How does an ischemic stroke differ from a hemorrhagic stroke?

An ischemic stroke occurs when blood flow to a part of the brain is blocked, typically due to a blood clot or plaque buildup in the arteries (a process known as thrombosis or embolism). This blockage prevents oxygen and nutrients from reaching brain tissues, leading to cell death and neurological deficits. The focus here is on the interruption of blood flow as the primary cause of ischemic strokes.

In contrast, hemorrhagic strokes are caused by bleeding into or around the brain, often due to the rupture of a blood vessel. The mechanisms, symptoms, and treatments for these two types of strokes are quite different. Other options provided, such as infection, tumors, and head trauma, do not specifically relate to the mechanisms behind ischemic or hemorrhagic strokes, further reinforcing that option B is the most appropriate choice.