Myofascial and visceral pain syndromes: Visceral-somatic pain representations

Objective: To describe the relationship between viscero-somatic pain syndromes and myofascial pain syndromes [MPS]. Findings: Myofascial pain syndromes can be primary conditions or secondary. When they are secondary, they occur as a manifestation of another disorder. A regional pain referral from a visceral disorder can induce secondary MPS. Visceral disorders induce central sensitization with hypersensitivity and expansion in the number and size of receptive fields. Central sensitization is topographically organized in the spinal cord, being segmentally predominant at the level of the affected viscera. The associated MPS tend to be regional, but are related to the segmental innervation of the affected viscera. Regional MPS in turn can mimic visceral disease, or be the diagnostic sign of visceral disease. Cardiac disease, gastrointestinal disorders, hepatic and biliary disorders, irritable bowel syndrome and interstitial cystitis are some of the conditions in which MPS can occur secondarily or mimic. Conclusion: Myofascial pain syndromes can occur as a result of visceral disorders, but can also mimic visceral disease. Visceral disease must be considered in the differential diagnosis of regional MPS.