title: Uppermost synchronized generators of spike-wave activity are localized in limbic cortical areas in late-onset absence status epilepticus.
abstract: OBJECTIVE
  Absence status (AS) epilepticus with generalized spike-wave pattern is frequently found in severely ill patients in whom several disease states co-exist. The cortical generators of the ictal EEG pattern and EEG functional connectivity (EEGfC) of this condition are unknown. The present study investigated the localization of the uppermost synchronized generators of spike-wave activity in AS.
  
  
  METHODS
  Seven patients with late-onset AS were investigated by EEG spectral analysis, LORETA (Low Resolution Electromagnetic Tomography) source imaging, and LSC (LORETA Source Correlation) analysis, which estimates cortico-cortical EEGfC among 23 ROIs (regions of interest) in each hemisphere.
  
  
  RESULTS
  All the patients showed generalized ictal EEG activity. Maximum Z-scored spectral power was found in the 1-6 Hz and 12-14 Hz frequency bands. LORETA showed that the uppermost synchronized generators of 1-6 Hz band activity were localized in frontal and temporal cortical areas that are parts of the limbic system. For the 12-14 Hz band, abnormally synchronized generators were found in the antero-medial frontal cortex. Unlike the rather stereotyped spectral and LORETA findings, the individual EEGfC patterns were very dissimilar.
  
  
  CONCLUSIONS
  The findings are discussed in the context of nonconvulsive seizure types and the role of the underlying cortical areas in late-onset AS. The diversity of the EEGfC patterns remains an enigma. Localizing the cortical generators of the EEG patterns contributes to understanding the neurophysiology of the condition.
authors.affiliation: Department of Neurology, Kenezy Gyula Hospital, Bartok Bela ut 2-26, H-4031 Debrecen, Hungary. Electronic address: pirospalma@freemail.hu.
authors.forename: Palma
authors.initials: P
authors.lastname: Piros
authors.affiliation: Department of Neurology, Medical and Health Science Center, University of Debrecen, Moricz Zsigmond krt. 22, H-4032 Debrecen, Hungary.
authors.forename: Szilvia
authors.initials: S
authors.lastname: Puskas
authors.affiliation: Department of Nuclear Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary.
authors.forename: Miklos
authors.initials: M
authors.lastname: Emri
authors.affiliation: Department of Nuclear Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary.
authors.forename: Gabor
authors.initials: G
authors.lastname: Opposits
authors.affiliation: Department of Nuclear Medicine, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, H-4032 Debrecen, Hungary.
authors.forename: Tamas
authors.initials: T
authors.lastname: Spisak
authors.affiliation: Department of Neurology, Medical and Health Science Center, University of Debrecen, Moricz Zsigmond krt. 22, H-4032 Debrecen, Hungary. Electronic address: prof.fekete@yahoo.com.
authors.forename: Istvan
authors.initials: I
authors.lastname: Fekete
authors.affiliation: Department of Neurology, Kenezy Gyula Hospital, Bartok Bela ut 2-26, H-4031 Debrecen, Hungary.
authors.forename: Bela
authors.initials: B
authors.lastname: Clemens
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000473:pathology*; D005260:Female; D006801:Humans; D008032:Limbic System / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D013223:Statistics as Topic; D014054:Tomography
keywords: Absence status epilepticus; LORETA; LORETA Source Correlation