title: The identification of distinct high-frequency oscillations during spikes delineates the seizure onset zone better than high-frequency spectral power changes.
abstract: OBJECTIVE
  Interictal high-frequency oscillations (HFOs, 80-500Hz) can predict the seizure onset zone (SOZ), but visual detection of HFOs is time consuming. Time-frequency analysis can reveal large high-frequency (HF) power changes (80-500Hz) associated with inter-ictal spikes. The present study determines how well the rate of HFOs and spike-related HF power changes were co-localized with SOZ.
  
  
  METHODS
  We analyzed 583 channels (68 in the SOZ) sampled from 14 patients who underwent intracranial EEG recording. We determined if the rate of visually-marked HFOs and spike-related HF power changes differed between SOZ and non-SOZ.
  
  
  RESULTS
  Significantly higher rates of HFOs were found in SOZ. The degree of spike-related HF power augmentation failed to differ between SOZ and non-SOZ, whereas that of post-spike HF power attenuation was significantly more severe in SOZ compared to in non-SOZ. Regions showing HFOs and large spike-related HF-changes showed a partial overlap in distribution in 7/14 patients.
  
  
  CONCLUSIONS
  Strong HF augmentation during spikes and high HFO rates occurred over different brain locations. The rate of HFOs showed the best performance in identifying SOZ. Post-spike HF power attenuation may represent increased inhibition in these channels and should be investigated further.
  
  
  CONCLUSIONS
  Strong HF power changes during spikes and HFOs per se seem to reflect distinct phenomena.
authors.affiliation: Department of Neuropediatrics and Muscular Diseases, University Medical Center Freiburg, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Jacobs
authors.affiliation: Department of Neuropediatrics and Muscular Diseases, University Medical Center Freiburg, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Vogt
authors.affiliation: Medical Physics, University Medical Center Freiburg, Germany.
authors.forename: Pierre
authors.initials: P
authors.lastname: LeVan
authors.affiliation: Montreal Neurological Institute, McGill University, Canada.
authors.forename: Rina
authors.initials: R
authors.lastname: Zelmann
authors.affiliation: Montreal Neurological Institute, McGill University, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Gotman
authors.affiliation: Department of Child Neurology, Okayama University Hospital, Kita-ku, Okayama, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Kobayashi
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D012640:Seizures / Q000175:diagnosis* / Q000503:physiopathology
keywords: Epilepsy surgery; Fast ripple; Ripple; Seizure onset zone; Spikes