Myofascial pain syndrome is a common painful muscle disorder defined by the presence of myofascial trigger points. Myofascial pain syndrome frequently occurs in patients with fibromyalgia. Trigger points may occur in patients, but they are distinctly different from the tender points of fibromyalgia.
Trigger points are focal, discrete, hyperirritable spots located in a taut band of skeletal muscle. The points are painful on compression and can produce referred pain, referred tenderness and motor dysfunction.
Tender points, by comparison, are associated with pain at the site of palpation only, are not associated with referred pain, and occur in the insertion zone of muscles, not in taut bands in the muscle belly. Patients with fibromyalgia have tender points by definition. Concomitantly, patients may also have trigger points with myofascial pain syndrome. These two pain syndromes may overlap in symptoms and be difficult to differentiate.
Acute trauma or repetitive microtrauma may lead to the development of a trigger point. Lack of exercise, prolonged poor posture, sleep disturbances, and joint problems may all predispose to the development of micro-trauma. Occupational and recreational activities that produce repetitive stress on a specific muscle or muscle group commonly cause chronic stress in muscle fibers, leading to trigger points.
Acute sports injuries caused by acute sprain or repetitive stress ( pitcher’s or tennis elbow, golf shoulder), surgical scars, and tissues under tension frequently found after spinal surgery and hip replacement may also predispose a patient to the development of trigger points.
Patients with trigger points frequently report persistent, regional pain that usually results in a decreased range of motion of the muscle in question. Often, the muscles used to maintain body posture are affected, namely the muscles in the neck, shoulders, and pelvic girdle, including the upper trapezius, scalene, sternocleidomastoid, levator scapulae, and quadratus lumborum. The pain is usually related to muscle activity, but it may be constant.
The pain is reproducible and does not follow a dermatomal or nerve root distribution. Signs such as joint swelling and neurologic deficits are generally absent.
Myofascial pain syndrome with trigger points in the head and neck can manifest as tension headache, tinnitus, temporomandibular joint pain, eye symptoms, and torticollis. Pain in the shoulders may resemble visceral pain or mimic tendonitis and bursitis. Trigger points in the legs may involve pain in the quadriceps and calf muscles and may lead to a limited range of motion in the knee and ankle. In the gluteus maximus and gluteus medius, trigger points often produces severe pain in the low back region.