title: Increased cortical BOLD signal anticipates generalized spike and wave discharges in adolescents and adults with idiopathic generalized epilepsies.
abstract: OBJECTIVE
  Electroencephalography-functional magnetic resonance imaging (EEG-fMRI) coregistration has recently revealed that several brain structures are involved in generalized spike and wave discharges (GSWDs) in idiopathic generalized epilepsies (IGEs). In particular, deactivations and activations have been observed within the so-called brain default mode network (DMN) and thalamus, respectively. In the present study we analyzed the dynamic time course of blood oxygen level-dependent (BOLD) changes preceding and following 3 Hz GSWDs in a group of adolescent and adult patients with IGE who presented with absence seizures (AS). Our aim was to evaluate cortical BOLD changes before, during, and after GSWD onset.
  
  
  METHODS
  Twenty-one patients with IGE underwent EEG-fMRI coregistration. EEG-related analyses were run both at the single-subject and at group level (random effect). The time-course analysis was conducted for 3 s time windows before, during, and after GSWDs, and they were included until no further BOLD signal changes were observed.
  
  
  RESULTS
  Fifteen patients (nine female, mean age 28 years) had GSWDs during EEG-fMRI coregistration (262 total events, mean duration 4 s). Time-course group analysis showed BOLD increments starting approximately 10 s before GSWD onset located in frontal and parietal cortical areas, and especially in the precuneus-posterior cingulate region. At GSWD onset, BOLD increments were located in thalamus, cerebellum, and anterior cingulate gyrus, whereas BOLD decrements were observed in the DMN regions persisting until 9 s after onset.
  
  
  CONCLUSIONS
  Hemodynamic changes (BOLD increments) occurred in specific cortical areas, namely the precuneus/posterior cingulate, lateral parietal, and frontal cortices, several seconds before EEG onset of GSWD. A dysfunction of these brain regions, some of which belongs to the DMN, may be crucial in generating GSWDs in patients with IGE.
authors.affiliation: Department of Neuroscience, NOCSAE Hospital, University of Modena e Reggio Emilia, Modena, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Benuzzi
authors.forename: Laura
authors.initials: L
authors.lastname: Mirandola
authors.forename: Matteo
authors.initials: M
authors.lastname: Pugnaghi
authors.forename: Valentina
authors.initials: V
authors.lastname: Farinelli
authors.forename: Carlo Alberto
authors.initials: CA
authors.lastname: Tassinari
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Capovilla
authors.forename: Gaetano
authors.initials: G
authors.lastname: Cantalupo
authors.forename: Francesca
authors.initials: F
authors.lastname: Beccaria
authors.forename: Paolo
authors.initials: P
authors.lastname: Nichelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Meletti
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D002540:Cerebral Cortex / Q000098:blood supply* / Q000503:physiopathology*; D004569:Electroencephalography; D004829:Epilepsy, Generalized / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000098:blood supply / Q000503:physiopathology; D010100:Oxygen / Q000097:blood; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D010100:Oxygen