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 relaxatio