Reconstructed Bladder Innervation Below the Level of Spinal Cord Injury: The Knee-Tendon to Bladder Artificial Reflex Arc

Background/Objective: To study the effectiveness of knee-tendon to bladder artificial reflex arc in dogs. Methods: In 6 beagles, the proximal end of the right L5 anterior motor root and the distal end of the right S2 anterior root were anastomosed to build a knee-tendon to bladder reflex, whereas the right L5 posterior sensory root was kept intact. Action potential (AP) curves and electromyograms (EMGs) of the detrusor muscle, the intravesical pressure, horseradish peroxidase (HRP)-labeled neurons, and the passing rates of myelinic nerve fibers were calculated to evaluate its feasibility. Results: AP curves and EMG detected in all 6 dogs were similar to those of the control. Six and 18 months after surgery, the means for bladder contraction induced by percussion of the right knee-tendon were 38 +/- 27% and 62 +/- 5% that of the normal control, respectively. The mean duration times induced by percussion of the right knee-tendon at 6 and 18 months after surgery were 51 +/- 37% and 84 +/- 12% that of the normal control, respectively. HRP retrograde tracing and neurohistologic observation indicated the feasibility of the artificial reflex arc. Conclusions: Our data showed the effectiveness of bladder innervation below the level of spinal cord injury producing urination by knee-tendon to bladder reflex contractions, and therefore, might provide a new clinical approach for restoring bladder function in individuals with paraplegia.