Referred muscle pain: Clinical and pathophysiologic aspects

Abstract

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. Referred muscle pain from viscera with hyperalgesia is not completely understood; it is hypothesized that it is due to both central (sensitization process) and peripheral (intervention of reflex arcs) mechanisms. Referred muscle pain from other muscles or from joints is not easily explained by the mechanism of "central convergence" in its original form, because in dorsal horn neurons there is little convergence from deep tissues. It has been proposed that convergent connections from deep tissues to dorsal horn neurons are not present from the beginning but are opened by nociceptive input from skeletal muscle, and referral to myotomes outside the lesion is due to a spread of central sensitization to adjacent spinal segments.

Dry needling — peripheral and central considerations

“…[98][99][100][101] It is conceivable that initially the taut band formation reflects a normal physiologic, protective, and stabilizing mechanism, for example, associated with damage or potential muscle damage, joint hypermobiity, visceral dysfunction, or abnormal breathing patterns. Prolonged contractures are likely to lead to the formation of latent trigger points, which can evolve into active trigger points.…”

Endometriosis and Abdominal Myofascial Pain in Adults and Adolescents

“…Flank pain and trigger points can be produced by ureterolithiasis [46]. One of the important characteristics of these trigger points is that they may dissipate after the original condition has resolved but they also may remain for significant periods of time [47,48].…”

Effect of Treatment on Trigger Points

“…However, the best possible mechanism that may explain the referred pain is convergence and facilitation. Convergence, or wind-up, is a phenomenon that results from amplification and wind-up of dorsal horn neurons leading to spreading to adjacent segments [43,44]. This leads to persistent pain due to sensitization in the dorsal horn and increased sensitivity and excitability of neurons [45][46][47][48][49].…”