Objective: To collect pilot data on the efficacy of intramuscular botulinum toxin type A (BTX/A) injection into the levator ani muscles to relieve coital pain, reduce pelvic floor tension and instability, and reduce vestibular hyperalgesia in vestibulodynia.
Study design: Two subjects meeting diagnostic criteria for vestibulodynia were treated with 20 units and 40 units of BTX/A at 12-week intervals. Outcomes included a visual analogue scale (VAS), weekly coital pain diaries, surface electromyography (sEMG) and a vulvar algesiometer.
Results: BTX/A modestly reduced coital pain in 1 patient and was ineffective in the other. Pelvic floor hypertonicity and variability were markedly reduced in both patients, but negligible changes occurred in vestibular hyperalgesia. The patient with greater pelvic floor tension had more of a reduction in diary-rated coital pain 2 weeks after the injection (29% vs. 9%) and on the VAS at 12 weeks (15% vs. 3%).
Conclusion: BTX/A injections may be effective in reducing coital pain in vestibulodynia with levator ani tenderness but have little effect on vestibular allodynia. The relationship between pelvic floor hypertonicity and decreased coital pain suggests that vestibulodynia may be a variant of chronic regional pain syndrome. The dose and volume of BTX/A injected may be related to the degree of relief.