Definition & Core Concept
Acute Ischemic Stroke (AIS) is a catastrophic, time-sensitive neurological emergency defined by the sudden cessation of cerebral blood flow, typically secondary to a thrombotic or embolic arterial occlusion. Stroke remains a leading cause of long-term global disability; in the United States alone, over 800,000 individuals experience an incident or recurrent stroke annually, and the prevalence is projected to increase sharply with an aging population.
The pathophysiological principle driving AIS management is time-dependent neuronal salvage, encapsulated by the axiom ‘time is brain.’ Following occlusion, the central infarct core is rapidly subjected to irreversible necrosis, while the surrounding hypoperfused tissue—the ischemic penumbra—remains viable but electrically silent. If rapid reperfusion is achieved, the penumbra can be fully salvaged.