Ischemic stroke occurs when a blood vessel supplying the brain becomes blocked, usually by a clot, leading to reduced blood flow and oxygen deprivation in affected tissue. It is the most common type of stroke and a leading cause of death and long term disability worldwide. Risk rises with age and is strongly linked to high blood pressure, smoking, diabetes, high cholesterol, obesity, atrial fibrillation and physical inactivity.

Research has clarified that time is critical because brain cells die rapidly once circulation stops. This has driven development of emergency treatments that reopen blocked vessels. Intravenous thrombolysis with tissue plasminogen activator can dissolve clots if given within a few hours of symptom onset. Mechanical thrombectomy, in which specialists physically remove clots from large brain arteries using catheters, has greatly improved outcomes for selected patients and can be effective even later in the course of stroke.

Imaging advances, particularly CT and MRI techniques, are central to diagnosis, allowing clinicians to distinguish ischemic from hemorrhagic stroke, identify the blocked artery, and estimate the amount of salvageable brain tissue. This helps select patients who may benefit from aggressive reperfusion therapy.

Prevention research emphasizes controlling vascular risk factors through lifestyle changes, antihypertensive drugs, statins and glucose management. Antiplatelet agents such as aspirin and anticoagulants for atrial fibrillation reduce the risk of recurrent ischemic events. Studies on neuroprotection, brain repair and rehabilitation aim to limit damage and enhance recovery, including early mobilization, task specific training and support for cognitive and emotional consequences after stroke.