A stroke occurs when the blood supply is reduced or cut off to a part of the brain. This reduces oxygen levels in the brain and can lead to death of the oxygen deprived brain cells. It only takes 3-4 minutes for a brain cell to die when deprived of oxygen, hence a stroke is a very serious event that requires immediate medical attention at the emergency room. There are primarily two types of strokes – Ischemic stroke and Haemorrhagic stroke Ischemic stroke is the most common type of stroke, in which a blood clot in the brain prevents oxygenated blood from reaching a part of the brain tissue. Haemorrhagic stroke occurs when a blood vessel ruptures, usually as a result of an aneurysm or an arteriovenous malformation. Transient Ischemic stroke is a brief disruption in blood supply to tissues in the brain. Normal blood flow resumes shortly and the symptoms resolve without treatment soon after. This is also called a “mini-stroke”.