Transient global amnesia and stroke: not that benign?

After more than 50 years since Fisher and Adams’ original description in 1964,1 transient global amnesia (TGA) is still a puzzling syndrome. Over time, several mechanisms have been proposed for TGA pathogenesis, including venous congestion, cortical spreading depression, seizures and arterial ischaemia.2–4 A sufficient amount of studies in favour and against each of these mechanisms has emerged, fostering uncertainty regarding aetiology as well as prognosis. To this extent, most of the controversy stands on whether TGA represents a risk factor for stroke, or whether this is just as benign as originally thought.5 In this volume of Stroke and Vascular Neurology, Lee and colleagues add a further episode to the saga, building on data from a large propensity-matched cohort study.6 Using records from the Korean National Health Insurance Service, they selected 10 447 patients with TGA and 20 493 controls through greedy nearest neighbour method, following both cohorts for up to 11 years to assess the occurrence of stroke. After adjusting for enrolment year—a strategy to mitigate differences in follow-up duration—TGA was associated with a higher risk of stroke compared with control population. Hypertension, diabetes and atrial fibrillation substantially increased the risk …