Supplementary Motor Cortical Changes Explored by Resting-State Functional Connectivity in Brachial Plexus Injury

BACKGROUND: Brachial plexus injury (BPI) is a serious peripheral nerve injury, and clinical outcomes are generally unsatisfactory. It has been reported that cortical plasticity could influence the restoration of motor function. However, the neurologic mechanism of BPI is unclear, which provides a basis for further investigation. The supplementary motor area (SMA) plays an important role in the regulation of motor function. This study aims to explore SMA-whole brain functional connectivity after deafferentation of the brachial plexus. METHODS: Study subjects included 16 patients with BPI and 8 healthy volunteers. The seed region was defined by a block-design functional magnetic resonance imaging program that used unilateral imaginary hand grasp motion as a task stimulus. Next, the voxel-wise functional connectivity between the predefined region and the other regions of the brain was calculated. RESULTS: We discovered decreased voxelewise functional connectivity between the SMA and multiple brain regions, including precuneus, posterior cingulum cortex, and anterior cingulum cortex, that are closely associated with information integration or motor processing in patients with BPI. CONCLUSIONS: Patients with BPI showed weakened functional connectivity between hand grasp-related areas and the SMA and multiple regions associated with motor processing or information integration. A clear image of the functional status of the brain after deafferentation was provided. On the basis of this discovery, a relationship between changes in neuroimaging measurements and clinical outcomes can be determined in future studies.