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Botulinum Toxin A as a Treatment for Provoked Vestibulodynia: A Randomized Controlled Trial
Philip Haraldson1, Hanna Mühlrad, Ulrika Heddini
1Department of Clinical Sciences, Division of Obstetrics and Gynecology, Karolinska Institutet Danderyd Hospital, Stockholm, and the Center for Clinical Research, Uppsala University, County Council of Västmanland Central Hospital, and the School of Health, Care and Social Welfare, Mälardalen University, Västerås, Sweden.
Objective:
To evaluate pain reduction after two injections of 50 units botulinum toxin A compared with placebo for provoked vestibulodynia.
Methods:
We conducted a double-blinded, placebo-controlled randomized trial of 50 units botulinum toxin A or placebo injected in the bulbocavernosus muscles twice, 3 months apart, in women with provoked vestibulodynia. Primary outcome was self-reported dyspareunia or pain at tampon use on a visual analog scale (VAS, 0-100). Secondary outcomes were pain at weekly tampon insertion (VAS score), reduction of pelvic floor hypertonicity (measured with a vaginal manometer), adverse events, and sexual function and distress. A sample size of 38 participants for each group was calculated to achieve a statistical power of 80% based on an effect size of 20 VAS units (0-100) (mean score range 56-76±31 SD).
Results:
Between May 2016 and June 2018, 124 women with provoked vestibulodynia were assessed, and 88 were randomized to botulinum toxin A (BTA group, n=44) or placebo (placebo group, n=44). Primary outcome showed a lower but statistically nonsignificant pain rating by 7 VAS units (95% CI -15.0 to 0.4) in the BTA group compared with the placebo group. Secondary results showed a significant decrease in pain at weekly tampon insertion by 11 VAS units (95% CI -16.6 to 6.0) with botulinum toxin A injection. The vaginal manometer measured lower maximum contraction strength by 7 mm Hg (95% CI -12.7 to -2.4) and lower 10-second endurance strength by 4 mm Hg (95% CI -7.72 to -1.16) in the BTA group compared with the placebo group. No changes were observed for sexual function and distress, but there was a significant increase in women attempting vaginal intercourse in the BTA group (0.27, 95% CI 0.06-0.48). No severe adverse events were reported.
Conclusion:
Twice-repeated injections of 50 units of botulinum toxin A in women with provoked vestibulodynia did not reduce dyspareunia or pain at tampon use, but secondary outcomes suggested positive effects of the treatment.
Clinical Trial Registration:
ClinicalTrials.gov, NCT02773641.
