The role of cortex in central pain syndromes: preliminary results of a long-term technetium-99 hexamethylpropyleneamineoxime single photon emission computed tomography study.

The role of the somatosensory cortex in central pain syndromes is widely questioned. Two recent position emission tomography studies detected a strong activation of the parietal and cingular cortices after brief nociceptive stimuli. On the other hand, a recent single photon emission computed tomography study found no cortical activation in five patients affected by central poststroke pain and algodystrophia. In this study, we present the single photon emission computed tomography findings in five patients suffering from central pain syndromes. Two of these, one with facial postrhizotomy anesthesia dolorosa and the other with central poststroke pain, showed a decrease of blood flow in the parietal lobe, further decreasing after stimulation by nonpainful maneuvers. Our results suggest that somatosensory cortical areas might be involved in the generation of anomalous pain states in some cases of central pain syndromes.