There are more than a dozen terms denoting “complex regional pain syndrome,” a condition previously known as “reflex sympathetic dystrophy.” The numerous “synonyms” reflect not only its importance in pain medicine (not unlike the linguistic lore that within Eskimo-Aleut languages, there are more than 50 words for snow and sea ice), but also the ambiguity and subjectivity involved in diagnosis. In addition to a quest for standardization, one of the reasons for the name change was the realization that only around 30% of people with reflex sympathetic dystrophy actually had sympathetically-maintained pain, with the identification of sympathetically-maintained pain being contingent on the means of sympathetic blockade (nerve blocks have low specificity compared to phentolamine tests).1,2  Compared with diseases, which are characterized by distinct pathophysiologic mechanisms and biomarkers, syndromes merely describe a constellation of signs and symptoms in the absence of other conditions that might explain them; hence,...

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