title: High frequency oscillations are less frequent but more specific to epileptogenicity during rapid eye movement sleep.
abstract: OBJECTIVE
  We hypothesized that high frequency oscillations (HFOs) are differently suppressed during rapid eye movement sleep (REM) between epileptogenic and less epileptogenic cortices, and that the suppressive effect can serve as a specific marker of epileptogenicity.
  
  
  METHODS
  Intracranial electroencephalography (EEG) was recorded in 13 patients with drug-resistant epilepsy. HFOs between 80 and 200Hz were semi-automatically detected from total 15-min EEG epochs each for REM and slow wave sleep (SWS). z-Score of HFO occurrence rate was calculated from the baseline rate derived from non-epileptogenic cortex. Intracranial electrodes were labeled as REM dominant HFO (RdH) if REM z-score was greater than SWS z-score or as SWS dominant HFO (SdH) if SWS z-score was greater than REM z-score. Relationship of electrode location to the area of surgical resection was compared between RdH and SdH electrodes.
  
  
  RESULTS
  Out of 1070 electrodes, 101 were defined as RdH electrodes and 115 as SdH electrodes. RdH electrodes were associated with the area of resection in patients with postoperative seizure freedom (P<0.001), but not in patients without seizure freedom.
  
  
  CONCLUSIONS
  HFOs near the epileptogenic zone are less suppressed during REM.
  
  
  CONCLUSIONS
  The less suppressive effect of REM may provide a specific marker of epileptogenicity.
authors.affiliation: Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Sakuraba
authors.affiliation: Department of Neurosurgery, Tohoku University School of Medicine, Sendai, Japan. Electronic address: iwa@nsg.med.tohoku.ac.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Iwasaki
authors.affiliation: Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Okumura
authors.affiliation: Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Jin
authors.affiliation: Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kakisaka
authors.affiliation: Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kato
authors.affiliation: Department of Neurosurgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Teiji
authors.initials: T
authors.lastname: Tominaga
authors.affiliation: Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Nakasato
mesh_terms: D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D000069279:Drug Resistant Epilepsy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012895:Sleep, REM
keywords: Epilepsy surgery; High-frequency oscillations; Intracranial electroencephalography; Rapid eye movement sleep; Seizure outcome