Micturition reflex arc reconstruction including sensory and motor nerves after spinal cord injury: Urodynamic and electrophysiological responses

Objective: To evaluate artificial reflex arcs for micturition using urodynamics and electrophysiological recordings. Design: Sixteen beagles were equally and randomly divided into two groups. Methods: In group A, anastomosis of the proximal end of the left L7 ventral root (VR) and distal end of the left S2 VR was performed, as well as anastomosis of the L7 dorsal root (DR) and S2 DR to reconstruct the sensory and the motor function of the bladder. In group B the proximal end of the left L7 VR and the distal end of the left S2 VR were anastomosed, while the left L7 DR was kept intact to reconstruct the motor function of the bladder. Outcome measures included electrophysiological testing and the urodynamic measures. In addition, we also monitored urinary infection rates. Results: Stimulation to the left S2 DR in groups A and B both elevated the bladder pressure before and after the spinal lower motor neuron lesion. Single stimulation of the two groups both elicited evoked action potentials. Urinary infections occurred in group A (three occurrences) and in group B (eight occurrences) during the 3 months after the spinal lower motor neuron lesion. Conclusion: Data showed that both reconstructive methods could induce bladder micturition and evoked action potentials. However, in group A the micturition response was better and the urinary infection rates were lower after the spinal lower motor neuron lesion. Thus, the artificial physiological reflex arc reconstruction method used in group A, with sensory input above the lesion, might provide a better alternative in clinical practice.