Identification of the sources of embolism has been problematic [Mohr JP and Sacco RL, 1992]. Traditionally, the term “embolism” refers to arterial thromboembolism stemming from an abnormality with the heart, such as atrial fibrillation. Atrial fibrillation is the leading source of cardioembolic stroke.
Cardiogenic emboli lodge in the middle cerebral artery or its branches in 80 percent of cases; in the posterior cerebral artery or its branches 10 percent of the time, and in the vertebral artery or its branches in the remaining 10 percent of cases [Kistler JP, et al. In: Braunwald E, et al (eds). Harrison’s Principles of Internal Medicine. New York, McGraw-Hill, 1994:2250]. Cardiac emboli rarely reach the anterior cerebral artery. If an embolus is large enough to occlude the proximal stem of the middle cerebral artery (3 to 4 mm), a major stroke results.
A cerebral embolus can also originate in the internal carotid artery, where deposits of atheroma cause stenosis of the artery. The site of this stenosis is most often at the bifurcation of the common carotid artery into its internal and external branches.
Acute Ischemic Stroke: New Concepts of Care
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