What is the role of botulinum toxin (BTX) injection for pelvic pain management?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Chronic pelvic pain occurs in about 15% of women and has various causes that require accurate diagnosis and appropriate treatment if pain reduction is to be effected. Superficial conditions such as provoked vestibulodynia and deeper pelvic issues such as pelvic floor myalgia were traditionally difficult to diagnose and adequately treat. [98]

To determine whether BTX-A is more effective than placebo for reducing pain and pelvic floor pressure in women with chronic pelvic pain and pelvic floor muscle spasm, Abbott et al enrolled 60 women with chronic pelvic pain lasting 2 years or longer who demonstrated evidence of pelvic floor muscle spasm. [99] The methodology was a double-blind, randomized controlled trial, wherein 30 women received 80 U of BTX-A by injection into the pelvic floor muscles, and 30 women received injections of NS. The severity of dysmenorrhea, dyspareunia, dyschezia, and nonmenstrual pelvic pain were assessed by VAS at baseline and then monthly for 6 months. Pelvic floor pressures were measured by vaginal manometry.

A significant change from baseline in the BTX-A group was noted for dyspareunia and nonmenstrual pelvic pain. In the placebo group, only dyspareunia was significantly reduced from baseline. A significant reduction in pelvic floor pressure (cm of H2 0) was noted in the BTX-A group from baseline; the placebo group also had lower pelvic floor muscle pressures. The authors found an objective reduction of pelvic floor muscle spasm, which reduces some types of pelvic pain. BTX-A reduced pressure in the pelvic floor muscles more than placebo; therefore, BTX-A may be a useful agent in women with pelvic floor muscle spasm and chronic pelvic pain who do not respond to conservative treatment, including physical therapy.

Abbott has studied and reviewed the gynecological use of BTX for the treatment of chronic pelvic pain in women. [100] In a review, he advocated the use of BTX for inflammatory conditions and in areas where muscle spasm is thought to contribute to pain. He acknowledged the limited data that support or specify the use of BTX for gynecological indications. Support for use in the vulva consists of case reports and small series, which indicate that BTX-A, when used in the vulva, may provide benefit for 3-6 months after injection of 20-40 U of BTX-A for women with provoked vestibulodynia. Retreatment is reportedly successful, and side effects are limited. Controlled studies are essential to further explore this indication.

For pelvic floor muscle spasm, a greater number of women have been studied and a double-blind, randomized controlled study reported a significant reduction in pelvic floor pressures, with significant pain reduction for some types of pelvic pain compared with baseline. No differences in pain were noted when compared with the control group who had physical therapy as an intervention. Physical therapy can be used as a first line treatment or adjunctively with BTX-A injections in cases of refractory pain and muscle spasm.

In a review by Rao and Abbott, they cited pain symptoms caused by pelvic floor muscle spasm, daily pelvic pain, and dyspareunia are the most likely to be improved by BTX-A. [101] Limited data supporting the use of BTX for provoked vestibulodynia indicate an improvement in pain scores. In the lower GI tract, BTX injection into puborectalis has demonstrated objective improvement in intravaginal pressures, although no randomized controlled trials (class I studies) have validated its use in this setting. Class I studies demonstrate a role for BTX-A in the management of idiopathic detrusor overactivity, although long-term follow-up data are lacking.

Potential problems with BTX-A use include reactions to the toxin and urinary and fecal incontinence. A single class I study supports the use of BTX-A for refractory pelvic floor spasm; however, further adequately powered class I studies for this indication and for provoked vestibulodynia are warranted.

For pelvic floor myalgia, 1 class-I study and 3 class-II to -III studies have indicated efficacy of BTX-A. In the only double-blind, randomized controlled trial, significant reduction in pelvic floor pressures with significant pain reduction for some types of pelvic pain were reported compared with baseline. No differences in pain occurred compared with the control group who had physical therapy as an intervention. Physical therapy should be used as first-line treatment and then adjunctively with BTX-A injections for those who remain refractory to treatment.

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