Objective: A better understanding of the mechanistic underpinnings of focal to bilateral tonic-clonic seizures (FBTCS) would aid treatment decisions, and improve disease management for drug-refractory patients. We sought to examine the microstructural white matter differences in patients with FBTCS, compared to those with focal epilepsy without FBTCS, and control participants.
Methods: We combined a superior tract segmentation model with track-weighted tensor metrics (TW-TM) in an advanced, automated image analysis and tract reconstruction pipeline. Univariate analysis of covariance (ANCOVA) tests were used to compare group differences in both whole-tract metrics and hemispheric tract metrics.
Results: We identified a range of white matter regions that displayed significantly altered white matter in patients with and without FBTCS, compared to controls. Specifically, patients without FBTCS had significantly increased white matter disruption in the inferior fronto-occipital fascicle and the striato-occipital tract. In contrast, patients with FBTCS were more similar to healthy controls in most regions, except for distinct alterations in the inferior cerebellar region compared to the non-FBTCS group and controls.
Significance: This study exploited track-weighted tensor metrics (TW-TM) to investigate white matter changes in FBTCS. Our findings revealed marked alterations in a range of subcortical regions widely considered critical in the genesis of seizures. Our application of TW-TM in a new clinical dataset allowed the identification of specific tracts that may act as a predictive biomarker to distinguish patients who are likely to develop FBTCS.
Characterization of Functional and Structural Integrity in Experimental Focal Epilepsy: Reduced Network Efficiency Coincides with White Matter Changes
