Methodological approaches to botulinum toxin for the treatment of chronic pelvic pain, vaginismus, and vulvar pain disorders.

Botulinum toxin (BoNT) is increasingly used for pain, especially with muscle spasm. We describe our methodology for BoNT treatment of chronic pelvic pain (CPP) in women and place it in the context of the literature on techniques for this use. Databases were searched using terms "botulinum toxin," "pelvic pain," and "vaginismus." Reports on vaginismus/vulvodynia/vestibulodynia (included if pelvic floor muscles were injected) were grouped as "vaginismus/vulvar pain disorders" (V/VPD). We analyzed the type of report, condition, toxin serotype/brand, dose/dilution, muscle selection, guidance technique, and anesthesia. Publications from the same authors without unique information were combined for specific analyses. Thirty-eight reports had analyzable information; many lacked complete information. Most were open-label prospective reports; there were four technical reports, one randomized comparison of doses and one placebo-controlled study of efficacy. Pelvic floor muscles were approached transvaginally, transperineally or transgluteally. BoNT brand/dose/dilution varied widely. Muscle localization techniques included anatomical landmarks only, electromyography, electrical stimulation with/without ultrasound, and fluoroscopy/CT scanning. Papers discussing analgesia utilized general anesthesia, conscious sedation with/without topical/local anesthesia, topical/local agent alone or pudendal block before or after injection. Cumulatively, 58-100% of patients with CPP and 71-100% of those with V/VPD improved. Serious adverse events (transient fecal incontinence/constipation, urinary incontinence/retention) were more frequent with higher doses. BoNT can be safely and tolerably injected into pelvic floor muscles in women as an out-patient procedure. This study identifies methodological factors to be considered in future studies and the critical need for high-quality clinical trials for this emerging treatment.