The story of complex regional pain syndrome (CRPS) begins in 1864. During the American Civil War, the father of American neurology, Silas Weir Mitchell (fig 1), together with Morehouse and Keen, observed that soldiers sustaining major nerve injuries affecting their limbs sometimes experienced long-lasting pain that was burning in quality, and “so frequent and terrible as to demand from us the fullest description”.¹ Soon afterwards he termed the condition causalgia (Greek: kausos (heat) + algos (pain)). Mitchell’s account, in which he graphically describes many of the associated features shown in table 1, is one of the classics of neurology.

At the beginning of the 20th century, Paul Sudeck made two important contributions.² First, only five years after x rays had been discovered, he identified the localised bone atrophy (“Knochenatrophie”) that can develop in the presence of acute, focal limb disorders—and so, strictly speaking, the term Sudeck’s atrophy should be reserved for the radiological appearance of osteoporosis. Second, he postulated an inflammatory (“entzündliche”) cause—a concept now thought increasingly plausible.

The next landmark contribution was the paper from the famous French vascular surgeon, René Leriche. Thinking the limb of patients with causalgia resembled an ischaemic limb, and recalling that sympathectomy was used to treat ischaemic limbs, in 1916 he described how he had performed extensive stripping of the peri-arterial nerve plexus from the affected limb of a patient with causalgia, and pain relief ensued.³ Stemming from this pivotal report of a single case (fig 2), the conceptual leap, whereby the sympathetic nervous system became implicated in the phenomenon of causalgia, resulted in the 100-year search for sympathetically mediated mechanisms, and vast numbers of diverse procedures being performed with the aim of interrupting the sympathetic outflow …