Innervation of reconstructed bladder above the level of spinal cord injury for inducing micturition by contractions of the abdomen-to-bladder reflex arc.

OBJECTIVE: To establish an artificial bladder reflex arc in dogs via an abdominal reflex pathway above the level of spinal cord injury to reinnervate the neurogenic bladder and restore controllable micturition.
METHODS: Ten beagles were used in the experiment. We anastomosed the proximal end of the right T12 ventral root and distal end of the right S2 ventral root by performing autogenous nerve grafting to build an abdomen-to-bladder reflex, whereas the right T12 dorsal root was kept intact. The early function of the reflex arc was evaluated by performing electrophysiological studies as well as by the measurement of intravesicular pressure and histological examination.
RESULTS: Single focal stimulation of the right T12 intercostal nerves elicited evoked action potentials at the right vesicular plexus before and after horizontal spinal cord transaction between the L4 and S3 levels. Bladder contraction was successfully initiated by trains of stimuli targeting the right T12 intercostal nerves. The bladder pressures and amplitude of the complex action potentials at the bladder smooth muscles were unchanged after paraplegia was induced; they were comparable to those of the control. Prominent axonal sprouting was observed in the distal part of the nerve graft.
CONCLUSION: Our data showed the effectiveness of bladder innervation above the level of spinal cord injury in inducing micturition by abdomen-to-bladder reflex contractions and, therefore, might provide a new clinical approach for restoring bladder function in individuals with paraplegia.