One-third of ischemic strokes are classified as cryptogenic. The classic risk factors for stroke are usually absent, such as cardio-embolism or large artery atherosclerosis. In the United States, about 200,000 strokes without a known cause occur annually, according to the American Stroke Association (ASA). What’s even more striking is that a recent American Heart Association (AHA) survey revealed more than half of U.S. physicians admit being uncertain about the best approaches to finding the underlying causes of cryptogenic strokes.
