Transient Global Amnesia: Multi-timepoint 3T and 7T MRI Analysis of Acute Hippocampal Lesions - A One-year Longitudinal Prospective Study

Motivation: Transient global amnesia (TGA) presents with temporary DWI-visible hippocampal lesions. The long-term implications of these lesions remain unclear, particularly whether they cause permanent structural changes. Goal(s): To evaluate whether acute TGA-associated hippocampal lesions lead to permanent structural changes detectable with state-of-the-art neuroimaging. Approach: 18TGA patients underwent same-day comparative 3T and 7T MRI scanning at three timepoints over one year (24-72h, 1 month, 12 months post-event), utilizing high-resolution morphological and diffusion-weighted imaging. Results: Initial DWI-hyperintense lesions were detected in 16/18 patients, but no residual signal changes or structural abnormalities were observed at either field strength during follow-up examinations, suggesting complete resolution without permanent damage. Impact: Leveraging ultra-high field MRI, this study provides evidence for clinicians and patients that acute hippocampal lesions in TGA do not result in chronic structural changes. The comprehensive multi-timepoint imaging protocol establishes a methodological framework for future investigations into TGA pathophysiology.