Stroke is an abrupt interruption of constant blood flow to the brain that causes loss of neurological function. The interruption of blood flow can be caused by a blockage, leading to the more common ischemic stroke, or by bleeding in the brain, leading to the more deadly hemorrhagic stroke. Ischemic stroke constitutes an estimated 87 percent of all stroke cases. Stroke often occurs with little or no warning, and the results can be devastating.

It is crucial that proper blood flow and oxygen be restored to the brain as soon as possible. Without oxygen and important nutrients, the affected brain cells are either damaged or die within a few minutes. Once brain cells die, they generally do not regenerate, and devastating damage may occur, sometimes resulting in physical, cognitive, and mental disabilities.

Types

There are two types of stroke.

Ischemic Stroke 

• Thrombotic (cerebral thrombosis) is the most common type of ischemic stroke. A blood clot forms inside a diseased or damaged artery in the brain resulting from atherosclerosis (cholesterol-containing deposits called plaque), blocking blood flow.
• Embolic (cerebral embolism) is caused when a clot or a small piece of plaque formed in one of the arteries leading to the brain or in the heart, is pushed through the bloodstream and lodges in narrower brain arteries. The blood supply is cut off from the brain due to the clogged vessel.

Hemorrhagic Stroke

• Subarachnoid Hemorrhage: bleeding that occurs in the space between the surface of them brain and the skull. A common cause of subarachnoid hemorrhagic stroke is a ruptured cerebral aneurysm, an area where a blood vessel in the brain weakens, resulting in a bulging or ballooning out of part of the vessel wall; or the rupture of an arteriovenous malformation, a tangle of abnormal and poorly formed blood vessels (arteries and veins), with an innate propensity to bleed.
• Intracerebral Hemorrhage: bleeding that occurs within the brain tissue. Many intracerebral hemorrhages are due to changes in the arteries caused by long-term hypertension. Other potential causes may be delineated through testing.