Cerebral blood flow in Sjögren's syndrome using 99Tcm-HMPAO brain SPET

Neuropsychiatric disturbances are frequent in connective tissue diseases. Little is known about the cerebral pathophysiology of Sjögren's syndrome, including cerebral blood flow disturbances. 99Tcm-HMPAO brain SPET was performed in 21 Sjögren's syndrome patients. We also studied 77 patients with systemic lupus erythematosus and 27 healthy individuals. Our results demonstrate the high rate of alterations in cerebral blood flow in Sjögren's syndrome, both psychoneurologically symptomatic and asymptomatic. Focal interhemispherical perfusion deficits were seen in 17 of 21 patients (80.9%) with Sjögren's syndrome: 13/15 symptomatic (86.6%) and 4/6 asymptomatic (66.6%). These changes were mostly localized in the prefrontal and frontal areas, occipital lobes and occipitoparietal area, and less frequently so in the temporal, parietal and central areas. Diffuse hypoperfusion of the frontal lobes (bilateral hypofrontality) was seen in 29% of patients in the Sjögren's group. An acetazolamide stress test was performed in seven patients. There was an increase in perfusion deficits in two patients, no change in two patients, and hypoperfusion decreased in three patients compared with baseline. The results indicate that most Sjögren's syndrome patients experience alterations in cerebral blood flow that are consistent with systemic lupus erythematosus, with heterogeneous reactivity to acetazolamide-induced hypercapnia. These alterations present as focal perfusion deficits and bilateral diffuse hypoperfusion of the lobes. The mechanism of cerebral blood flow alterations is unknown, although it might be the result of diffuse cerebral vasculitis.