A watershed infarct is typically caused by which condition?

A watershed infarct is typically caused by which condition?

• A. Low BP, low flow state, limited perfusion
• B. High BP
• C. Severe infection
• D. Direct vascular trauma

Answer: (A)

Watershed infarcts result from global cerebral hypoperfusion, so the border zones between major arterial territories are the first to suffer ischemia. When blood pressure or overall cerebral perfusion drops—such as in a low flow state from severe hypotension or shock—these watershed areas (between the anterior and middle cerebral arteries, and between the middle and posterior cerebral arteries) become ischemic due to limited perfusion. This pattern is characteristic of reduced flow, not of a single vessel blockage. High blood pressure would not produce this border-zone pattern; severe infection can cause vasculitis or septic emboli with different distributions, and direct vascular trauma leads to focal, not border-zone, injury. So the cause is low perfusion from a low blood pressure state leading to border-zone infarction.

Watershed infarcts result from global cerebral hypoperfusion, so the border zones between major arterial territories are the first to suffer ischemia. When blood pressure or overall cerebral perfusion drops—such as in a low flow state from severe hypotension or shock—these watershed areas (between the anterior and middle cerebral arteries, and between the middle and posterior cerebral arteries) become ischemic due to limited perfusion. This pattern is characteristic of reduced flow, not of a single vessel blockage. High blood pressure would not produce this border-zone pattern; severe infection can cause vasculitis or septic emboli with different distributions, and direct vascular trauma leads to focal, not border-zone, injury. So the cause is low perfusion from a low blood pressure state leading to border-zone infarction.