Ischemic Stroke

An ischemic stroke is when a blood vessel of the brain is blocked. Most strokes are ischemic. It may be blocked by:

• Carotid artery stenosis —Narrowing of the carotid arteries that bring blood to the brain. It happens fromatherosclerosis. This is the buildup of plaque inside artery walls.
• Thrombus —A blood clot that forms in the arteries of the brain. It is often from atherosclerosis.
• Embolism —A blood clot that travels from some other part of the body. Often, the clot travels from the heart and gets trapped in the arteries that bring blood to the brain. It is often due toatrial fibrillation, a type of heart arrhythmia.
• Arterial spasm —Blood vessel walls can tighten or loosen to help blood flow. Problems with nerves, blood vessel structure, injuries, or stimulants can cause them to do this. This makes it hard for blood to flow. Spasms can cause problems on their own, but they may be more likely to cause blockages in blood vessels with atherosclerosis.

Hemorrhagic Stroke

A stroke may also happen if a blood vessel breaks and bleeds into or around the brain. Hemorrhagic stroke is the most common type of stroke in young people. The main causes are:

• Hypertension —Blood pressure is the force of blood on arteries walls. High blood pressure harms and weakens blood vessels.
• Brain aneurysm —An aneurysm is an outpouching of a blood vessel wall in the brain that forms in places where the artery wall is weak or thin. The bulging, blood-filled pocket can put pressure on parts of the brain. Aneurysms that burst can be deadly.
• Arteriovenous malformations (AVM)—A rare problem due to unusual links between arteries and veins. Instead of an artery bringing blood to the brain, it is linked to a vein that takes it away, going past the brain tissue that needs it. The blood vessels may get weaker over time. This may cause the vessels to widen or burst.

Silent Stroke

A silent stroke happens without any of the usual signs or symptoms. They cause harm to brain tissue and raise the risk of a major stroke in the future. They tend to happen in silent parts of the brain that aren't clearly active for thinking or moving. Brain tissue harm is often found during imaging tests.