The role of high-frequency oscillations in epilepsy surgery planning

Gloss, David; Nolan, Sarah J; Staba, Richard J.

doi:10.1002/14651858.cd010235.pub2

Cited by 22 publications

(18 citation statements)

References 59 publications

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“…A Cochrane review 49 assessing this question identified two studies with a total of 11 participants who implemented identification of ictal HFOs in their surgical decision making. The authors concluded that no reliable conclusions could be drawn regarding the efficacy of HFO recordings in epilepsy surgery decision making, due to methodological limitations and the small sample size.…”

Section: Hfos As Markers Of the Epileptogenic Zonementioning

confidence: 99%

High‐frequency oscillations: The state of clinical research

et al. 2017

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Summary 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 post-surgical 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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Section: Hfos As Markers Of the Epileptogenic Zonementioning

confidence: 99%

High‐frequency oscillations: The state of clinical research

et al. 2017

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“…As a biomarker of epileptogenesis, pathological HFOs could help identify individuals at risk for developing epilepsy after an epileptogenic insult and could be useful in the design of animal screening models for discovery of new anti-seizure and anti-epileptogenic drugs [23]. However, significant work remains to be done in order for HFOs (and similarly for IIS and microseizures) to fulfill their potential as biomarkers, including identifying strategies to reliably distinguish pathological from normal HFOs in the human epileptic brain [23][24][25]; developing non-invasive methods to record HFOs, which are now best detected using intracerebral EEG recording; efficient and accurate detection methods and automated tools for unbiased quantification of HFOs in wide bandwidth recordings across patients [8]; and, ultimately, prospective studies that can incorporate individual patient HFO data in planning the area for resection and follow patients to determine postsurgical seizure freedom [26]. Here we discuss HFOs, microseizures, and IIS, although a significant portion of this review focuses on HFOs based on the recent number of studies supporting their potential role as an electrophysiological biomarker of epilepsy.…”

Section: Introductionmentioning

confidence: 99%

Electrophysiological Biomarkers of Epilepsy

2014

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In patients being evaluated for epilepsy and in animal models of epilepsy, electrophysiological recordings are carried to capture seizures to determine the existence of epilepsy. Electroencephalography recordings from the scalp, or sometimes directly from the brain, are also used to locate brain areas where seizure begins, and in surgical treatment help plan the area for resection. As seizures are unpredictable and can occur infrequently, ictal recordings are not ideal in terms of time, cost, or risk when, for example, determining the efficacy of existing or new anti-seizure drugs, evaluating potential anti-epileptogenic interventions, or for prolonged intracerebral electrode studies. Thus, there is a need to identify and validate other electrophysiological biomarkers of epilepsy that could be used to diagnose, treat, cure, and prevent epilepsy. Electroencephalography recordings in the epileptic brain contain other interictal electrophysiological disturbances that can occur more frequently than seizures, such as interictal spikes (IIS) and sharp waves, and from invasive studies using wide bandwidth recording and small diameter electrodes, the discovery of pathological high-frequency oscillations (HFOs) and microseizures. Of IIS, HFOs, and microseizures, a significant amount of recent research has focused on HFOs in the pathophysiology of epilepsy. Results from studies in animals with epilepsy and presurgical patients have consistently found a strong association between HFOs and epileptogenic brain tissue that suggest HFOs could be a potential biomarker of epileptogenicity and epileptogenesis. Here, we discuss several aspects of HFOs, as well as IIS and microseizures, and the evidence that supports their role as biomarkers of epilepsy.

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“…Although HFOs or ripple, fast ripples can record with intracranial recordings in epilepsy [28][29][30][31], it has significant limitation. Specifically, intracranial recordings are typically done with micro-or macroelectrode EEG placed within the scalp.…”

Section: Editorialmentioning

confidence: 99%

“…Specifically, intracranial recordings are typically done with micro-or macroelectrode EEG placed within the scalp. Those recordings are also called intracranial EEG (iEEG), or ECoG [28][29][30][31]. The placement of electrodes require risky surgery, it is very invasive.…”

Section: Editorialmentioning

confidence: 99%