Transient Global Amnesia (TGA) is characterised by sudden onset of anterograde and retrograde amnesia which resolves within 24 hours. Though defined clinically, MRI findings of focal diffusion lesions in the hippocampus can help support the diagnosis.[1] These lesions develop over 24–48 hours on diffusion weighted images (DWI) and can be seen for up to 7- 10 days.[1] The size of the lesions and the duration of the TGA correlated with impairment in place memory in patients with TGA in a recent study indicating a role of these lesions in the pathogenesis.[2] The mechanism of development of this restricted diffusion in hippocampus remains uncertain. Some authors feel that this supports the ischaemic hypothesis for pathogenesis of TGA but others feel that these findings are not supportive of a cerebrovascular aetiology. [3, 4]
We report a case of a 78-year-old male who presented with TGA and characteristic bilateral MRI appearances.

References-
1)Bartsch T, Deuschl G. Transient Global Amnesia: functional anatomy and clinical implications. Lancet Neurology 2010; 9(2): 205 – 214.
2) Bartsch T, Schönfeld R, et al. Focal Lesions of Human Hippocampal CA1 Neurons in Transient Global Amnesia Impair Place Memory .Science , June 11, 2010; 328(5984): 1412 – 1415.
3) Winbeck K, Etgen T, et al . DWI in transient global amnesia and TIA: proposal for an ischaemic origin of TGA. J Neurol Neurosurg Psychiatry 2005; 76:438–441.
4) Enzinger C, Thimary F, Kapeller P. Transient global amnesia: diffusion-weighted imaging lesions and cerebrovascular disease. Stroke. 2008 Aug; 39 (8): 2219-2225.