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Stroke continues to be a leading cause of morbidity and mortality. In the U.S., approximately 795,000 persons experience strokes yearly; of these events, 77% are primary strokes, whereas 23% represent recurrent strokes.1 In addition to the human costs, the financial implications of stroke are massive—strokes are expected to account for an estimated $73.3 billion total expenditures in the U.S. in 2010.1 Despite these grim statistics, from 1996 to 2006 the stroke death rate has fallen 32.7%,1 and with the growing use of thrombolysis, stroke units, and other new therapies, there is new hope for patients with acute stroke who present to the ED.

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Stroke may be generally defined as any disease process that interrupts blood flow to the brain. Injury is related to the loss of oxygen and glucose substrates necessary for high-energy phosphate production and the presence of mediators of secondary cellular injury. Subsequent factors, such as edema and mass effect, may exacerbate the initial insult.

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Vascular Supply

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An understanding of the diagnosis and treatment of stroke must begin with a working knowledge of the relevant vascular supply and neuroanatomy of the brain.

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The arterial supply to the brain is illustrated in Figures 161-1 and 161-2.

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Figure 161-1.
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Diagram of a cerebral hemisphere, lateral aspect, showing the branches and distribution of the middle cerebral artery and the principal regions of cerebral localization. Note the bifurcation of the middle cerebral artery into a superior and inferior division. a. = artery; ant. = anterior; inf. = inferior; post. = posterior; sup. = superior. (Modified with permission from Fauci AS, Braunwald E, Kasper DL, et al: Harrison’s Principles of Internal Medicine, 17th ed. New York, McGraw-Hill Professional, 2008.)

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Figure 161-2.
Graphic Jump Location

Diagram of a cerebral hemisphere, medial aspect, showing the branches and distribution of the anterior cerebral artery, posterior cerebral artery, and the principal regions of cerebral localization. a. = artery; ant. = anterior; post. = posterior. (Reproduced with permission from Fauci AS, Braunwald E, Kasper DL, et al: Harrison’s Principles of Internal Medicine, 17th ed. New York, McGraw-Hill Professional, 2008.)

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The vascular supply is divided into anterior and posterior circulations. Clinical findings in stroke are determined by the location of the lesion(s) (Table 161-1), but the degree of collateral circulation may cause variations in the specific clinical symptoms and their severity.

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Table Graphic Jump Location
Table 161-1 Anterior and Posterior Circulation of the Brain

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