Acute Ischemic Stroke Treatment in 2007

Abstract

A variety of interventions have proven effective in reducing the risk of a first stroke.1 Nevertheless, each year, more than 700 000 Americans have strokes and more than 150 000 die, making stroke the country’s third-leading cause of death.2 More than 25% of stroke survivors older than age 65 years are disabled 6 months later.2 On the basis of the results of prospective randomized clinical trials and other studies performed over the past decade, the general approach to the management of acute stroke has evolved from nihilism to active intervention. A large volume of experimental studies delineates the various aspects of the ischemic cascade. The results of the single laboratory study shown in Figure 1 provide a conceptual framework that guides the current clinical approach to patients with acute ischemic stroke.3 The experiment, performed in awake monkeys, shows that focal symptoms (in this case, paralysis) develop when local cerebral blood flow drops below a certain threshold (in this experiment, <23 mL · 100 g−1 · min−1). In Figure 1, the hatched area between the development of symptoms and infarction is a graphic representation of the so-called penumbra, an area of brain that is functionally inactive but structurally intact and potentially salvageable. Neurological function is completely recoverable if local cerebral blood flow is restored promptly. For a given level of reduced blood flow, the likelihood of sustaining irreversible injury (ie, ischemic stroke) increases as a function of time. This essential biology is the basis of the mantra, “Time lost is brain lost.” Timely restoration of blood flow to ischemic brain offers the chance of reversing or limiting the injury. Figure 1. Relationship between cerebral blood flow, time, functional impairment, and infarction. Even within 3 hours, ischemic tissue might go on to infarction or be …