How does a stroke develop when blood flow to part of the brain is interrupted?

A stroke occurs when the blood supply to a portion of the brain is interrupted, leading to a state of ischemia—a severe starvation of blood—that can result in the death of brain tissue, known as infarction.1

The most common pathological cause is atherosclerosis, which narrows or blocks arteries in the neck and brain. Other mechanisms include:1

• Occlusion: Blood vessels may be blocked by emboli (such as blood cell or cholesterol fragments) or by small-vessel disease associated with high blood pressure.1
• Systemic factors: A severe global decrease in cerebral blood flow, such as from a heart attack or hemorrhage, can deprive the brain of oxygen.1
• Vessel-wall damage: Conditions like inflammation, arterial wall splitting, or direct injury can also obstruct flow.1

When brain cells are deprived of oxygen-rich blood, they begin to die. If the interruption is brief, as in a transient ischemic attack, symptoms may be temporary; however, prolonged deprivation leads to permanent structural damage.213