An aneurysm is defined as which of the following?

• A. Bubble forms a weakening of a vessel
• B. Blockage that obstructs the flow of blood to brain
• C. Blood clot elsewhere that travels to the brain
• D. Elevated intracranial pressure

Answer: (A)

An aneurysm is a localized dilation of a blood vessel caused by weakening of the vessel wall. The vessel balloons outward under the pressure of blood flow, forming a bulge that can be saccular (berry-like) or more diffuse. This weakness in the wall is what allows the vessel to expand, and if it ruptures, it can lead to serious bleeding. This concept distinguishes aneurysms from other cerebrovascular problems: a blockage obstructs blood flow to the brain (ischemia), a traveling clot represents an embolic event, and elevated intracranial pressure reflects pressure dynamics inside the skull rather than a ballooning vessel wall.