1. Introduction
myofascial pain, masticatory myalgia, TMD, traumatic injuries, TMDs, dystonia, masticatory muscle disorders, strabismus, pain, musculoskeletal disorders, parafunction, muscle hyperfunction, hyperhidrosis, blepharospasm
MYOFASCIAL PAIN, TMJ, DYSTONIA, STRABISMUS, MUSCULOSKELETAL DISORDERS, HEMIFACIAL SPASM, TEMPOROMANDIBULAR DISORDERS, BLEPHAROSPASM
Temporomandibular disorders (TMDs) refer to a range of conditions affecting the masticatory muscles or the temporomandibular joint (TMJ) and are the second most common musculoskeletal disorders causing pain and functional impairment [TMDs are considered to have a multifactorial etiology, commonly associated with muscle hyperfunction, oral parafunction, traumatic injuries, hormonal influences, and articular changes within the joint [It has been reported that approximately 50% of all TMDs comprise masticatory myalgia or painful masticatory muscle disorders [Since the US Food and Drug Administration first approved Botulinum toxin type A (BoNT/A) for the treatment of strabismus and blepharospasm in 1989, it has been approved for the treatment of hemifacial spasm, cervical dystonia, and hyperhidrosis and for cosmetic treatment [However, several double-blind randomized clinical trials (RCTs) failed to indicate significant differences with respect to myofascial pain in TMD between patients treated with BoNT/A and a saline placebo [