Cryptogenic strokes are cerebral infarcts for which no probable underlying pathophysiologic cause is identified after adequate diagnostic evaluation [1]. However, it's been shown that some strokes classified as cryptogenic are actually caused by cardioembolism from medium-grade cardiac sources, such as paradoxical embolism related to presence of a patent foramen ovale (PFO) [1]. A meta-analysis of randomized controlled trials suggests that device closure plus medical therapy, compared with medical therapy alone, reduces the risk of recurrent ischemic stroke among patients with cryptogenic strokes [2], supporting a causal role for PFO and paradoxical embolism in the genesis of embolic stroke in some cryptogenic stroke patients [3].
