Reflex Sympathetic Dystrophy RSD, more properly known since 1993
as CRPS (complex regional pain syndrome) usually with SMP
(sympathetically mediated pain) is a complicated neurologic
disorder of the autonomic nervous system. The autonomic nervous
system is distinct from the central nervous system (brain) and
peripheral nervous system (spinal cord and peripheral nerves).
The sympathetic portion of this system is located alongside the
spinal column and exists as chains of ganglia (like bunches of
bait worms) and is responsible for the spontaneous constriction
of blood vessels in response to certain stimuli such as heat,
cold, fear, etc. Rarely, and for unknown reasons, a stimulus can
cause an abnormally vigorous and sustained response, leading to
a cold, clammy, sweaty, swollen, blue extremity with searing or
burning pain. Usually starting distally, e.g., in a finger or
toe, and if unrecognized or untreated early, this dystrophic
response can spread throughout the extremity. Via certain
neurons in the spinal co