Only 33% of women receiving Botulinum Toxin A injections for chronic pelvic pain experienced a 33% reduction in pain scores compared to 20% receiving placebo, according to a recent study.

The double-blind, randomized controlled trial, conducted from January 2020 to April 2023, assessed the efficacy of Botulinum Toxin A (BTA) injections in conjunction with pelvic floor muscle therapy (PFMT) for women with chronic pelvic pain (CPP) and high pelvic floor muscle tone. Conducted in four hospitals in the Netherlands, the study, published in BJOG: An International Journal of Obstetrics & Gynaecology, included 94 women who had previously undergone PFMT without adequate improvement. Participants were randomly assigned to receive either a 100-unit BTA injection or a saline placebo injection in the pelvic floor muscle, followed by four sessions of PFMT. Improvement was defined by the study as either a 33% or greater reduction in pain scores or a rating of 'much better' or 'very much better' improvement on the Patient Global Impression of Improvement scale.

At the 26-week follow-up, 33% of participants in the BTA group reported at least a 33% reduction in average pain scores compared to 20% in the placebo group. Both groups showed similar rates of perceived improvement, with 17% reporting substantial improvement in each group. While the BTA group demonstrated a significant reduction in pelvic floor resting muscle activity, this did not correlate with a significant reduction in pain intensity or improvement in quality-of-life metrics.

Secondary analyses indicated modest improvements in pelvic function and reduction in pain catastrophizing across both groups, independent of treatment type. The findings align with prior research showing no significant difference between BTA and placebo in CPP management. Based on these results, the researchers concluded that the findings do not support the use of BTA injections in the management of CPP in women.

Adverse events were generally mild, with immediate post-treatment bleeding occurring in 4% of both groups. In the first week following treatment, mild bleeding was more common in the BTA group (8%) compared to placebo (2%) (P=0.053). Constipation occurred in 6% of the BTA group versus 0% in the placebo group (P=0.08), and one case of stress urinary incontinence was reported in the BTA group.

The study faced some limitations due to the COVID-19 pandemic, which extended the inclusion period by approximately eight months and led to the cancellation of 19 scheduled follow-up visits. Further research could identify patient subgroups that may respond to BTA treatment.

Full disclosures can be found in the published study.