Treatment of acute dysmenorrhoea and pelvic pain syndrome of uterine origin with myometrial botulinum toxin injections under hysteroscopy: A pilot study.

[BACKGROUND] Acute dysmenorrhoea in women which has been shown to be anatomically negative for endometriosis is a very common condition. It is frequently associated with Chronic Pelvic Pain (CPP) from uterine origin, including painful uterine contractions and deep dyspareunia. We call this association Painful Uterine Syndrome (PUS).

[SEARCH STRATEGY] In these women in failure of the usual treatments, we proposed a new treatment, with Uterine Toxin Botulinic injections (BTX) under hysteroscopy, as a compassionate option, among women in severe pain and therapeutic failure. Indeed, increased uterine contractility has been confirmed using cine magnetic resonance imaging in patients with acute dysmenorrhea and PUS. These findings, associated with the hypothesis of a possible uterine sensitization on the same model as irritable bowel syndrome (IBS) or painful bladder syndrome (PBS), led to the application of botulinum toxin (BTX) injections under hysteroscopy of the uterine myometrium in this indication.

[MATERIAL AND METHODS] In 2018, we conducted an open-label non comparative study, on 30 patients, with severe dysmenorrhea and PUS in therapeutic failure situation. All women had failure of usual treatments, with painkillers, anti-inflammatory drugs, contraceptive pill, menstrual suppressant therapy and a negative MRI and laparoscopy. The BTX units (200 IU of Incobotulinum-toxin A) were evenly distributed in the anterior and posterior myometrial wall under hysteroscopic control. Patients were reviewed between 8 and 12 weeks after BTX injections and then, at 6 months.

[MAIN RESULTS] Median VAS scores were significantly improved at 8-12 weeks follow up for dysmenorrhoea, deep dyspareunia, and pelvic pain outside of menstruation. Quality of life scores all improved dramatically. No major side effect has been reported in this pilot study. At 6 months, 12 patients (40 %), were given new injections for pain reccurence. But 14 patients (47 %), were still improved and did not require repeat injection at that time. 4 patients, were improvement was not significant, did not ask for repat BTX injections. These patients were all positive for Pelvic Sensitization criteria.

[CONCLUSIONS] Uterine BTX injection could be a very interesting therapeutic option in women with acute dysmenorrheoa and PUS in therapeutic failure. Only long-term randomised studies will be able to confirm that BTX injections are useful as a treatment for this condition. The randomised long-term study, Uteroxine, will shortly release its results.