Objectives To examine urethral pressure changes and compare nerve recruitment driven by pudendal nerve stimulation (PNS) intraoperatively in female patients receiving an implanted neurostimulator.

Subjects and methods Patients receiving PNS for pelvic pain and/or urinary symptoms were recruited. During the implant surgery, urethral pressure was measured with a multi-sensor pressure catheter placed in the lower urinary tract. PNS-driven changes in urethral pressure and external anal sphincter (EAS) electromyography were compared to determine the relative perineal and rectal nerve recruitment order. Participants completed pelvic pain, bladder, bowel, and sexual function surveys before and after the surgery. The primary outcome measure was the relative nerve recruitment order during PNS. Secondary outcome measures were the PNS-driven urethral responses and changes in survey symptom scores due to PNS.

Results Data was collected from thirteen intraoperative sessions. Seven participants had rectal nerve recruitment first, four participants had perineal nerve recruitment first, and two participants had mixed nerve recruitment during intraoperative PNS. The average normalized urethral pressure change was 4.7% at the EAS threshold, 59.2% at twice EAS threshold, and 68.2% at three times the EAS threshold. Urethral pressure changes for each participant often varied between different active PNS electrodes. Participants had significant improvements in pelvic pain and bladder function survey scores with PNS (p < 0.04). There was no relationship between nerve recruitment order and changes in any surveys.

Conclusion PNS can recruit the perineal nerve before the rectal nerve. Each lead electrode may trigger different urethral response patterns within a participant. This study provided new insights into the effect of PNS on the recruitment of nerves in the pelvis and may help guide future surgical placement of PNS systems.

The authors have declared no competing interest.

NCT04236596

This project was funded by NIH SPARC award OT2OD028191.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The IRB of the University of Michigan Medical School (IRBMED) gave ethical approval for this work.

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The data set from the study will be found on the SPARC Science data portal at DOI: 10.26275.pc8r-r3iu after completing the SPARC curation process.

https://doi.org/10.26275.pc8r-r3iu