Myofascial pain (MP) is a common, painful disorder that is responsible for many pain clinic visits. MP can affect any skeletal muscles in the body. Skeletal muscle accounts for approximately 50% of body weight, and approximately 400 muscles make up the body. MP is responsible for many cases of chronic musculoskeletal pain. MP can cause local or referred pain, tightness, tenderness, popping and clicking, stiffness and limitation of movement, autonomic phenomena, local twitch response (LTR) in the affected muscle, and muscle weakness without atrophy. Trigger points (TrPs), which cause referred pain in characteristic areas for specific muscles, restricted range of motion (ROM), and a visible or palpable LTR to local stimulation, are classic signs of MP. Over 70% of TrPs correspond to acupuncture points used to treat pain. Underlying medical causes of MP need to be ruled out. These include anemia and low levels of calcium, potassium, iron, and vitamins C, B-1, B-6, and B-12. Chronic infections and sleep deprivation have been cited as causative factors, as have radiculopathy, prolonged inactivity, stress, visceral diseases, and depression. Hypothyroidism, hyperuricemia, and hypoglycemia also have been implicated in MP. The pathogenesis likely has a central mechanism, with peripheral clinical manifestations. Patients will usually respond well to a combination of trigger point injections, physical therapy, development of a home excercise program, electromuscular stimulation therapy, and medication management. Stress reduction and behavioral therapy are also useful.
