A decrease in cerebral blood flow to zero causes death of brain tissue within

(A) 4-10 minutes # Decrease in cerebral blood flow to zero causes death of brain tissue within 4-10 minutes;> Values <16-18 mL/100 g tissue per minute cause infarction within an hour; and> Values <20 mL/100 g tissue per minute cause ischemia without infarction unless prolonged for several hours or days.> If blood flow is restored prior to a significant amount of cell death, the patient may experience only transient symptoms, and the clinical syndrome is called a TIA.> Tissue surrounding the core region of infarction is ischemic but reversibly dysfunctional and is referred to as the ischemic penumbra.> The penumbra may be imaged by using perfusion-diffusion imaging with MRI or CT