The Origin

Abstract Complex regional pain syndrome (CRPS) is a chronic pain condition triggered by fracture, sprain, or minor surgery, often in combination with immobility or casting. It is characterized by pain and vasomotor, sudomotor, and motor symptoms in the injured limb that outlast the expected time course of healing from the antecedent injury. CRPS occurs in 5.5–26.2 people per 100,000 person-years and has a two- to four-fold higher prevalence in females. Additional risk factors for CRPS include a history of migraines and the use of angiotensin-converting enzyme (ACE) inhibitors, though the mechanisms connecting these findings remain unclear. Psychological factors do not seem to predispose to CRPS; however, they can exacerbate the disease course and should be considered in the development of a multidisciplinary treatment plan. Finally, it is unlikely that vaccination causes CRPS, but viral illness may exacerbate CRPS symptoms. Overall, CRPS remains a rare condition but is likely underrecognized and underdiagnosed due to lack of familiarity with the condition and overlap between initial symptoms and normal post-injury inflammation.