Cortical and subcortical morphometric changes in patients with frontal focal cortical dysplasia type II.

Purpose: This study investigates the morphometric changes in the brains of patients with frontal focal cortical dysplasia (FCD) Type II, distinguishing between right and left FCD, using voxel-based morphometry (VBM), surface-based morphometry (SBM), and subcortical shape analysis.

Methods: The study included 53 patients with frontal lobe FCD Type II (28 left-sided, 25 right-sided) and 66 age- and gender-matched healthy controls. VBM and SBM analyses were conducted using Computational Anatomy Toolbox 12.8 (CAT12.8) and Statistical Parametric Mapping 12 (SPM12). Subcortical structures were segmented using FSL-FIRST. Statistical analyses were performed using non-parametric tests, with a significance threshold of p < 0.05.

Results: VBM revealed increased gray matter volume in the bilateral ventral diencephalon, left putamen, and left thalamus in the left FCD group. SBM indicated reduced sulcal depth in the right precentral, postcentral, and caudal middle frontal gyrus in the right FCD group. Subcortical shape analysis showed internal deformation in the left hippocampus and external deformation in bilateral putamen in the left FCD group, and external deformation in the left caudate nucleus, left putamen, and right amygdala in the right FCD group.

Conclusion: Morphometric changes in frontal FCD Type II patients vary depending on the hemisphere. Right FCD Type II is associated with sulcal shallowing and external deformation in contralateral subcortical structures, while left FCD Type II shows internal and external deformations in the hippocampus and putamen, respectively, along with increased gray matter volume in the basal ganglia. These findings highlight the need for hemisphere-specific analyses in epilepsy research.