Does the Use of Botulinum Toxin Reduce the Intensity of Myofascial Pain in Adult Patients? A Systematic Review and Meta-Analysis

Objective: A systematic review was performed to evaluate if the use of botulinum toxin was able to reduce the intensity of myofascial pain compared to other treatments in adult patients. Material and Methods: A comprehensive search was carried out in the MEDLINE via Pub-Meb, Scopus, Web of Science, LILACS, BBO and Cochrane Library. In addition, the gray literature was also researched. The risk of bias tool from the Cochrane Collaboration was used by two independent reviewers for quality assessment of the studies. Results: A total of 4372 studies were identified, 9 remained in qualitative study, 8 of these studies were considered at “unclear” risk of bias and just one study was “low” risk of bias in the key domains. Only two studies presented similar data to be included in the meta-analysis. Both studies evaluated the pain relief used the botulinum toxin (BTX-A) versus saline solution. The meta-analysis demonstrated that after 3 months follow-up the pain relief was 15.70 (95 % confidence interval [CI] = 0.80 to 30.61; p = 0.04). Conclusion: The BTX-A reduced the intensity of myofascial pain compared to saline solution in adults after 3 months. However, further studies should be conducted to corroborate this finding. Keywords: Meta-analysis; Myofascial Pain Syndromes; Botulinum Toxins. Abbreviations: TMD: Temporomandibular disorders, TMJ: temporomandibular joint, MPS: myofascial pain syndrome, BTX-A: Botulinum Toxin Type A, CI: confidence interval, LI-LACS: Latin American and Caribbean Health Sciences Literature database, BBO: Brazilian Library in Dentistry, RCTs: randomized clinical trials, GRADE: Grading of Recommenda-tions: Assessment, Development and Evaluation, MPQ: Mc GillPain Questionnaire.