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Large-scale desynchronization during interictal epileptic discharges recorded with intracranial EEG

Elie Bou Assi, Younes Zerouali, Manon Robert, Frédéric Lesage, Philippe Pouliot and Dang K. Nguyen

Article (2020)

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Abstract

It is increasingly recognized that deep understanding of epileptic seizures requires both localizing and characterizing the functional network of the region where they are initiated, i. e., the epileptic focus. Previous investigations of the epileptogenic focus' functional connectivity have yielded contrasting results, reporting both pathological increases and decreases during resting periods and seizures. In this study, we shifted paradigm to investigate the time course of connectivity in relation to interictal epileptiform discharges. We recruited 35 epileptic patients undergoing intracranial EEG (iEEG) investigation as part of their presurgical evaluation. For each patient, 50 interictal epileptic discharges (IEDs) were marked and iEEG signals were epoched around those markers. Signals were narrow-band filtered and time resolved phase-locking values were computed to track the dynamics of functional connectivity during IEDs. Results show that IEDs are associated with a transient decrease in global functional connectivity, time-locked to the peak of the discharge and specific to the high range of the gamma frequency band. Disruption of the long-range connectivity between the epileptic focus and other brain areas might be an important process for the generation of epileptic activity. Transient desynchronization could be a potential biomarker of the epileptogenic focus since 1) the functional connectivity involving the focus decreases significantly more than the connectivity outside the focus and 2) patients with good surgical outcome appear to have a significantly more disconnected focus than patients with bad outcomes.

Uncontrolled Keywords

intracranial electroencephalography; epileptiform discharges; epileptic focus; epilepsy surgery; surgical outcome; functional connectivity

Subjects: 1900 Biomedical engineering > 1900 Biomedical engineering
1900 Biomedical engineering > 1901 Biomedical technology
2500 Electrical and electronic engineering > 2500 Electrical and electronic engineering
Department: Department of Electrical Engineering
Institut de génie biomédical
Funders: Canadian Institutes of Health Research, Institute for Data Valorization, Canada Research Chair in Epilepsy and Functional Anatomy of Human Brain, GRSNG / NSERC
Grant number: 390044, PD-2018b-AP-03, 232075, 289987
PolyPublie URL: https://publications.polymtl.ca/47105/
Journal Title: Frontiers in Neurology (vol. 11)
Publisher: Frontiers Media
DOI: 10.3389/fneur.2020.529460
Official URL: https://doi.org/10.3389/fneur.2020.529460
Date Deposited: 18 Apr 2023 15:00
Last Modified: 30 Sep 2024 09:35
Cite in APA 7: Assi, E. B., Zerouali, Y., Robert, M., Lesage, F., Pouliot, P., & Nguyen, D. K. (2020). Large-scale desynchronization during interictal epileptic discharges recorded with intracranial EEG. Frontiers in Neurology, 11, 529460 (12 pages). https://doi.org/10.3389/fneur.2020.529460

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