Prime Time for Dissecting the Entity of Cryptogenic Stroke

Abstract

See related article, p 1186. The term cryptogenic ischemic stroke (or stroke of undetermined pathogenesis) encompasses ischemic strokes without specific cause detected after adequate diagnostic workup. Cryptogenic stroke is, thus, a diagnosis done by exclusion. Strokes may remain cryptogenic if diagnostic evaluation is incomplete for one or another reason or in the presence of multiple competitive causes, such as atrial fibrillation (AF) and atherosclerotic stenosis in an ipsilateral relevant artery. Choosing the particular diagnostic investigation should always be balanced between the cost and potential yield, considering patient characteristics and the effect on treatment decisions. The only patients with stroke in whom thorough pathogenic workup may be unnecessary are those whose poor prognosis cannot be improved reasonably by pathogenic diagnosis. A substantial proportion of all strokes end up being cryptogenic. Among the 5017 patients in the German Stroke Data Bank, cryptogenic strokes accounted for 23%.1 Notably, the cryptogenic category is even larger among younger patients reflecting major challenges in defining their pathogenesis and interpreting causally relevant findings. A total of 40% of patients aged <50 years remained without elusive cause for their stroke in a recent large multicenter survey.2 Furthermore, another prospective study with MR-imaged patients aged <55 years showed higher rates of cryptogenic strokes with lower age.3 There is paucity of data to guide secondary prevention after cryptogenic stroke. Current guidelines either did not give statements specifically on cryptogenic stroke or recommended antiplatelet therapy.4,5 Anticoagulation (warfarin with target international normalized ratio, 1.4–2.8) has been compared against aspirin (325 mg/d) only in 1 …