Recording of Ictal Epileptic Activity Using on‐Scalp Magnetoencephalography

Feys, Odile; Corvilain, Pierre; Hecke, Audrey Van; Sculier, Claudine; Rikir, Estelle; Legros, Benjamin; Gaspard, Nicolas; Leurquin-Sterk, Gil; Holmes, Niall; Brookes, Matthew J.; Goldman, Serge; Wens, Vincent; Tiège, Xavier De

doi:10.1002/ana.26562

Cited by 20 publications

(27 citation statements)

References 6 publications

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“…They have shown their ability to detect IEDs in patients with ETLE with a higher amplitude and a higher signal‐to‐noise ratio than MEG 67 . Magnetic source imaging (MSI) based on OPMs can localize IEDs with localization potential similar to that of MEG 67 and record ictal discharges from multiple neocortical areas 68 . OPMs are user‐friendly and comfortable for patients 67 .…”

Section: Diagnostic Methods In Insular Epilepsymentioning

confidence: 99%

“…67 Magnetic source imaging (MSI) based on OPMs can localize IEDs with localization potential similar to that of MEG 67 and record ictal discharges from multiple neocortical areas. 68 OPMs are user-friendly and comfortable for patients. 67 This new technology could have a particular value in insular epilepsy due to the low efficiency of EEG and the high added value of MEG.…”

Section: Simultaneous Recordingsmentioning

confidence: 99%

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Diagnostic and therapeutic approaches in refractory insular epilepsy

et al. 2023

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Due to heterogenous seizure semiology and poor contribution of scalp electroencephalography (EEG) signals, insular epilepsy requires use of the appropriate diagnostic tools for its diagnosis and characterization. The deep location of the insula also presents surgical challenges. The aim of this article is to review the current diagnostic and therapeutic tools and their contribution to the management of insular epilepsy. Magnetic resonance imaging (MRI), isotopic imaging, neurophysiological imaging, and genetic testing should be used and interpretated with caution. Isotopic imaging and scalp EEG have demonstrated a lower value in epilepsy from insular compared to temporal origin, which increases the interest of functional MRI and magnetoencephalography. Intracranial recording with stereoelectroencephalography (SEEG) is often required. The insular cortex, being highly connected and deeply located under highly functional areas, is difficult to reach, and its ablative surgery raises functional issues. Tailored resection based on SEEG or alternative curative treatments, such as radiofrequency thermocoagulation, laser interstitial thermal therapy, or stereotactic radiosurgery, have produced encouraging results. The management of insular epilepsy has benefited from major advances in the last years. Perspectives for diagnostic and therapeutic procedures will contribute to better management of this complex form of epilepsy.

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Section: Diagnostic Methods In Insular Epilepsymentioning

confidence: 99%

Section: Simultaneous Recordingsmentioning

confidence: 99%

Diagnostic and therapeutic approaches in refractory insular epilepsy

et al. 2023

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“…He-OPM data were first resampled at 1200 Hz with prior anti-aliasing low-pass filter (330 Hz), as were EEG data, and all acquisitions were then re-synchronized on the basis of the common trigger signal. He- and Rb-OPM data were then further band-pass filtered at 3–38 Hz (usual 3-40Hz band-pass filter dedicated to IED detection (14, 15) adapted to exclude an unprecedented 40Hz noise).…”

Section: Methodsmentioning

confidence: 99%

Interest of tri-axial rubidium and helium optically pumped magnetometers for on-scalp magnetoencephalography recording of interictal epileptiform discharges

Feys,

Corvilain,

Labyt

et al. 2023

Preprint

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Cryogenic magnetoencephalography (MEG) enhances the presurgical assessment of refractory focal epilepsy (RFE). Optically pumped magnetometers (OPMs) are cryogen-free sensors that enable on-scalp MEG recordings. Here, we investigate the interest of tri-axial OPMs (87Rb (Rb-OPM) and4He gas (He-OPM)) for the detection of interictal epileptiform discharges (IEDs).IEDs were recorded simultaneously with 4 tri-axial Rb- and 4 tri-axial He-OPMs in a child with RFE. IEDs were identified visually, isolated from magnetic background noise using independent component analysis (ICA), and the orientation of magnetic field generated by the IEDs was reconstructed at each sensor location.Most IEDs (>1,000) were detectable by both He- and Rb-OPM recordings. IEDs were isolated by ICA and the resulting magnetic field oriented mostly tangential to the scalp in Rb-OPMs and radial in He-OPMs. Likely due to differences in sensor locations, the IED amplitude was higher with Rb-OPMs.This case study shows comparable ability of Rb-OPMs and He-OPMs to detect IEDs and the substantial benefits of triaxial OPMs to detect IEDs from different sensor locations. Tri-axial OPMs allow to maximize spatial brain sampling for IEDs detection with a limited number of sensors.

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“…Moreover, OPMs can be mounted in a lightweight helmet and move with the head, meaning that (assuming background field is controlled or a closed loop system is employed (Holmes, et al, 2018) (Holmes, et al, 2019) (Mellor, et al, 2022) (Robinson, et al, 2022)) the MEG signal can be measured as a person moves (Boto, et al, 2018). Whole head OPM-MEG systems are emerging (e.g., (Hill, et al, 2020) (Boto, et al, 2021) (Rea, et al, 2022) (Alem, et al, 2023) (Rhodes, et al, 2023)) and the clinical potential of OPM-MEG is also being shown (Vivekananda, et al, 2020) – for example OPM-MEG offers higher sensitivity (compared to conventional MEG) for detection of epileptic spikes in children (Feys, et al, 2022); it can record patient data during a seizure (Feys, et al, 2022) (Hillebrand, et al, 2023) and a recent case study reported that, even for a deep source (mesiotemporal cortex), it could measure ∼60% of the epileptic discharges that were identified using invasive EEG (Feys, et al, In Submission). These initial studies indicate that OPM-MEG therefore provides the technical advantages of MEG within a package that is similar in form to EEG – a wearable, motion robust helmet.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous whole-head electrophysiological recordings using EEG and OPM-MEG

Seedat,

Pier,

Holmes

et al. 2023

Preprint

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Electroencephalography (EEG) and magnetoencephalography (MEG) non-invasively measure human brain electrophysiology. They differ in nature; MEG offers better performance (higher spatial precision) whilst EEG (a wearable platform) is more practical. They are also complementary, with studies showing that concurrent MEG/EEG provides advantages over either modality alone, and consequently clinical guidelines for MEG in epilepsy recommend simultaneous acquisition of EEG. In recent years, new instrumentation, optically pumped magnetometers (OPMs), has had a significant impact on MEG, offering improved performance, lifespan compliance, and wearable sensors. Nevertheless, the ability to carry out simultaneous EEG/OPM-MEG remains critical. Here, we investigated whether simultaneous, wearable, whole-head EEG and OPM-MEG measurably degrades signal quality in either modality. We employed two tasks: a motor task known to modulate beta oscillations, and an eyes-open/eyes-closed task known to modulate alpha oscillations. In both, we characterised the performance of EEG alone, MEG alone, and concurrent EEG/OPM-MEG. Our results show that the SNR of the beta response was very similar, regardless of whether modalities were used individually or concurrently. Likewise, our alpha band recordings demonstrated that signal contrast was stable, regardless of the concurrent recording. These results combined suggest that there are no fundamental barriers to simultaneous wearable EEG/OPM-MEG, and consequently this technique is ripe for neuroscientific and clinical adoption. This will be particularly important in the clinical sphere where a direct comparison between simultaneous EEG and OPM-MEG recordings will facilitate interpretation of OPM-MEG data in patients.

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Recording of Ictal Epileptic Activity Using on‐Scalp Magnetoencephalography

Cited by 20 publications

References 6 publications

Diagnostic and therapeutic approaches in refractory insular epilepsy

Diagnostic and therapeutic approaches in refractory insular epilepsy

Interest of tri-axial rubidium and helium optically pumped magnetometers for on-scalp magnetoencephalography recording of interictal epileptiform discharges

Simultaneous whole-head electrophysiological recordings using EEG and OPM-MEG

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