Ictal wideband ECoG: Direct comparison between ictal slow shifts and high frequency oscillations

Imamura, Hisaji; Matsumoto, Riki; Inouchi, Morito; Matsuhashi, Masao; Mikuni, Nobuhiro; Takahashi, Ryōsuke; Ikeda, Akio

doi:10.1016/j.clinph.2010.12.060

Cited by 48 publications

(46 citation statements)

References 14 publications

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“…[4849] More recent studies by other investigators further confirmed that DC shifts were indeed recordable using AC amplifiers if long time constants were used during acquisition, and appropriate filters and time scales were used for display. [14505152535455] In line with these observations, more recent studies using dedicated DC-coupled amplifiers have also shown the occurrence of ictal DC shifts in both scalp and intracranial recordings in humans. [565758] To avoid confusion with the terminology when AC recordings are analyzed, the term IBSs was used to refer to the DC shifts.…”

Section: Ibss and Isamentioning

confidence: 65%

“…[14] Similarly, in a patient with right TLE analyzed with 0.016-600 Hz bandwidth EEG, the IBSs were found to precede the HFOs by 1.6 s and conventional EEG by 20.4 s, and the patient achieved seizure freedom after resection of the broadband EEG contacts. [52] In addition to these 2 case reports, in a series of 6 patients with neocortical epilepsy analyzed with 0.016-300 Hz bandwidth EEG, Modur et al ., found that the seizure onset defined by CFA was delayed by <1 s compared to HFO+ (ictal HFOs with evolution, see above) or IBSs. Temporally, the HFO+ preceded or followed the IBSs by ~300-ms; spatially, the HFO+ and IBSs had similar distribution (18 vs. 15 contacts, P = 0.09) and concordance (Cohen k = 0.50).…”

Section: Broadband Eeg Analysis Of High Infraslow and Conventional Fmentioning

confidence: 99%

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High frequency oscillations and infraslow activity in epilepsy

Modur

2014

Ann Indian Acad Neurol

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In pre-surgical evaluation of epilepsy, there has been an increased interest in the study of electroencephalogram (EEG) activity outside the 1-70 Hz band of conventional frequency activity (CFA). Research over the last couple of decades has shown that EEG activity in the 70-600 Hz range, termed high frequency oscillations (HFOs), can be recorded intracranially from all brain regions both interictally and at seizure onset. In patients with epilepsy, HFOs are now considered as pathologic regardless of their frequency band although it may be difficult to distinguish them from the physiologic HFOs, which occur in a similar frequency range. Interictal HFOs are likely to be confined mostly to the seizure onset zone, thus providing a new measure for localizing it. More importantly, several studies have linked HFOs to underlying epileptogenicity, suggesting that HFOs can serve as potential biomarkers for the illness. Along with HFOs, analysis of ictal baseline shifts (IBS; or direct current shifts) and infraslow activity (ISA) (ISA: <0.1 Hz) has also attracted attention. Studies have shown that: IBSs can be recorded using the routine AC amplifiers with long time constants; IBSs occur at the time of conventional EEG onset, but in a restricted spatial distribution compared with conventional frequencies; and inclusion of IBS contacts in the resection can be associated with favorable seizure outcome. Only a handful of studies have evaluated all the EEG frequencies together in the same patient group. The latter studies suggest that the seizure onset is best localized by the ictal HFOs, the IBSs tend to provide a broader localization and the conventional frequencies could be non-localizing. However, small number of patients included in these studies precludes definitive conclusions regarding post-operative seizure outcome based on selective or combined resection of HFO, IBS and CFA contacts. Large, preferably prospective, studies are needed to further evaluate the implications of different EEG frequencies in epilepsy.

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Section: Ibss and Isamentioning

confidence: 65%

Section: Broadband Eeg Analysis Of High Infraslow and Conventional Fmentioning

confidence: 99%

High frequency oscillations and infraslow activity in epilepsy

Modur

2014

Ann Indian Acad Neurol

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“…It is noteworthy that the ictal ISA, conventional iEEG, and HFOs are temporally related. The onset of an ictal baseline shift precedes the onset of ictal HFOs or conventional EEG onset [68,[76][77][78]. Interestingly, Ren [79] found in three patients that periodic slow negative baseline shifts, named ''very low frequency oscillation'', precede seizure onset by 8-22 min.…”

Section: Infra-slow Activitymentioning

confidence: 99%

Advances of Intracranial Electroencephalography in Localizing the Epileptogenic Zone

Jin

Wang

2016

Neurosci. Bull.

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Intracranial electroencephalography (iEEG) provides the best precision in estimating the location and boundary of an epileptogenic zone. Analysis of iEEG in the routine EEG frequency range (0.5-70 Hz) remains the basis in clinical practice. Low-voltage fast activity is the most commonly reported ictal onset pattern in neocortical epilepsy, and low-frequency high-amplitude repetitive spiking is the most commonly reported ictal onset pattern in mesial temporal lobe epilepsy. Recent studies using wideband EEG recording have demonstrated that examining higher (80-1000 Hz) and lower (0.016-0.5 Hz) EEG frequencies can provide additional diagnostic information and help to improve the surgical outcome. In addition, novel computational techniques of iEEG signal analysis have provided new insights into the epileptic network. Here, we review some of these recent advances. Although these sophisticated and advanced techniques of iEEG analysis show promise in localizing the epileptogenic zone, their utility needs to be further validated in larger studies.

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“…The duration of ISWs varied between 0.3 to 6.0 s and maximum amplitude varied from 0.2 to 1.4 mV. Imamura et al (2011) found that in wideband ECoG, negative slow shifts coexisted with HFO (100-300 Hz) in the ictal onset zone in all investigated seizures. Slow shifts always preceded HFO and conventional initial EEG changes by a mean value of 1.6 and 20.4 s, respectively.…”

Section: Bmentioning

confidence: 93%

“…Along with HFOs, analysis of ictal baseline shifts (IBSs or direct current shifts) and infraslow activity (< 0.1 Hz) attracted attention (John et al, 2005;Imamura et al, 2011;Modur 2014). It has been shown that the initial ictal slow shift may be seen as the first sign of an ictal event, occurring at the time of conventional EEG seizure onset or before the later typical Heinz Gregor Wieser Figure 4.…”

Section: Bmentioning

confidence: 99%

Presurgical diagnosis of epilepsies – concepts and diagnostic tools

Wieser

2016

Journal of Epileptology

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Introduction. Numerous reviews of the currently established concepts, strategies and diagnostic tools used in epilepsy surgery have been published. The focus concept which was initially developed by Forster, Penfield and Jasper and popularised and enriched by Lüders, is still fundamental for epilepsy surgery. Aim. To present different conceptual views of the focus concept and to discuss more recent network hypothesis, emphasizing so-called "critical modes of an epileptogenic circuit". Method. A literature search was conducted using keywords: presurgical evaluation, epileptic focus concepts, cortical zones, diagnostic tools. Review and remarks. The theoretical concepts of the epileptic focus are opposed to the network hypothesis. The definitions of the various cortical zones have been conceptualized in the presurgical evaluation of candidates for epilepsy surgery: the seizure onset zone versus the epileptogenic zone, the symptomatogenic zone, the irritative and functional deficit zones are characterized. The epileptogenic lesion, the "eloquent cortex" and secondary epileptogenesis (mirror focus) are dealt with. The current diagnostic techniques used in the definition of these cortical zones, such as video-EEG monitoring, non-invasive and invasive EEG recording techniques, magnetic resonance imaging, ictal single photon emission computed tomography, and positron emission tomography, are discussed and illustrated. Potential modern surrogate markers of epileptogenicity, such as High frequency oscillations, Ictal slow waves/DC shifts, Magnetic resonance spectroscopy, Functional MRI, the use of Magnetized nanoparticles in MRI, Transcranial magnetic stimulation, Optical intrinsic signal imaging, and Seizure prediction are discussed. Particular emphasis is put on the EEG: Scalp EEG, semi-invasive and invasive EEG (Stereoelectroencephalography) and intraoperative electrocorticography are illustrated. Ictal SPECT and 18 F-FDG PET are very helpful and several other procedures, such as dipole source localization and spike-triggered functional MRI are already widely used. The most important lateralizing and localizing ictal signs and symptoms are summarized. It is anticipated that the other clinically valid surrogate markers of epileptogenesis and epileptogenicity will be further developed in the near future. Until then the concordance of the results of seizure semiology, localization of epileptogenicity by EEG and MRI remains the most important prerequisite for successful epilepsy surgery. Conclusions and future perspectives. Resective epilepsy surgery is a widely accepted and successful therapeutic approach, rendering up to 80% of selected patients seizure free. Although other therapies, such as radiosurgery, and responsive neurostimulation will increasingly play a role in patients with an unresectable lesion, it is unlikely that they will replace selective resective surgery. The hope is that new diagnostic techniques will be developed that permit more direct definition and measurement of the epileptogenic zone.

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Ictal wideband ECoG: Direct comparison between ictal slow shifts and high frequency oscillations

Cited by 48 publications

References 14 publications

High frequency oscillations and infraslow activity in epilepsy

High frequency oscillations and infraslow activity in epilepsy

Advances of Intracranial Electroencephalography in Localizing the Epileptogenic Zone

Presurgical diagnosis of epilepsies – concepts and diagnostic tools

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