Chronic pelvic pain affects approximately 6 to 27% of women and 10% of men worldwide. There are several causes of pelvic pain, including increased pelvic floor mucle tone associated with tenderness on exam (pelvic floor tension myalgia, PFTM). Pelvic floor physical therapists employ a number of tools targeting these muscles to improve pain, bowel, bladder, and sexual dysfunction. For patients whose pelvic floor has been refractory to pelvic PT, targeting the increased tone pelvic floor muscles with injection of botulinum toxin is an emerging therapeutic option. This study aimed to assess the success of pelvic floor muscle botulinum toxin injection (PFMB) at relieving chronic pelvic pain.

Patient reported outcome included the Global Response Assessment (GRA), 1-10 visual analogues scores, and opportunity for structured comment. Questionnaires were sent to all patients (93) with PT-refractory PFTM who underwent pelvic floor muscle (primarily coccygeus, iliococcygeus, puborectalis/pubococcygeus/pubovaginalis and, if tender, obturator, directed to asymmetries of the awake exam) botulinum injection between March 2024 and March 2026. Responses were analyzed to assess self-reported improvement in chronic pelvic pain, pelvic symptoms, and satisfaction with treatment.

53/93 (57%) of patients have thus far completed the questionnaire. Mean # of pelvic PT sessions prior to PFM Botulinum was “6-12”, with VAS for improvement from PT = 0.73 (SD±4.7). Average dose of Botulinum toxin to PFM was 115 units (SD±35). Patients reported 3.3 (SD±2.3) prior rounds of botulinum, lasting an average of 4 (SD±1.6) months. Based on accompanying urodynamic findings and symptoms in this refractory population, 31 patients (58%) received concurrent botulinum to bladder neck, 13 to bladder (25%), 10 to external sphincter (19%), 8 (15%) to vulva, and 1 (2%) to clitoris.

72% of patients reported improvement after PFM Botulinum toxin (34% markedly, 21% moderately, and 17% slightly), reporting mean 1.4 (SD±1.8) slightly to moderately improved on the GRA and mean 5.7 (SD±5.2) improvement in pain and pelvic symptoms according to the 1-10 visual analogue scale. 70% would definitely and 4% would maybe repeat the procedure. 17 patients who had not been sexually active became sexually active. Patients reported improvement not only in pelvic pain but also pelvic pressure, sense of fullness, incomplete bladder emptying, pain with intercourse, urinary frequency and urgency, urge incontinence which they attributed to the pelvic floor muscle improvement.

45% of patients reported a flare after their first PFMB lasting a median of 1-2 weeks.  For many, flare did not occur when the second round of PFMB was repeated before the 1st round wore off. 
A small percentage of patients reported they were worse. Some seemed to have a paradoxical response to chemodenervation and one reported “The reason I said worse isn’t due to the PFMB, it’s due to insurance not letting me continue my PFMB injections that were helping me 100%”.

The majority of people with pelvic pain refractory to pelvic floor physical therapy as well as numerous of other trials of therapy saw benefit with pelvic floor muscle botulinum toxin which they attributed to the pelvic floor muscle improvement. Often PFMB was administered in the setting of additional botulinum sites.

Conclusion: PFMB was associated with improvement in pelvic pain based on patient-reported outcomes, with several reporting marked improvement following PFMB. High willingness to undergo the procedure also suggests substantive benefit. Flare and paradoxical worsening should be counseled alongside the above benefits. Further investigation is needed to understand applications and durability of treatment.