As far as my understanding RSD is full body when it has reached each and every body part.
I have full body RSD- RSD in each area of my body and I also deal with immune system problems, autonomic nervous system problems, lots of neurological problems, etc...
My neurologist diagnosed me with full body RSD after testing each part of my body for signs of RSD- color changes, temperature changes, swelling, allodynia, muscle spasms/ tremors and that sort of thing, etc..
I am not 100% sure though, as all I knew was my neuro found RSD in each part of my body. Is the organ problems from RSD internally or neurological/ immune/ etc problems from RSD?
It is all confusing... just some thoughts from my experience.