When you sprain an ankle, first you feel a sharp electric pain, and then you feel a burning pain. The sharp pain comes from the fast pain fiber, and the burning pain comes from the sympathetic nerve fiber. Normally the burning pain stops over time.

Sometimes, however, the burning will not stop. In addition, the painful part may always feel cold, and sensitivity to cold temperature, rain or falling barometric pressure can occur. If the condition becomes more severe, then the skin can become sweaty, change colors, and become painful to move. A natural tendency to avoid touch by anyone or anything develops. We call this Reflex Sympathetic Dystrophy (RSD) Stage 1.