Reconstruction of atonic bladder innervation after spinal cord injury: A bladder reflex arc with afferent and efferent pathways.

Background Establishing bladder reflex arcs only with the efferent pathway to induce micturition after spinal cord injury (SCI) has been successful. However, the absence of sensory function and micturition desires can lead to serious complications. Objectives To reconstruct a bladder reflex arc with both afferent and efferent pathways to achieve atonic bladder innervation after SCI. Methods A reflex arc was established by microanastomosis of the S2 dorsal root to the peripheral process of the L5 dorsal ganglion and the L5 ventral root to the S2 ventral root. The functions of the reflex arc were evaluated using electrophysiology, wheat germ agglutinin-horseradish peroxidase (WGA-HRP) tracing, and calcitonin gene-related peptide (CGRP) immunocytochemistry analysis. Hind-paw motion was evaluated by CatWalk gait. Results Compound action potentials and compound muscle action potentials were recorded at the right L5 dorsal root following electrical stimulation of right S2 dorsal root. Similar to the control side, these were not significantly different before or after the spinal cord destruction between L6 and S4. WGA-HRP tracing and CGRP immunocytochemistry showed that construction of the afferent and efferent pathways of the bladder reflex arc encouraged axonal regeneration of motor and sensory nerves, which then made contact with the anterior and posterior horns of the spinal cord, ultimately reestablishing axoplasmic transportation. Gait analysis showed that at 3 months following the operation, only the regularity index was significantly different as compared with 1 day before the operation, other parameters showing no difference. Conclusion Bladder reflex arc with the afferent and efferent pathways reconstructs the micturition function without great influence on the motion of leg.