Brain network characteristics of epileptogenic zone in drug ⁃ resistant epilepsy based on stereo⁃electroencephalography

Abstract

Objective To analyze stereo ⁃electroencephalography (SEEG) data from patients with drug⁃resistant epilepsy (DRE) and explore the differences in graph theory indices of brain network between the epileptogenic zone (EZ) and the non⁃ictal zone (NIZ). Methods Reviewed data from 11 patients who underwent SEEG implantation at Beijing Tiantan Hospital, Capital Medical University from August 2022 to December 2023. Based on the SEEG and structural imaging data, we calculated the epileptogenicity index and constructed epileptogenic map to differentiate the EZ from the NIZ. We then used Granger causality analysis to calculate functional adjacency matrices for both regions during interictal and epileptic periods, combining graph theory indices such as global efficiencies (Eglob), local efficiencies (Eloc), clustering coefficients (Cp), characteristic path length (Lp), normalized clustering coefficients (γ), normalized characteristic path length (λ), and small⁃world parameter (σ). We analyzed changes in the graph theory indices of patients in interictal and epileptic periods. Results Compared with the interictal period, both γ (t = ⁃ 3.730, P = 0.005) and λ (t = ⁃ 6.436, P = 0.001) decreased in the NIZ during the epileptic period, while the differences of γ and λ in the EZ during the epileptic period were not statistically significant (P > 0.05, for all). In terms of network efficiency, compared with the interictal period, Eglob (t = 5.360, P = 0.002; t = 5.577, P = 0.001) and Eloc (t = 4.450, P = 0.003; t = 4.038, P = 0.005) in both the EZ and NIZ increased during the epileptic period, while Lp decreased (t = ⁃ 5.127, P = 0.002; t = ⁃ 3.912, P = 0.005). Conclusions During the epileptic period, both the EZ and NIZ exhibit increased synchronization across the whole brainnetwork. Changes in graph theory indices, particularly the γ and λ may serve as the potential biomarkersfor distinguishing the EZ and NIZ in epilepsy patients.

doi：10.3969/j.issn.1672⁃6731.2024.11.012