Complex Regional Pain Syndrome (CRPS)
Complex regional pain syndrome (CRPS) is a debilitating condition, characterised by pain in a limb, in association with sensory, vasomotor, sudomotor, motor and dystrophic changes. It commonly arises after an injury to that limb. Pain is typically the leading symptom of CRPS but is often associated with limb dysfunction and psychological distress. Patients frequently report neglect-like symptoms or a feeling that the limb is ‘alien’.
CRPS can be divided into two types based on the absence (type 1, much more common) or presence (type 2) of a lesion to a major nerve. The subtype of CRPS has no consequences for the general approach to management, but the cause of nerve damage in CRPS 2 should always be clarified – urgently in acute cases.
Historically, among the many names that CRPS has been called, RSD and causalgia are the best known and still are commonly used. The existence of this confusing taxonomy for CRPS stems, in part, from the many nonstandardized, idiosyncratic, diagnostic schemes used throughout the past century and a half . In 1851, Claude Bernard (1813–1878) was the first to mention a pain syndrome that was linked to sympathetic nervous system dysfunction. Later, a student of Bernard, Silas Weir-Mitchell (1829–1914), employed the term “causalgia” to describe the pain he diagnosed in post-bellum union veterans. (Greek: kausos = heat, algos = pain). Evans first coined the term “reflex sympathetic dystrophy”. Although “RSD” became the most common name to describe this medical condition in the latter 20th century, this name is
Evans first coined the term “reflex sympathetic dystrophy”. Although “RSD” became the most common name to describe this medical condition in the latter 20th century, this name is problematic for several reasons: if a true “reflex” is indeed involved, it is complicated/multisynaptic and not fully characterized; it has since been shown that the assumed “sympathetic”/autonomic changes may not be a constant or causative pain component and furthermore may not be physiologically involved throughout the entire course of the condition in every patient, and actual “dystrophy” is present in perhaps only 15% of cases. The historical lack of agreement regarding standardized nosology and diagnostic criteria for CRPS/RSD has hindered medical and scientific progress in many ways, including lack of comparative studies of treatment of the disorder, and thus has delayed progress in identifying optimal treatments and treatment sequences for its sufferers.