Mercy Stroke Center

Types of Stroke

There are three major types of stroke: ischemic, hemorrhagic, and transient ischemic attacks (TIAs).

Ischemic stroke accounts for 87% of all stroke cases in the U.S. It occurs when a blood vessel within the brain is blocked. The blocked vessel means that less oxygenated blood is able to circulate within the brain. Atherosclerosis is the most common condition that causes blood vessel obstruction. The two types of obstruction are:

• cerebral thrombosis – when a blood clot develops at the point of blockage in the vessel
• cerebral embolism – when a blood clot breaks loose from another part of the circulatory system and travels to a point in the brain where it blocks a too-narrow blood vessel.

Hemorrhagic stroke occurs when a blood vessel within the brain ruptures and bleeds into the surrounding area. The most common cause of hemorrhagic stroke is chronic hypertension (high blood pressure). Common symptoms include a sudden severe headache that is often described as “the worst headache of their life”. There are two types of hemorrhagic stroke:

• Intracerebral hemorrhage (ICH) – bleeding into brain tissue itself
• Subarachnoid hemorrhage (SAH) – bleeding into the subarachnoid space of the brain

Transient Ischemic Attacks (TIAs) are often called “mini-strokes” and are caused by a temporary clot within the brain that temporarily blocks blood flow. TIAs do not cause permanent damage but need to be taken seriously as they may indicate that you are at greater risk for an ischemic stroke. Nearly 1 in 3 people who have a TIA have a full-blown stroke at some future point, and half of those occur within one year of the TIA.