, the number of channels that were inside the resected area. We compared the resection ratio between seizure free and not seizure free patients. In total, 11 studies were included. In 10 studies, ripples (80-200 Hz) were analyzed, and in 7 studies, fast ripples (>200 Hz) were studied. We found comparable differences (dif) and largely overlapping confidence intervals (CI) in resection ratios between outcome groups for ripples (dif = 0.18; CI: 0.10-0.27) and fast ripples (dif = 0.17; CI: 0.01-0.33). Subgroup analysis showed that automated detection (dif = 0.22; CI: 0.03-0.41) was comparable to visual detection (dif = 0.17; CI: 0.08-0.27). Considering frequency of HFOs (dif = 0.24; CI: 0.09-0.38) was related more strongly to outcome than considering each electrode that was showing HFOs (dif = 0.15; CI = 0.03-0.27). The effect sizes found in the meta-analysis are small but significant. Automated detection and application of a detection threshold in order to detect channels with a frequent occurrence of HFOs is important to yield a marker that could be useful in presurgical evaluation. In order to compare studies with different methodological approaches, detailed and standardized reporting is warranted.
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Affiliation(s)
- Yvonne Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Austria
| | - Raoul Kutil
- Department of Mathematics, Paris Lodron University Salzburg, Austria
| | - Lukas Klaffenböck
- Department of Mathematics, Paris Lodron University Salzburg, Austria
| | - Aljoscha Thomschewski
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Austria
| | - Peter M Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Austria
| | - Arne C Bathke
- Department of Mathematics, Paris Lodron University Salzburg, Austria
| | - Julia Jacobs
- Department of Neuropediatrics and Muscular Diseases and Epilepsy Center, University Medical Center Freiburg, Germany
| | - Alexandra C Taylor
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Austria
| | - Raffaele Nardone
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Austria ; Department of Neurology, Franz Tappeiner Hospital Merano, Italy
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Paracelsus Medical University Salzburg, Austria
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Abstract
Single neuron actions and interactions are the sine qua non of brain function, and nearly all diseases and injuries of the CNS trace their clinical sequelae to neuronal dysfunction or failure. Remarkably, discussion of neuronal activity is largely absent in clinical neuroscience. Advances in neurotechnology and computational capabilities, accompanied by shifts in theoretical frameworks, have led to renewed interest in the information represented by single neurons. Using direct interfaces with the nervous system, millisecond-scale information will soon be extracted from single neurons in clinical environments, supporting personalized treatment of neurologic and psychiatric disease. In this Perspective, we focus on single-neuronal activity in restoring communication and motor control in patients suffering from devastating neurological injuries. We also explore the single neuron's role in epilepsy and movement disorders, surgical anesthesia, and in cognitive processes disrupted in neurodegenerative and neuropsychiatric disease. Finally, we speculate on how technological advances will revolutionize neurotherapeutics.
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Affiliation(s)
- Sydney S Cash
- Neurotechnology Trials Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
| | - Leigh R Hochberg
- Neurotechnology Trials Unit, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; School of Engineering and Institute for Brain Science, Brown University, Providence, RI 02912, USA; Center for Neurorestoration and Neurotechnology, Providence VA Medical Center, Providence, RI 02908, USA.
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Shiri Z, Herrington R, Lévesque M, Avoli M. Neurosteroidal modulation of in vitro epileptiform activity is enhanced in pilocarpine-treated epileptic rats. Neurobiol Dis 2015; 78:24-34. [PMID: 25814046 PMCID: PMC4880464 DOI: 10.1016/j.nbd.2015.03.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 03/14/2015] [Accepted: 03/16/2015] [Indexed: 10/23/2022] Open
Abstract
We employed field potential recordings in brain slices obtained from pilocarpine-treated epileptic (4-5weeks following a pilocarpine-induced status epilepticus) and age-matched, non-epileptic control (NEC) rats to establish the effects of the neurosteroid allotetrahydrodeoxycorticosterone (THDOC) on the epileptiform activity - including high frequency oscillations (HFOs; ripples: 80-200Hz, fast ripples: 250-500Hz) - induced by 4-aminopyridine (4AP) in piriform (PC) and entorhinal (EC) cortices. Both structures are highly susceptible to generate seizures and may also be involved in epileptogenesis. We found that THDOC application to pilocarpine-treated slices: (i) decreased interictal discharge frequency in PC while increasing it in EC; (ii) abolished ictal discharges in both areas in approx. one third of the experiments and reduced them in frequency and duration in the remaining experiments; and (iii) increased the occurrence of ripples and fast ripples associated to interictal events, and modified their pattern of occurrence during ictal discharges in both PC and EC. These effects were either weaker or absent in NEC tissue. Our results demonstrate that THDOC plays a structure-dependent modulatory role in epileptiform synchronization in the pilocarpine-treated epileptic rat brain where its actions are more pronounced than in NEC tissue. This evidence supports the application of neurosteroids as potential antiepileptic tools.
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Affiliation(s)
- Zahra Shiri
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC H3A 2B4, Canada
| | - Rochelle Herrington
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC H3A 2B4, Canada
| | - Maxime Lévesque
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC H3A 2B4, Canada
| | - Massimo Avoli
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC H3A 2B4, Canada.
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Differentiation of specific ripple patterns helps to identify epileptogenic areas for surgical procedures. Clin Neurophysiol 2014; 125:1339-45. [PMID: 24368032 DOI: 10.1016/j.clinph.2013.11.030] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/14/2013] [Accepted: 11/19/2013] [Indexed: 11/20/2022]
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Chaibi S, Lajnef T, Sakka Z, Samet M, Kachouri A. A reliable approach to distinguish between transient with and without HFOs using TQWT and MCA. J Neurosci Methods 2014; 232:36-46. [PMID: 24814526 DOI: 10.1016/j.jneumeth.2014.04.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 04/22/2014] [Indexed: 11/18/2022]
Abstract
Recent studies have reported that discrete high frequency oscillations (HFOs) in the range of 80-500Hz may serve as promising biomarkers of the seizure focus in humans. Visual scoring of HFOs is tiring, time consuming, highly subjective and requires a great deal of mental concentration. Due to the recent explosion of HFOs research, development of a robust automated detector is expected to play a vital role in studying HFOs and their relationship to epileptogenesis. Therefore, a handful of automated detectors have been introduced in the literature over the past few years. In fact, all the proposed methods have been associated with high false-positive rates, which essentially arising from filtered sharp transients like spikes, sharp waves and artifacts. In order to specifically minimize false positive rates and improve the specificity of HFOs detection, we proposed a new approach, which is a combination of tunable Q-factor wavelet transform (TQWT), morphological component analysis (MCA) and complex Morlet wavelet (CMW). The main findings of this study can be summarized as follows: The proposed method results in a sensitivity of 96.77%, a specificity of 85.00% and a false discovery rate (FDR) of 07.41%. Compared to this, the classical CMW method applied directly on the signals without pre-processing by TQWT-MCA achieves a sensitivity of 98.71%, a specificity of 18.75%, and an FDR of 29.95%. The proposed method may be considered highly accurate to distinguish between transients with and without HFOs. Consequently, it is remarkably reliable and robust for the detection of HFOs.
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Affiliation(s)
- Sahbi Chaibi
- Sfax University, National Engineering School of Sfax, LETI Laboratory, ENIS BPW, 3038 Sfax, Tunisia.
| | - Tarek Lajnef
- Sfax University, National Engineering School of Sfax, LETI Laboratory, ENIS BPW, 3038 Sfax, Tunisia
| | - Zied Sakka
- Sfax University, National Engineering School of Sfax, LETI Laboratory, ENIS BPW, 3038 Sfax, Tunisia
| | - Mounir Samet
- Sfax University, National Engineering School of Sfax, LETI Laboratory, ENIS BPW, 3038 Sfax, Tunisia
| | - Abdennaceur Kachouri
- Sfax University, National Engineering School of Sfax, LETI Laboratory, ENIS BPW, 3038 Sfax, Tunisia; Gabes University, ISSIG: Higher Institute of Industrial Systems, Gabes CP 6011, Tunisia
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Asano E, Brown EC, Juhász C. How to establish causality in epilepsy surgery. Brain Dev 2013; 35:706-20. [PMID: 23684007 PMCID: PMC3740064 DOI: 10.1016/j.braindev.2013.04.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 04/09/2013] [Accepted: 04/12/2013] [Indexed: 11/27/2022]
Abstract
Focality in electro-clinical or neuroimaging data often motivates epileptologists to consider epilepsy surgery in patients with medically-uncontrolled seizures, while not all focal findings are causally associated with the generation of epileptic seizures. With the help of Hill's criteria, we have discussed how to establish causality in the context of the presurgical evaluation of epilepsy. The strengths of EEG include the ability to determine the temporal relationship between cerebral activities and clinical events; thus, scalp video-EEG is necessary in the evaluation of the majority of surgical candidates. The presence of associated ictal discharges can confirm the epileptic nature of a particular spell and whether an observed neuroimaging abnormality is causally associated with the epileptic seizure. Conversely, one should be aware that scalp EEG has a limited spatial resolution and sometimes exhibits propagated epileptiform discharges more predominantly than in situ discharges generated at the seizure-onset zone. Intraoperative or extraoperative electrocorticography (ECoG) is utilized when noninvasive presurgical evaluation, including anatomical and functional neuroimaging, fails to determine the margin between the presumed epileptogenic zone and eloquent cortex. Retrospective as well as prospective studies have reported that complete resection of the seizure-onset zone on ECoG was associated with a better seizure outcome, but not all patients became seizure-free following such resective surgery. Some retrospective studies suggested that resection of sites showing high-frequency oscillations (HFOs) at >80Hz on interictal or ictal ECoG was associated with a better seizure outcome. Others reported that functionally-important areas may generate HFOs of a physiological nature during rest as well as sensorimotor and cognitive tasks. Resection of sites showing task-related augmentation of HFOs has been reported to indeed result in functional loss following surgery. Thus, some but not all sites showing interictal HFOs are causally associated with seizure generation. Furthermore, evidence suggests that some task-related HFOs can be transiently suppressed by the prior occurrence of interictal spikes. The significance of interictal HFOs should be assessed by taking into account the eloquent cortex, seizure-onset zone, and cortical lesions. Video-EEG and ECoG generally provide useful but still limited information to establish causality in presurgical evaluation. A comprehensive assessment of data derived from multiple modalities is ultimately required for successful management.
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Affiliation(s)
- Eishi Asano
- Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA.
| | - Erik C Brown
- MD-PhD Program School of Medicine, Wayne State University, Detroit, Michigan, 48201, USA,Department of Psychiatry and Behavioral Neurosciences, School of Medicine, Wayne State University, Detroit, Michigan, 48201, USA
| | - Csaba Juhász
- Department of Pediatrics Children's Hospital of Michigan, Wayne State University, Detroit, Michigan, 48201, USA,Department of Neurology, Children's Hospital of Michigan, Wayne State University, Detroit, Michigan, 48201, USA
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Pearce A, Wulsin D, Blanco JA, Krieger A, Litt B, Stacey WC. Temporal changes of neocortical high-frequency oscillations in epilepsy. J Neurophysiol 2013; 110:1167-79. [PMID: 23761699 DOI: 10.1152/jn.01009.2012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
High-frequency (100-500 Hz) oscillations (HFOs) recorded from intracranial electrodes are a potential biomarker for epileptogenic brain. HFOs are commonly categorized as ripples (100-250 Hz) or fast ripples (250-500 Hz), and a third class of mixed frequency events has also been identified. We hypothesize that temporal changes in HFOs may identify periods of increased the likelihood of seizure onset. HFOs (86,151) from five patients with neocortical epilepsy implanted with hybrid (micro + macro) intracranial electrodes were detected using a previously validated automated algorithm run over all channels of each patient's entire recording. HFOs were characterized by extracting quantitative morphologic features and divided into four time epochs (interictal, preictal, ictal, and postictal) and three HFO clusters (ripples, fast ripples, and mixed events). We used supervised classification and nonparametric statistical tests to explore quantitative changes in HFO features before, during, and after seizures. We also analyzed temporal changes in the rates and proportions of events from each HFO cluster during these periods. We observed patient-specific changes in HFO morphology linked to fluctuation in the relative rates of ripples, fast ripples, and mixed frequency events. These changes in relative rate occurred in pre- and postictal periods up to thirty min before and after seizures. We also found evidence that the distribution of HFOs during these different time periods varied greatly between individual patients. These results suggest that temporal analysis of HFO features has potential for designing custom seizure prediction algorithms and for exploring the relationship between HFOs and seizure generation.
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Affiliation(s)
- Allison Pearce
- Department of Computer Science, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Châtillon CE, Zelmann R, Hall JA, Olivier A, Dubeau F, Gotman J. Influence of contact size on the detection of HFOs in human intracerebral EEG recordings. Clin Neurophysiol 2013; 124:1541-6. [PMID: 23578565 DOI: 10.1016/j.clinph.2013.02.113] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 02/08/2013] [Accepted: 02/27/2013] [Indexed: 10/27/2022]
Abstract
OBJECTIVE High frequency oscillations (HFOs) are brief electroencephalographic events associated with epileptic activity, and likely representing biological markers of the epileptogenic zone. HFOs are usually detected with intracranial EEG and detection is influenced by contact size. The size of commercially available intracerebral electrodes varies widely. This study assesses HFO detection rates from adjacent electrode contacts in human intracerebral recordings. METHODS Intracerebral recordings were collected from 11 patients undergoing stereoelectroencephalographic investigation using hybrid depth electrodes containing adjacent large (0.8 or 5 mm(2)) and small (0.2 or 0.3 mm(2)) contacts. HFOs were marked manually during 5-min tracings in 131 pairs of adjacent large and small contacts. HFO rates per minute and mean event durations were compared between adjacent contacts. RESULTS A minimal but statistically significant advantage in ripple detection was found in a subgroup of large contacts. Otherwise, HFO rates and mean event durations were not statistically different between groups. CONCLUSION The size of clinical contacts within the studied range did not influence HFO detection in a clinically relevant manner. Larger contacts provide a minimal advantage for ripple detection. SIGNIFICANCE Our findings suggest that commercially available intracerebral electrodes with contacts between 0.2 and 5 mm(2) likely possess similar HFO detection abilities.
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Affiliation(s)
- C E Châtillon
- Department of Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada.
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Jacobs J, Staba R, Asano E, Otsubo H, Wu JY, Zijlmans M, Mohamed I, Kahane P, Dubeau F, Navarro V, Gotman J. High-frequency oscillations (HFOs) in clinical epilepsy. Prog Neurobiol 2012; 98:302-15. [PMID: 22480752 PMCID: PMC3674884 DOI: 10.1016/j.pneurobio.2012.03.001] [Citation(s) in RCA: 284] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Revised: 03/04/2012] [Accepted: 03/06/2012] [Indexed: 11/18/2022]
Abstract
Epilepsy is one of the most frequent neurological diseases. In focal medically refractory epilepsies, successful surgical treatment largely depends on the identification of epileptogenic zone. High-frequency oscillations (HFOs) between 80 and 500Hz, which can be recorded with EEG, may be novel markers of the epileptogenic zone. This review discusses the clinical importance of HFOs as markers of epileptogenicity and their application in different types of epilepsies. HFOs are clearly linked to the seizure onset zone, and the surgical removal of regions generating them correlates with a seizure free post-surgical outcome. Moreover, HFOs reflect the seizure-generating capability of the underlying tissue, since they are more frequent after the reduction of antiepileptic drugs. They can be successfully used in pediatric epilepsies such as epileptic spasms and help to understand the generation of this specific type of seizures. While mostly recorded on intracranial EEGs, new studies suggest that identification of HFOs on scalp EEG or magnetoencephalography (MEG) is possible as well. Thus not only patients with refractory epilepsies and invasive recordings but all patients might profit from the analysis of HFOs. Despite these promising results, the analysis of HFOs is not a routine clinical procedure; most results are derived from relatively small cohorts of patients and many aspects are not yet fully understood. Thus the review concludes that even if HFOs are promising biomarkers of epileptic tissue, there are still uncertainties about mechanisms of generation, methods of analysis, and clinical applicability. Large multicenter prospective studies are needed prior to widespread clinical application.
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Affiliation(s)
- J Jacobs
- Department of Neuropediatrics and Muscular Diseases, University of Freiburg, Freiburg, Germany.
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Fujiwara H, Greiner HM, Lee KH, Holland-Bouley KD, Seo JH, Arthur T, Mangano FT, Leach JL, Rose DF. Resection of ictal high-frequency oscillations leads to favorable surgical outcome in pediatric epilepsy. Epilepsia 2012; 53:1607-17. [PMID: 22905734 DOI: 10.1111/j.1528-1167.2012.03629.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Intracranial electroencephalography (EEG) is performed as part of an epilepsy surgery evaluation when noninvasive tests are incongruent or the putative seizure-onset zone is near eloquent cortex. Determining the seizure-onset zone using intracranial EEG has been conventionally based on identification of specific ictal patterns with visual inspection. High-frequency oscillations (HFOs, >80 Hz) have been recognized recently as highly correlated with the epileptogenic zone. However, HFOs can be difficult to detect because of their low amplitude. Therefore, the prevalence of ictal HFOs and their role in localization of epileptogenic zone on intracranial EEG are unknown. METHODS We identified 48 patients who underwent surgical treatment after the surgical evaluation with intracranial EEG, and 44 patients met criteria for this retrospective study. Results were not used in surgical decision making. Intracranial EEG recordings were collected with a sampling rate of 2,000 Hz. Recordings were first inspected visually to determine ictal onset and then analyzed further with time-frequency analysis. Forty-one (93%) of 44 patients had ictal HFOs determined with time-frequency analysis of intracranial EEG. KEY FINDINGS Twenty-two (54%) of the 41 patients with ictal HFOs had complete resection of HFO regions, regardless of frequency bands. Complete resection of HFOs (n = 22) resulted in a seizure-free outcome in 18 (82%) of 22 patients, significantly higher than the seizure-free outcome with incomplete HFO resection (4/19, 21%). SIGNIFICANCE Our study shows that ictal HFOs are commonly found with intracranial EEG in our population largely of children with cortical dysplasia, and have localizing value. The use of ictal HFOs may add more promising information compared to interictal HFOs because of the evidence of ictal propagation and followed by clinical aspect of seizures. Complete resection of HFOs is a favorable prognostic indicator for surgical outcome.
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Affiliation(s)
- Hisako Fujiwara
- Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA
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Lévesque M, Bortel A, Gotman J, Avoli M. High-frequency (80-500 Hz) oscillations and epileptogenesis in temporal lobe epilepsy. Neurobiol Dis 2011; 42:231-41. [PMID: 21238589 PMCID: PMC4873283 DOI: 10.1016/j.nbd.2011.01.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 11/17/2010] [Accepted: 01/02/2011] [Indexed: 11/25/2022] Open
Abstract
High-frequency oscillations (HFOs), termed ripples (80-200 Hz) and fast ripples (250-600 Hz), are recorded in the EEG of epileptic patients and in animal epilepsy models; HFOs are thought to reflect pathological activity and seizure onset zones. Here, we analyzed the temporal and spatial evolution of interictal spikes with and without HFOs in the rat pilocarpine model of temporal lobe epilepsy. Depth electrode recordings from dentate gyrus (DG), CA3 region, subiculum and entorhinal cortex (EC), were obtained from rats between the 4th and 15th day after a status epilepticus (SE) induced by i.p. injection of pilocarpine. The first seizure occurred 6.1 ± 2.5 days after SE (n = 7 rats). Five of 7 animals exhibited interictal spikes that co-occurred with fast ripples accounting for 4.9 ± 4.6% of all analyzed interictal spikes (n = 12,886) while all rats showed interictal spikes co-occurring with ripples, accounting for 14.3 ± 3.4% of all events. Increased rates of interictal spikes without HFOs in the EC predicted upcoming seizures on the following day, while rates of interictal spikes with fast ripples in CA3 reflected periods of high seizure occurrence. Finally, interictal spikes co-occurring with ripples did not show any specific relation to seizure occurrence. Our findings identify different temporal and spatial developmental patterns for the rates of interictal spikes with or without HFOs in relation with seizure occurrence. These distinct categories of interictal spikes point at dynamic processes that should bring neuronal networks close to seizure generation.
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Affiliation(s)
- Maxime Lévesque
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
| | - Aleksandra Bortel
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
| | - Jean Gotman
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
| | - Massimo Avoli
- Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montreal, Qc, Canada H3A 2B4
- Dipartimento di Medicina Sperimentale, Sapienza Università di Roma, Viale del Castro Laurenziano 9, 00185 Roma, Italy
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Hsu D, Hsu M, Grabenstatter HL, Worrell GA, Sutula TP. Time-frequency analysis using damped-oscillator pseudo-wavelets: Application to electrophysiological recordings. J Neurosci Methods 2010; 194:179-92. [PMID: 20933002 DOI: 10.1016/j.jneumeth.2010.09.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2010] [Revised: 09/17/2010] [Accepted: 09/27/2010] [Indexed: 10/19/2022]
Abstract
The damped-oscillator pseudo-wavelet is presented as a method of time-frequency analysis along with a new spectral density measure, the data power. An instantaneous phase can be defined for this pseudo-wavelet, and it is easily inverted. The data power measure is tested on both computer generated data and in vivo intrahippocampal electrophysiological recordings from a rat. The data power spectral density is found to give better time and frequency resolution than the more conventional total energy measure, and additionally shows intricate time-frequency structure in the rat that is altered in association with the emergence of epilepsy. With epileptogenesis, the baseline theta oscillation is severely degraded and is absorbed into a broader gamma band. There are also broad 600 Hz and 2000 Hz bands which localize to hippocampal layers that are distinct from those of the theta and gamma bands. The 600 Hz band decreases in prominence with epileptogenesis while the 2000 Hz band increases in prominence. The origins of these high frequency bands await further study. In general, we find that the damped-oscillator pseudo-wavelet is easy to use and is particularly suitable for problems where a wide range of oscillator frequencies is expected.
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Affiliation(s)
- David Hsu
- Department of Neurology, University of Wisconsin, Madison, WI, USA.
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35
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Abstract
PURPOSE OF REVIEW It has been 10 years since pathological high-frequency oscillations (pHFOs) were described in the brain of epileptic animals and patients. This review summarizes progress in research on mechanisms of their generation and potential clinical applications over that period. RECENT FINDINGS Initially, pHFOs were recorded with microelectrodes in the hippocampus of rodents and patients with mesial temporal lobe epilepsy (MTLE), but recently pHFOs have also been recorded with clinical depth and grid electrodes in multiple brain areas including the hippocampus and neocortex of patients with different types of epilepsy. One hypothesis is that pHFOs reflect fields of hypersynchronized action potentials (bursts of population spikes) within small discrete neuronal clusters responsible for seizure generation. Studies suggest that pHFOs can be used as a reliable biomarker for epileptogenesis, epileptogenicity, and the delineation of the epileptogenic region. SUMMARY Recording of pHFOs with clinical electrodes provides a means for further investigation of their functional role in the epileptic brain and as a potential biomarker of epileptogenesis and epileptogenicity and for presurgical mapping.
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Affiliation(s)
- Anatol Bragin
- Department of Neurology, David Geffen School of Medicine at UCLA,, Los Angeles, California, USA
- Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Jerome Engel
- Department of Neurology, David Geffen School of Medicine at UCLA,, Los Angeles, California, USA
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Richard J. Staba
- Department of Neurology, David Geffen School of Medicine at UCLA,, Los Angeles, California, USA
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