title: Generalized spike and waves: effect of discharge duration on brain networks as revealed by BOLD fMRI.
abstract: In the past decade, the possibility of combining recordings of EEG and functional MRI (EEG-fMRI), has brought a new insight into the brain network underlying generalized spike wave discharges (GSWD). Nevertheless, how GSWD duration influences this network is not fully understood. In this study we aim to investigate whether GSWD duration had a threshold (non-linear) and/or a linear effect on the amplitude of the associated BOLD changes in any brain regions. This could help in elucidating if there is an hemodynamic background supporting the differentiation between interictal and ictal events. We studied a population of 42 patients with idiopathic generalized epilepsies (IGE) who underwent resting-state EEG-fMRI recordings in three centres (London, UK; Modena, Italy; Rome, Italy), applying a parametric analysis of the GSWD duration. Patients were classified as having Childhood Absence epilepsy, Juvenile Absence Epilepsy, or Juvenile Myoclonic Epilepsy. At the population level linear GSWD duration-related BOLD signal changes were found in a network of brain regions: mainly BOLD increase in thalami and cerebral ventricles, and BOLD decrease in posterior cingulate, precuneus and bilateral parietal regions. No region of significant BOLD change was found in the group analysis for the non-linear effect of GSWD duration. To explore the possible effect of both the different IGE sub-syndromes and the different protocols and scanning equipment used in the study, a full-factorial ANOVA design was performed revealing no significant differences. These findings support the idea that the amplitude of the BOLD changes is linearly related to the GSWD duration with no universal threshold effect of spike and wave duration on the brain network supporting this activity.
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pugnaghi
authors.forename: David W
authors.initials: DW
authors.lastname: Carmichael
authors.forename: Anna E
authors.initials: AE
authors.lastname: Vaudano
authors.forename: Umair J
authors.initials: UJ
authors.lastname: Chaudhary
authors.forename: Francesca
authors.initials: F
authors.lastname: Benuzzi
authors.forename: Carlo
authors.initials: C
authors.lastname: Di Bonaventura
authors.forename: Anna T
authors.initials: AT
authors.lastname: Giallonardo
authors.forename: Roman
authors.initials: R
authors.lastname: Rodionov
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Walker
authors.forename: John S
authors.initials: JS
authors.lastname: Duncan
authors.forename: Stefano
authors.initials: S
authors.lastname: Meletti
authors.forename: Louis
authors.initials: L
authors.lastname: Lemieux
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D004569:Electroencephalography; D004829:Epilepsy, Generalized / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net; D055815:Young Adult