Use of Botulinum Toxin (Botox®) in Cases of Refractory Pelvic Floor Muscle Dysfunction

Introduction: Pelvic floor muscle (PFM) dysfunction is a sexual pain disorder characterized by involuntary spasm of pelvic floor muscles (PFMs) around the vagina that interferes with intercourse or any kind of vaginal penetration, making it impossible or extremely painful. Recently, researchers have shown increased interest in botulinum toxin (BoNTA) as an alternative option for refractory cases of PFM dysfunction, especially those that fail first-line treatments. Questions have been raised about the efficacy of BoNTA for the treatment of PFM dysfunction. Objectives: To provide an updated and comprehensive review on the role of BoNTA in the management of refractory PFM dysfunction. Methods: We reviewed the literature using a systematic search strategy via PubMed and Google Scholar databases, to identify articles investigating the use of BoNTA in PFM dysfunction. We included studies that explored its indications, mechanism of action, injection dosing and technique, success rate, side effects, and contraindications. Results: We identified 20 relevant articles. Of these, 12 were original studies: 7 clinical trials, 1 retrospective cohort study and 4 case reports or case series. Doses of BoNTA that were used in these studies ranged between 20 and 500 units. The most commonly injected sites were levator ani muscles. Success rates varied between 62 and 100 %. Most studies showed no recurrence within 1 year after treatment. The majority of these studies used BoNTA after conventional first-line treatments have failed. Conclusion: PFM dysfunction is a debilitating condition that adversely affects quality of life. There is promising evidence to support the use of BoNTA in cases of refractory PFM dysfunction. Further randomized controlled trials are warranted to standardize the use of BoNTA as a treatment option for these cases. Copyright (C) 2021 The Authors. Published by Elsevier Inc. on behalf of the International Society for Sexual Medicine.