Norepinephrine in reflex sympathetic dystrophy: an hypothesis

Reflex sympathetic dystrophy (RSD) usually occurs in an individual who has been experiencing significant personal stress, a state associated with increased discharge of norepinephrine (NE) from perivascular postganglionic sympathetic neurons. RSD is often precipitated by this sequence: traumatic arterial spasm, regional ischemia, neurogenic inflammation, and ischemic/edematous damage to membranes of preterminal perivascular nociceptive neurons. In the natural repair of these membranes, it is suggested that adrenoceptors appear and are ordinarily transitory; but in RSD, they are retained by the increased adjacent NE. This process delays further healing, produces pain, and releases inflammatory substances, resulting in interacting pathophysiologic vicious cycles.