1. Introduction
TrPs, MM, TrP, pain, Masticatory myalgia, muscle pain, muscle hyperactivity, chronic pain, muscle stiffness
TMJ, CONTRACTION, DISORDERS, AUTONOMIC DYSFUNCTION, CHRONIC PAIN
Masticatory myalgia (MM) is a common musculoskeletal condition produced by a sustained and persistent contraction of a group of muscles responsible for mandibular movement, whose main characteristic feature is the frequent occurrence of chronic pain in multiple trigger points (TrPs). These TrPs correspond to hyperirritable spots in skeletal muscle associated with palpable nodules in taut bands of muscle fibers within the affected muscles, accompanied by regional muscle pain, or referred pain, to the nearby masticatory muscles or the temporomandibular joint (TMJ). On examination, TrPs may be identified within a tight band of the involved muscle, which may cause referred pain and a local twitch reaction upon palpation. Regional discomfort may be associated with muscle stiffness, limitation of movement, weakness, and, in some cases, autonomic dysfunction [Management of MM consists of alleviating the patient’s pain and achieving a correct relationship between the TMJ and the affected muscles, with an adequate range of motion. Several treatments have been proposed for MM. The main management modalities are patient education and control of predisposing factors; analgesics, pharmacological therapies, such as myorelaxants and antidepressants; occlusion splints; various physiotherapy treatments; dry needling; ultrasound; transcutaneous electrical nerve stimulation; psychotherapy; or TrP injections and wet needling of different substances [For decades, botulinum toxin A (BTA) has been applied in a multitude of disorders related to muscle hyperactivity and injected into the affected muscles, producing chemical denervation and deep and persistent relaxation [