title: MEG correlates of epileptic high gamma oscillations in invasive EEG.
abstract: In patients with pharmacoresistant focal epilepsy,we demonstrate that magnetoencephalography (MEG) detects spike-locked and spike-independent epileptic high gamma oscillations (HGOs) using combined MEG and invasive electroencephalography (iEEG) from subdural macroelectrodes. Six patients, who underwent presurgical workup for epilepsy surgery with preoperative simultaneous MEG and subdural iEEG recordings,were investigated. HGOs in iEEG were detected automatically and served as triggers for averaging and localization of simultaneous MEG data. iEEG-HGOs were detected in all patients and MEG-HGOs in five patients. HGOs were highly associated with epileptic networks and correctly identified seizure-onset zones in five (MEG) and six patients (iEEG). Minimum-norm source analysis of MEG data yielded concordant localizations. Noninvasive analysis of HGOs may allow investigation of epileptic networks independent of spikes and seizures. Determination of sensitivity and specificity, as well as development of MEG-HGO analysis without the need of iEEG should be addressed in a larger study.
authors.affiliation: University Hospital Erlangen, Epilepsy Center, Department of Neurology, Erlangen, Germany. stefan.rampp@uk-erlangen.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Rampp
authors.forename: Martin
authors.initials: M
authors.lastname: Kaltenhäuser
authors.forename: Daniel
authors.initials: D
authors.lastname: Weigel
authors.forename: Michael
authors.initials: M
authors.lastname: Buchfelder
authors.forename: Ingmar
authors.initials: I
authors.lastname: Ingmar Blümcke
authors.forename: Arndt
authors.initials: A
authors.lastname: Dörfler
authors.forename: Hermann
authors.initials: H
authors.lastname: Stefan
mesh_terms: D000328:Adult; D001683:Biological Clocks / Q000502:physiology*; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008875:Middle Aged; D013057:Spectrum Analysis / Q000379:methods; D055815:Young Adult