Sometimes it's the little things that can make a difference between potential spread. I have multiple RSD/CRPS symptoms in both arms but burning pain in only the original injury site/arm. Often an IV means severe burning pain and my "good" arm has gotten into scary territory. Once I started being proactive about putting lidocaine patches on asap, I haven't had the same type of escalation again. It took me more than a few years to figure that out...