CEREBRAL RESPONSES TO PAIN IN PATIENTS WITH ATYPICAL FACIAL-PAIN MEASURED BY POSITRON EMISSION TOMOGRAPHY

The localised PET cerebral correlates of the painful experience in the normal human brain have previously been demonstrated. This study exam ined whether these responses are different in patients with chronic at ypical facial pain. The regional cerebral responses to nonpainful and painful thermal stimuli in six female patients with atypical facial pa in and six matched female controls were studied by taking serial measu rements of regional blood flow by PET. Both groups displayed highly si gnificant differences in responses to painful heat compared with non-p ainful heat in the thalamus, anterior cingulate cortex (area 24), lent iform nucleus, insula, and prefrontal cortex. These structures are clo sely related to the ''medial pain system''. The atypical facial pain g roup had increased blood flow in the anterior cingulate cortex and dec reased blood flow in the prefrontal cortex. These findings show the im portance of the anterior cingulate cortex and the reciprocal (possibly inhibitory) connections with the prefrontal cortex in the processing of pain in patients with this disorder. A hypothesis is proposed to ex plain the mechanisms of cognitive and pharmacological manipulation of these pain processes.