Anesthesiology
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Primary afferent nociceptor sensitization and its accompanying spontaneous discharge are believed to be the proximate cause of the spontaneous pain and hypersensitivity that follow an acute tissue injury. Evidence for this comes almost entirely from studies limited to the first few minutes to an hour or two after injury, when the inflammatory reaction to injury has just begun. However, there is evidence that inflammatory pain mechanisms differ from acute pain mechanisms and that the mechanisms that drive and modulate inflammatory pain may evolve over time. ⋯ The pain, allodynia, and hyperalgesia associated with an established inflammatory condition are associated with a persistent low-frequency spontaneous discharge in both A-fiber and C-fiber sensory afferents.