Source-level EEG and graph theory reveal widespread functional network alterations in focal epilepsy. Issue 7 (July 2021)

• Record Type: Journal Article
• Authors: Hatlestad-Hall, Christoffer; Bruña, Ricardo; Syvertsen, Marte Roa; Erichsen, Aksel; Andersson, Vebjørn; Vecchio, Fabrizio; Miraglia, Francesca; Rossini, Paolo M.; Renvall, Hanna; Taubøll, Erik; Maestú, Fernando; Haraldsen, Ira H.
• Is Part Of: Clinical neurophysiology. Volume 132:Issue 7(2021)
• Page Start: 1663
• Page End: 1676
• Publication Date: 2021-07
• Subjects: Focal epilepsy -- Network analysis -- Functional connectivity -- Source-level EEG -- Graph theory; AAL Automated Anatomical Labeling -- ASM anti-seizure medication -- DT (network) density threshold -- FC functional connectivity -- FDR false discovery rate -- FE focal epilepsy -- HC healthy control -- LCR left central region -- LPL left parietal lateral (surface) -- PLV phase-locking value; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2021.04.008
• Languages: English
• ISSNs: 1388-2457

Abstract

Highlights: Focal epilepsies are associated with widespread interictal functional network alterations, extending beyond the epilepsy focus. Graph theory analyses of source EEG functional connectivity capture these network changes, and might thus be clinically relevant. Group-level differences in network metrics are relatively stable across network analysis parameters. 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.