title: Should spikes on post-resection ECoG guide pediatric epilepsy surgery?
abstract: OBJECTIVE
  There is wide variation in clinical practice regarding the role of electrocorticography immediately after resection (post-resection ECoG) for pediatric epilepsy surgery. Results can guide further resection of potentially epileptogenic tissue. We hypothesized that post-resection ECoG spiking represents a biomarker of the epileptogenic zone and predicts seizure outcome in children undergoing epilepsy surgery.
  
  
  METHODS
  We retrospectively identified 124 children with post-resection ECoG performed on the margins of resection. ECoG records were scored in a blinded fashion based on presence of frequent spiking. For patients identified as having additional resection based on clinical post-resection ECoG interpretation, these "second-look" ECoG results were re-reviewed for ongoing discharges or completeness of resection. Frequent spike populations were grouped using a standard scoring system into three ranges: 0.1-0.5Hz, 0.5-1Hz, >1Hz. Seizure outcomes were determined at minimum 12-month followup.
  
  
  RESULTS
  Of 124 patients who met inclusion criteria, 60 (48%) had an identified spike population on post-resection ECoG. Thirty (50%) of these had further resection based on clinical interpretation. Overall, good outcome (ILAE 1) was seen in 56/124 (45%). Completeness of resection of spiking (absence of spiking on initial post-resection ECoG or resolution of spiking after further resection) showed a trend toward good outcome (OR 2.03, p=0.099). Patients with completeness of resection had good outcome in 41/80 (51%) of cases; patients with continued spikes had good outcome in 15/44 (35%) of cases.
  
  
  CONCLUSIONS
  Post-resection ECoG identifies residual epileptogenic tissue in a significant number of children. Lower frequency or absence of discharges on initial recording showed a trend toward good outcome. Completeness of resection demonstrated on final ECoG recording did not show a significant difference in outcome. This suggests that post-resection discharges represent a prognostic marker rather than a remediable biomarker of the epileptogenic zone in all patients. Resecting residual spike-generating cortex may be beneficial in selected patients, including children with tumors.
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA. Electronic address: hansel.greiner@cchmc.org.
authors.forename: Hansel M
authors.initials: HM
authors.lastname: Greiner
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Horn
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Tenney
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Ravindra
authors.initials: R
authors.lastname: Arya
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Sejal V
authors.initials: SV
authors.lastname: Jain
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Holland
authors.affiliation: Division of Neuroradiology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Leach
authors.affiliation: Division of Pathology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Lili
authors.initials: L
authors.lastname: Miles
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Rose
authors.affiliation: Division of Neurology, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Hisako
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Division of Pediatric Neurosurgery, Cincinnati Childrens Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Francesco T
authors.initials: FT
authors.lastname: Mangano
mesh_terms: D000293:Adolescent; D001921:Brain / Q000503:physiopathology* / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D000069280:Electrocorticography / Q000379:methods*; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods; D019635:Neurosurgical Procedures / Q000379:methods*; D011379:Prognosis; D012008:Recurrence; D012189:Retrospective Studies; D016037:Single-Blind Method; D055815:Young Adult
keywords: Epilepsy surgery; Invasive EEG; Pediatric epilepsy