title: Ictal electrocorticographic findings related with surgical outcomes in nonlesional neocortical epilepsy.
abstract: OBJECTIVE
  To characterize ictal electrocorticographic features related to surgical outcomes in nonlesional neocortical epilepsy (NE).
  
  
  METHODS
  We analyzed 187 ictal electrocorticograms (ECoG) obtained from 18 patients who had undergone presurgical evaluation and subsequent neocortical resections (frontal: seven, parietal: one, occipital: four, multilobar: six). None of them had any MRI-detectable lesions. Various ECoG data sets recorded from eight patients who achieved a favorable surgical outcome (either seizure free or more than 90% reduction of seizure frequencies) were compared with that from ten patients with unfavorable outcome (less than 90% reduction of seizure frequencies) (follow up duration: 47+/-11 months).
  
  
  RESULTS
  Reproducible ictal onset zone (IOZ) in recurrent seizures (P=0.013) and persistent ictal discharges in IOZ from the onset to the end of seizure (P=0.004) were found more frequently in the patients with good outcome. Ictal onset patterns consisting of low voltage fast or high amplitude beta spikes predicted a good surgical outcome while rhythmic sinusoidal activity or rhythmic spike/sharp waves of slow frequency were predictive of poor outcome (P=0.01). The ictal onset rhythm consisting of gamma or beta frequencies was more prevalent in the favorable group (P=0.015).
  
  
  CONCLUSIONS
  The presence of stable ictal circuit suggested by the consistent earliest activation of specific electrodes in the repetitive seizures (reproducible IOZ) and the active participation of IOZ throughout the attack were valuable prognostic factors in addition to the morphology and frequency of ictal onset rhythm.
authors.affiliation: Department of Neurology, Yonsei University College of Medicine, Severance Hospital, CPO Box 8044, Seoul, South Korea.
authors.forename: S A
authors.initials: SA
authors.lastname: Park
authors.forename: S R
authors.initials: SR
authors.lastname: Lim
authors.forename: G S
authors.initials: GS
authors.lastname: Kim
authors.forename: K
authors.initials: K
authors.lastname: Heo
authors.forename: S C
authors.initials: SC
authors.lastname: Park
authors.forename: J W
authors.initials: JW
authors.lastname: Chang
authors.forename: S S
authors.initials: SS
authors.lastname: Chung
authors.forename: J U
authors.initials: JU
authors.lastname: Choi
authors.forename: T S
authors.initials: TS
authors.lastname: Kim
authors.forename: Byung In
authors.initials: BI
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D004569:Electroencephalography / Q000706:statistics & numerical data*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D019579:Neocortex / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome