title: Botulinum toxin A for myofascial trigger point injection: a qualitative systematic review.
abstract: Botulinum toxin injection is used to treat various pain conditions including muscle spasticity, dystonia, headache and myofascial pain. Results are conflicting regarding the use of Botulinum toxin for trigger point injection in terms of improvement in pain. The aim of this study was to carry out a systematic review to assess the evidence for efficacy of Botulinum toxin A (BTA) compared with placebo for myofascial trigger point injection. Electronic databases on Medline, Cochrane Library, Scopus, CINAHL were queried using key words such as "botulinum toxin", "myofascial pain", "trigger point", "chronic pain" and "musculoskeletal pain". Relevant published randomized controlled trials that described the use of BTA as injection therapy for trigger points were considered for inclusion. The five-item 0-16 point Oxford Pain Validity Scale (OPVS) was used as a selection criteria for suitable clinical trials. Trials were also assessed based on quality using the Oxford Rating Scale. Data extracted from qualified trials included outcome measures such as pain intensity and pain pressure threshold. All studies were ranked according to the OPVS and the authors' conclusions were compared. Five clinical trials met the inclusion criteria. One trial concluded that BTA was effective, and four concluded that it was not effective for reducing pain arising from trigger points. OPVS scores ranged from 8 to 14 with the negative studies corresponding with higher validity scores. The current evidence does not support the use of BTA injection in trigger points for myofascial pain. The data is limited and clinically heterogeneous.
authors.affiliation: Pain Management Services, Department of Anaesthesia and Surgical Intensive Care, Singapore General Hospital, Outram Road, Singapore 169608, Singapore. hokokyuen@yahoo.com.sg
authors.forename: Kok-Yuen
authors.initials: KY
authors.lastname: Ho
authors.forename: Kian-Hian
authors.initials: KH
authors.lastname: Tan
mesh_terms: D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D002908:Chronic Disease / Q000188:drug therapy; D016206:Databases, Bibliographic; D006801:Humans; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000503:physiopathology; D009209:Myofascial Pain Syndromes / Q000188:drug therapy*; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D017063:Outcome Assessment, Health Care / Q000379:methods; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D016896:Treatment Outcome
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A