Transient global amnesia (TGA) is a clinical syndrome with no clear aetiology identified. Most symptoms are transient and resolve within a few hours.
Most common in patients of older age (50-70 years old).
Anterograde and partial retrograde amnesia lasting less than 24 hours without any other neurological or congestive symptoms. Most cases show complete resolution of symptoms within a few hours from onset of symptoms.
Several hypothesis (e.g. epileptic phenomena, stroke, focal ischemia) have been proposed with no consensus on the exact mechanism 1.
Brain CT scan and conventional sequences of MRI brain show no abnormalities.
Prospective and retrospective studies based on small number of patients show diffusion weighted imaging (DWI) can detect small punctate hyperintense lesion(s) in the CA1 area of the hippocampus in patients with TGA 2-4.
Typical appearance is a small punctate hyperintense focus on the lateral edge of the hippocampal gyrus abutting the temporal horn. Although these lesions can be bilateral and even multifocal 2-4.
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- 2. Choi BS, Kim JH, Jung C et-al. High-Resolution Diffusion-Weighted Imaging Increases Lesion Detectability in Patients with Transient Global Amnesia. 2012;doi:10.3174/ajnr.A3072 - Pubmed citation
- 3. Weon YC, Kim JH, Lee JS et-al. Optimal diffusion-weighted imaging protocol for lesion detection in transient global amnesia. AJNR Am J Neuroradiol. 2008;29 (7): 1324-8. doi:10.3174/ajnr.A1105 - Pubmed citation
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