title: Frequency-independent characteristics of high-frequency oscillations in epileptic and non-epileptic regions.
abstract: OBJECTIVE
  The purpose of the presented study is to determine whether there are frequency-independent high-frequency oscillation (HFO) parameters which may differ in epileptic and non-epileptic regions.
  
  
  METHODS
  We studied 31 consecutive patients with medically intractable focal (temporal and extratemporal) epilepsies who were examined by either intracerebral or subdural electrodes. Automated detection was used to detect HFO. The characteristics (rate, amplitude, and duration) of HFO were statistically compared within three groups: the seizure onset zone (SOZ), the irritative zone (IZ), and areas outside the IZ and SOZ (nonSOZ/nonIZ).
  
  
  RESULTS
  In all patients, fast ripples (FR) and ripples (R) were significantly more frequent and shorter in the SOZ than in the nonSOZ/nonIZ region. In the group of patients with favorable surgical outcomes, the relative amplitude of FR was higher in the SOZ than in the IZ and nonIZ/nonSOZ regions; in patients with poor outcomes, the results were reversed. The relative amplitude of R was significantly higher in the SOZ, with no difference between patients with poor and favorable surgical outcomes.
  
  
  CONCLUSIONS
  FR are more frequent, shorter, and have higher relative amplitudes in the SOZ area than in other regions. The study suggests a worse prognosis in patients with higher amplitudes of FR outside the SOZ.
  
  
  CONCLUSIONS
  Various HFO parameters, especially of FR, differ in epileptic and non-epileptic regions. The amplitude and duration may be as important as the frequency band and rate of HFO in marking the seizure onset region or the epileptogenic area and may provide additional information on epileptogenicity.
authors.affiliation: Brno Epilepsy Center, Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic. Electronic address: martin.pail@fnusa.cz.
authors.forename: Martin
authors.initials: M
authors.lastname: Pail
authors.affiliation: Brno Epilepsy Center, Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Řehulka
authors.affiliation: International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Cimbálník
authors.affiliation: Brno Epilepsy Center, Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors.forename: Irena
authors.initials: I
authors.lastname: Doležalová
authors.affiliation: Brno Epilepsy Center, Department of Neurosurgery, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Chrastina
authors.affiliation: Brno Epilepsy Center, Department of Neurology, St. Anne's University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic; Behavioral and Social Neuroscience Research Group, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
authors.forename: Milan
authors.initials: M
authors.lastname: Brázdil
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods*; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
keywords: Epileptogenic zone; Extratemporal lobe epilepsy; Fast ripples; High frequency oscillations; Irritative zone; Ripples; Seizure onset zone; Temporal lobe epilepsy