Structural brain analysis in focal upper limb dystonia

Prior structural magnetic resonance imaging (MRI) studies that investigated structural alterations in focal dystonia have reported inconsistent findings, potentially due to methodological limitations or sample heterogeneity. This work investigates gray and white matter changes in patients with upper limb dystonia using T1-weighted images and diffusion tensor imaging (DTI). Imaging data collected with MRI at 3T from 28 right-handed individuals with right upper limb dystonia and 29 healthy controls were analyzed. T1-weighted images were analyzed using FreeSurfer to examine cortical thickness, volume and area. DTI data were assessed using tract-based spatial statistics, regions of interest (ROI) analysis and probabilistic tractography. ROI included the basal ganglia, thalamus and cerebellum. Between-group differences were tested using permutation-based statistics. Whole-brain vertex-wise analyses revealed no significant differences in cortical morphology between groups. Tract and ROI-based analyses showed no changes in DTI metrics. These findings indicate preserved gray and white matter microstructural integrity in individuals with focal upper limb dystonia compared to controls, although finer abnormalities might still become evident using higher-resolution imaging methods. The absence of significant findings suggests potential for neuromodulation therapies and network-based approaches in this condition. Larger, multi-modal studies are warranted to further characterize anatomical substrates in focal dystonia.