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Five right-handed patients with pure transient global amnesia were evaluated with technetium-99m hexamethylpropyleneamine oxime single photon emission computed tomography after the amnesic attack.Independent of the interval between the procedure and the amnesic episode,single photon emission computed tomography demonstrated a decreased cerebral blood flow in the left temporal lobe in one patient and in the left parietotemporal region in three patients,with a more marked reduction in the temporal lobe.The remaining three patients were normal.A control single photon emission computed tomographic study was carried out in one patient 3 months after the amnesic attack and showed a left-sided persistent temporal hypoperfusion.These findings suggest that in some patients, transient global amnesia can be due to a vascular mechanism requiring strong investigations for vascular risk factors and appropriate treatment. During a follow-up period of 12 to 32 months,none of the patients with regional hypoperfusion suffered cerebrovascular events,suggesting that single photon emission computed tomography has no predictive value for further stroke. |
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