Treatment of painful muscle syndromes with botulinum toxin: A review

Purpose: To review literature regarding clinical response to injections of botulinum toxin type A for a variety of painful disorders of involuntary muscular contraction. Methods: A MEDLINE search for the headings 'botulinum toxin','myofascial pain' and 'pain' was performed for the period 1966 to September 1997. Results: Eighteen references including 463 subjects were generated. Seven studies included 'pain' or 'myofascial pain' within the article title, while the remaining references reported pain response within the context of treatment for underlying spasticity, cervical dystonia, fibromyalgia, focal dystonia, hemifacial spasm, painful dystonia of Parkinson's disease, pain of chronic pancreatitis, writer's cramp and masseteric hypertrophy. Results of pain response in the cited studies were favorable in all except in fibromyalgia and chronic pancreatitis. The authors discuss instruments to measure pain intensity and physical functioning for future research and introduce a new instrument that includes self-reported pain assessment linked to joint position. Conclusion: Evidence suggests that BTX-A effectively reduces painful muscular contractions associated with a variety of neurologic conditions. Further research is needed to define conditions in which injections will be most effective. (C) 1998 Elsevier Science Ireland Ltd.