Botulinum toxin infiltrations versus local anaesthetic infiltrations in pelvic floor myofascial pain: Multicentre, randomized, double-blind study.

[BACKGROUND] Many studies have demonstrated a link between pelvic floor myofascial syndromes and chronic pelvic pain. Botulinum toxin has been extensively used for several years in the field of pain, especially due to its action on muscle spasm. However, the efficacy of botulinum toxin in the context of chronic pelvic pain remains controversial.

[OBJECTIVES] This multicentre, randomized, controlled, double-blind study was designed to compare the efficacy of botulinum toxin and local anaesthetic (LA) injection versus LA injection alone for pelvic floor myofascial syndrome and chronic pelvic pain.

[METHODS] According to the number of painful trigger points detected on physical examination, patients received from 1 to 4 injections of botulinum toxin with LA (BTX) or LA alone. The primary endpoint was Patient Global Impression of Improvement (PGI-I) score on day 60 after infiltration. Secondary endpoints were pain intensity, number of painful trigger points on palpation, analgesic drug consumption and quality of life.

[RESULTS] We included 80 patients, 40 in each group. This study failed to demonstrate a significant difference between the 2 groups on day 60 in the primary endpoint or secondary endpoints (PGI-I score≤2=20% [LA] versus 27.5% [BTX], P=0.43). However, both groups showed significant alleviation of global pain.

[CONCLUSION] This study does not justify the use of botulinum toxin in the context of chronic pelvic pain with myofascial syndrome but does justify muscle injections with LA alone. ClinicalTrials.gov: NCT01967524.