A piece of plaque breaks off and travels to smaller arteries, lodging and blocking blood flow. What is this event called?

• A. Subarachnoid hematoma
• B. Embolism
• C. Intracerebral hematoma
• D. Thrombus

Answer: (B)

An embolism is a blockage in a blood vessel caused by something that travels through the bloodstream. Here, a piece of atherosclerotic plaque breaks off (an atheroembolus) and travels to smaller arteries, where it lodges and stops blood flow. This distal occlusion causes ischemia in the tissue supplied by that artery.

This differs from a hematoma, which is bleeding into the brain (subarachnoid or intracerebral) rather than a traveling fragment causing a blockage. It also differs from a thrombus, which is a clot that forms in place; a thrombus can embolize, but the scenario described specifically involves a plaque fragment traveling and occluding vessels, i.e., an embolism.