title: Lateralization of interictal spikes after corpus callosotomy.
abstract: OBJECTIVE
  Corpus callosotomy may limit secondary bilateral synchrony into the primary epileptogenic hemisphere. This study investigated whether pre-operative EEG can predict post-operative spike lateralization.
  
  
  METHODS
  The subjects included 14 patients with medically intractable drop attacks who underwent total corpus callosotomy. Pre-operative patterns of inter-hemispheric propagation were quantified by peak-latency analysis with the template-based spike averaging technique.
  
  
  RESULTS
  Postoperative lateralization of interictal spikes was observed in 5 of the 14 patients. Inter-hemispheric latency was significantly longer in these 5 patients (mean 14.0 ms, range from 0 to 78 ms, versus mean 5.2 ms, range from 0 to 29 ms, p<0.01). The lateralization occurred in association with the presence of structural lesions (p<0.05). The post-operative spikes were lateralized to the lesion side in 3 of 4 patients with unilateral epileptogenic lesion. Three patients presented one-way inter-hemispheric propagation pattern pre-operatively. The post-operative spikes were lateralized to the hemisphere of the leading spikes in two.
  
  
  CONCLUSIONS
  Interictal spikes are lateralized to the epileptogenic hemisphere in some patients after callosotomy. Lateralization can be expected in the presence of structural lesions and/or longer inter-hemispheric latency.
  
  
  CONCLUSIONS
  Analysis of pre-operative EEG spikes may predict the primary epileptogenic hemisphere before corpus callosotomy.
authors.affiliation: Department of Neurosurgery, Tohoku University School of Medicine, Sendai, Miyagi, Japan. epinetmi@gmail.com
authors.forename: Masaki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Nakasato
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kakisaka
authors.forename: Akitake
authors.initials: A
authors.lastname: Kanno
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Uematsu
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Haginoya
authors.forename: Teiji
authors.initials: T
authors.lastname: Tominaga
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000293:Adolescent; D058256:Brain Waves / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003337:Corpus Callosum / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D004569:Electroencephalography / Q000379:methods*; D004827:Epilepsy / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007223:Infant; D008297:Male; D055815:Young Adult