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https://www.readbyqxmd.com/read/29111591/magnetoencephalographic-imaging-of-ictal-high-frequency-oscillations-80-200%C3%A2-hz-in-pharmacologically-resistant-focal-epilepsy
#1
Jayabal Velmurugan, Srikantan S Nagarajan, Narayanan Mariyappa, Shankar G Ravi, Kandavel Thennarasu, Ravindranadh C Mundlamuri, Kenchaiah Raghavendra, Rose Dawn Bharath, Jitender Saini, Arimappamagan Arivazhagan, Jamuna Rajan, Anita Mahadevan, Malla B Rao, Parthasarathy Satishchandra, Sanjib Sinha
OBJECTIVE: Specificity of ictal high-frequency oscillations (HFOs) in identifying epileptogenic abnormality is significant, compared to the spikes and interictal HFOs. The objectives of the study were to detect and to localize ictal HFOs by magnetoencephalography (MEG) for identifying the seizure onset zone (SOZ), evaluate the cortical excitability from preictal to ictal transition, and establish HFO concordance rates with other modalities and postsurgical resection. METHODS: Sixty-seven patients with drug-resistant epilepsy had at least 1 spontaneous seizure each during MEG acquisition, and analysis was carried out on 20 seizures from 20 patients...
November 7, 2017: Epilepsia
https://www.readbyqxmd.com/read/29093566/hypertension-induces-additional-cardiometabolic-impairments-and-attenuates-aerobic-exercise-training-adaptations-in-fructose-fed-ovariectomized-rats
#2
Janaina de O Brito-Monzani, Iris Callado Sanches, Nathalia Bernardes, Kátia Ponciano, Ivana C Moraes-Silva, Maria-Cláudia Irigoyen, Susana Llesuy, Kátia De Angelis
We tested whether hypertension favors the development of additional cardiometabolic changes in fructose-fed ovariectomized rats and how it affects aerobic exercise training (ET) effects. All rats received fructose in drinking water (10%) beginning at weaning, were ovariectomized at 10 weeks of age and divided into the normotensive sedentary (NFOS) and trained (NFOT) and hypertensive sedentary (HFOS) and trained (HFOT) groups. ET was performed on a treadmill. Arterial pressure (AP) was directly recorded; heart rate and AP variabilities were analyzed...
November 2, 2017: Hypertension Research: Official Journal of the Japanese Society of Hypertension
https://www.readbyqxmd.com/read/29062105/resection-of-high-frequency-oscillations-predicts-seizure-outcome-in-the-individual-patient
#3
Tommaso Fedele, Sergey Burnos, Ece Boran, Niklaus Krayenbühl, Peter Hilfiker, Thomas Grunwald, Johannes Sarnthein
High frequency oscillations (HFOs) are recognized as biomarkers for epileptogenic brain tissue. A remaining challenge for epilepsy surgery is the prospective classification of tissue sampled by individual electrode contacts. We analysed long-term invasive recordings of 20 consecutive patients who subsequently underwent epilepsy surgery. HFOs were defined prospectively by a previously validated, automated algorithm in the ripple (80-250 Hz) and the fast ripple (FR, 250-500 Hz) frequency band. Contacts with the highest rate of ripples co-occurring with FR over several five-minute time intervals designated the HFO area...
October 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29060055/a-novel-hfo-based-method-for-unsupervised-localization-of-the-seizure-onset-zone-in-drug-resistant-epilepsy
#4
Paige M Murphy, Adam J von Paternos, Sabato Santaniello
High frequency oscillations (HFOs) are potential biomarkers of epileptic areas. In patients with drug-resistant epilepsy, HFO rates tend to be higher in the seizure onset zone (SOZ) than in other brain regions and the resection of HFO-generating areas positively correlates with seizure-free surgery outcome. Nonetheless, the development of robust unsupervised HFO-based tools for SOZ localization remains challenging. Current approaches predict the SOZ by processing small samples of intracranial EEG (iEEG) data and applying patient-specific thresholds on the HFO rate...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28983917/influence-of-the-location-and-type-of-epileptogenic-lesion-on-scalp-interictal-epileptiform-discharges-and-high-frequency-oscillations
#5
Carolina Cuello-Oderiz, Nicolas von Ellenrieder, François Dubeau, Jean Gotman
OBJECTIVE: To increase the diagnostic power of scalp electroencephalography (EEG) by investigating whether lesion type and location influence the morphology of interictal epileptic discharges (IEDs) and the likelihood that IEDs and high-frequency oscillations (HFOs) are present. METHODS: We studied EEG activity in epilepsy patients with lesional epilepsy. Lesions were classified by type and by location (region and depth). We marked a maximum of 50 IEDs during deep non-rapid eye movement sleep...
October 6, 2017: Epilepsia
https://www.readbyqxmd.com/read/28981957/the-role-of-high-frequency-oscillations-in-epilepsy-surgery-planning
#6
REVIEW
David Gloss, Sarah J Nevitt, Richard Staba
BACKGROUND: Epilepsy is a serious brain disorder characterized by recurrent unprovoked seizures. Approximately two-thirds of seizures can be controlled with antiepileptic medications (Kwan 2000). For some of the others, surgery can completely eliminate or significantly reduce the occurrence of disabling seizures. Localization of epileptogenic areas for resective surgery is far from perfect, and new tools are being investigated to more accurately localize the epileptogenic zone (the zone of the brain where the seizures begin) and improve the likelihood of freedom from postsurgical seizures...
October 5, 2017: Cochrane Database of Systematic Reviews
https://www.readbyqxmd.com/read/28961101/low-to-high-cross-frequency-coupling-in-the-electrical-rhythms-as-biomarker-for-hyperexcitable-neuro-glial-networks-of-the-brain
#7
Vasily Grigorovsky, Berj L Bardakjian
OBJECTIVE: One of the features used in the study of hyperexcitablility are high frequency oscillations (HFOs, >80Hz). HFOs have been reported in the electrical rhythms of the brain's neuro-glial networks under physiological and pathological conditions. Cross-frequency coupling (CFC) of HFOs with low frequency rhythms was used to identify pathologic HFOs (pHFOs) (i) in the epileptogenic zones of epileptic patients, and (ii) as a biomarker for the severity of seizure-like events in genetically modified rodent models...
September 28, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28948998/bimodal-coupling-of-ripples-and-slower-oscillations-during-sleep-in-patients-with-focal-epilepsy
#8
Inkyung Song, Iren Orosz, Inna Chervoneva, Zachary J Waldman, Itzhak Fried, Chengyuan Wu, Ashwini Sharan, Noriko Salamon, Richard Gorniak, Sandra Dewar, Anatol Bragin, Jerome Engel, Michael R Sperling, Richard Staba, Shennan A Weiss
OBJECTIVE: Differentiating pathologic and physiologic high-frequency oscillations (HFOs) is challenging. In patients with focal epilepsy, HFOs occur during the transitional periods between the up and down state of slow waves. The preferred phase angles of this form of phase-event amplitude coupling are bimodally distributed, and the ripples (80-150 Hz) that occur during the up-down transition more often occur in the seizure-onset zone (SOZ). We investigated if bimodal ripple coupling was also evident for faster sleep oscillations, and could identify the SOZ...
November 2017: Epilepsia
https://www.readbyqxmd.com/read/28917017/physiological-ripples-%C3%A2-%C3%A2-100%C3%A2-hz-in-spike-free-scalp-eegs-of-children-with-and-without-epilepsy
#9
Anne H Mooij, Renee C M A Raijmann, Floor E Jansen, Kees P J Braun, Maeike Zijlmans
Pathological high frequency oscillations (HFOs, >80 Hz) are considered new biomarkers for epilepsy. They have mostly been recorded invasively, but pathological ripples (80-250 Hz) can also be found in scalp EEGs with frequent epileptiform spikes. Physiological HFOs also exist. They have been recorded invasively in hippocampus and neocortex. There are no reports of spontaneously occurring physiological HFOs recorded with scalp EEG. We aimed to study ripples in spike-free scalp EEGs. We included 23 children (6 with, 17 without epilepsy) who had an EEG without interictal epileptiform spikes recorded during sleep...
November 2017: Brain Topography
https://www.readbyqxmd.com/read/28860077/the-cs-algorithm-a-novel-method-for-high-frequency-oscillation-detection-in-eeg
#10
Jan Cimbálník, Angela Hewitt, Greg Worrell, Matt Stead
BACKGROUND: High frequency oscillations (HFOs) are emerging as potentially clinically important biomarkers for localizing seizure generating regions in epileptic brain. These events, however, are too frequent, and occur on too small a time scale to be identified quickly or reliably by human reviewers. Many of the deficiencies of the HFO detection algorithms published to date are addressed by the CS algorithm presented here. NEW METHOD: The algorithm employs novel methods for: 1) normalization; 2) storage of parameters to model human expertise; 3) differentiating highly localized oscillations from filtering phenomena; and 4) defining temporal extents of detected events...
August 30, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28750290/high-frequency-activity-overriding-cortico-cortical-evoked-potentials-reflects-altered-excitability-in-the-human-epileptic-focus
#11
Katsuya Kobayashi, Riki Matsumoto, Masao Matsuhashi, Kiyohide Usami, Akihiro Shimotake, Takeharu Kunieda, Takayuki Kikuchi, Kazumichi Yoshida, Nobuhiro Mikuni, Susumu Miyamoto, Hidenao Fukuyama, Ryosuke Takahashi, Akio Ikeda
OBJECTIVE: We aimed to clarify that high frequency activity (HFA) of cortico-cortical evoked potentials (CCEPs), elicited by single pulse electrical stimulation (SPES), reflects cortical excitability. METHODS: We recruited 16 patients with refractory partial epilepsy who had chronic subdural electrode implantation for presurgical evaluation. A repetitive SPES was given to (1) the seizure onset zone (SOZ) and (2) the control cortices (non-seizure onset zone: nSOZ)...
September 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28748408/a-simple-statistical-method-for-the-automatic-detection-of-ripples-in-human-intracranial-eeg
#12
K Charupanit, B A Lopour
High frequency oscillations (HFOs) are a promising biomarker of epileptic tissue, but detection of these electrographic events remains a challenge. Automatic detectors show encouraging results, but they typically require optimization of multiple parameters, which is a barrier to good performance and broad applicability. We therefore propose a new automatic HFO detection algorithm, focusing on simplicity and ease of implementation. It requires tuning of only an amplitude threshold, which can be determined by an iterative process or directly calculated from statistics of the rectified filtered data (i...
July 26, 2017: Brain Topography
https://www.readbyqxmd.com/read/28702346/automatic-detection-and-visualisation-of-meg-ripple-oscillations-in-epilepsy
#13
Nicole van Klink, Frank van Rosmalen, Jukka Nenonen, Sergey Burnos, Liisa Helle, Samu Taulu, Paul Lawrence Furlong, Maeike Zijlmans, Arjan Hillebrand
High frequency oscillations (HFOs, 80-500 Hz) in invasive EEG are a biomarker for the epileptic focus. Ripples (80-250 Hz) have also been identified in non-invasive MEG, yet detection is impeded by noise, their low occurrence rates, and the workload of visual analysis. We propose a method that identifies ripples in MEG through noise reduction, beamforming and automatic detection with minimal user effort. We analysed 15 min of presurgical resting-state interictal MEG data of 25 patients with epilepsy. The MEG signal-to-noise was improved by using a cross-validation signal space separation method, and by calculating ~ 2400 beamformer-based virtual sensors in the grey matter...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28681378/update-on-the-mechanisms-and-roles-of-high-frequency-oscillations-in-seizures-and-epileptic-disorders
#14
REVIEW
Premysl Jiruska, Catalina Alvarado-Rojas, Catherine A Schevon, Richard Staba, William Stacey, Fabrice Wendling, Massimo Avoli
High-frequency oscillations (HFOs) are a type of brain activity that is recorded from brain regions capable of generating seizures. Because of the close association of HFOs with epileptogenic tissue and ictogenesis, understanding their cellular and network mechanisms could provide valuable information about the organization of epileptogenic networks and how seizures emerge from the abnormal activity of these networks. In this review, we summarize the most recent advances in the field of HFOs and provide a critical evaluation of new observations within the context of already established knowledge...
August 2017: Epilepsia
https://www.readbyqxmd.com/read/28676240/local-nmda-receptor-hypofunction-evokes-generalized-effects-on-gamma-and-high-frequency-oscillations-and-behavior
#15
Jaime Lee, Matthew R Hudson, Terence J O'Brien, Jess Nithianantharajah, Nigel C Jones
The NMDA receptor (NMDAr) hypofunction theory of schizophrenia suggests that aberrant signaling through NMDAr underlies the pathophysiology of this disease. This is commonly modeled in rodents via treatment with NMDAr antagonists, which causes a range of behavioral effects that represent endophenotypes related to schizophrenia. These drugs also disrupt high-frequency neural oscillations within the brain, also potentially relevant to disease. We studied the effect of localized NMDAr hypofunction on the generation of neural oscillations occurring both locally and in distant brain regions, and on behaviors routinely used as endophenotypes to model psychosis in rodents...
July 1, 2017: Neuroscience
https://www.readbyqxmd.com/read/28669244/automated-detector-of-high-frequency-oscillations-in-epilepsy-based-on-maximum-distributed-peak-points
#16
Guo-Ping Ren, Jia-Qing Yan, Zhi-Xin Yu, Dan Wang, Xiao-Nan Li, Shan-Shan Mei, Jin-Dong Dai, Xiao-Li Li, Yun-Lin Li, Xiao-Fei Wang, Xiao-Feng Yang
High frequency oscillations (HFOs) are considered as biomarker for epileptogenicity. Reliable automation of HFOs detection is necessary for rapid and objective analysis, and is determined by accurate computation of the baseline. Although most existing automated detectors measure baseline accurately in channels with rare HFOs, they lose accuracy in channels with frequent HFOs. Here, we proposed a novel algorithm using the maximum distributed peak points method to improve baseline determination accuracy in channels with wide HFOs activity ranges and calculate a dynamic baseline...
April 17, 2017: International Journal of Neural Systems
https://www.readbyqxmd.com/read/28666056/high-frequency-oscillations-the-state-of-clinical-research
#17
REVIEW
Birgit Frauscher, Fabrice Bartolomei, Katsuhiro Kobayashi, Jan Cimbalnik, Maryse A van 't Klooster, Stefan Rampp, Hiroshi Otsubo, Yvonne Höller, Joyce Y Wu, Eishi Asano, Jerome Engel, Philippe Kahane, Julia Jacobs, Jean Gotman
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...
August 2017: Epilepsia
https://www.readbyqxmd.com/read/28655938/significance-of-high-frequency-electrical-brain-activity
#18
REVIEW
Katsuhiro Kobayashi, Tomoyuki Akiyama, Takashi Agari, Tatsuya Sasaki, Takashi Shibata, Yoshiyuki Hanaoka, Mari Akiyama, Fumika Endoh, Makio Oka, Isao Date
 Electroencephalogram (EEG) data include broadband electrical brain activity ranging from infra-slow bands (< 0.1 Hz) to traditional frequency bands (e.g., the approx. 10 Hz alpha rhythm) to high-frequency bands of up to 500 Hz. High-frequency oscillations (HFOs) including ripple and fast ripple oscillations (80-200 Hz and>200 / 250 Hz, respectively) are particularly of note due to their very close relationship to epileptogenicity, with the possibility that they could function as a surrogate biomarker of epileptogenicity...
June 2017: Acta Medica Okayama
https://www.readbyqxmd.com/read/28644911/interictal-oscillations-and-focal-epileptic-disorders
#19
Maxime Lévesque, Pariya Salami, Zahra Shiri, Massimo Avoli
Neuronal network oscillations represent a main feature of the brain activity recorded in the EEG under normal and pathological conditions such as epilepsy. Specific oscillations occur between seizures in patients and in animal models of focal epilepsy, and thus they are termed interictal. According to their shape and intrinsic signal frequency, interictal oscillations are classified as spikes and high frequency oscillations (HFOs). Interictal spikes are recorded in the "wideband" EEG signal and consist of large-amplitude events that usually last less than 1 s; HFOs, in contrast, are extracted by amplifying the appropriately filtered EEG signal, and are usually categorized as ripples (80-200 Hz) and fast ripples (250-500 Hz)...
June 23, 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28622421/how-to-record-high-frequency-oscillations-in-epilepsy-a-practical-guideline
#20
REVIEW
Maeike Zijlmans, Gregory A Worrell, Matthias Dümpelmann, Thomas Stieglitz, Andrei Barborica, Marcel Heers, Akio Ikeda, Naotaka Usui, Michel Le Van Quyen
OBJECTIVE: Technology for localizing epileptogenic brain regions plays a central role in surgical planning. Recent improvements in acquisition and electrode technology have revealed that high-frequency oscillations (HFOs) within the 80-500 Hz frequency range provide the neurophysiologist with new information about the extent of the epileptogenic tissue in addition to ictal and interictal lower frequency events. Nevertheless, two decades after their discovery there remain questions about HFOs as biomarkers of epileptogenic brain and there use in clinical practice...
August 2017: Epilepsia
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