Altered degree centrality and resting-state functional connectivity in epilepsy patients with focal to bilateral tonic-clonic seizures

Focal to bilateral tonic-clonic seizures (FBTCS) is a severe form of seizure associated with various adverse events. This study aimed to characterize abnormalities in the resting-state brain network related to FBTCS and use those findings to fit machine learning models for individual-level identification of patients with FBTCS. T1-weighted and resting-state functional magnetic resonance imaging (rfMRI) data were acquired from 84 patients with FBTCS (FBTCS+), 47 patients without FBTCS (FBTCS-), and 81 matched healthy controls (HCs). Amplitude of low-frequency fluctuations (ALFF), regional homogeneity (ReHo), and degree centrality (DC) were calculated across whole brain and compared among 3 groups. Brain regions with significant differences between FBTCS+ and FBTCS- groups were seeded for resting-state functional connectivity (rs-FC) analysis. Four models were employed to classify FBTCS+ from FBTCS- patients at the individual level. Compared to HCs, both FBTCS+ and FBTCS- patients exhibited diffuse alterations in ALFF, ReHo, and DC, with similar patterns but more significant and widespread in FBTCS+ patients. Direct comparison demonstrated significant increase of DC in the ipsilateral temporal pole, with rs-FC increase to the ipsilateral lingual gyrus and the contralateral temporal pole and superior temporal gyrus, in the FBTCS+ patients relative to FBTCS- patients. Using significant differences as features, four classifiers performed well to distinguish FBTCS+ patient from FBTCS- patient, achieving an average AUC of 0.76. Ipsilateral temporal pole showed increased neural activity and hyper-connection to the temporo-occipital regions in FBTCS+ patients, which provide additional insights for FBTCS and carry individual-level information for sensitive identification of FBTCS+ patient.