Spatial variation in high-frequency oscillation rates and amplitudes in intracranial EEG

Guragain, H.; Cimbálník, Jan; Stead, Matt; Groppe, David M.; Berry, Brent M.; Kremen, Václav; Kenney‐Jung, Daniel L.; Britton, Jeffrey W.; Worrell, Gregory A.; Brinkmann, Benjamin H.

doi:10.1212/wnl.0000000000004998

Cited by 58 publications

(65 citation statements)

References 40 publications

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“…Their generation has been related to local balance of excitation and inhibition, interneurons being a likely key player in their generation. 39 Fast Ripples Are Very Rare in Both Eloquent and Noneloquent Cortical Areas Only 5% of all channels had 1 fast ripple every 5 minutes; these channels were also located in eloquent cortex. 34,35 Regions identified with higher ripple rates correspond to cortical regions that have a higher degree of myelination.…”

Section: Selection Of Channels From Presumably Normal Brain Regionsmentioning

confidence: 96%

“…The usefulness of this approach is underlined by a paper investigating anatomic variation of HFO rates and amplitudes inside and outside the seizure-onset zone. 39 Fast Ripples Are Very Rare in Both Eloquent and Noneloquent Cortical Areas Only 5% of all channels had 1 fast ripple every 5 minutes; these channels were also located in eloquent cortex. These findings are in keeping with work done in a smaller number of patients and brain regions.…”

Section: Selection Of Channels From Presumably Normal Brain Regionsmentioning

confidence: 96%

See 1 more Smart Citation

High‐Frequency Oscillations in the Normal Human Brain

Frauscher

Ellenrieder

Zelmann

et al. 2018

Annals of Neurology

169

178

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This multicenter atlas is the first to provide region-specific normative values for physiological HFO rates and HFA in common stereotactic space; rates above these can now be considered pathological. Physiological ripples are frequent in eloquent cortex. In contrast, physiological fast ripples are very rare, making fast ripples a good candidate for defining the epileptogenic zone. Ann Neurol 2018;84:374-385.

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Section: Selection Of Channels From Presumably Normal Brain Regionsmentioning

confidence: 96%

Section: Selection Of Channels From Presumably Normal Brain Regionsmentioning

confidence: 96%

High‐Frequency Oscillations in the Normal Human Brain

Frauscher

Ellenrieder

Zelmann

et al. 2018

Annals of Neurology

169

178

View full text Add to dashboard Cite

show abstract

“…These interictal HFOs can be seen in both physiologic and pathologic situations. The HFO rates also vary according the cerebral area (Guragain et al, 2018). In pathologic situations, HFO are related to the seizure onset zone in interictal periods and have been identified in a large variety of clinical scenarios (e.g.…”

Section: High Frequency Oscillationsmentioning

confidence: 99%

Focal epilepsies and focal disorders

Lagarde¹,

Bartolomei²

2019

Handbook of Clinical Neurology

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Electroencephalographic (EEG) investigations are crucial in the diagnosis and management of patients with focal epilepsies. EEG may reveal different interictal epileptiform discharges (IED: spikes, sharp waves). The EEG visibility of spike depends on the surface area of cortex involved (>10cm 2) and the brain localisation of cortical generators. Regions generating IED (defining the "irritative zone") are not necessarily equivalent to the seizure onset zone. Focal seizures are dynamic processes originating from one or several brain regions (generating fast oscillations and called "epileptogenic zone") before to spread to other structures (generating lower frequency oscillations and called "propagation zone"). Several factors limit the expression of seizures on scalp EEG, such as area involved, degree of synchronization and depth of the cortical generators. Different scalp EEG seizure onset patterns may be observed: fast discharge, background flattening, rhythmic spikes, sinusoidal discharge, or sharp activity but to a large extent EEG changes are linked to seizure propagation. Finally, in the context of presurgical evaluation, the combination of interictal and ictal EEG features is crucial to provide optimal hypothesis about the epileptogenic zone.

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“…Recent studies have shown that high frequency oscillations (HFOs) occur more frequently in the SOZ, [2][3][4][5][6][7][8][9] and the surgical removal of brain regions with high incidences of HFOs has been correlated to a higher likelihood of seizure freedom after surgery. 2,3,[10][11][12][13] These results suggest that HFOs may be a valuable marker for localization of epileptogenic tissue during surgical planning. Moreover, HFOs occur in interictal periods, so their use may enable clinicians to shorten the duration of invasive monitoring.…”

Section: Introductionmentioning

confidence: 81%

“…Several other studies have suggested that HFO amplitude differs between SOZ and nSOZ channels. One study has shown amplitude to be significantly higher in SOZ compared to non-SOZ electrodes (regardless of contact location) during interictal, preictal, and ictal periods, 11 but others have shown that this difference was not significant during nonictal periods. 44 Furthermore, pathological HFOs have been reported to demonstrate higher amplitude than physiologically-induced HFOs.…”

Section: Characteristics Of Ahfa and Chfomentioning

confidence: 99%

Detection of anomalous high frequency events in human intracranial EEG

Charupanit¹,

Sen‐Gupta²,

Lin³

et al. 2019

Preprint

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SummaryObjectiveHigh-frequency oscillations (HFOs) are a promising biomarker for the epileptogenic zone. However, no physiological definition of an HFO has been established, so detection relies on the empirical definition of an HFO derived from visual observation. This can bias estimates of HFO features such as amplitude and duration, thereby hindering their utility as biomarkers. Therefore, we set out to develop an algorithm that detects high frequency events in the intracranial EEG that stand out from the background and does not require assumptions about event amplitude or morphology.MethodWe propose the anomaly detection algorithm (ADA), which integrates several unsupervised machine learning techniques to identify segments of data that are distinct from the background. We apply ADA and a standard HFO detector using a root-mean-square amplitude threshold to intracranial EEG from 11 patients undergoing evaluation for epilepsy surgery. The rate, amplitude, and duration of the detected events and the percent overlap between the two detectors are compared.ResultIn the seizure onset zone (SOZ), ADA detected a subset of conventional HFOs. In non-SOZ channels, ADA detected at least twice as many events as the standard approach, including some conventional HFOs; however, ADA also identified many low and intermediate amplitude events missed by the standard amplitude-based method. The rate of ADA events was similar across all channels; however, the amplitude of ADA events was significantly higher in SOZ channels, and the threshold between SOZ and non-SOZ channels was relatively consistent across patients.SignificanceADA does not require human supervision, parameter optimization, or prior assumptions about event shape, amplitude, or duration. It provides an unbiased estimate of HFO features, and our results suggest that amplitude may differentiate SOZ and non-SOZ channels. Further studies will examine the utility of HFO amplitude as a biomarker for epilepsy surgical outcome.

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Spatial variation in high-frequency oscillation rates and amplitudes in intracranial EEG

Abstract: 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.

Cited by 58 publications

References 40 publications

High‐Frequency Oscillations in the Normal Human Brain

High‐Frequency Oscillations in the Normal Human Brain

Focal epilepsies and focal disorders

Detection of anomalous high frequency events in human intracranial EEG

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