Botulinum Toxin a for Provoked Vestibulodynia: 12 Months’ Follow-Up of a Randomized Controlled Trial

Abstract

Abstract Background Provoked vestibulodynia (PVD) is a common pain disorder afflicting primarily young women, and botulinum toxin A (BTA) has been to a limited extent tested as a treatment. Aim Evaluate outcome 12 months after injection with BTA as a treatment for PVD. Methods We conducted a double-blinded, placebo-controlled trial of twice repeated injections of 50 units of BTA or placebo in the bulbocavernosus muscles, 3 months apart, in women with PVD. Treatment outcome after six months’, failed to show any significant difference in pain reduction between the groups, as previously reported. Here, we report treatment outcomes 12 months after the first injections. In addition to injections, participants where instructed to perform pelvic floor exercises during month 6-12. 38 participants/group was calculated to achieve a statistical power of 80% based on an effect size of 20 VAS units (mean score range 56-76±31 SD). Outcomes Primary outcome was self-reported dyspareunia or pain at tampon use, using a visual analogue scale (VAS) 0-100. Secondary outcomes were vaginal pressure measurements, psychological health, sexual function and distress. Results From the initial 88 randomized women with PVD, 75 remained at 12 months; 38 in the BTA and 37 in the placebo group. There was no significant difference in primary outcome between the groups. Vaginal pressure in the BTA group had been restored to pre-treatment levels, with no differences between the groups at 12 months. There was an increase in sexual function in the BTA group, with a Female Sexual Function Index of 22.8 (±4.8) compared to the placebo group to 19.7 (±5.0), P=.048. No differences were observed in sexual distress, stress and anxiety. There was an increase in number of women attempting intercourse in the BTA group (74%) compared with placebo (43%), P=.005. Too few patients performed the pelvic floor exercises for this intervention to be analyzed. Clinical Implications This study highlights BTA as a safe treatment option for patients with PVD. Strengths and limitations The randomized, double-blinded design and repeated treatments are the major strengths of this study and it is the first study to objectively evaluate muscular effect after BTA injections. The major shortcoming is that few participants performed the pelvic floor exercises, preventing analyses. Conclusion At 12 months’ follow up, no significant difference in reduction of dyspareunia or pain at tampon use was observed. Women receiving BTA attempted intercourse more often and improved their sexual function compared with women receiving placebo.