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Complex regional pain syndrome occurs in two types with similar signs and symptoms, but different causes:

• Type I. Previously known as reflex sympathetic dystrophy syndrome, this type occurs after an illness or injury that didn't directly damage the nerves in your affected limb. About 90 percent of people withcomplex regional pain syndrome have type I.
• Type II. Once referred to as causalgia, this type follows a distinct nerve injury.

Many cases of complex regional pain syndrome occur after a forceful trauma to an arm or a leg, such as a gunshot wound or shrapnel blast. Other major and minor traumas — surgery, heart attacks, infections, fractures and even sprained ankles — also can lead to complex regional pain syndrome. It's not well understood why these injuries sometimes trigger complex regional pain syndrome.

The syndrome was first described after the U.S. Civil War when soldiers continued to report severe pain after their wounds had healed. It was often referred to as "hot pain" during that period.

2007-04-02

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