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

• A. a thrombus.
• B. an embolism.
• C. cerebral vasodilation
• D. an acute arterial rupture.

Answer: (C)

When cerebral blood flow is interrupted, it’s usually due to something that blocks or bleeds from a vessel. A thrombus forms inside a vessel and obstructs flow. An embolism travels from another location and lodges downstream, cutting off perfusion. An acute arterial rupture causes bleeding that can create pressure and disrupt the supply to surrounding brain tissue. In contrast, cerebral vasodilation means widening of the arteries, which lowers resistance and increases blood flow rather than stopping it. So vasodilation would not interrupt cerebral blood flow; it would help maintain or even improve perfusion. That’s why this option is the exception.