Functional connectivity alterations in patients with post-stroke epilepsy based on source-level EEG and graph theory

Abstract Purpose:We investigated the differences in functional connectivity based on the source-level electroencephalography (EEG) analysis between stroke patients with and without post-stroke epilepsy (PSE). Methods: Thirty stroke patients with PSE and 35 stroke patients without PSE were enrolled. EEG was conducted during a resting state period. We used a Brainstorm program for source estimation and the connectivity matrix. Data were processed according to EEG frequency bands. We used a BRAPH program to apply a graph theoretical analysis. Results: In the beta band, radius and diameter were increased in patients with PSE than in those without PSE (2.699 vs. 2.579, p=0.003; 2.261 vs. 2.171, p=0.003). In the low gamma band, radius was increased in patients with PSE than in those without PSE (2.808 vs. 2.617, p=0.004). In the high gamma band, the radius, diameter, eccentricity, and characteristic path length were increased (1.828 vs. 1.559, p=0.001; 2.653 vs. 2.306, p=0.002; 2.212 vs. 1.913, p=0.001; 1.425 vs. 1.286, p=0.002), whereas average strength, global efficiency, local efficiency, mean clustering coefficient, and transitivity were decreased in patients with PSE than in those without PSE (49.955 vs. 55.055, p=0.001; 0.756 vs. 0.827, p=0.001; 4.795 vs. 5.741, p=0.002; 0.727 vs. 0.810, p=0.001; 1.091 vs. 1.215, p=0.001). However, in the delta, theta, and alpha bands, none of the functional connectivity measures were different between groups. Conclusion: We demonstrated significant alterations of functional connectivity in patients with PSE, who have decreased segregation and integration in brain network, compared to those without PSE.