Myofascial pain syndromes are common dis-orders characterized by aching muscle pain,muscle spasm, stiffness, weakness, and, occasion-ally, autonomic dysfunction. Patients have discrete areas (trigger points) of marked tenderness in one or more muscles or the associated connective tissue. Palpation of the involved muscles may reveal tight, ropy bands over trigger points. Signs of autonomic dysfunction (vasoconstriction or piloerection) in the overlying muscles may be present. The pain characteristically radiates in a fixed pattern that does not follow dermatomes.
Gross trauma or repetitive microtrauma is thought to play a major role in initiating myofas-cial pain syndromes. Trigger points develop follow-ing acute injury; stimulation of these active trigger points produces pain, and the ensuing muscle spasm sustains the pain. When the acute episode subsides, the trigger points become latent (tender, but not pain producing) only to be reactivated at a later time by subsequent stress. The pathophysiology is poorly understood.
The diagnosis of a myofascial pain syndrome is suggested by the character of the pain and by palpation of discrete trigger points that reproduce it. Common syndromes produce trigger points in the levator scapulae, masseter, quadratus lumbo-rum, and gluteus medius muscles. The latter two syndromes produce low back pain and should be considered in all patients with back pain; moreover, gluteal trigger points can mimic S1 radiculopathy.
Although myofascial pain may spontaneously resolve without sequelae, many patients continue to have latent trigger points. When trigger points are active, treatment is directed at regaining muscle length and elasticity. Analgesia may be provided uti-lizing local anesthetic (1–3 mL) trigger point injec-tions. Topical cooling with either an ethyl chloride or fluorocarbon (fluoromethane) spray can also induce reflex muscle relaxation, facilitating massage (“stretch and spray”) and ultrasound therapy. Physi-cal therapy is important in establishing and main-taining normal range of motion for affected muscles, and biofeedback may be helpful.