Seizure Onset Zone Localization in Inter-ictal Stereo-encephalography: Robustness and Stability of Relative Entropy in Prolonged Recordings Contrasted to Spikes and High-frequency Oscillations
Abstract number :
1.034
Submission category :
1. Basic Mechanisms / 1C. Electrophysiology/High frequency oscillations
Year :
2022
Submission ID :
2204499
Source :
www.aesnet.org
Presentation date :
12/3/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:25 AM
Authors :
Petr Klimes, PhD – Institute of Scientific Instruments, The Czech Academy of Sciences; Jan Cimbalnik, PhD – International Clinical Research Center, St. Anne’s University Hospital; Vojtech Travnicek, MSc. – Institute of Scientific Instruments, The Czech Academy of Sciences; Pavel Jurak, PhD – Institute of Scientific Instruments, The Czech Academy of Sciences; Josef Halamek, PhD – Institute of Scientific Instruments, The Czech Academy of Sciences; Martin Pail, MD – Brno Epilepsy Center, Department of Neurology, St. Anne’s University Hospital, Faculty of Medicine, Masaryk University; Milan Brazdil, MD – Brno Epilepsy Center, Department of Neurology, St. Anne’s University Hospital, Faculty of Medicine, Masaryk University
Rationale: In drug-resistant epilepsy, the current gold standard is identifying the seizure onset zone from ictal stereo-encephalography (SEEG) recordings. Inter-ictal SEEG features proved to provide additional information without seizure recording.1 However, inter-ictal evaluation is often focused on short segments of recordings, unable to capture the variability of analyzed features. In this study, we hypothesize that (1) the most commonly analyzed inter-ictal features of spikes, and high-frequency oscillations (HFOs) vary significantly across different states of vigilance and that (2) the recently proposed relative entropy (REN) is more robust in prolonged recordings.
Methods: We analyzed 24 hours of SEEG recordings (5 kHz sampling rate) from 3056 SEEG contacts on depth electrodes implanted in 19 consecutive patients with drug-resistant, focal epilepsy, recorded at the Brno Epilepsy Center (St Anne’s University Hospital) between 2017 and 2020. Eight patients had the post-surgical outcome of Engel1, with > 2-year follow-up. The seizure onset zone (SOZ) was marked in SEEG data by certified epileptologists. Spikes and HFOs in ripple (80-250 Hz) and fast ripple (250-600 Hz) bands were detected by validated detectors. Relative entropy was calculated as a nearest-neighbor bivariate measure of signal spectral complexity in a ripple, and fast ripple frequency ranges [Cimbalnik J. et al. Multi-feature localization of epileptic foci from interictal, intracranial EEG. Clin. Neurophysiol. 2019;130:1945-1953.]. Standard deviation (STD) was calculated on z-scored features across 5-minute long Wake, NREM, and REM sleep segments. For every patient, three segments in each state were selected. The differences in STD between calculated features and between SOZ (132 contacts) and NON-SOZ (2924 contacts) were tested by The Mann-Whitney U test and Cliff’s Delta effect size. Results with p< 0.001 (after Bonferroni correction) and a large effect size were considered significant.
Basic Mechanisms