title: Ictal high-frequency oscillations at 80-200 Hz coupled with delta phase in epileptic spasms.
abstract: Previous studies of epileptic spasms reported that ictal events were associated with high-frequency oscillations (HFOs) or delta waves involving widespread regions. We determined whether ictal HFOs at 80-200 Hz were coupled with a phase of slow-wave, whether ictal slow-waves were diffusely or locally synchronous signals, and whether the mode of coupling between HFOs and slow-wave phases differed between ictal and interictal states. We studied 11 children who underwent extraoperative electrocorticography (ECoG) recording. The phases and amplitudes of slow-waves were measured at the peak of ictal and interictal HFOs in the seizure-onset sites. Ictal HFOs were locked tightly to the phase of slow-wave at ≤1 Hz. Ictal slow-waves propagated from the seizure-onset site to other regions. In contrast, interictal HFOs in the seizure-onset site were loosely locked to the phase of slow-wave at ≤1 Hz but tightly to that of ≥3-Hz. Ictal slow-waves coupled with HFOs can be explained as near-field and locally synchronized potentials generated by the neocortex rather than far-field potentials generated by subcortical structures. Ictal slow-waves in epileptic spasms may be generated by a mechanism different from what generates interictal HFOs-slow-wave complexes.
authors.affiliation: Department of Pediatrics, Children's Hospital of Michigan, Wayne State University, Detroit Medical Center, Detroit, Michigan 48201, USA.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nariai
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Matsuzaki
authors.forename: Csaba
authors.initials: C
authors.lastname: Juhász
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Nagasawa
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: D002648:Child; D002675:Child, Preschool; D003700:Delta Rhythm / Q000502:physiology*; D004569:Electroencephalography; D004585:Electrooculography; D006801:Humans; D007223:Infant; D008991:Monitoring, Physiologic; D012640:Seizures / Q000503:physiopathology*; D014741:Video Recording