PATHOGENESIS OF MYOFASCIAL PAIN SYNDROME:
It may develop from a muscle lesion or excessive strain on a particular ms/group, ligament or tendon. The lesion or the strain prompts the development of a "trigger point" that, in turn, causes pain. Trigger points are usually associated with a taut band, a ropey thickening of the muscle tissue. Trigger point, when pressed upon, will cause the pain to be felt elsewhere. This is what is considered "referred pain".
Trigger points may develop due to following reasons:
1. Sudden trauma to musculoskeletal tissues (muscles, ligaments, tendons, bursae)
2. Injury to intervertebral discs
3. Repetitive motions; Excessive exercise; Muscle strain due to over activity
4. Systemic conditions (eg, MI, appendicitis, etc.)
5. Lack of activity, Nutritional deficiencies, Hormonal changes (eg,PMS)
6. Nervous tension or stress
7. Chilling of areas of the body (eg, sitting under AC)
In these trigger points; there is sensitization of low-threshold mechanosensitive afferents associated with dysfunctional motor endplates in the area of the Trigger Points projecting to sensitized dorsal horn neurons in the spinal cord. Pain referred from Trigger Points and Low Threshold Receptor may be mediated through the spinal cord after stimulation of a sensitive locus.