Cryptogenic Stroke and Migraine Headache: The Clinical Cardiologist’s View

Cryptogenic stroke and migraine headache are disorders which most commonly affect persons younger than 55 years of age. In recent years these disorders have been found to have a strong association with inter-atrial cardiac defects, such as patent foramen ovale and atrial septal defect, and support the pathophysiological mechanism of paradoxical embolism with a right-to-left shunt. With the evolution of technology, magnetic resonance imaging has more clearly defined cryptogenic stroke, and percutaneous cardiac interventional devices have offered a simplified approach to closure of inter-atrial cardiac defects. Nevertheless, the evidence-based data of which sub-populations of patients with cryptogenic stroke or migraine headache will benefit from closure of inter-atrial cardiac defects is just being defined. This review offers a clinical cardiologist’s viewpoint of these developments. C R Y P T O G E N I C S T R O K E T H E C L I N I C A L P R O B L E M Stroke is a leading cause of death and long-term disability worldwide. Eighty-five percent of strokes are ischemic, and most ischemic strokes occur in persons older than 65 years of age in tandem with the development of atherosclerosis. Although a minority of ischemic strokes in the community affect younger adults, as many as half the patients referred to tertiary care centers are younger than 65 years of age, and up to 12% are younger than 45 years [1]. Young patients with ischemic stroke often have few, if any, risk factors for atherosclerosis. Initial evaluation of the cerebral arteries is essential but frequently unrevealing, and thus in many cases the focus must shift to the detection of potential cardiac sources of embolism that are commonly associated with, and that may cause, unexplained stroke in young persons [2]. In as many as 43% of affected young adults, strokes are cryptogenic (i.e., they do not have a definite cause despite extensive evaluation) [1]. This brain infarction which is commonly revealed by a magnetic resonance imaging (MRI) abnormality without an etiology is the essence of a cryptogenic stroke. The most prevalent potential source of cardioembolism in young adults (<55 years) with cryptogenic stroke is a patent foramen ovale (PFO), which is detected in more than half of such persons undergoing evaluation [3]. On the other hand, cryptogenic strokes in the middle-aged and elderly (>55 years) patients account for approximately one-third of ischemic strokes, and have most commonly been associated with aortic arch atheromatous plaques [4,5]. TransCARDIOLOGY UPDATE 2006 Division of Cardiovascular Disease, Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA