Functional network reorganization following VIM-MRgFUS for essential tremor

Magnetic resonance-guided focused ultrasound (MRgFUS) is a promising, noninvasive therapeutic approach for essential tremor (ET), yet the effects of the respective lesions on functional brain network organization remain poorly understood. Here, we performed graph theory analysis to investigate changes in small-world properties and modular architecture in ET patients six months after unilateral MRgFUS of the thalamic ventral intermediate (VIM) nucleus. Small-worldness and normalized clustering coefficient increased significantly after MRgFUS, while clustering coefficient, characteristic path length, normalized characteristic path length, global efficiency, and local efficiency remained unchanged. Modular organization was largely preserved, but trend-level enhancements in inter-modular connectivity were observed between frontoparietal and subcortical modules, as well as between frontoparietal and frontotemporal-parietal modules. Within these modules, betweenness centrality increased significantly in specific cortical hubs, including the left superior frontal gyrus, right superior parietal lobule, and left postcentral gyrus. These findings indicate that unilateral VIM-MRgFUS induces selective functional network reorganization, particularly affecting relative clustering and nodal centrality patterns.