Clinical features of algodystrophy: is the sympathetic nervous system involved?

There is a spectrum of conditions which have in common burning pain, often with hyperpathia, hyperalgesia, vasomotor and sudomotor changes. When due to major nerve damage, the condition is known as causalgia; when due to minor nerve damage or other factors, various terms such as algodystrophy or reflex sympathetic dystrophy are employed. Radiography and isotopic bone scanning may be helpful investigations, and procedures which interrupt the local sympathetic nervous system are those most likely to help the pain. The classical view that the peripheral sympathetic nervous system is involved in generation of pain is questioned, and the possible roles of the central nervous system and of non-adrenergic mechanisms are summarised. That pain could be due to dysfunction of the polymodal nociceptor neurone is considered.