title: Source localization of interictal spike-locked neuromagnetic oscillations in pediatric neocortical epilepsy.
abstract: OBJECTIVE
  To evaluate the utility of an event-related beamforming (ERB) algorithm in source localization of interictal discharges.
  
  
  METHODS
  We analyzed interictal magnetoencephalography data in 35 children with intractable neocortical epilepsy. We used a spatiotemporal beamforming method to estimate the spatial distribution of source power in individual interictal spikes. We compared ERB results to source localization using the equivalent current dipole model and to the seizure onset zones on intracranial EEG.
  
  
  RESULTS
  Focal beamformer localization was observed in 66% of patients and multifocal in the remaining 34%. ERB localized within 2 cm of the equivalent current dipole cluster centroid in 77% of the patients. ERB localization was concordant with the seizure onset zone on intracranial EEG at the gyral level in 69% of patients. Focal ERB localization area was included in the resection margin in 22/23 patients. However, focal ERB localization was not statistically associated with better surgical outcome.
  
  
  CONCLUSIONS
  ERB can be used for source localization of interictal spikes and can be predictive of the ictal onset zone in a subset of patients with neocortical epilepsy.
  
  
  CONCLUSIONS
  These results support the utility of beamformer source localization as a fast semi-automated method for source localization of interictal spikes and planning the surgical strategy.
authors.affiliation: Department of Pediatrics, IWK Health Center, Dalhousie University, Halifax, NS, Canada. ismailsmohamed@me.com
authors.forename: Ismail S
authors.initials: IS
authors.lastname: Mohamed
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Otsubo
authors.forename: Paul
authors.initials: P
authors.lastname: Ferrari
authors.forename: Rohit
authors.initials: R
authors.lastname: Sharma
authors.forename: Ayako
authors.initials: A
authors.lastname: Ochi
authors.forename: Irene
authors.initials: I
authors.lastname: Elliott
authors.forename: Cristina
authors.initials: C
authors.lastname: Go
authors.forename: Sylvester
authors.initials: S
authors.lastname: Chuang
authors.forename: James
authors.initials: J
authors.lastname: Rutka
authors.forename: Carter
authors.initials: C
authors.lastname: Snead
authors.forename: Douglas
authors.initials: D
authors.lastname: Cheyne
mesh_terms: D002648:Child; D002675:Child, Preschool; D004827:Epilepsy / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007223:Infant; D015225:Magnetoencephalography; D008297:Male; D019579:Neocortex / Q000503:physiopathology*
keywords: Epilepsy; Epilepsy surgery; Event-related beamformer; Interictal spikes; Magnetoencephalography