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INTRODUCTION AND EPIDEMIOLOGY
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In the United States, 795,000 people experience strokes annually (one stroke every 40 seconds and one death from stroke every 4 minutes).1 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 enormous—strokes accounted for an estimated $33.9 billion of total expenditures in the United States in 2012 to 2013.1 Despite these grim statistics, from 2004 to 2014, the age-adjusted stroke death rate fell 28.7%.1 With the growing use of stroke units, thrombolysis, mechanical retrieval, and the ever-expanding treatment time window, there is potential for improving patient outcomes.
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PATHOPHYSIOLOGY AND ANATOMY
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Stroke is 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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An understanding of the diagnosis and treatment of stroke begins with a working knowledge of the relevant vascular supply and neuroanatomy of the brain. The arterial supply to the brain is illustrated in Figures 167-1 and 167-2.
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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 167-1), but the degree of collateral circulation may cause variations in the specific clinical symptoms and their severity.
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