Authors :
Presenting Author: M. Rabiul Islam, PhD – Cleveland Clinic, Cleveland, United States
Juan C. Bulacio, MD – Cleveland Clinic, Cleveland, United States
Balu Krishnan, PhD – Cleveland Clinic
Demitre Serletis, MD, PhD – Cleveland Clinic Epilepsy Center, USA
Rationale:
Cingulate epilepsy is associated with polymorphic semiology, complex network propagation pathways and challenging surgical anatomy. In order to investigate cross-frequency interactions in cingulate epilepsy-related stereoelectroencephalography (sEEG) recordings, our study investigates dynamic, band-specific frequency (BSF) phase-amplitude coupling (PAC) in sEEG data, collected from cingulate epilepsy patients who underwent subsequent resective or ablative surgery and achieved seizure-freedom. We hypothesize that identification of individualized BSF coupling patterns may enhance epileptogenic zone (EZ) lateralization and localization, potentially offering new insights into the spatiotemporal dynamics underlying epileptiform cingulate network activity.
Methods:
We retrospectively analyzed 25 sEEG seizure recordings from four patients with cingulate epilepsy, who underwent subsequent resection or laser ablation of the cingulate region, and achieved sustained seizure freedom of at least 12 months. Our study was approved by the Cleveland Clinic Institutional Review Board. For each seizure, the ictal period was annotated by an epileptologist, and all sEEG electrode contacts were annotated by an epilepsy surgeon, including contacts removed following resection or ablation (thereby serving as the ‘ground truth’ for EZ localization). For each seizure, the pre-ictal period was defined as the 100-second interval immediately preceding ictal onset. For BSF analysis, low-frequency oscillations (1–13 Hz) of each electrode contact were subdivided into delta (δ, 1–5 Hz), theta (θ, 4–8 Hz), and alpha bands (α, 9–13 Hz), while higher-frequency oscillations (14–250 Hz) were subdivided into beta (β, 14–28 Hz), gamma (γ, 29–83 Hz), and ‘ripple-plus’ bands (r, 84–250 Hz). After filtering the signals into these specified frequency bands, the sEEG data were segmented into consecutive 10-second epochs prior to the use of PAC analysis. PAC analysis was conducted separately for every paired frequency-band combination, for pre-ictal and ictal epochs. Finally, for each patient, average PAC values across multiple seizures were statistically compared between electrode contacts located in resected EZ tissue and those in non-resected tissue, using the Mann-Whitney U test.
Results:
Statistical analysis revealed significant coupling between low-frequency oscillations (δ, θ) and high-frequency oscillations (β, γ) across all four patients (p< 0.05), facilitating visualization and identification of implicated electrode contacts involved in the EZ (which had been treated by resection or laser ablation,