Risk of detrusor denervation in antireflux surgery demonstrated in a neurophysiological animal model

Purpose: Earlier anatomical studies have shown a close connection between the ureterovesical junction and detrusor innervation. It prompted us to develop an animal model to demonstrate the risk of partial or complete impairment of this neuronal connection during antireflux surgery. Materials and Methods: Six female Gottinger minipigs were anesthetized and laminectomized. After placement of the S3 sacral nerves into separate electrode compartments of a modified Brindley electrode the lower urinary tract was exposed by an abdominal midline incision. After bladder instillation with 150 ml NaCl 1 bilateral and 2 unilateral stimulations (left and right sides) were performed and intravesical pressure was recorded urodynamically. The left ureter was then prepared circularly in 3 steps 10, 5 and 1 cm, respectively, proximal to the ureterovesical junction. After each preparation step bilateral and unilateral stimulation was repeated. Results were recorded urodynamically and video documented. Results: Bilateral stimulation before preparation of the left ureter led to a concentric detrusor contraction with an average maximum detrusor pressure of 51 cm H2O. Unilateral stimulation resulted in ipsilateralbound bladder tilting with an intravesical pressure of 18 and 19 cm H2O on the right and left sides, respectively. After preparation of the left ureter 10, 5 and 1 cm from the ureterovesical junction a maximum detrusor pressure of 17, 10 and 1 cm H2O was documented, respectively. While there was almost no stimulation response of the bladder after the last preparation step at 1 cm on the left ureter, the initial bladder pressure of 18 cm H2O could be reproduced under stimulation on the right side. Conclusions: Analogous to human cadaver studies, we were able to prove neurophysiologically strictly unilateral detrusor innervation, drawing from the pelvic plexus dorsomedial to the ureterovesical junction into the bladder. Preparation of this ureterovesical junction during antireflex surgery, coagulating measures in this area or the affixation of anchor sutures after a Vest suture involves the risk of unilateral or bilateral detrusor decentralization.