Reflections of very high-frequency oscillations (> 500Hz) in routine stereo-EEG

0566969 - ÚPT 2023 US eng A - Abstract
Vašíčková, Zuzana - Klimeš, Petr - Cimbálník, J. - Pail, M. - Halámek, Josef - Jurák, Pavel - Brázdil, M.
Reflections of very high-frequency oscillations (> 500Hz) in routine stereo-EEG.
Epilepsia. Wiley. Roč. 63, S2 (2022), s. 6-7. ISSN 0013-9580. E-ISSN 1528-1167.
[European Epilepsy Congress /14./. 09.07.2022-13.07.2022, Geneva]
Institutional support: RVO:68081731
https://onlinelibrary.wiley.com/doi/epdf/10.1111/epi.17388

Purpose: The aim of the study was to investigate intracranial stereo-EEG (SEEG) recorded in patients with drug-resistant epilepsy. Recently, very high frequency-oscillations (VHFOs, > 500 Hz) might be more specific in localizing the epileptogenic zone, than high-frequency oscillations (HFOs, < 500 Hz). However, to measure VHFOs, immense sampling frequencies of SEEG recordings are necessary. The focus was to investigate possible reflections of the VHFOs in the recordings undersampled to 1 kHz. We hypothesized that it is possible to distinguish SEEG undersampled signals with or without the presence of VHFOs. Methods: The initial cohort of patients included 67 adult patients with drug-resistant epilepsy who underwent SEEG and surgery with ≥2 years follow up. 13 patients met the criteria for further analysis of VHFOs: good outcome Engel IA or IB, localized seizure onset zone and its overlap with resection, implanted hippocampus, and detected VHFOs. 5 kHz recordings from 141 SEEG contacts were manually classified into RED (channels with HFOs and VHFOs = 50) and GREEN (channels with HFOs and without VHFOs = 91) contacts. Undersampled 1 kHz were analyzed based on the calculated maximum of absolute amplitude, 75th percentile of power spectral density estimate, Shannon entropy, and Teager-Kaiser energy operator. Results: The p values of calculated features of RED and GREEN contacts with 1 kHz sampling frequency were all p < 0.0001 (corrected for multiple comparisons). Further, the p values of ripple and fast ripple rates calculated from the original 5kHz contact recordings were p = 0.4795 and p = 0.7237. Conclusion: Our results suggest that VHFO reflections can be found in recordings with sampling frequency of 1kHz and thus classify recordings pre-examined for HFOs into GREEN and RED SEEG contacts.
Permanent Link: https://hdl.handle.net/11104/0338230