Proper brain cell function requires a constant delivery of oxygen and glucose from the bloodstream. A stroke occurs when the blood supply to part of your brain is interrupted or severely reduced, depriving brain tissue of oxygen and food and causing the brain cell to die.
Types of Stroke
There are two chief types of strokes: Ischemic stroke and Hemorrhagic stroke.
ISCHEMIC STROKE is the result of a blocked artery due to blood clot. This is the most common type of stroke and it is the cause of 90% of all strokes.This type of stroke can occur in 2 ways:
Thrombotic stroke – This occurs when the blood clot (thrombus) forms in an artery that supply blood to your brain due to a blood vessel that is already narrow. The clot deprives a part of the brain of oxygen and blood causing the cells of that part of the brain to die. The narrowed blood vessel is typically caused by atherosclerosis – a disease in which the arteries are clogged by fatty deposits called plaques.
Embolic stroke -This is also called cerebral embolism and it occurs when a blood clot or other debris breaks off from a blood vessel away from your brain and travels through your bloodstream to lodge in narrower brain arteries. This type of blood clot is called an embolus. Atrial fibrillation (irregular heartbeat) is the most common cause of embolic stroke.
HEMORRHAGIC STROKE – The second chief type of stroke occurs when a blood vessel in a part of the brain becomes weak and leaks or ruptures, causing blood to leak into the brain (Hemorrhage). Hypertension (high blood pressure), and Aneurysms (weak spots in blood vessels) are the most common cause of brain hemorrhages. It may also be caused by the rupture of a defective blood vessel. There are two types of hemorrhagic stroke:
Intracerebral hemorrhage is a type of stroke in which a blood vessel in the brain ruptures and bleeds into the surrounding brain tissue and damage the cells. A cerebral hemorrhage (bleeding in the brain) causes stroke symptoms by depriving blood and oxygen to parts of the brain in a variety of ways. This type of hemorrhagic stroke is mostly caused by high blood pressure because small arteries become brittle and are subject to cracking and rupturing due to the high pressure.
Subarachnoid hemorrhage – In this type of hemorrhage , blood accumulates in the space beneath the arachnoid membrane that lines the brain. This is usually caused by the rupture of an aneurysm. It is usually signalled by a sudden, intense headache.
Transient Ischemic Attack (TIA) – This is also called a mini stroke and is caused by a temporary decrease in blood supply to part of your brain due to a clot or debris. They often last less than five minutes and have similar symptoms like a stroke.