Functional Imaging Study On Brain Plasticity After Defecation Reconstruction Following Spinal Cord Injury

Objectives: Through identification of the most efficient nerve rootlet innervating defecation,animal model building and use of 7.0T fMRI(functional magnetic resonance imaging),brain plasticity after defecation reconstruction via neural approaches was explored in rats with spinal cord injury.Methods: Adult female SD rats(weighing 200-250g)were selected.The most efficient nerve rootlet innervating defecation were identified by nerve stimulation,nerve retrograde tracing and pressure change of anal canal and rectum.The animal model was built by bilateral anastomosis of L5 root and S1 root.Brain resting-state fMRI was performed using 7.0T fMRI in normal rats.Brain resting-state fMRI was performed to the 3 groups' rats 1 month,6 months and 12 months after the surgery.Results: S1 nerve rootlet could be the most efficient nerve innervating defecation in rats.The defecation was reconstructed by bilateral anastomosis of L5 dorsal and ventral root with S1 dorsal and ventral root in rats with spinal cord injury.Somatosensory and motor cortex,thalamus and insula were activated when anal canal and rectum were under different pressure stimulations.Compared with normal rats,somatosensory and motor cortex in rats of experimental rats was deactivated 1 month after the surgery,activated 6 months after the surgery and same at 12 months.While the relevant functional areas in the experimental control group present deactivated firstly and normal with no significant changes thereafter.Conclusions: Relevant brain functional areas were changed after defecation reconstruction through somato-autonomic nerve transfer.The experiment results can provide experimental basis for patients with spinal cord injury to achieve voluntary defecation.