Interruption of cerebral blood flow may result from all of the following, EXCEPT

• A. Cerebral vasodilation
• B. Intracranial pressure
• C. Cerebral edema
• D. Cerebral vasoconstriction

Answer: (A)

The key idea is how cerebral blood flow is controlled and what tends to reduce it. Interruption of flow happens when perfusion pressure to brain tissue drops or when a blockage narrows or compresses vessels. When intracranial pressure rises, it compresses cerebral vessels and lowers cerebral perfusion pressure, reducing blood flow. Edema adds volume inside the skull, boosting pressure and similarly hindering flow. Vasoconstriction also raises resistance in the cerebral vessels, making it harder for blood to reach brain tissue.

Cerebral vasodilation does the opposite: it widens the vessels, lowers resistance, and helps maintain or even increase blood flow to the brain. So it would not interrupt cerebral blood flow; it acts to preserve perfusion rather than disrupt it.