Functional Neural Imaging Research On The Plasticity Of Supplementary Motor Area And Its Connectome Of The Patients With Brachial Plexus Injury

Background:Brachial plexus injury is one of the most serious peripheral nerve injuries. Patients always suffer from hand dysfunction for several reasons. One is the slow neurotization of peripheral nerve. Another reason is the muscular dystrophy. According to the current scientific research, the brain functional reorganization stands for the main course. Specifically, most of the researches focus on the primary motor cortex. The high order functional area, which is called supplementary motor area, is rarely mentioned. Our subject aims to prove the relevance between the hand dysfunction and the functional silence of supplementary motor area utilizing functional neural imaging on patients with brachial plexus injury.Methods:The research recruited 16 BPI patients and 8 healthy volunteers. We raised one block-design fMRI program using unilateral imaginary hand grasp motion as task stimulus in order to explore the functional change of SMA in the period of motor planning. After the acquisition of the SMA activation map, we defined the activated SMA region as region of interest(ROI). Then we calculated the voxel-wise functional connectivity between the ROI and the rest of brain. Finally we will discuss the impact of such functional change on hand dysfunction according to the specialization of each brain area.Results:The BPI patients displayed functional silence in SMA 6-7 months after injury. The healthy subjects were able to activate SMA confronting imaginary task. On the contrary, the range and density of activation in BPI group was obviously lower. The functional connectivity between SMA and precuneus, cingulate cortex also demonstrated a significant decrease in BPI group.Conclusion:The silence of SMA in BPI patients resulted in the decrease of the functional connectivity between SMA and precuneus, cingulate cortex, which abolished the self-sensory and motor control ability. This showed relevance with hand dysfunction. The therapeutic interference should not only include the primary motor cortex, but also include the SMA.