Publications by authors named "Odile Feys"
Objective: Intracranial single-pulse electrical stimulation (SPES) can elicit cortico-cortical evoked potentials. Their investigation with intracranial EEG is biased by the limited number and selected location of electrodes, which could be circumvented by simultaneous non-invasive whole-scalp recording. This study aimed at investigating the ability of magnetoencephalography (MEG) to characterize cortico-cortical evoked fields (CCEFs) and effective connectivity between the epileptogenic zone (EZ) and non-epileptogenic zone (i.
View Article and Find Full Text PDFA novel, robust, and portable platform for magnetoencephalography using optically-pumped magnetometers.
Imaging Neurosci (Camb)
September 2024
Magnetoencephalography (MEG) measures brain function via assessment of magnetic fields generated by neural currents. Conventional MEG uses superconducting sensors, which place significant limitations on performance, practicality, and deployment; however, the field has been revolutionised in recent years by the introduction of optically-pumped magnetometers (OPMs). OPMs enable measurement of the MEG signal without cryogenics, and consequently the conception of "OPM-MEG" systems which ostensibly allow increased sensitivity and resolution, lifespan compliance, free subject movement, and lower cost.
View Article and Find Full Text PDFArticle Synopsis
- This study investigates the variability of cortico-cortical evoked potentials (CCEPs) during single-pulse electrical stimulations to understand their relationship with seizure activity in patients with epilepsy.
- Researchers analyzed data from 20 patients with a focus on how CCEP measurements changed in relation to the location of the epileptogenic zone (EZ) and the occurrence of interictal discharges.
- Findings indicate that increased seizure frequency correlates with decreased variability in CCEP measurements, suggesting that the epileptogenic network becomes more interconnected with frequent seizures, emphasizing the need for timely epilepsy surgery.
Magnetoencephalography (MEG) measures brain function via assessment of magnetic fields generated by neural currents. Conventional MEG uses superconducting sensors, which place significant limitations on performance, practicality, and deployment; however, the field has been revolutionised in recent years by the introduction of optically-pumped-magnetometers (OPMs). OPMs enable measurement of the MEG signal without cryogenics, and consequently the conception of 'OPM-MEG' systems which ostensibly allow increased sensitivity and resolution, lifespan compliance, free subject movement, and lower cost.
View Article and Find Full Text PDFBackground: Epileptic seizures are an established comorbidity of Alzheimer's disease (AD). Subclinical epileptiform activity (SEA) as detected by 24-h electroencephalography (EEG) or magneto-encephalography (MEG) has been reported in temporal regions of clinically diagnosed AD patients. Although epileptic activity in AD probably arises in the mesial temporal lobe, electrical activity within this region might not propagate to EEG scalp electrodes and could remain undetected by standard EEG.
View Article and Find Full Text PDFArticle Synopsis
- The study looks at how single-pulse electrical stimulations can help identify areas in the brain that cause epilepsy by measuring responses like spikes and special electrical signals called CCEPs.
- Researchers tested these responses in 28 patients who have a hard-to-treat form of epilepsy.
- They found that delayed signals in the epileptogenic zone could help doctors decide where to operate to fix the problem.
Background: The analysis of clinical magnetoencephalography (MEG) in patients with epilepsy traditionally relies on visual identification of interictal epileptiform discharges (IEDs), which is time consuming and dependent on subjective criteria.
New Method: Here, we explore the ability of Independent Components Analysis (ICA) and Hidden Markov Modeling (HMM) to automatically detect and localize IEDs. We tested our pipelines on resting-state MEG recordings from 10 school-aged children with (multi)focal epilepsy.
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 application of tri-axial OPMs [Rb (Rb-OPM) and He gas (He-OPM)] for the detection of interictal epileptiform discharges (IEDs).
View Article and Find Full Text PDFFrom cryogenic to on-scalp magnetoencephalography for the evaluation of paediatric epilepsy.
Dev Med Child Neurol
March 2024
Magnetoencephalography (MEG) is a neurophysiological technique based on the detection of brain magnetic fields. Whole-head MEG systems typically house a few hundred sensors requiring cryogenic cooling in a rigid one-size-fits-all (commonly adult-sized) helmet to keep a thermal insulation space. This leads to an increased brain-to-sensor distance in children, because of their smaller head circumference, and decreased signal-to-noise ratio.
View Article and Find Full Text PDFDue 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.
View Article and Find Full Text PDFArticle Synopsis
- Magnetoencephalography (MEG) is a technique used to identify and localize focal interictal epileptiform discharges (IEDs), but traditional cryogenic MEG has limitations, especially for children, because of its rigid design and numerous sensors.
- A study compared cryogenic MEG with a newer on-scalp MEG utilizing optically pumped magnetometers (OPMs) to assess its effectiveness in detecting IEDs in children with epilepsy.
- Results showed that on-scalp MEG had significantly higher IED amplitudes and signal-to-noise ratios, while still providing comparable neural localization of IEDs, suggesting it could be a better option for pediatric patients.
Article Synopsis
- The study aimed to assess the effectiveness of combining Functional Connectivity (FC) with low-density ictal Electrical Source Imaging (ESI) for better localization of seizure onset zones (SOZ) in patients with extratemporal lobe epilepsy (ETLE).
- Researchers developed an automated algorithm to analyze long-term EEG data from 24 patients undergoing surgery and compared two methods for localizing SOZ: ESI power alone and ESI combined with FC analysis.
- Results showed that adding FC significantly improved diagnostic accuracy (61%) compared to ESI alone (45%), suggesting that this combined approach could enhance presurgical evaluations, particularly for patients with challenging EEG interpretations.