Final answer:
Ischemic strokes occur when there is a lack of blood flow to the brain due to a blood clot in an artery. They are the most common type of stroke, accounting for about 90% of all strokes. Prompt treatment is crucial to prevent further damage.
Step-by-step explanation:
An ischemic stroke occurs when there is a lack of blood flow to the brain due to a blood clot in an artery. Ischemic strokes are more frequent than hemorrhagic strokes and account for almost 90 percent of all strokes. The blockage of blood flow to the brain causes the death of brain cells, leading to various symptoms and potential permanent damage. Treatment with clot-busting drugs within a few hours of the stroke may prevent further damage.