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How Many Types of Strokes Are There?

Stroke is the third leading cause of death in the United States, according to the American Stroke Association, and the number one cause of disability. With statistics like these, knowledge about stroke, its types and its causes is key in learning how to fight it. There are two broad types of stroke: ischemic and hemorrhagic. Each is distinct and has its own causes, but both can be devastating to brain tissue.

  1. Ischemic Stroke

    • Ischemia means that a body part is deprived of blood. In an ischemic stroke, blood deprivation in the brain is caused by a blockage of a blood vessel. The brain needs oxygen to function, and the only way that oxygen can get to the brain tissue is from the blood supply. If this blood supply is blocked off by a clot or by a narrowing of a blood vessel, then the tissue on the other side begins to die. Brain tissue that dies cannot regenerate itself. The result is the loss of memory and function seen in stroke victims.

    Causes of Ischemic Stroke

    • Many diseases can cause an ischemic stroke. Atherosclerosis is the narrowing of arteries caused by the buildup of cholesterol on the walls of the vessels. This can block the off the blood supply to tissue beyond the narrowing where it occurs. Blood clots can also form on these plaques and block the vessel in the same way. A blood clot that forms in the heart from the irregular heartbeat known as atrial fibrillation can also go to the brain and cause a stroke.

    Hemorrhagic Stroke

    • Hemorrhagic strokes occur when a blood vessel begins to bleed inside the brain cavity. There are two types of hemorrhagic stroke: intracerebral and subarachnoid. Intracerebral hemorrhagic strokes occur inside the deep structures of the brain. A subarachnoid hemorrhagic stroke occurs on the periphery of the brain. The excess blood from either stroke increases the pressure inside the skull and deprives brain tissue of oxygen. A large bleed can lead to sudden death.

    Causes of Hemorrhagic Stroke

    • There are different causes for the different types of hemorrhagic strokes. Intracerebral hemorrhagic strokes are most commonly caused by high blood pressure. Often a patient will not even be aware of a problem with high blood pressure until a stroke has already occurred. A subarachnoid hemorrhagic stroke is typically caused by a cerebral aneurysm. This is a weakened area of a blood vessel that bulges outward and eventually bursts. There is no known cause of cerebral aneurysms.

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