Subcutaneous accessory pain system (SAPS): A novel pain pathway for myofascial trigger points.

Despite the accumulating neuro-physiological evidence of myofascial pain, many clinicians are skeptical about its existence as a separate disease entity. No single theory can fully explain the four cardinal features of MPS; taut bands, local tenderness, local twitching and the characteristic pattern of referred pain. Bridging the gap between basic and clinical knowledge mandates coupling the local trigger point changes with the clinically seen distant somatically innervated referred pain. The main question addressed by the present theory is why do trigger points behave differently in comparison to the surrounding muscle tissue and are trigger points the primary problem or secondary to a primary pathology. We propose that trigger points have an extra-innervation system that connect them with other spinal structures such as the facet, the annulus and other trigger points with a role for the subcutaneous fascia as part of trigger points pathogenesis or passage for the extra-innervation. The extra-innervation system is Subcutaneous accessory pain system (SAPS). The novel SAPS system connecting trigger points to the spinal segments via dorsal rami is presented. Individuals with this accessory pathway are prone to myofascial pain, trigger point activation and segmental referred somatic pain similar to other axial spinal structures. Despite the high prevalence of myofascial pain, the mechanism is not universally agreed upon. Why do the trigger points act differently from surrounding muscle tissue and are almost constant in location in different individuals is controversial. Why does myofascial pain and its two components, trigger points and referred pain, exist or are more prevalent in some individuals than in others is unexplained. The correlation between axial spinal structures pathology and the trigger points is not explored well. The existing theories about trigger point formation and referred pain is scientifically credible for each separate component and the SAPS novel system can provide the link between the two.