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A syndrome characterized by severe burning pain in an extremity accompanied by sudomotor, vasomotor, and trophic changes in bone without an associated specific nerve injury. This condition is most often precipitated by trauma to soft tissue or nerve complexes. The skin over the affected region is usually erythematous and demonstrates hypersensitivity to tactile stimuli and erythema. (Adams et al., Principles of Neurology, 6th ed, p1360; Pain 1995 Oct;63 (1):127-33)