18: Randomized placebo-controlled trial of onabotulinamtoxina trigger point injections for myofascial pelvic pain

Abstract

To compare the effect of onabotulinumtoxinA versus placebo injections to the pelvic floor in women with myofascial pelvic pain. This was a double-blind, randomized, placebo-controlled trial in women with myofascial pelvic pain. Women ≥18 years were eligible if they reported pain ≥6 on a 10-point visual analog scale (VAS) ≥50% of the time and had pain on palpation ≥6 on the VAS in ≥1 of 6 pelvic floor muscle groups. Participants were randomly allocated to a pelvic floor injection of 200 units of onabotulinumtoxinA or 20 mL of saline. All participants started 8 weeks of physical therapy 4 weeks after the injection. Participants completed validated questionnaires at baseline, and 2, 4, and 12 weeks after injection. At each of these visits, a urogynecologist who was blinded to treatment arm performed a clinical examination with palpation of the left and right sides of 6 pelvic floor muscle groups. The primary outcome was change in patient-reported pain on palpation at 2 weeks. Analyses were intention-to-treat. Sixty women were enrolled and randomized. One participant in the placebo group was lost to follow-up. The groups were similar with regard to baseline demographic and clinical characteristics. With regard to the primary outcome, there was no significant difference between the intervention and placebo groups in the change in patient-reported pain on palpation at 2 weeks for any muscle except for the left coccygeus. There were no significant differences in patient-reported pain on palpation for any muscle group at 4 or 12 weeks. However, at 4 and 12 weeks, participants in the intervention group reported greater declines in overall pelvic pain on the VAS compared to the placebo group, though these differences were not statistically significant (both p=0.16). Using the Patient Global Impression of Improvement index, participants in the intervention group were more likely to report their symptoms were improved at 4 and 12 weeks compared to the placebo group, though this difference was significant only at 4 weeks (p=0.03 and p=0.10, respectively). At 2 weeks, the placebo group had a significant improvement in the Pelvic Floor Disability Index score compared to the intervention group (p=0.01); however, this difference did not persist at 4 and 12 weeks (p=0.19, p=0.11). At 2 weeks, the most common adverse event was constipation in the intervention (36%) and placebo (25%) groups. This was followed by urinary incontinence in the intervention group (22%) and urinary tract infection (9%) in the placebo group. Pelvic floor onabotulinumtoxinA injection for myofascial pelvic pain was not more effective than saline injections at decreasing muscle pain on palpation. Despite this, participants who received onabotulinumtoxinA were more likely than those who received saline to report that their overall pelvic floor pain improved at 4 and 12 weeks.