Source-level EEG and graph theory reveal widespread functional network alterations in focal epilepsy

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Hatlestad-Hall , C , Bruna , R , Syvertsen , MR , Erichsen , A , Andersson , V , Vecchio , F , Miraglia , F , Rossini , PM , Renvall , H , Tauboll , E , Maestu , F & Haraldsen , IH 2021 , ' Source-level EEG and graph theory reveal widespread functional network alterations in focal epilepsy ' , Clinical Neurophysiology , vol. 132 , no. 7 , pp. 1663-1676 .

Title: Source-level EEG and graph theory reveal widespread functional network alterations in focal epilepsy
Author: Hatlestad-Hall, C; Bruna, R; Syvertsen, MR; Erichsen, A; Andersson, V; Vecchio, F; Miraglia, F; Rossini, PM; Renvall, H; Tauboll, E; Maestu, F; Haraldsen, IH
Contributor organization: HUS Neurocenter
HUS Medical Imaging Center
Neurologian yksikkö
Date: 2021-07
Language: eng
Number of pages: 14
Belongs to series: Clinical Neurophysiology
ISSN: 1388-2457
Abstract: Objective: The hypersynchronous neuronal activity associated with epilepsy causes widespread functional network disruptions extending beyond the epileptogenic zone. This altered network topology is considered a mediator for non-seizure symptoms, such as cognitive impairment. The aim of this study was to investigate functional network alterations in focal epilepsy patients with good seizure control and high quality of life. Methods: We compared twenty-two focal epilepsy patients and sixteen healthy controls on graph metrics derived from functional connectivity of source-level resting-state EEG. Graph metrics were calculated over a range of network densities in five frequency bands. Results: We observed a significantly increased small world index in patients relative to controls. On the local level, two left-hemisphere regions displayed a shift towards greater alpha band "hubness". The findings were not mediated by age, sex or education, nor by age of epilepsy onset, duration or focus lateralisation. Conclusions: Widespread functional network alterations are evident in focal epilepsy, even in a cohort characterised by successful anti-seizure medication therapy and high quality of life. These findings might support the position that functional network analysis could hold clinical relevance for epilepsy. Significance: Focal epilepsy is accompanied by global and local functional network aberrancies which might be implied in the sustenance of non-seizure symptoms. (c) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. This is an open access article under the CC BY license (
Subject: Focal epilepsy
Network analysis
Functional connectivity
Source-level EEG
Graph theory
3126 Surgery, anesthesiology, intensive care, radiology
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion

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