A pilot study of chronic pudendal nerve stimulation for faecal incontinence for those who have failed sacral nerve stimulation

The ENTRAMI technique: Endoscopic transgluteal minimal invasive technique for implantation of a pudendal electrode under full visual control: A cadaver study

AIM

The aim of this article is to describe a minimal invasive trans gluteal endoscopic approach to implant a pudendal electrode for neuromodulation under full visual control.

METHODS

Eight trans gluteal approaches were performed on four cadavers. The sacral transforaminal percutaneous technique was performed to implant the electrode. The electrode was then picked up and placed under visual control next to the pudendal nerve.

RESULTS

The first trocar was placed in the upper lateral quadrant of the gluteal region. The 0° optical system was used to help with the pneumodissection to identify the sciatic nerve. At that point a second 3 mm trocar was placed to insert a dissecting grasping forceps. In some cases, a second 3 mm trocar was placed. A step by step dissection, based on anatomical findings, was necessary to be able to locate the pudendal nerve. The electrode, which was placed percutaneously and transforaminal through S3 or S4, was picked up and placed under full visual control next to the pudendal nerve, slightly entering the Alcock's canal. The electrode was placed in an ideal manner, meaning that all 4-contact points of the electrode are in parallel and in contact with the targeted nerve. The electrode was fixed in that ideal position at the level of the sacrospinous ligament. After placement of that electrode, an X-ray of the pelvic area was done.

CONCLUSIONS

The ENTRAMI technique allows optimal pudendal electrode placement under full visual control and should now be tested in a clinical setting.

Stimulation of the sensory pudendal nerve increases bladder capacity in the rat

Pudendal nerve stimulation is a promising treatment approach for lower urinary tract dysfunction, including symptoms of overactive bladder. Despite some promising clinical studies, there remain many unknowns as to how best to stimulate the pudendal nerve to maximize therapeutic efficacy. We quantified changes in bladder capacity and voiding efficiency during single-fill cystometry in response to electrical stimulation of the sensory branch of the pudendal nerve in urethane-anesthetized female Wistar rats. Increases in bladder capacity were dependent on both stimulation amplitude and rate. Stimulation that produced increases in bladder capacity also led to reductions in voiding efficiency. Also, there was a stimulation carryover effect, and increases in bladder capacity persisted during several nonstimulated trials following stimulated trials. Intravesically administered PGE₂ reduced bladder capacity, producing a model of overactive bladder (OAB), and sensory pudendal nerve stimulation again increased bladder capacity but also reduced voiding efficiency. This study serves as a basis for future studies that seek to maximize the therapeutic efficacy of sensory pudendal nerve stimulation for the symptoms of OAB.