Low pressure voiding induced by a novel implantable pudendal nerve stimulator

Abstract

Aim To validate the functionality of an implantable pudendal nerve stimulator under development for Food and Drug Administration approval to restore bladder function after spinal cord injury. Methods In nine cats under anesthesia, two tripolar cuff electrodes were implanted bilaterally on the pudendal nerves and one bipolar cuff electrode was implanted on the right pudendal nerve central to the tripolar cuff electrode. The pudendal nerve stimulator was implanted subcutaneously on the left lower back along the lumbosacral spine and connected to the cuff electrodes. In five cats, a double lumen catheter was inserted into the bladder through the urethra to infuse saline and measure bladder pressure and another catheter was inserted into the distal urethra to perfuse and measure the back pressure caused by urethral contraction. In four cats, a bladder catheter was inserted into the bladder dome and the urethra was left open so that voiding could occur without urethral outlet obstruction. Results The implantable pudendal nerve stimulator was controlled wirelessly and successfully provided the required stimulation waveforms to different cuff electrodes. Pudendal nerve stimulation (PNS) at 5 Hz increased bladder capacity to about 200% of control capacity. PNS at 20 to 30 Hz induced large (80‐100 cmH2O) bladder contractions under isovolumetric conditions. When combined with ipsilateral or bilateral pudendal nerve block induced by 6 to 10 kHz stimulation, PNS at 20 to 30 Hz elicited low pressure (<40 cmH 2O) efficient (70%) voiding. Conclusions The implantable stimulator generated the required stimulation waveforms and successfully induced low pressure efficient voiding in anesthetized cats.

Kilohertz alternating current neuromodulation of the pudendal nerves: effects on the anal canal and anal sphincter in rats

“…Other studies in anesthetized cats, showed that a stimulus of 1 to 15 kHz applied to the pudendal nerve induced voiding (Cai et al, 2019;Gaunt and Prochazka, 2009;Yang et al, 2014). Several studies also showed that urethral pressure decreases during KHFAC stimulation of the pudendal nerves in cats and that this pressure decrease is reversible (Cai et al, 2019;Yang et al, 2014).…”

“…High-frequency stimulation of the pudendal nerve to achieve nerve blockage and relaxation of the EUS has been studied previously in several animal models by using cuff electrodes. It has been shown to temporarily relax the EUS, enabling voiding (Bhadra et al, 2006;Cai et al, 2019;Tai et al, 2007). However, no evidence exists on the effects of high-frequency electrical nerve blockage with electrode arrays (leads) of the pudendal nerve on the anal sphincter.…”

Pudendal Nerve Block by Low-Frequency (≤1 kHz) Biphasic Electrical Stimulation

“…During two to five minutes of complete pudendal nerve block by post‐LFBS (Fig. 6b), DSD will be blocked, thereby relaxing the EUS and allowing efficient voiding at a low bladder pressure (11,12).…”

Laparoscopic selective pudendal neuromodulation for neurogenic bladder: a review of literature

“…This is consistent with the important role of pudendal urethral afferents activating the augmenting reflex to produce efficient voiding. There is also evidence suggesting that the augmenting reflex operates in humans and use of electrical stimulation to amplify the sensory feedback from PN urethral afferents provides a means to enhance bladder emptying with low pressure in persons with retention [9]. Our implantation technique is unique, since it was performed under laparoscopic vision of the PN, and selective stimulation resulted in afferent transmission to sacral roots and restored voiding function in a women with a severe sacral bone anomaly who previously failed sacral nerve stimulation for treatment of urinary retention.…”