Clinical, electrophysiological and imaging findings in patients suffering from complex regional pain syndrome (CRPS)

The diagnosis CRPS bases on the typical history of an acute injury and the development of a neuropathic pain syndrome with abnormalities in the sensory, motor and autonomic nervous systems. Inflammatory and rheumatologic diseases and complications of the initial trauma have to be excluded. In spite of clinically marked sensory and motor dysfunction electrophysiological routine tests like myography, neurography and evoked potentials typically are normal. From actual experimental studies there is good evidence that mechanisms within the central nervous system might play an important role in the pathophysiology of CRPS. A significant shrinkage of the extension of the cortical area representing the affected limb has been shown. This cortical reorganisation correlates with the pain intensity. There is dysfunction of the central control of sympathetic vascular reflexes. Furthermore, a bilateral disinhibition of the motor cortex was shown in patients with CRPS. These experimental findings might explain otherwise unexplained clinical findings in CRPS patients. The correlation of the extent of cortical reorganisation and pain intensity is of special interest. Further studies should answer the question whether cortical reorganisation can be modulated in CRPS and whether such a modulation has favourable effects on pain intensity and chronification.