The study, “Botulinum toxin for chronic pelvic pain in women with endometriosis: a cohort study of a pain-focused treatment,” was published in the journal Regional Anesthesia & Pain Medicine.
Even with ideal surgical or hormonal treatment, recurrent pelvic pain affects many people with endometriosis. This pain has been linked to muscle spasms of the pelvic floor. Treating these spasms, therefore, may be a viable strategy for preventing pain, improving these patients’ quality of life.
Botulinum toxins (the most well-known being Botox) interfere with a neurotransmitter called acetylcholine, which blocks signals from nerve cells that tell muscles to contract. In a big enough dose, this can lead to lethal paralysis, but in very small amounts, these toxins have been therapeutically exploited to treat movement disorder and migraines — but they haven’t been studied in people with endometriosis.
The new study details results from a clinical trial (NCT01553201) that included 13 people with endometriosis who had previously been treated surgically but were still experiencing pain. All participants were treated with 100 units of the botulinum toxin onabotulinumtoxinA, which was injected into the pelvic muscles through the vagina.
Prior to treatment, 11 of the 13 participants reported at least moderate pain and had muscle spasms in at least two-thirds of the pelvic floor muscles assessed.
Within one to two months after the injection, muscle spasms were absent or had decreased in all participants, and 11 reported that their pain was now mild or had disappeared. Seven of the 13 participants reported a decrease in their use of pain medications.
Additionally, six of the eight women who reported moderate or severe disability before the treatment noted an improvement.
These effects were long-lasting, with some patients reporting pain relief that lasted six months or more, and side effects were “mild and transient,” according to the study.
“These findings suggest pelvic floor spasm may be a major contributor to endometriosis-associated pelvic pain. Botulinum toxin injection may provide meaningful relief of pain and associated disability,” the researchers concluded.
“The botulinum toxin injections were incredibly effective in decreasing pain levels, as well as patients’ use of pain medications, including opioids,” Pamela Stratton, MD, a researcher at the National Institute of Neurological Disorders and Stroke and co-author of the study, said in a press release. “This treatment may be able to help [the study participants] get their lives back.”