Afferent-driven cortical remodeling: multimodal neuroimaging insights into carpal tunnel syndrome-related plasticity

Carpal tunnel syndrome (CTS), the most common peripheral entrapment neuropathy, often leads to persistent hand dysfunction. Given the dual role of the human hand as both a motor effector and a cognitive interface, understanding network-level brain remodeling is crucial for developing effective rehabilitation strategies. This cross-sectional study investigated CTS-related cortical reorganization using resting-state functional magnetic resonance imaging (fMRI) in 52 patients with bilateral CTS and 30 matched healthy controls. All participants underwent standardized clinical and neuroimaging evaluations. Local neural activity was assessed using amplitude of low-frequency fluctuation (ALFF) and regional homogeneity (ReHo), voxel-wise connectivity was measured via functional connectivity density (FCD), and interregional coupling was quantified through functional connectivity (FC) based on the Brainnetome Atlas. Network-level organization was further evaluated using graph theoretical metrics. Compared with controls, CTS patients exhibited significantly reduced ALFF and ReHo in the left precuneus and postcentral gyrus, and lower FCD in the left lingual gyrus, right postcentral gyrus, and precuneus. FC analysis revealed widespread reductions in interregional coupling, especially between the sensorimotor and default mode networks. Graph analysis showed increased global efficiency and decreased characteristic path length and lambda values in CTS, suggesting reorganization toward more efficient global information transfer. These findings indicate that CTS involves both local and distributed brain alterations, highlighting the importance of considering central mechanisms when developing rehabilitation strategies aimed at restoring fine motor function in patients with CTS.