http://www.ajnr.org/cgi/content/full/30/7/1279

Cool pictures of functional MRI of the brain

SUMMARY: In complex regional pain syndrome (CRPS), functional imaging studies gave evidence for an important role of the central nervous system (CNS) in the pathogenesis of the disease. Especially, reorganization in central somatosensory and motor networks was demonstrated, leading to an altered central processing of tactile and nociceptive stimuli, as well as to an altered cerebral organization of movement. These findings may explain a number of clinical signs and symptoms occurring in the course of the disease and seem to be closely related to chronic pain in CRPS. Neurorehabilitative strategies, which target cortical areas and aim to restore impaired sensorimotor function in patients with CRPS, therefore, may be effective not only in restoring impaired function but also in pain reduction. This article reviews findings of functional imaging studies, which have been conducted to clarify CNS involvement in the course of CRPS.


Conclusions
During the last decade, functional imaging studies provided increasing evidence for an important role of the CNS in the pathogenesis of CRPS. Especially, reorganization in central somatosensory and motor networks was demonstrated, leading to an altered central processing of tactile and nociceptive stimuli, as well as to an altered cerebral organization of movement. In a number of studies, typical clinical CRPS symptoms could be directly linked to this CNS reorganization, such as impaired tactile perception (hypoesthesia) in the absence of peripheral nerve lesions, dystonia, or reduced finger-tapping frequency as a marker of motor impairment.32,48,51 Many studies provided evidence for a close relationship between chronic pain and CNS reorganization in somatosensory and motor networks in CRPS. It can be hypothesized that persistent nociceptive CNS inputs, probably due to peripheral mechanisms such as neurogenic inflammation, interfere with central networks of tactile perception and motor control, therefore inducing plastic changes in these networks. An alternative but not mutually exclusive hypothesis is that the disturbance of cortical representations of movement and tactile perception itself promotes pain perception, being at least in part cause and not only consequence of chronic pain in patients with CRPS. The latter hypothesis is supported by the fact that neurorehabilitative strategies, which target cortical areas and aim to restore impaired sensorimotor function in patients with CRPS, have proved to be effective not only in restoring impaired function, but also in pain reduction.52,53 Again functional imaging techniques might be a useful tool to accompany such therapy studies,34 to help in developing optimized therapies to restore the alterations occurring in somatosensory and motor network in patients with CRPS.