Myofascial pain syndrome (MPS) is a musculoskeletal disorder that can develop in one or more skeletal muscles, resulting in chronic pain. “Myo” refers to muscle, and “fascia” is a membrane that covers muscles.

MPS is defined by the presence of trigger points (“TrPs”). Responsible for causing the pain, TrPs are localized areas of deep tenderness in the taut bands of skeletal muscles. They which may occur as a result of trauma, a repetitive motion injury, prolonged improper posture or an illness such as arthritis, diabetes or hypothyroidism.

TrPs are commonly found in the muscles of the trunk and head (axial muscles), especially those used for maintaining posture, in people of all ages. When pressure is applied, TrPs cause a local twitch response, also known as a “jump sign,” that is an involuntary shortening of the fibrous muscle band.

When felt (palpated), TrPs feel extremely tender and lumpy, like hardened nodules or peas. Not only are TrPs very painful, but they also transmit (“refer”) pain to other parts of the body. For instance, TrPs in the head, neck and upper back may result in headaches, TMJ-like jaw pain, neck pain, shoulder pain or lower back pain. The referred pain is often described as dull, aching and deep, and it can be constant or sporadic.

MPS patients often have TrPs in more than one location. Just applying pressure on a TrP will elicit the referred pain. If the patient has chronic pain, palpation can worsen the pain.

TrPs can be classified as either active or latent. Active TrPs cause ongoing, persistent pain, whereas latent TrPs are inactive until pressure is applied. In addition, psychological stress, muscle tension and physical factors such as poor body mechanics and posture and ergonomics can cause a latent TrP to become active.

The likelihood of developing active TrPs increases with age. Research suggests that sedentary people are more prone to develop active TrPs than individuals who exercise regularly. However, overexertion can aggravate the condition. When palpated, both active and inactive TrPs cause pain, decreased range of motion and weakness in the affected muscle group as well as a decreased ability of the muscle to stretch.

Often, active TrPs can trigger secondary TrPs or satellite myofascial points that respond because of the increased stress to the involved muscle groups.

• A secondary TrP can occur when a person avoids using the affected muscle and instead overloads another muscle used in compensation.
  
  
• A satellite myofascial point occurs when the pain from the affected muscle spreads to a nearby muscle. The new area of pain occurs because the muscle is located within the referred pain region of another TrP.

Though pain is the main component of this syndrome, MPS may also involve fatigue in addition to disturbances in sleep and mood (e.g., insomnia, depression, anxiety). Myofascial pain syndrome is not inflammatory, degenerative (such as osteoarthritis) or life-threatening, but it does impair quality of life. However, prognosis for recovery is good if treatment is started early and factors aggravating the TrPs are corrected or eliminated.

MPS is common and can affect men and women alike. However, patients with the syndrome are often misdiagnosed because not enough is known about it and symptoms are similar to various other conditions and disorders, such as, fibromyalgia, migraines, TMJ disorder and chronic fatigue syndrome. In addition, it is possible for MPS and fibromyalgia to co-exist in a patient. In such cases, each disorder reinforces and exacerbates the symptoms of the other.