There are two main types of stroke: strokes caused by blood clots (TIA/ischemic) and bleeding stroke (hemorrhagic).
Transient ischemic attack
If an artery leading to the brain, or inside the brain, becomes blocked by a blood clot for a short period of time, the blood flow to an area of the brain slows or stops completely. This lack of blood and oxygen can cause a transient ischemic (TRAN-see-ynt is- KEEM-ik) attack, or TIA. Also called a mini-stroke, TIA can cause symptoms such as numbness, trouble speaking, and loss of balance or coordination. It is common for these symptoms to last for a very short period of time and then resolve. While TIAs cause no permanent brain damage, they are a serious warning sign and precede about 15 percent of all strokes and should not be ignored.
An ischemic (is-KEEM-ik) stroke occurs when a blood clot blocks an artery, cutting off or narrowing the flow of oxygen-rich blood to the brain cells. Unless nearby blood vessels can deliver enough blood to the affected area, brain cells will begin to die and stroke sufferers will start to have problems using certain parts of their bodies or completely lose some abilities.
Facts about ischemic stroke:
- the most common type of stroke and account for about 85 percent of all stroke cases
- symptoms develop over a few minutes or worsen over hours
- typically preceded by symptoms or warning signs that may include loss of strength or sensation on one side of the body, problems with speech and language or changes in vision or balance
- TIA or “mini stroke” may give some warning of a major ischemic stroke
There are three types of ischemic stroke categorized by their specific cause:
Embolic ischemic stroke – a blood clot or plaque fragment forms somewhere in the body (usually the heart or neck arteries) and moves through the bloodstream to the brain. Once in the brain, the clot blocks a blood vessel and leads to a stroke.
Thrombotic ischemic stroke – a blood clot blocks an artery which supplies blood to the brain. The clot may interrupt the blood flow and cause a stroke. This is common in arteries damaged by arteriosclerosis.
Systemic hypoperfusion – means low blood flow and occurs because of circulatory failure caused by the failing of the heart’s pumping action (heart attack) and too little blood reaches the brain.
Strokes caused by a bursting blood vessel in the brain that spills blood into the brain are called hemorrhagic (hem-o-RAYG-ik) strokes. High blood pressure and brain aneurysms can both cause the blood vessel to be weak and possibly cause this type of stroke.
Facts about hemorrhagic stroke:
- fatality rate is higher and overall prognosis poorer for those who have hemorrhagic strokes
- people who have hemorrhagic strokes are usually younger
- often associated with a very severe headache, “worst headache of my life”, stiff neck, inability to tolerate bright lights (photophobia), nausea and vomiting and the symptoms usually appear suddenly
- TIA or any other stroke warning sign may not precede this type of stroke
There are two types of hemorrhagic stroke categorized by their specific cause:
Intracerebral hemorrhage – a type of hemorrhagic stroke, is caused when a burst blood vessel bleeds deep into the brain tissue. High blood pressure, also called hypertension, is the most common cause of this type of stroke. The bleeding causes brain cells to die, and that part of the brain no longer works correctly.
Subarachnoid hemorrhage – a blood vessel bursts near the surface of the brain and blood pours into the area between the brain and the skull. This bleeding may increase pressure in the brain, injuring brain cells. This type of stroke has many possible causes, but is usually the result of a burst aneurysm or an arteriovenous malformation, or AVM.
Aneurysm – a weak spot on the wall of an artery that may balloon out, forming a thin-walled bubble. As it gets bigger, the aneurysm gets weaker and can burst, leaking blood into or outside of the brain.
Arteriovenous (ar-tir”-e-o-ve-nus) malformation – an irregular connection of arteries and veins in the brain that can rupture.