Referred muscle pain: Clinical and pathophysiologic aspects

Referred pain, that is, pain perceived in an area other than that in which the noxious stimulation takes place, is very frequent in the clinical setting. There are various forms of referred muscle pain from viscera and from somatic structures. Examples of the latter are referred pain from one muscle to another muscle (as in myofascial pain syndromes) and referred pain from joints (as in osteoarthritis of the knee). Whatever the origin of the symptom, a condition of secondary hyperalgesia very often takes place in the referred zones, together with trophic tissue changes. Referred muscle pain from viscera without hyperalgesia is explained on the basis of the convergence of visceral and somatic afferent fibers on the same central neurons.