Of birds and nests and brain emboli.

Technological methods for diagnosing brain embolism have improved. Both donor sources and recipient sites are now more readily documented. Embolism is a dynamic process. Thrombi develop and change in their cardiac or arterial 'nests', discharge into the vascular system, lodge in brain or systemic arteries, and often break up and move on. Traditionally, clinicians have sought to distinguish a cardiac from intraarterial source in order to prescribe warfarin for cardiac origin embolism. Most often surgery or aspirin is given for intraarterial embolism. Yet substances that embolize from either site are diverse. Might identification of the embolic material ("birds") be a more rational guide to treatment than simply the locations of the "nests"?