Pain and plasticity: is chronic pain always associated with somatosensory cortex activity and reorganization?

The somatosensory cortex remodels in response to sensory deprivation, with regions deprived of input invaded by neighboring representations. The degree of cortical reorganization is correlated with ongoing pain intensity, which has led to the assumption that chronic pain conditions are invariably associated with somatosensory cortex reorganization. Because the presentation and etiology of chronic pain vary, we determined whether cortical changes in human subjects are similar for differing pain types. Using functional and anatomical magnetic resonance imaging, we found that, while human patients with neuropathic pain displayed cortical reorganization and changes in somatosensory cortex activity, patients with non-neuropathic chronic pain did not. Furthermore, cortical reorganization in neuropathic pain patients was associated with changes in regional anatomy. These data, by showing that pain per se is not associated with cortical plasticity, suggest that treatments aimed at reversing cortical reorganization should only be considered for use in patients with certain types of chronic pain.