A 63-year-old migrainous woman was presented with sudden onset of isolated anterograde amnestic syndrome, which lasted for less than 24 h. She started to make repetitive questions to her husband and had no recollection of the event. The episode was witnessed by her husband, who did not report any neurological focal sign or seizure. It fulfilled the criteria for transient global amnesia (TGA). ^{Reference Arena and Rabinstein1} There was no prior history of head injury or epilepsy. Concurrently with the TGA episode, the patient had a severe left-sided headache accompanied by mild nausea, similar to her prior migraine episodes, which lasted between 48 and 72 h. No aura or focal sign accompanied the episode, though.

A magnetic resonance of the brain (MRI) was performed for 72 h, which is later shown in Figures 1 and 2. Transthoracic echocardiogram was performed and did not show atrial enlargement or aortic arch atheroma. Carotid Doppler ultrasound was normal, and a 48-hour Holter monitor did not show any evidence of covert paroxysmal atrial fibrillation. Due to the likelihood of the episode being an isolated TGA episode, the absence of cardiovascular risk factors, and normal cardiac investigations, the patient did not receive antiplatelet or anticoagulant therapy. Six months after the episode, the patient remained asymptomatic.

Figure 1: Magnetic resonance imaging (MRI). (A) Diffusion-weighted imaging (DWI) shows a punctiform-restricted diffusion lesion in the right lenticular nucleus, in the outermost portion of the putamen. (B) Apparent diffusion coefficient (ADC) image shows a hypointense lesion at the described location, confirming that the diffusion restriction is real and not due to T2 “shine-through” phenomenon. (C) T2-weighted imaging shows no abnormalities.

Figure 2: (A) DWI-EPI imaging shows a punctiform-restricted diffusion lesion in the medial portion of right hippocampus. (B) ADC map confirms that diffusion restriction is real in the described location. (C) T2-weighted imaging findings are unremarkable.

TGA diagnosis is made upon clinical history. Nevertheless, MRI is a useful diagnostic tool when small restricted diffusion hippocampal lesions are found. ^{Reference Szabo, Hoyer and Caplan2} Extra-hippocampal locations such as posterior arterial territory and basal ganglia have been described in clinically typical cases. ^{Reference Kim, Kim, Lim, Moon and Han3} In these cases, a cardiovascular assessment is recommended in order to exclude acute stroke and embolism. Migraine and TGA are thought to be related, as it has been observed in the previous studies ^{Reference Yi, Sherzai and Ani4} that there is a higher prevalence of TGA episodes among migrainous patients.