An ischemic stroke occurs when a blood vessel that supplies blood to the brain becomes blocked, preventing oxygen and nutrient-rich blood from reaching the brain tissue. This blockage can be caused by a blood clot (thrombus) or by a buildup of fatty deposits (plaque) in the arteries (atherosclerosis). As a result, part of the brain is deprived of oxygen and nutrients, leading to cell death. This can cause various neurological deficits depending on which area of the brain is affected. Ischemic strokes make up about 80% of all stroke cases.