title: Extent of neocortical resection and surgical outcome of epilepsy: intracranial EEG analysis.
abstract: OBJECTIVE
  Intracranial electroencephalography (EEG) monitoring is an important process in the presurgical evaluation for epilepsy surgery. The objective of this study was to identify the ideal resection margin in neocortical epilepsy guided by subdural electrodes. For this purpose, we investigated the relationship between the extent of resection guided by subdural electrodes and the outcome of epilepsy surgery.
  
  
  METHODS
  Intracranial EEG studies were analyzed in 177 consecutive patients who had undergone resective epilepsy surgery. We reviewed various intracranial EEG findings and resection extent. We analyzed the relationships between the surgical outcomes and intracranial EEG factors: the frequency, morphology, and distribution of ictal-onset discharges, the propagation speed, and the time lag between clinical and intracranial ictal onset. We also investigated whether the extent of resection, including the area showing ictal rhythm and various interictal abnormalities--such as frequent interictal spikes, pathologic delta waves, and paroxysmal fast activity--influenced the surgical outcome.
  
  
  RESULTS
  Seventy-five patients (42%) were seizure free. A seizure-free outcome was significantly associated with a resection that included the area showing ictal spreading rhythm during the first 3 s or included all the electrodes showing pathologic delta waves or frequent interictal spikes. However, subgroup analysis revealed that the extent of resection did not affect the surgical outcome in lateral temporal lobe epilepsy.
  
  
  CONCLUSIONS
  The extent of resection is closely associated with surgical outcome, especially in extratemporal lobe epilepsy. Resection that includes the area with total pathologic delta waves and frequent interictal spikes predicts a good surgical outcome.
authors.affiliation: Department of Neurology, Konkuk University Medical Center, Seoul, Korea.
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Kim
authors.forename: Hyun Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Sang Kun
authors.initials: SK
authors.lastname: Lee
authors.forename: Kon
authors.initials: K
authors.lastname: Chu
authors.forename: Chun Kee
authors.initials: CK
authors.lastname: Chung
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019579:Neocortex / Q000503:physiopathology* / Q000601:surgery*; D012189:Retrospective Studies; D013355:Subdural Space / Q000503:physiopathology; D016896:Treatment Outcome; D055815:Young Adult