The variation of motor-related brain structure and its relation to abnormal motor behaviors in end-stage renal disease patients with restless legs syndrome

Restless legs syndrome (RLS) is common in the end-stage renal disease (ESRD) population; however, their interrelationship remains largely unclear. In the current study, we aimed to investigate the brain structure variation in ESRD patients with RLS (ERSD-RLS) and its potential relation with the severity of RLS. Diffusion tensor imaging and T1-weighted imaging were obtained from 64 ERSD-RLS and 64 matched healthy controls. Voxel-based morphometry (VBM) analysis and tractography atlas-based analysis (TABS) were used to detect the alteration of gray matter (GM) volume and white matter (WM) microstructural characterization. The corticospinal tract (CST), which is a main motor-pathway, was selected as a fiber bundle of interest in the TABS analysis. The severity of RLS was evaluated by using the International RLS Study Group scale. Lastly, a correlation analysis was performed to explore the interrelationship between RLS rating scores and brain structure measurements. For the results, ERSD-RLS showed abnormal GM volume of motor-related brain regions located in the bilateral superior frontal gyri, precentral gyrus, and putamen. Significant differences in the diffusion properties were found at the posterior limb of the internal capsule. Furthermore, the severity of RLS was only significantly associated with the diffusion properties, which was not found in the motor-related regions of GM. Our results suggest that the motor-related brain structure was altered in ERSD-RLS. The abnormal WM microstructure of the CST may serve as an imaging marker correlated with the severity of motor dysfunction in ERSD-RLS, indicating that WM neuroprotection should be considered when improving motor function in ERSD-RLS.