ABSTRACT: The etiology of chronic pelvic pain is poorly understood. The condition is usually multifactorial; it has both physical and psychological components. Myofascial pain is a component of chronic pelvic pain. Management of myofascial pain is multidisciplinary and includes use of several different drugs, pelvic floor physical therapy/exercise, and trigger point injection of local anesthetic agents, steroids, botulinum toxin type A (Botox), and various other substances. A number of studies have shown that Botox improves pain symptoms resulting from muscle spasm in the head, neck, and back and other parts of the body. There are few data in the literature, however, on the effectiveness of Botox injection to the pelvic floor muscle (intralevator injection) in the treatment of myofascial pelvic pain.
This retrospective cohort study investigated the effectiveness of intralevator injections of Botox for myofascial pelvic pain with a short tight pelvic floor that has been refractory to other treatments. Participants were women who had at least 1 intralevator injection of Botox (100–300 U) at a single institution from 2005 through 2010. The primary study outcome was patient-reported pain on levator palpation and symptom improvement. Secondary outcomes included postinjection complications and time to and number of second injections. Follow-up visits to assess pain were stratified into 2 time periods: less than 6 weeks after injection and 6 weeks or longer after injection. During digital palpation of the pelvic floor muscles at each visit, pain was assessed using a scale of 0 to 10, with 10 being the worst. Data are presented as median (interquartile range) or proportion.
Thirty-one patients met study eligibility criteria; 2 were lost to follow-up and excluded from the analysis. The median age of the patients was 55.0 years (38.0–62.0 years).
The median pain score was 9.5 (8.0–10.0) before the Botox injection. Of the 29 (93.5%) who returned for the first follow-up visit, 23 (79.3%) reported improvement in pain, whereas 6 (20.7%) reported no improvement. The median pain score with levator palpation at visit 1 was significantly lower than the preinjection pain score (P< 0.0001).
Eighteen women (62.1%) returned for visit 2 and had a median pain score of 3.0, which remained lower than the preinjection score (P < 0.0001). More than half of the patients (51.7%) elected to have a second Botox injection; the median time from the first to the second injection was 4.0 months (3.0–7.0 months). Three women (10.3%) reported constipation and/or rectal pain, 2 patients (6.9%) reported fecal incontinence, and 3 (10.3%) developed de novo urinary retention. All adverse effects were reversible and resolved spontaneously.
These findings indicate that intralevator injection of Botox is effective in women with refractory myofascial pelvic pain and has few self-limiting adverse effects. Placebo-controlled randomized trials are needed to fully establish both the long-term outcomes and adverse effects of Botox in this patient population.