ABSTRACT
Complex Regional Pain Syndrome, Type I (CRPS I) is a potentially disabling neuropathic condition characterized by regional pain that is often disproportionate to or occurs in the absence of an identifiable inciting event. This poorly understood disease is the result of a multifactorial interplay between altered somatosensory, motor, autonomic, and inflammatory systems. Peripheral and central sensitization is a common feature in CRPS. The condition is associated with hyperalgesia, allodynia, spontaneous pain, abnormal skin color, changes in skin temperature, abnormal sudomotor activity, edema, active and passive movement disorders, and trophic changes of nails and hair. CRPS I usually begins after minor or major trauma to soft tissue (e.g., strain, sprain, or surgery). Although rare, it can also occur following fracture, visceral trauma, or central nervous system insult (e.g., cerebrovascular accident; CVA). Although similar-if not identical-in presentation, a related syndrome, Type II (CRPS II), occurs following direct insult or injury to peripheral nerve. A complete address of CRPS II is beyond the scope of this chapter (see [1], for review). Sandroni et al. [2] report that CRPS I occurs more frequently than CRPS II (i.e., CRPS I incidence of 5.5/100,000 person years at risk vs. CRPS II incidence of 0.8/100,000 person years at risk), is more prevalent (21/100,000 vs. 4/100,000), and occurs more in females than males with reported ratios of 2:1 or greater [3].
