title: Altered EEG resting-state effective connectivity in drug-naïve childhood absence epilepsy.
abstract: OBJECTIVE
  We investigated interictal EEG activity in patients with childhood absence seizures with the aim of detecting markers of network defects generating "idiopathic" hyperexcitability in this form of epilepsy.
  
  
  METHODS
  We included 11 drug-naïve patients with childhood absence epilepsy (CAE), and 11 age matched controls (CTRL). We analyzed interictal EEG using partial directed coherence (PDC), a connectivity estimator in frequency domain based on autoregressive multivariate (MVAR) modeling giving the advantage of indicating the direction and strength of the interactions between multiple variables.
  
  
  RESULTS
  Our results revealed the presence of an abnormal cortico-cortical network occurring in the interictal condition in CAE and involving a large span of frequencies, with prominence in the alpha band; the most evident finding was a highly significant increase of out-going connectivity involving frontal and central cortical areas in CAE patients compared to CTRL subjects.
  
  
  CONCLUSIONS
  Our observation indicates that, in interictal conditions, a distorted network characterizes CAE, and a hyperconnected network is already detectable under resting conditions in the delta, theta and alpha bands.
  
  
  CONCLUSIONS
  The increased interictal EEG connectivity demonstrated here provides support for a persistent abnormal relationship between the thalamus and a hyperexcitable cortex outside the ictal phase.
authors.affiliation: Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Milan, Italy; Department of Informatics, Bioengineering, Robotics and System Engineering (DIBRIS), University of Genova, Genova, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Rotondi
authors.affiliation: Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Milan, Italy.
authors.forename: Silvana
authors.initials: S
authors.lastname: Franceschetti
authors.affiliation: Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Milan, Italy.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Avanzini
authors.affiliation: Department of Neurophysiology, Epilepsy Centre, C. Besta Neurological Institute IRCCS Foundation, Milan, Italy. Electronic address: ferruccio.panzica@istituto-besta.it.
authors.forename: Ferruccio
authors.initials: F
authors.lastname: Panzica
mesh_terms: D000293:Adolescent; D058256:Brain Waves / Q000502:physiology; D002648:Child; D004569:Electroencephalography / Q000379:methods*; D004832:Epilepsy, Absence / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D009415:Nerve Net / Q000503:physiopathology; D012146:Rest / Q000502:physiology
keywords: Absence epilepsy; EEG; Effective connectivity; PDC; Resting state