Does pudendal nerve block improve perioperative pain following OnabotulinumtoxinA injection for myofascial pelvic pain?

OBJECTIVE

OnabotulinumtoxinA (BTA) injections are useful for treatment of myofascial pelvic pain. Concurrent pudendal nerve block (PNB) has been suggested to decrease postoperative pain, as BTA does not take an immediate effect. The efficacy of PNB for this purpose has not been well elucidated. We aim to determine if PNB improves pain in the postoperative period following pelvic floor BTA injections.

DESIGN

A subgroup analysis was performed from a retrospective cohort study including 202 patients encompassing 416 BTA injections at a single high volume, academic institution. Post Anesthesia Care Unit (PACU) visual analog scale (VAS) pain score and oral morphine equivalents (OME) data between 2018 and 2022 were reviewed.

RESULTS

A total of 64 patients met inclusion criteria, encompassing 96 BTA injection events. Thirty-three BTA injections were done with concurrent PNB (BTA/PNB), while 63 injections were performed without PNB (BTA). Demographics of patients were similar in both groups. Mean VAS upon discharge from PACU was 1.7 for BTA alone and 1.9 for BTA/PNB (p = 0.610). Mean time (minutes) in PACU was 100.7 for BTA alone and 100.5 for BTA/PNB (p = 0.692). Mean OMEs given in PACU were 12.5 for BTA alone and 15.0 for BTA/PNB (p = 0.443).

CONCLUSION

This study may suggest a limited benefit of PNB at improving postoperative pain following pelvic floor BTA injection. Additional research is needed to determine the efficacy of PNB at time of pelvic floor BTA injections.