title: Statistical mapping of ictal high-frequency oscillations in epileptic spasms.
abstract: OBJECTIVE
  We assessed 636 epileptic spasms seen in 11 children (median 44 spasms per child) and determined the spatial and temporal characteristics of ictal high-frequency oscillations (HFOs) in relation to the onset of spasms.
  
  
  METHODS
  Electrocorticography (ECoG) signals were sampled from 104-148 cortical sites per child, and the dynamic changes of ictal HFOs were animated on each individual's three-dimensional (3D) magnetic resonance (MR) image surface.
  
  
  RESULTS
  Visual assessment of ictal ECoG recordings revealed that each spasm event was characterized by augmentation of HFOs. Time-frequency analysis demonstrated that ictal augmentation of HFOs at 80-200 Hz was most prominent and generally preceded those at 210-300 Hz and at 70 Hz and slower. Recruitment of HFOs in the rolandic cortex preceded the clinical onset objectively visualized as electromyographic deflection. The presence or absence of ictal motor symptoms was related more to the amplitude of HFOs in the Rolandic cortex than in the seizure-onset zone. In a substantial proportion of epileptic spasms, seizure termination began at the seizure-onset zone and propagated to the surrounding areas; we referred to this observation as the "ictal doughnut phenomenon." Univariate analysis suggested that complete resection of the sites showing the earliest augmentation of ictal HFOs was associated with a good surgical outcome.
  
  
  CONCLUSIONS
  Recruitment of HFOs at 80-200 Hz in the rolandic area may play a role in determining seizure semiology in epileptic spasms. Our study using macroelectrodes demonstrated that ictal HFOs at 80-200 Hz preceded those at 210-300 Hz.
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, Michigan, USA.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nariai
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Nagasawa
authors.forename: Csaba
authors.initials: C
authors.lastname: Juhász
authors.forename: Sandeep
authors.initials: S
authors.lastname: Sood
authors.forename: Harry T
authors.initials: HT
authors.lastname: Chugani
authors.forename: Eishi
authors.initials: E
authors.lastname: Asano
mesh_terms: D001931:Brain Mapping / Q000379:methods* / Q000706:statistics & numerical data; D002540:Cerebral Cortex / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D004567:Electrodes, Implanted / Q000706:statistics & numerical data; D004569:Electroencephalography / Q000379:methods* / Q000706:statistics & numerical data; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology; D019305:Epilepsy, Rolandic / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008959:Models, Neurological; D012640:Seizures / Q000175:diagnosis / Q000503:physiopathology*; D013036:Spasms, Infantile / Q000175:diagnosis / Q000503:physiopathology