[Pathogenesis of complex regional pain syndrome (CRPS)]

Neuropathic pain results from injury to neural structures within the peripheral or central nervous systems. Such injury promotes spontaneous and ectopic firing of nerves as well as reorganization of the nervous system. Neuropathic pain persists chronically. Patients who suffer from neuropathic pain exhibit persistent or paroxysmal pain without apparent immediate cause or pain hypersensitivity after tissue damage. This hypersensitivity is manifest as hyperalgesia and allodynia. Complex regional pain syndrome, CRPS is a category of neuropathic pain and is further divided into type I(reflex sympathetic dystrophy: RSD) and type II(causalgia). CRPS is characterized by localized autonomic dysregulation in the affected area with vasomotor and/or sudomotor changes, edema, colour difference, sweating abnormality, and atrophy.