A stroke, or an attack of the brain, happens when a blood vessel in the brain bursts or becomes blocked. The brain is an organ that cannot store oxygen, so blood vessels deliver oxygen through the blood. A lack of blood supply can cause a stroke, therefore causing surrounding nerve cells to be cut off from nutrients and oxygen. If the brain tissue lacks oxygen for more than three or four minutes, the tissue begins to die.
Strokes can appear in three types: as hemorrhagic strokes, ischemic strokes or transient ischemic attacks.
- Hemorrhagic stroke — The stroke takes place when a weak blood vessel in the brain ruptures. Bleeding from the vessel, also known as a hemorrhage, happens suddenly and the force of blood that escapes from the blood vessel can also damage surrounding brain tissue. Hemorrhagic stroke is the most serious kind of stroke. About 13% of all strokes are hemorrhagic.
- Ischemic stroke — This type of stroke occurs when a blood vessel in the brain develops a clot and cuts off the blood supply to the brain. A blood clot that forms in a blood vessel in the brain is called a “thrombus.” A blood clot that forms in another part of the body, such as the neck or lining of the heart, and travels to the brain is called an “embolus.” About 87% of all strokes are ischemic. Treatment for ischemic strokes depends on how quickly after the symptoms start the stroke victim arrives at the hospital.
- Transient ischemic attack (TIA) — A TIA should be treated as seriously as a stroke. A TIA has the same symptoms as a stroke, but they only last several minutes, or up to 24 hours. Unlike a stroke, a TIA does not kill the brain cells, so there is no lasting damage to the brain. A TIA is considered a serious warning sign of stroke. About 1 in 3 people who have a TIA will go on to have a stroke.
The effects of a stroke depend on the extent and the location of damage in the brain. Among the many types of disabilities that can result from a stroke are
Strokes can cause effects based on the extent and location of damage in the brain. Disabilities that can result from a stroke include:
- Weakness or numbness in parts of the body
- Inability to speak or comprehend words
- Difficulty communicating
- Difficulty swallowing
- Vision loss
- Memory loss, confusion or poor judgment
- Change in personality; emotional problems
Nerve cells in the brain tissue communicate with cells in the rest of the nervous system to control functions including memory, speech, and movement. When a stroke happens, the nerve cells in the brain become injured, and as a result the cells cannot communicate. This is how impairment occurs.
A stroke is a medical emergency, and 9-1-1 should be called immediately if they exhibit any of these major warning signs:
- Sudden weakness or numbness in a part of the face or limbs on one side of the body
- Sudden difficulty seeing
- Sudden confusion, difficulty speaking or slurred speech
- Sudden problems with walking, dizziness
- Sudden, severe headache for no reason
- Difficulty swallowing
The faster a potential stroke victim is taken to the hospital, the better chance they have of avoiding damage. If you are waiting for an emergency vehicle to arrive, the stroke victim should be lied down. Watch the person and lift the chin to open the airway. Check for breathing and pulse, and if necessary, perform CPR. If the person is breathing but unconscious, roll him or her to his or her side. If conscious, reassure the victim and comfort him or her. If they are having difficulty swallowing, turn him or her to the side and do not give them anything to drink.
Understanding how to identify and respond to a stroke is important in helping the victim avoid unnecessary damage to the brain and body.