Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired bone-marrow disorder characterized by hemolytic anemia, hemoglobinuria, and cytopenia. Most patients die from venous thrombotic events. Stroke is a common cause of morbidity and mortality in PNH and it is almost exclusively a result of cerebral venous thrombosis. Case reports of ischemic stroke complicating PNH have implicated a similar propensity for arterial events caused by the disease. We present a case of recurrent cerebral infarctions complicating PNH initially attributed to arterial thrombosis but ultimately determined to be a result of the disease and a concomitant patent foramen ovale identified only after repeated evaluations. This case emphasizes the pitfalls of diagnostic testing and the importance of a persistent search for a venous cause for cerebral embolic events in patients with hematologic diseases not classically known to involve the arterial system
