Fast (40–150 Hz) oscillations are associated with positive slow waves in the ictal EEGs of epileptic spasms in West syndrome

Katsuhiro Kobayashi, Tomoyuki Akiyama, Makio Oka, Fumika Endoh, Harumi Yoshinaga

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Objective To elucidate the generative mechanisms of epileptic spasms (ESs) in West syndrome, we investigated the temporal relationship between scalp fast (40–150 Hz) oscillations (FOs) and slow waves in the ictal electroencephalograms (EEGs) of ESs. Methods In 11 infants with WS, ictal FOs were detected in a bipolar montage based on spectral and waveform criteria. Their temporal distribution was analyzed in terms of the positive peaks (trough point, TT) of identical EEG data in a referential montage. Among six EEG data sections defined according to TT, the number of FOs, peak power values, and peak frequencies were compared. Results We identified a total of 1014 FOs (946 gamma and 68 ripple oscillations), which clustered closely at TT. The number of gamma oscillations in the 1 s epoch including TT was significantly higher than those in the prior and subsequent phases. Peak power values and frequencies tended to be higher in these positive phase sections. Conclusions The temporal association of FO clustering and positive slow waves in the ictal EEGs of ES indicated that active neuronal firing related to FOs underlies the generation of ESs and their ictal slow waves.

Original languageEnglish
Pages (from-to)909-914
Number of pages6
JournalBrain and Development
Issue number10
Publication statusPublished - Nov 1 2016


  • Fast oscillations
  • High-frequency oscillations
  • Ictal EEG
  • Infantile spasms
  • Slow wave
  • West syndrome

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Developmental Neuroscience
  • Clinical Neurology


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