Altered EEG microstate dynamics and cortical structure-function associations in temporal lobe epilepsy with FBTCS

This study aimed to characterize alterations in electroencephalographic (EEG) microstate dynamics and their structural correlates in patients with temporal lobe epilepsy (TLE) with and without focal to bilateral tonic-clonic seizures (FBTCS). A total of 37 patients with TLE and a history of FBTCS (TLE-FBTCS), 36 patients without FBTCS (TLE-NFBTCS), and 31 healthy controls were included. Resting-state EEG microstate analysis was performed to derive temporal and transition-related parameters from five canonical microstates. Cortical surface-based morphometry was performed using structural MRI, and correlations between EEG microstate parameters and regional composite morphometric profiles were examined. Five EEG microstates (A-E) were identified across all groups. Compared with TLE-NFBTCS, TLE-FBTCS exhibited increased occurrence and time coverage of microstate D, together with reduced occurrence and time coverage of microstate E. TLE-FBTCS also showed fewer transitions toward microstate E and more transitions toward microstate D. Compared with TLE-NFBTCS, structure–function associations were more widespread and bilateral in TLE-FBTCS, whereas they remained relatively localized in TLE-NFBTCS. TLE patients with and without FBTCS exhibit distinct alterations in EEG microstate dynamics and their associations with cortical structural morphology. Compared with TLE-NFBTCS, TLE-FBTCS demonstrates more widespread and bilateral patterns of structure-function coupling, suggesting more extensive network-level reorganization associated with seizure generalization. These findings highlight the potential value of combining EEG microstate analysis with structural MRI to characterize large-scale brain network alterations in TLE.