This is for our readers that treat pain patients.
Author: Louise Gagnon
Injecting onabotulinumtoxinA into pelvic floor muscles with spasms provided pain relief in women with endometriosis-related chronic pain refractory to standard treatment, according to a study presented at the 2021 Annual Meeting of the American Society for Reproductive Medicine (ASRM).
“We chose to study only women with endometriosis and chronic pain because we have some idea of how endometriosis lesions are related to chronic pain,” said Pamela Stratton MD, tNational Institute of Neurological Disorders and Stroke, part of the National Institutes of Health, Bethesda, Maryland. “Chronic pelvic pain persists despite conventional treatment in about 30% of women with endometriosis and pain.”
The study randomised 29 women aged 18 to 55 years to receive a masked injection of onabotulinumtoxinA or placebo. They were followed for up to 1 year and could request an open second injection anytime between 1 month and 12 months after the masked injection. Subjects rated response to injection as benefit/no benefit, percent (%) improvement, and benefit duration.
At 1 month after masked injection, 11 of the 15 patients treated with onabotulinumtoxinA saw benefit compared with only 4 of the 14 placebo-treated patients (P = .027). Treatment with onabotulinumtoxinA led to longer-lasting benefit (P = .023) and greater improvement (P = .034) compared to placebo.
Prior to the second injection, patients in the placebo arm had more days with no benefit than patients in the onabotulinumtoxinA arm (P = .02).
The number of pelvic floor muscles in spasm was reduced only in the onabotulinumtoxinA arm (P = .019).
Women with focal pelvic pain at baseline gynecological examination had more durable benefit compared with those with diffuse pain over 1 year, particularly in the arm treated with onabotulinumtoxinA.
There was no difference in the incidence of adverse events between groups.
“The relief from pain spasm from onabotulinumtoxinA persisted over time compared with placebo,” said Dr. Stratton. “One advantage of this report approach is that it can safely be combined with standard treatment of nutrients associated with chronic pelvic pain.”
More investigations would likely involve finding appropriate doses of botulinum toxin for patients, according to Dr. Stratton.
“Future clinical trials could help define optimal dosage and other aspects of this approach to treatment,” she said.