A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue (cerebral infraction) and causing sudden symptoms.
In Western countries, strokes are the third most common cause of death and the most common cause of disabling neurologic damage. In the United States, over 600,000 people have a stroke and about 160,000 die of stroke each year. Strokes are much more common among older people than among younger adults, usually because the disorders that lead to strokes progress over time. Over two thirds of all strokes occur in people older than 65. Slightly more than 50% of all strokes occur in men, but more than 60% of deaths due to stroke occur in women, possibly because women are on average older when the stroke occurs. Blacks are more likely than whites to have a stroke and to die of it.
Types: There are two types of strokes: ischemic and hemorrhagic. About 80% of strokes are ischemic – usually due to a block artery, often blocked by a blood clot. Brain cells, thus deprived of their blood supply, do not received enough oxygen and glucose (a sugar), which are carried by blood. The damage that results depends on how long brain cells are deprived of blood. If they are deprived for only a brief time brain cells are stressed, but they may recover. If brain cells are deprived longer (but possibly for only several minutes), brain cells die, and some functions may be lost. However, in such cases, a different area of the brain can sometimes learn how to do the functions previously done by the damaged area.
Transient ischemic attacks (TIAs), sometimes called ministrokes, are often an early warning sign of an impending ischemic stroke. They are caused by a brief interruption of the blood supply to part of the brain. Because of the blood supply is restored quickly, brain tissue may not die, as it does in a stroke.
The other 20% of strokes are hemorrhagic – due to bleeding in or around the brain. In this type of stroke, a blood vessel ruptures, interfering with normal blood flow and allowing blood to leak into brain tissue. Blood that comes into direct contact with brain tissue irritates the tissue and can cause scarring, leading to seizures.
Symptoms Of Having A Stroke
Symptoms of stroke or transient ischemic attack occur suddenly. They vary depending on the precise location of the blockage or bleeding in the brain. Each area of the brain is supplied by specific arteries. for example, if an artery supplying the area of the brain that controls the left leg’s muscle movements is blocked, the leg becomes weak or paralyzed. If the area of the brain that senses touch in the right arm is damaged, sensation in the right arm is lost.
Because early treatment can help limit loss of function and sensation, everyone should know what the early symptoms of stroke are. People who have any of these symptoms should see a doctor immediately, even if the symptoms goes away quickly. Most strokes, whether ischemic or hemorrhagic, typically cause one or more of the following symptoms
- Sudden weakness or paralysis on one side of the body (for example, half of the face, one arm or leg, or all of one side).
- Sudden loss of sensation or abnormal sensations on one side of the body.
- Sudden difficulty speaking, sometimes with slurred speech.
- Sudden dimness, blurring, or loss of vision, particularly in one eye.
- Sudden dizziness or loss of balance and coordination, leading to falls.
- Symptoms of a transient ischemic attack are the same, but they usually disappear within minutes and rarely last more than 1 hour.
- Symptoms of a hemorrhagic stroke may also include the following.
- Sudden severe headache.
- Nausea and vomiting.
- Temporary or persistent loss of consciousness.
- Very high blood pressure.
Other symptoms that may occur early include problems with memory, thinking, attention, or learning. People may be unable to recognize parts of the body and may be unaware of the stroke’s effects. The peripheral field of vision may be reduced, and hearing may be partially lost. Dizziness and vertigo may develop or persist. Control of bowel or bladder function may be lost.
Later symptoms may include stiffening and spasms of the muscles (spasticity) and inability to control emotions. A stroke can cause depression, or people may feel depressed because of the stroke.
In most people who have had an ischemic stroke, loss of function is usually greatest immediately after the stroke occurs. However, in about 15% to 20%, the stroke is progressive, causing greatest loss of function after a day or two. In people who have had a hemorrhagic stroke, function usually is lost progressively over minutes to hours.
Over days to months, some function is usually regained because even though some brain cells die, others are only stressed and may recover. Also certain areas of the brain can sometimes switch to the functions previously done by the damaged part – a characteristic called plasticity. However, the early effects of a stroke, including paralysis, can become permanent. Muscles that re not used usually become permanently spastic and stiff, and painful muscle spasms may occur. Walking, swallowing, physically saying words clearly, and doing daily activities may remain difficult. Various problems with memory thinking, attention, learning or controlling emotions may persist. Depression, impairments in hearing or vision, or vertigo may be continuing problems. Control of bowel or bladder function may be permanently impaired.
Treatment For Having A Stroke
Anyone with symptoms of a stroke should seek medical attention immediately. Doctors check the person’s vital functions, such as heart rate, breathing, temperature, and blood pressure, to make sure they are adequate. If they are not, measures to correct them are taken immediately. For example, if people are in a coma or unresponsive (as may result from brain herniation), mechanical ventilation (with a breathing tube inserted through the mouth or nose) may be needed to help them breathe. If symptoms suggest that pressure within the skull is high, drugs may be given to reduce swelling in the brain, and monitor may be put in the brain to periodically measure the pressure.
Other treatments used during the first hours depend on the type of stroke. These treatments include drugs (such as antiplatelet drugs, anticoagulants, drugs to break up clots, and drugs to control high blood pressure) and surgery to remove blood that has accumulated.
Later and ongoing treatments focus on preventing subsequent strokes, treating and preventing problems that strokes can cause, and helping people regain as much functions as possible (rehabilitation).