"In His Hands" -- I'm new to this board, but I've had RSD for a few years now. I found your post interesting, and think you've posted a good question, for what it is is worth I always explain RSD like this, and I will write nearly verbatim of what I say, just as if I am speaking to someone:

My sympathetic nervous system is involuntarily 'stuck' on over-drive. You likely don't know what this nervous system is, as most people have never heard of it -- I had never known what it was either, before developing this condition. But your sympathetic nervous system is completely different from the central nervous system -- which you likely are familiar with: you know like your brain tells hand to move, and hand moves. Well the sympathetic nervous system is the body's nervous system that reacts to outside stimulus; for instance it's your sympathetic nervous system that registers it's cold/snowy outside -- you better put a jacket on, it's also this nervous system that reacts pain sensations, and if your hand is was thrown into a pot of boiling water it is this nervous system that would make your react and respond immediately -- like ow! ... remove your hand out of the pot immediately.

The sympathetic nervous system (which in a healthy, normal functioning capacity) responds to this painful stimulus in way to warn you to protect your body by sending out the pain signals to/from your brain by sending pain signals to/from your brain, and it also reacts in a physical protection mode by automatically restricting blood vessels, for instance.

Unfortunately in the condition I have (RSD) the sympathetic nervous system is 'stuck' in a permanent malfunctioning, over-drive capacity. Meaning, my body/brain believes I am continuously being attacked by outside painful stimulus long after the stimulus is gone. My sympathetic nervous system is continuing to react just as if it is currently being attacked.

The result is it continuously sending out erroneous pain signals to/from my brain, and it continuous to do all things it would do just as if if there was painful outside stimulus there, i.e.: restricting blood vessels, etc. And, moreover, it often doesn't just stay contained to the limb/or local area where the initial injury was -- with RSD your body becomes so confused that it manifests this bizarre painful pattern throughout different limbs, and throughout your entire body.

I think this often gives them a thorough understanding of what is, and an indication of how painful and frustrating it must be to deal with. I think there is some great information on the web that helps with best defining RSD, and helps with determing the best way you can define it to others when explaining it -- and determine what works best for you. I know it can be very frustrating to try to get people to understand what on earth is *wrong* with you. Best wishes.