1 CRPS is a Disease of the CNS . The Disturbed Communication between brain and Body

For almost a century it is discussed that activity in the sympathetic nervous system may be involved in the generation of pain, e.g., in causalgia and reflex sympathetic dystrophy. This assumption is based mainly upon two observations: (1) the pain is spatially correlated with signs of autonomic dysfunction, i.e., with abnormalities in blood flow and sweating, as well as with trophic changes, and (2) blocking the efferent sympathetic supply to the affected part relieves the pain. In 1995 the terminology of these pain syndromes was changed and is now based entirely on elements of history, symptoms and findings on clinical examination with no implied pathophysiological mechanism. Reflex sympathetic dystrophy and causalgia are now called Complex Regional Pain Syndromes (CRPS). In CRPS type I (reflex sympathetic dystrophy) minor injuries at the limb or lesions in remote body areas precede the onset of symptoms. CRPS type II (causalgia) develops after injury of a major peripheral nerve [16,21]. CRPS patients presenting with exactly the same clinical signs and symptoms can be divided into two groups by the negative or positive effect of sympathetic blockade. The pain component that is relieved by specific sympatholytic procedures is considered ”sympathetically maintained pain“ (SMP). Thus, SMP is defined to be a symptom and not a clinical entity. I will first present a hypothesis stating that CRPS is a disease of the central nervous system and argue on which clinical and experimental data this hypothesis is based with special focus on the sympathetic nervous system.