Interictal epileptiform discharges in focal epilepsy are preceded by increase in low-frequency oscillations

Karin Westin*, Gerald Cooray, Sándor Beniczky, Daniel Lundqvist

*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskriftArtikelForskningpeer review


OBJECTIVE: Interictal epileptiform discharges (IEDs) constitute a diagnostic signature of epilepsy. These events reflect epileptogenic hypersynchronization. Previous studies indicated that IEDs arise from slow neuronal activation accompanied by metabolic and hemodynamic changes. These might induce cortical inhibition followed hypersynchronization at IED onset. As cortical inhibition is mediated by low-frequency oscillations, we aimed to analyze the role of low-frequency oscillations prior the IED using magnetencephalography (MEG).

METHODS: Low-frequency (1-8 Hz) oscillations pre-IED ([-1000 milliseconds (ms), IED onset]) were analyzed using MEG in 14 focal epilepsy patients (median age = 23 years, range = 7-46 age). Occurrence of local pre-IED oscillations was analyzed using Beamformer Dynamical Imaging of Coherent Sources (DICS) and event-related desynchronization/synchronization (ERD-ERS) maps constructed using cluster-based permutation tests. The development of pre-IED oscillations was characterized using Hilbert transformation.

RESULTS: All patients exhibited statistically significant increase in delta (1-4 Hz) and/or theta (4-8 Hz) oscillations pre-IED compared to baseline [-2000 ms, -1000 ms]. Furthermore, all patients exhibited low-frequency power increase up to IED onset.

CONCLUSIONS: We demonstrated consistently occurring, low-frequency oscillations prior to IED onset.

SIGNIFICANCE: As low-frequency activity mediates cortical inhibition, our study demonstrates that a focal inhibition precedes hypersynchronization at IED onset.

Sider (fra-til)191-205
Antal sider15
TidsskriftClinical Neurophysiology
Tidlig onlinedato14 feb. 2022
StatusUdgivet - apr. 2022

Bibliografisk note

Copyright © 2022 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.


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