Pathophysiology of Complex Regional Pain Syndrome Type I: Update

Background: Complex regional pain syndrome type I (CRPS I), also known as reflex sympathetic dystrophy (RSD), develops as disabling painful disorder following a trauma or surgery to a limb. We provide a review based on the current literature concerning the epidemiology and pathophysiology of CRPS I. Possible pathophysiological mechanisms of CRPS I are inflammation, sympathetic-afferent coupling and cortical changes. Methods: A literature search was conducted using, as electronic bibliographic database, Medline from 1980 until today. Results: CRPS I is a multifactorial disorder with complex aetiology and pathogenesis. Conclusions: The pathophysiology of CRPS I is complex and may change during its course. CRPS I is more than a peripheral disease because peripheral mechanisms such as neurogenic inflammation and sympathetic-afferent coupling inconclusively explain its pathophysiology. CRPS I is a pain disorder involving the somatosensory, the somatomotor and the sympathetic nervous systems. Genetic findings suggest there might be a predisposition to CRPS I and it has been confirmed in multiple studies that psychological factors are not predictors for the development of CRPS I. The complexity and diversity of the mechanisms involved will be liable to the heterogeneity of the clinical presentation and may explain the difficulty of achieving an evidence-based treatment of CRPS I.