Botulinum toxin type a injections for cervical and shoulder girdle myofascial pain using an enriched protocol design.
BACKGROUND
Myofascial pain syndrome is a regional condition of muscle pain and stiffness and is classically characterized by the presence of trigger points in affected musculature. Botulinum toxin type A (BoNT-A) has been shown to have antinociceptive properties and elicit sustained muscle relaxation, thereby possibly affording even greater relief than traditional strategies. Our goal was to determine whether direct injection of BoNT-A into painful muscle groups is effective for cervical and shoulder girdle myofascial pain.


METHODS
An enriched protocol design was used, wherein 114 patients with cervical and shoulder girdle myofascial pain underwent injection of BoNT-A to determine their response to the drug. Fifty-four responders were then enrolled in a 12-week, randomized, double-blind, placebo-controlled trial. Pain scales and quality of life measures were assessed at baseline and at routine follow-up visits until completion of the study after 26 weeks.


RESULTS
Injection of BoNT-A into painful muscle groups improved average visual numerical pain scores in subjects who received a second dose of BoNT-A compared to placebo (P = 0.019 [0.26, 2.78]). Subjects who received a second dose of BoNT-A had a reduced number of headaches per week (P = 0.04 [0.07, 4.55]). Brief Pain Inventory interference scores for general activity and sleep were improved (P = 0.046 [0.038, 3.700] and 0.02 [0.37, 4.33], respectively) in those who received a second dose of BoNT-A.


CONCLUSIONS
BoNT-A injected directly into painful muscle groups improves average pain scores and certain aspects of quality of life in patients experiencing severe cervical and shoulder girdle myofascial pain.
From the Department of Anesthesiology, David Geffen School of Medicine at UCLA, Los Angeles, California.
Andrea L
AL
Nicol
Irene I
II
Wu
F Michael
FM
Ferrante
D000293:Adolescent; D000328:Adult; D000368:Aged; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D009209:Myofascial Pain Syndromes / Q000188:drug therapy* / Q000523:psychology; D019547:Neck Pain / Q000188:drug therapy* / Q000523:psychology; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D010147:Pain Measurement / Q000187:drug effects; D011788:Quality of Life; D020069:Shoulder Pain / Q000188:drug therapy* / Q000523:psychology; D012959:Socioeconomic Factors; D016896:Treatment Outcome; D055815:Young Adult
D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A