Hi there..
Bone scans show increased and decreased blood flow to the bones, they do not require needles in the hand, though you do get an injection for it in one arm. The tripple phase bone scan is more specific but like most of these tests it depends on one side to be the 'controll" or normal side to compare it to.

These tests lend suport to a diagnosis but is not the only thing considered. Same with blocks they can be used to help diagnose but negative results do not mean you do not have RSD, the more features of RSd and trest results sugestive of RSd that you have the more they consider it a definate dx but signs and symptoms are what RSD is generaly diagnosed with.
Good luck to ya numb,

Sandra