Bilateral Hippocampal DWI Lesions in Transient Global Amnesia

Abstract

Transient global amnesia (TGA) is characterized by anterograde memory disturbance of sudden onset that lasts for 1 to 24 hours. The etiology and pathogenesis of TGA are still uncertain, although an hypoxic-ischemic origin has been recently suggested on the basis of infarct-like diffusion-weighted imaging (DWI) lesions in the hippocampus of some affected individuals. Recent diffusion-weighted imaging (DWI) studies have indicated the presence of focal hyperintensities involving the hippocampus in TGA patients. These lesions detected by DWI, which peak at 48 to 72 hours, are small and punctate (1-3 mm) and in most studies are reported as unilateral. We describe one TGA patient with high signal-intensity lesions in the bilateral hippocampus on DWI at the acute stage. The mechanisms related to the pathophysiology are discussed with emphasis on the hypoxic-ischemic origin underlying the observation of infarct-like diffusion-weighted imaging (DWI) abnormalities.