Residual fast ripples in the intraoperative corticogram predict epilepsy surgery outcome

Klooster, Maryse A. van ‘t; Klink, Nicole E.C. van; Leijten, Frans S.S.; Zelmann, Rina; Gebbink, Tineke; Gosselaar, Peter H.; Braun, Kees P.J.; Huiskamp, Geertjan; Zijlmans, Maeike

doi:10.1212/wnl.0000000000001727

Cited by 132 publications

(143 citation statements)

References 39 publications

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“…HFOs are defined as spontaneous EEG patterns in the frequency range between 80-500 Hz, consisting of at least four oscillations that clearly stand out of the background activity . Interictal HFOs proved to be more specific in localizing the SOZ than spikes (Jacobs et al, 2008) and have shown a good correlation with the postsurgical outcome in epilepsy patients (Akiyama et al, 2011;Jacobs et al, 2010;van 't Klooster et al, 2015;Wu et al, 2010).…”

Section: Introductionmentioning

confidence: 91%

“…HFOs included a FR, which was shown to be a very specific indicator of epileptogenicity (van 't Klooster et al, 2015). Therefore, types 3 and 4 HFOs were thought to be associated with pathological activity.…”

Section: Patient Datasetsmentioning

confidence: 99%

“…FRs are considered more specific for epileptogenicity because of their close relation to the SOZ (Engel et al, 2009). Ripples were shown to be a less specific marker of the epileptogenic zone than FRs regarding the surgical outcome (Akiyama et al, 2011;van 't Klooster et al, 2015). This is best explained by the fact that there are not only epileptic and hence pathological ripples, but also spontaneous physiological ripples generated by the healthy brain.…”

Section: Introductionmentioning

confidence: 99%

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The morphology of high frequency oscillations (HFO) does not improve delineating the epileptogenic zone

Burnos

Frauscher

Zelmann

et al. 2016

Clinical Neurophysiology

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OBJECTIVE: We hypothesized that high frequency oscillations (HFOs) with irregular amplitude and frequency more specifically reflect epileptogenicity than HFOs with stable amplitude and frequency. METHODS: We developed a fully automatic algorithm to detect HFOs and classify them based on their morphology, with types defined according to regularity in amplitude and frequency: type 1 with regular amplitude and frequency; type 2 with irregular amplitude, which could result from filtering of sharp spikes; type 3 with irregular frequency; and type 4 with irregular amplitude and frequency. We investigated the association of different HFO types with the seizure onset zone (SOZ), resected area and surgical outcome. RESULTS: HFO rates of all types were significantly higher inside the SOZ than outside. HFO types 1 and 2 were strongly correlated to each other and showed the highest rates among all HFOs. Their occurrence was highly associated with the SOZ, resected area and surgical outcome. The automatic detection emulated visual markings with 93% true positives and 57% false detections. CONCLUSIONS: HFO types 1 and 2 similarly reflect epileptogenicity. SIGNIFICANCE: For clinical application, it may not be necessary to separate real HFOs from "false oscillations" produced by the filter effect of sharp spikes. Also for automatically detected HFOs, surgical outcome is better when locations with higher HFO rates are included in the resection. We hypothesized that high frequency oscillations (HFOs) with irregular amplitude and frequency more specifically reflect epileptogenicity than HFOs with stable amplitude and frequency. Methods:We developed a fully automatic algorithm to detect HFOs and classify them based on their morphology, with types defined according to regularity in amplitude and frequency: type 1 with regular amplitude and frequency; type 2 with irregular amplitude, which could result from filtering of sharp spikes; type 3 with irregular frequency; and type 4 with irregular amplitude and frequency. We investigated the association of different HFO types with the seizure onset zone (SOZ), resected area and surgical outcome. Results:HFO rates of all types were significantly higher inside the SOZ than outside. HFO types 1 and 2 were strongly correlated to each other and showed the highest rates among all HFOs. Their occurrence was highly associated with the SOZ, resected area and surgical outcome. The automatic detection emulated visual markings with 93% true positives and 57% false detections. Conclusions:HFO types 1 and 2 similarly reflect epileptogenicity. Significance:For clinical application, it may not be necessary to separate real HFOs from "false oscillations" produced by the filter effect of sharp spikes. Also for automatically detected HFOs, surgical outcome is better when locations with higher HFO rates are included in the resection.

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Section: Introductionmentioning

confidence: 91%

Section: Patient Datasetsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The morphology of high frequency oscillations (HFO) does not improve delineating the epileptogenic zone

Burnos

Frauscher

Zelmann

et al. 2016

Clinical Neurophysiology

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“…In this issue of Neurology ® , van 't Klooster et al 3 retrospectively studied high-frequency oscillations (HFO) as a biomarker of the epileptogenic zone during intraoperative electrocorticography. They reviewed the occurrence of HFOs after resection of an epileptogenic lesion, mainly glial tumors and cortical malformations, in 54 young patients.…”

mentioning

confidence: 99%

“…When reporting on HFOs, it is important to clearly define their frequency, as done in this study. 3 HFOs occur at the same time or separate from other epileptiform activity such as sharp waves and epileptic spikes. 5 van 't Klooster et al clearly distinguished FR from ripples with and without associated spikes.…”

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confidence: 99%

Is it time to replace epileptic spikes with fast ripples?

Jobst

Engel

2015

Neurology

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Physiological and pathological high frequency oscillations in focal epilepsy

Cimbálník

Brinkmann

Kremen

et al. 2018

Ann Clin Transl Neurol

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ObjectiveThis 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.MethodsWe 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.ResultsThere 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.InterpretationA 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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Residual fast ripples in the intraoperative corticogram predict epilepsy surgery outcome

Abstract: Residual FRs in post-resection ECoG are prognostic markers for seizure recurrence, especially if their number is high. Tailoring could rely on FRs, but requires careful assessment of the ECoG, as FRs in functionally eloquent areas might not be pathologic.

Cited by 132 publications

References 39 publications

The morphology of high frequency oscillations (HFO) does not improve delineating the epileptogenic zone

The morphology of high frequency oscillations (HFO) does not improve delineating the epileptogenic zone

Is it time to replace epileptic spikes with fast ripples?

Physiological and pathological high frequency oscillations in focal epilepsy

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