title: The frontal lobe in absence epilepsy: EEG-fMRI findings.
abstract: OBJECTIVE
  Studies of absence seizures (AS) using EEG with fMRI (EEG-fMRI) show a consistent network with prominent thalamic activation and a variety of cortical changes. Despite evidence suggesting a role of frontal cortex in seizure generation, group studies have not detected consistent AS-related changes in this region. We hypothesized that only a subgroup may show frontal cortical activation.
  
  
  METHODS
  We studied 13 subjects with AS during EEG-fMRI to classify the different individual patterns of frontal cortical activation associated with AS.
  
  
  RESULTS
  Based upon visual inspection of surface-rendered activation maps we identified 2 subgroups that could be distinguished by the activation in the dorsolateral prefrontal cortex (DLPFC). One group of patients (n = 7) showed a primarily positive signal change (DLPFC-POS), whereas the other group (n = 6) showed a primarily negative signal change (DLFPC-NEG). When the DLPFC-POS group was compared to the DLPFC-NEG group, time-course analysis revealed a larger positive blood oxygenation level-dependent deflection following onset of the AS in cortical and subcortical areas beyond the DLPFC. This suggests a basic biological difference between these groups.
  
  
  CONCLUSIONS
  These observations suggest that there may be at least 2 mechanisms underpinning AS in individuals with absence epilepsy. This may have phenotypic and genetic implications for understanding epilepsy syndromes.
authors.affiliation: Austin Health, Brain Research Institute, Department of Medicine, University of Melbourne, Heidelberg, Victoria, Australia.
authors.forename: P W
authors.initials: PW
authors.lastname: Carney
authors.forename: R A J
authors.initials: RA
authors.lastname: Masterton
authors.forename: D
authors.initials: D
authors.lastname: Flanagan
authors.forename: S F
authors.initials: SF
authors.lastname: Berkovic
authors.forename: G D
authors.initials: GD
authors.lastname: Jackson
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D017397:Prefrontal Cortex / Q000503:physiopathology