OverviewA stroke is the death of brain tissue that occurs when the brain does not get enough blood and oxygen.
What is going on in the body?Strokes are classified as ischemic strokes or hemorrhagic strokes. Ischemic strokes happen when the blood supply to the brain is interrupted. The brain cells then die from lack of oxygen.
Hemorrhagic strokes occur when blood vessels in the brain burst and release blood into the area around the brain cells. The blood then damages the brain cells. The products released when cells die cause swelling in the brain. Since the skull allows very little room for expansion, this swelling can damage the brain tissue even further.
Examples of ischemic strokes are:
• stroke from cardiogenic embolism, a condition in which blood clots travel from the heart. Blood clots from the heart may be caused by an irregular heartbeat called atrial fibrillation, severe congestive heart failure, and heart attack.
• stroke from atherosclerosis, which occurs when the arteries supplying the brain are narrowed by plaque formation on the vessel walls
• stroke from carotid stenosis, which is a blockage in one of the carotid arteries in the neck
• arteritis, or artery inflammation, in an artery that supplies the brain. This may be due to a condition called temporal arteritis, for example.
• stroke from carotid dissection. A carotid dissection occurs when one of the carotid arteries in the neck is torn by an injury and blood flow to the brain is blocked.
• polycythemia vera, a blood cancer that causes blood cells to multiply and the blood to thicken. The thickened blood prevents normal oxygenation of brain cells.
• stroke caused by cholesterol or plaque from an artery in the neck. When the cholesterol or plaque travels and blocks an artery supplying the brain, a stroke occurs.
• severe migraine headaches, which cause constriction of the blood vessels within the brain and deprive brain cells of oxygen
Hemorrhagic strokes occur when there is bleeding into the brain caused by damage to the blood vessels. A hemorrhagic stroke may be caused by:
• high blood pressure
• abnormal bleeding from blood-thinning medications, such as warfarin or heparin
• hemophilia A or hemophilia B, which are blood disorders that prevent normal blood clotting
• low numbers of platelets, a type of blood cell involved in blood clotting. Low platelet counts are seen in a number of diseases and conditions, including acute infections and a severe allergic reaction known as anaphylactic shock.
• rupture of a cerebral aneurysm, or weakened blood vessel wall within the brain
• sickle cell disease, an inherited condition that results in abnormal red blood cells
• a group of abnormal blood vessels within the brain known as an arteriovenous malformation (AVM)
• head injuries
• eclampsia, a complication of pregnancy that causes high blood pressure in the mother
Stroke is the third leading cause of death in the US and many other countries, behind heart disease and cancer.
What are the signs and symptoms of the condition?Strokes can cause many different signs and symptoms, depending on the area of the brain that is damaged. Some people have multiple areas of damage. Most strokes begin suddenly, develop rapidly, and cause brain damage within minutes. Signs or symptoms may include:
• problems with movement, such as weakness, clumsiness, or paralysis. These are often on only one side of the body. In some cases, people may only have weakness or clumsiness in their hand. In other cases, one entire half of the body becomes paralyzed.
• headache
• numbness or a lack of feeling, which is also often on only one side of the body
• speech impairments, including slurred speech or difficulty finding the correct word
• difficulty doing math or writing
• difficulty understanding speech or writing
• inability to recognize family members or common objects
• dementia, a condition that affects memory, understanding, and the ability to carry out the normal activities of daily life
• visual impairment, including blurred vision or total vision loss
• personality changes
• balance problems, known as ataxia
• coma
• the inability to breathe on one's own. This may require a person to be put on a ventilator (artificial breathing machine).
What are the causes and risks of the condition?
Strokes are caused by an interruption of the blood flow to brain cells or by damage to brain cells. The American Heart Association has recently issued guidelines for stroke prevention. The guidelines discuss risk factors for stroke in 3 categories: nonmodifiable, well-documented modifiable, and less well-documented or potentially modifiable.
What can be done to prevent the condition?
The American Heart Association guidelines for stroke prevention address both modifiable and less well-documented or potentially modifiable risk factors.
How is the condition diagnosed?
The first step in diagnosis of stroke is a medical history and physical exam. This may be all that is needed to make the diagnosis. In other cases, further tests may be needed. Cranial MRIs and cranial CT scans may be ordered to show the type, size, and location of the stroke. They can also show whether or not there is bleeding in the brain, which can help with some treatment decisions.
|
advertisement
HEALTH CENTERS
|
