Detection and Magnetic Source Imaging of Fast Oscillations (40–160 Hz) Recorded with Magnetoencephalography in Focal Epilepsy Patients

Ellenrieder, Nicolás von; Pellegrino, Giovanni; Hedrich, Tanguy; Gotman, Jean; Lina, Jean Marc; Grova, Christophe; Kobayashi, Eliane

doi:10.1007/s10548-016-0471-9

Cited by 75 publications

(116 citation statements)

References 40 publications

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“…Ellenrieder et al 38 ). NOTE: The MEM is an efficient technique that has been successfully used to determine the location and extent of sources of epileptic activity [62][63][64] .…”

Section: Hfo Source Localization At Both Eeg and Meg Using The Wavelementioning

confidence: 99%

“…A recent study proposed that HFOs recorded non-invasively with scalp EEG represent the sum of activity of multiple spatially distributed focal and coherent sources 60 . So far, few studies 28,29,37,38,60 managed to show that HFOs can be detected non-invasively using scalp EEG and MEG; even fewer localized this activity by solving the inverse problem [37][38] .…”

Section: Significance Of the Technique With Respect To Existing/altermentioning

confidence: 99%

“…Evidence from phantom constructions that simulate HFOs generators suggested that HFOs can be detected and localized with high localization accuracy (2 -3 mm) with MEG 32 . Several recent studies reported HFOs in the MEG signals recorded from patients with epilepsy in the ripple frequency band [33][34][35][36][37][38] . Time-frequency analysis has shown that MEG data contain high frequency components related to the EZ [33][34][35][36] .…”

Section: Introductionmentioning

confidence: 99%

“…Time-frequency analysis has shown that MEG data contain high frequency components related to the EZ [33][34][35][36] . However, only a few studies have identified interictal HFOs as visible events standing out of the background signal in the time domain, as typically done with iEEG [37][38] . Van Klink et al 37 detected HFOs in the ripple band using virtual channels constructed with beamforming techniques based on spatial information obtained from IEDs.…”

Section: Introductionmentioning

confidence: 99%

“…Van Klink et al 37 detected HFOs in the ripple band using virtual channels constructed with beamforming techniques based on spatial information obtained from IEDs. Von Ellenrieder et al 38 detected HFOs in MEG signals from the physical sensors independently of the IEDs and used the Maximum Entropy on the Mean (MEM) method to localize their sources and to investigate their correlation with the EZ. also detected epileptic high gamma oscillations with MEG, which were spike-locked or spike-independent, and localized this activity with minimum-norm source analysis 39 .…”

Section: Introductionmentioning

confidence: 99%

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Interictal High Frequency Oscillations Detected with Simultaneous Magnetoencephalography and Electroencephalography as Biomarker of Pediatric Epilepsy

Papadelis

Tamilia

Stufflebeam

et al. 2016

JoVE

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Crucial to the success of epilepsy surgery is the availability of a robust biomarker that identifies the Epileptogenic Zone (EZ). High Frequency Oscillations (HFOs) have emerged as potential presurgical biomarkers for the identification of the EZ in addition to Interictal Epileptiform Discharges (IEDs) and ictal activity. Although they are promising to localize the EZ, they are not yet suited for the diagnosis or monitoring of epilepsy in clinical practice. Primary barriers remain: the lack of a formal and global definition for HFOs; the consequent heterogeneity of methodological approaches used for their study; and the practical difficulties to detect and localize them noninvasively from scalp recordings. Here, we present a methodology for the recording, detection, and localization of interictal HFOs from pediatric patients with refractory epilepsy. We report representative data of HFOs detected noninvasively from interictal scalp EEG and MEG from two children undergoing surgery.The underlying generators of HFOs were localized by solving the inverse problem and their localization was compared to the Seizure Onset Zone (SOZ) as this was defined by the epileptologists. For both patients, Interictal Epileptogenic Discharges (IEDs) and HFOs were localized with source imaging at concordant locations. For one patient, intracranial EEG (iEEG) data were also available. For this patient, we found that the HFOs localization was concordant between noninvasive and invasive methods. The comparison of iEEG with the results from scalp recordings served to validate these findings. To our best knowledge, this is the first study that presents the source localization of scalp HFOs from simultaneous EEG and MEG recordings comparing the results with invasive recordings. These findings suggest that HFOs can be reliably detected and localized noninvasively with scalp EEG and MEG. We conclude that the noninvasive localization of interictal HFOs could significantly improve the presurgical evaluation for pediatric patients with epilepsy.

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“…Ellenrieder et al 38 ). NOTE: The MEM is an efficient technique that has been successfully used to determine the location and extent of sources of epileptic activity [62][63][64] .…”

Section: Hfo Source Localization At Both Eeg and Meg Using The Wavelementioning

confidence: 99%

Section: Significance Of the Technique With Respect To Existing/altermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Interictal High Frequency Oscillations Detected with Simultaneous Magnetoencephalography and Electroencephalography as Biomarker of Pediatric Epilepsy

Papadelis

Tamilia

Stufflebeam

et al. 2016

JoVE

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Scalp ripples as prognostic biomarkers of epileptogenicity in pediatric surgery

Tamilia

Dirodi

Alhilani

et al. 2020

Ann Clin Transl Neurol

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Objective To assess the ability of high‐density Electroencephalography (HD‐EEG) and magnetoencephalography (MEG) to localize interictal ripples, distinguish between ripples co‐occurring with spikes (ripples‐on‐spike) and independent from spikes (ripples‐alone), and evaluate their localizing value as biomarkers of epileptogenicity in children with medically refractory epilepsy. Methods We retrospectively studied 20 children who underwent epilepsy surgery. We identified ripples on HD‐EEG and MEG data, localized their generators, and compared them with intracranial EEG (icEEG) ripples. When ripples and spikes co‐occurred, we performed source imaging distinctly on the data above 80 Hz (to localize ripples) and below 70 Hz (to localize spikes). We assessed whether missed resection of ripple sources predicted poor outcome, separately for ripples‐on‐spikes and ripples‐alone. Similarly, predictive value of spikes was calculated. Results We observed scalp ripples in 16 patients (10 good outcome). Ripple sources were highly concordant to the icEEG ripples (HD‐EEG concordance: 79%; MEG: 83%). When ripples and spikes co‐occurred, their sources were spatially distinct in 83‐84% of the cases. Removing the sources of ripples‐on‐spikes predicted good outcome with 90% accuracy for HD‐EEG (P = 0.008) and 86% for MEG (P = 0.044). Conversely, removing ripples‐alone did not predict outcome. Resection of spike sources (generated at the same time as ripples) predicted good outcome for HD‐EEG (P = 0.036; accuracy = 87%), while did not reach significance for MEG (P = 0.1; accuracy = 80%). Interpretation HD‐EEG and MEG localize interictal ripples with high precision in children with refractory epilepsy. Scalp ripples‐on‐spikes are prognostic, noninvasive biomarkers of epileptogenicity, since removing their cortical generators predicts good outcome. Conversely, scalp ripples‐alone are most likely generated by non‐epileptogenic areas.

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