Strong coupling between slow oscillations and wide fast ripples in children with epileptic spasms: Investigation of modulation index and occurrence rate. (6th January 2018)

• Record Type: Journal Article
• Authors: Iimura, Yasushi; Jones, Kevin; Takada, Lynne; Shimizu, Itsuki; Koyama, Misaki; Hattori, Kyoko; Okazawa, Yushi; Nonoda, Yutaka; Asano, Eishi; Akiyama, Tomoyuki; Go, Cristina; Ochi, Ayako; Snead, O. Carter; Donner, Elizabeth J.; Rutka, James T.; Drake, James M.; Otsubo, Hiroshi
• Is Part Of: Epilepsia. Volume 59:issue 3(2018)
• Page Start: 544
• Page End: 554
• Publication Date: 2018-01-06
• Subjects: drug‐resistant epilepsy -- epilepsy surgery -- focal seizure -- intracranial EEG -- multilobar resection; Epilepsy -- Periodicals; 616.853
• DOI: 10.1111/epi.13995
• Languages: English
• ISSNs: 0013-9580

Abstract

Summary: 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.