
The Reflex Sympathetic Dystrophy Syndrome Association estimates that the CRPS affects between 200,000 and 1.2 million Americans. The underlying causes of the syndrome have yet to be defined, and no definitive diagnostic test exists even though CRPS was first described in the late 19th century by the neurologist Silas Weir Mitchell. Mitchell referred to the cluster of symptoms he noticed in some of the Civil War soldiers who were under his care as "causalgia.