Cerebral perfusion during transient global amnesia: Findings with HMPAO SPECT

The aim of this study was to investigate the pattern of regional cerebral blood flow changes associated with transient global amnesia (TGA). Methods: HMPAO SPECT was performed in six consecutive patients during the acute phase of TGA. A follow-up SPECT was performed 3-20 wk later in four of the six patients. Semiquantitative analysis of 14 regions of interest, including the basal ganglia and the basal section of the temporal lobes, was performed by comparing patient data with control data obtained from a matched group of healthy subjects. Results: During TGA, unilateral or bilateral hypoperfusion of the temporo-basal region was observed in four patients. Variable hypoperfusion of further cortical areas was observed in five patients. Two patients who exhibited the most marked cortical hypoperfusion also showed striatal and thalamic hypoperfusion. These changes were normalized in the control studies obtained in four patients. Conclusion: It remains unclear whether hypoperfusion during TGA represents a primary feature or a sequel of regional brain hypometabolism. Because hypoperfusion is not confined to the temporo-basal region or to the territory of the posterior cerebral artery, it is suggested that the origin of TGA-related changes lies at the level of subcortical structures that project diffusely to the cerebral cortex.