John Libbey Eurotext

Effects of a stable concentration of propofol on interictal high-frequency oscillations in drug-resistant epilepsy Volume 23, numéro 2, April 2021

Illustrations

  • Figure 1
  • Figure 2
  • Figure 3
  • Figure 4
  • Figure 5

Tableaux

Auteurs
1 Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
2 Department of Neurology, Kyoto University Graduate School of Medicine, 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
3 Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
4 Human Brain Research Centre, Kyoto University Graduate School of Medicine, 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
5 Department of Neurology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuo-ku, Kobe 650-0017, Japan
6 Kinugasa Research Organization, Ritsumeikan University, 56-1 Toji-in Kitamachi, Kita-ku, Kyoto, 603-8577, Japan
7 Department of Neurosurgery, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
8 Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital, Shikatacho 2-chome 5-1, Kita-ku, Okayama 700-8558, Japan
* Correspondence: Takayuki Kikuchi Department of Neurosurgery, Kyoto University Graduate School of Medicine, 54, Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507, Japan Katsuya Kobayashi Department of Neurology, Kyoto University Graduate School of Medicine, 54, Shogoin-Kawaharacho, Sakyo-ku, Kyoto 606-8507, Japan

Objective

The aim of this study was to clarify the effect of a stable concentration of propofol on interictal high-frequency oscillations (HFOs), which may contribute to identifying the epileptogenic zone intraoperatively for resection surgery.

Methods

Nine patients with drug-resistant focal epilepsy who underwent invasive pre-surgical evaluation with chronic subdural electrodes were recruited. Five-minute electrocorticograms during wakefulness, slow-wave sleep, and under a stable brain concentration of propofol were recorded with the same electrodes. In each patient, 1-10 pairs of electrodes were selected for both electrodes with EEG changes within 5 seconds from the ictal onset (ictal pattern for 5 seconds [IP5]) and those outside the area of IP5 with no interictal epileptiform discharges (non-epileptiform [nEPI]). The numbers of ripples (80-250 Hz) and fast ripples (>250 Hz) were measured semi-automatically using an established algorithm. Statistical testing was performed with a mixed effect model.

Results

Thirty-seven pairs of electrodes from nine patients were analysed for IP5 and 29 pairs from seven patients were analysed for nEPI. The numbers of HFOs differed between the areas (IP5 and nEPI) and among the conditions (wakefulness, slow-wave sleep, propofol anaesthesia) (all p <0.01). The HFO occurrence rates were significantly higher for IP5 than those for nEPI in all conditions (for both ripples and fast ripples in all conditions; p <0.01).

Significance

The occurrence rates of HFOs for IP5 were significantly higher than those for nEPI under propofol anaesthesia. These are fundamental findings for intraoperative HFO analysis, however, the following limitations should be considered: physiological HFOs could not be completely differentiated from pathological HFOs; in order to apply an HFO detector, an appropriate cut-off threshold is needed; an artefact of the impulse response filter appears as an HFO; and the series was comprised of a small number of heterogeneous patients.