Injectable Botulinum Toxin for Pelvic Pain: A Review of Clinical Effectiveness, Cost-Effectiveness, and Guidelines

Gynecological conditions of the pelvic floor region can include vulvodynia (vulvar pain lasting at least 3 months with no identifiable cause),¹ vaginismus (or genito-pelvic pain or penetration disorder, the inability to achieve non-painful vaginal penetration of any kind),² endometriosis (in which cells of the endometrium grows outside of the uterus), and provoked vestibulodynia (localized pain in the vulvar vestibule caused by physical contact).³ Gynecological conditions of the pelvic floor region are generally considered to occur as a result of a multifactorial process that includes genetics, hormonal changes, inflammation, musculoskeletal issues (such as hypertonic muscles), neurologic mechanisms, psychosocial factors (often related to sexual functioning), and structural issues (such as perineal descent), but etiologies are often unknown.^1,4,5 First-line treatments for these conditions include physiotherapy, dilation therapy, sex counseling, psychotherapy, or a combination of therapies.^2,6 Increasingly, botulinum toxin has become an alternative therapy option for individuals with pelvic pain.⁶ Botulinum toxin is a toxin produced by the Clostridium bacteria.⁶ Botulinum toxin is used in neuromuscular disorders, ophthalmic disorders, chronic pain, cosmetic and dermatological applications, pelvic floor disorders, gastrointestinal disorders, and spasticity.⁶ In pelvic pain, it is typically injected into the muscle, where it inhibits release of acetylcholine, causing blockage of muscle spasms.⁶ Pelvic pain disorders can affect an individual’s feelings of self worth, quality of life, sexual functioning, psychological well being, and relationships.^1–3 According to a 2017 cross-sectional study, the average hospital-associated cost of chronic pelvic pain (pelvic and perineal pain, dysmenorrhea, or dyspareunia) in Canada amounted to C$25 million per year between 2008 and 2012.⁷ Many cases of pelvic pain go undiagnosed, as patients often do not report sexual dysfunction, and it has been reported that patients with vulvodynia had the condition for an average of 7 years before seeking help.^2,3 Additionally, as vulvodynia is not well understood, individuals with the condition may wait an average of 5 years to receive a diagnosis after seeking treatment.³ There is uncertainty regarding the of effectiveness of botulinum toxin for some chronic pelvic pain conditions. The purpose of this report is to evaluate the evidence regarding the clinical effectiveness and safety of botulinum toxin compared with other treatments or placebo for patients with chronic pelvic floor dysfunction and pain. Evidence regarding the cost-effectiveness of botulinum toxin for pelvic pain was also sought to support decision making. Evidence-based recommendations were sought to provide guidance on the use of botulinum toxin for these conditions.