Strong coupling between slow oscillations and wide fast ripples in children with epileptic spasms: Investigation of modulation index and occurrence rate

Yasushi Iimura, Kevin Jones, Lynne Takada, Itsuki Shimizu, Misaki Koyama, Kyoko Hattori, Yushi Okazawa, Yutaka Nonoda, Eishi Asano, Tomoyuki Akiyama, Cristina Go, Ayako Ochi, O. Carter Snead, Elizabeth J. Donner, James T. Rutka, James M. Drake, Hiroshi Otsubo

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Objective: Epileptic spasms (ES) often become drug-resistant. To reveal the electrophysiological difference between children with ES (ES+) and without ES (ES−), we compared the occurrence rate (OR) of high-frequency oscillations (HFOs) and the modulation index (MI) of coupling between slow and fast oscillations. In ES+, we hypothesized that (1) pathological HFOs are more widely distributed and (2) slow oscillations show stronger coupling with pathological HFOs than in ES−. Methods: We retrospectively reviewed 24 children with drug-resistant multilobar onset epilepsy, who underwent intracranial video electroencephalography prior to multilobar resections. We measured the OR of HFOs and determined the electrodes with a high rate of HFOs by cluster analysis. We calculated MI, which reflects the degree of coupling between HFO (ripple/fast ripple [FR]) amplitude and 5 different frequency bands of delta and theta activities (0.5-1 Hz, 1-2 Hz, 2-3 Hz, 3-4 Hz, 4-8 Hz). Results: In ES+ (n = 10), the OR( FR s), the number of electrodes with high-rate FRs, and the MI( FR s & 3-4 Hz) in all electrodes were significantly higher than in ES− (n = 14). In both the ES+ and ES− groups, MI(ripples/ FR s & 3-4 Hz) was the highest among the 5 frequency bands. Within the good seizure outcome group, the OR( FR s) and the MI( FR s & 3-4 Hz) in the resected area in ES+ were significantly higher than in ES− (OR[FR s], P =.04; MI[ FR s & 3-4 Hz], P =.04). Significance: In ES+, the larger number of high-rate FR electrodes indicates more widespread epileptogenicity than in ES−. High values of OR( FR s) and MI( FR s & 3-4 Hz) in ES+ compared to ES− are a signature of the severity of epileptogenicity. We proved that ES+ children who achieved seizure freedom following multilobar resections exhibited strong coupling between slow oscillations and FRs.

Original languageEnglish
Pages (from-to)544-554
Number of pages11
JournalEpilepsia
Volume59
Issue number3
DOIs
Publication statusPublished - Mar 2018

Keywords

  • drug-resistant epilepsy
  • epilepsy surgery
  • focal seizure
  • intracranial EEG
  • multilobar resection

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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  • Cite this

    Iimura, Y., Jones, K., Takada, L., Shimizu, I., Koyama, M., Hattori, K., Okazawa, Y., Nonoda, Y., Asano, E., Akiyama, T., Go, C., Ochi, A., Snead, O. C., Donner, E. J., Rutka, J. T., Drake, J. M., & Otsubo, H. (2018). Strong coupling between slow oscillations and wide fast ripples in children with epileptic spasms: Investigation of modulation index and occurrence rate. Epilepsia, 59(3), 544-554. https://doi.org/10.1111/epi.13995