Approximately 2,400 years ago, Hippocrates and other medical practitioners tried to make sense of a strange disorder that involved paralysis. They called the phenomenon "apoplexy," a Greek word that translates to being violently struck down, as if from a club. Not knowing much about the brain, these ancient doctors attributed the condition to a crippling blow from the gods. Not until the 17th century would it be understood that this "stroke" of paralysis was a result of bleeding and blockage in the brain.
A stroke occurs when the arteries that carry blood to the brain are either blocked by a clot or when they rupture causing a hemorrhage. When the blood flow to the brain stops, the parts of the brain not getting oxygen or nutrients are almost immediately affected.
If there's no blood getting to the brain stem, basic life support functions including breathing and heart rate are threatened. If the clot blocks blood from reaching the cerebellum -- the center that regulates coordination and balance -- then a person might lose control of their muscles. In the cerebrum, there's plenty of damage that can be done, with lobes that process sensory information, produce speech and control motor function at risk. The two halves of the cortex are responsible for analytical and perceptive tasks, as well as movement for the opposite side of the body.
When any part of the hard-working brain is denied blood, these functions are threatened. When a stroke occurs, a person might immediately go limp on one side. The sufferer may not be able to form words or see straight. The brain is suddenly a battlefield, where supplies (blood) have been cut off and soldiers (brain cells) are dying. Time is of the essence -- brain cells may be permanently lost. That's why some neurologists prefer to call strokes "brain attacks." Just as with heart attacks, strokes should be treated with extreme urgency so that blood flow can be restored and permanent brain damage averted.
However, that doesn't always happen; strokes are the third leading cause of death in the United States, as well as the leading cause of permanent disability. About 700,000 strokes occur each year just in the United States [source: Kolata]. But these numbers may not have to be so high, and in this article we'll learn how most strokes can be prevented by controlling risk factors and how recognizing symptoms allows for earlier treatment. First, though, read the next page to learn about what's going on in the brain when a stroke occurs.
Ischemic Stroke and Hemorrhagic Stroke
As funk band Sly and the Family Stone let us know, there are different strokes for different folks. When it comes to brain attacks, though, there are two types of strokes: ischemic and hemorrhagic.
Ischemic strokes are caused by blood clots and are far more common than the hemorrhagic variety, accounting for 80 percent of all strokes [source: Meadows]. The clot is either classified as a cerebral thrombosis or a cerebral embolism. Cerebral thrombosis, the more common cause of ischemic stroke, is caused by a blood clot formed in an artery in or leading to the brain, usually the result of fatty plaque build up in the arteries. This is similar to how a heart attack occurs, but a key difference is that the arteries in the brain are much smaller to begin with, so a clot doesn't have to be too big to cause problems. A cerebral embolism is caused by a wandering clot that makes its way to the brain, usually from the heart. It occurs more suddenly than a thrombosis, which builds up over time. In either case, the blood clot cuts off blood flow to the brain.
Unlike other parts of the body, the brain doesn't have a backup system of oxygen or nutrients available to it, so it's extremely vulnerable once the blood gets cut off. Brain cells begin to die at a rate of 12 million cells per minute [source: Healy]. But it's not just the affected brain cells. In the case of an ischemic stroke, the dying cells release a chemical called glutamate, which inflames the surrounding cells. These cells might have been unaffected but the glutamate essentially leads these cells to commit suicide.
A hemorrhagic stroke is caused by bleeding in the brain. The bleeding could be caused by either a cerebral hemorrhage or a subarachnoid hemorrhage. In a cerebral hemorrhage, an artery in the brain bursts and blood is released into the surrounding tissue; this may be caused either by an aneurysm or a head injury. In a subarachnoid hemorrhage, the bleeding occurs between the brain and the skull, but blood doesn't seep directly into the brain. In either case, the accruing blood causes intense pressure on the brain while cutting off the blood supply that keeps the brain functioning.
While hemorrhagic strokes are less common than the ischemic type, they also have a higher death rate because it's more difficult to treat them [source: Altman]. If the patient survives the hemorrhagic stroke, however, they may have a better long-term prognosis because the part of the brain that was under pressure can bounce back once the pressure is released. We'll learn more about how doctors go about treating these strokes in a later section.
More than half of all strokes could be prevented, primarily because so many risk factors can be controlled [source: Appel and Llinas]. Check out the next page to find out what you can do to keep your brain safe.
Stroke Risk Factors
The main risk factor for both kinds of stroke is high blood pressure, consistently elevated above 140/90 mmHg (millimeters of mercury) [source: Ward]. This risk factor, which can be controlled with medication, is present in 70 percent of all occurrences of stroke [source: Appel and Llinas].
If you're at risk for heart disease, you've likely heard about steps such as quitting smoking, lowering cholesterol, becoming more active with exercise and eating a healthy diet to fight obesity. Working to address these issues not only wards off heart disease, but eliminates many of the major risks for stroke as well, simply because an ischemic stroke and a heart attack are so similar in cause.
Heart disease in and of itself is a risk factor for stroke because the heart's ability to pump blood becomes compromised. But, these factors for heart disease are also factors for stroke as well. For example, smokers have a 50 percent higher risk of stroke than nonsmokers, but that risk is eliminated within five years of quitting [source: Appel and Llinas].
Diabetics face three times the risk of stroke, but this also can be controlled by keeping their blood sugar count in check [source: Appel and Llinas]. Individuals with atrial fibrillation, a condition in which the heart doesn't pump properly, face an increased risk of ischemic stroke because the irregularly pumped blood pools and forms clots. This can also be addressed with medication.
Of course, some factors are out of a person's control, but simply being aware of them is important. If a close family member has suffered a stroke, then your risk increases. The chance of a stroke also increases with age -- between the ages of 55 and 85, risk of a stroke doubles every 10 years [source: Appel and Llinas]. Men have a higher stroke risk than women until later years, when the odds even out a bit. Race also plays a role. Blacks have twice the incidence and mortality rate from stroke than whites [source: Appel and Llinas]. It's possible that this gap may be explained by socioeconomic factors, such as poverty [source: New York Times]. Among both blacks and whites, socioeconomic factors matter, with impoverished areas in South Carolina, Arkansas, Tennessee and Georgia having the highest stroke fatality rates in the United States [source: New York Times].
So now you know whether you're at risk for a stroke, but how do you know when your brain is actually under attack? Read the next page for a list of stroke symptoms.
For all the differences between ischemic and hemorrhagic strokes, from onset to treatment, they are alike in their symptoms. The symptoms of a stroke are:
- Sudden weakness or numbness in the face or extremities
- Sudden problems with speech or comprehension
- Sudden issues with vision, such as blurriness or blindness
- Sudden coordination issues, including dizziness or difficulty walking
- Sudden severe headache
- Sudden nausea or vomiting
The key word you might notice in all these symptoms is "sudden." That's a huge tip-off that the symptom might be related to a stroke. Otherwise, many of these symptoms might seem like something else. You may just write off a headache accompanied by blurry vision as a bad migraine. Some stroke symptoms don't necessarily "hurt" the way other symptoms do, like chest pain hurts a heart attack victim. Many people try to ignore these symptoms and hope that they'll go away, but this is an extremely serious mistake.
Once these symptoms appear, the clock has started. Brain cells are dying rapidly, and for ischemic strokes, there's a very small window for certain treatments. If a person goes to bed hoping to sleep off a sudden headache, then they're wasting valuable time.
Sometimes you may receive advance notice of a major stroke in the form of a mini-stroke, more properly known as a transient ischemic attack (TIA). About 10 percent of all strokes are preceded by a mini-stroke [source: Wheatcraft]. Everything from the blocked blood flow to the bodily symptoms occurs, but for a very short time with no lasting effects. Even though the symptoms disappear on their own, you should still head to the hospital for evaluation. A major stroke could be on its way, either in a matter of days or in a few years. Doctors may determine that surgery can be performed to open slightly obstructed arteries, or they may do something as simple as prescribe an aspirin a day, which can help prevent clots by thinning the blood.
It may be hard for a stroke sufferer to know that they're experiencing
a stroke. An observer who can witness symptoms like facial drooping can ask questions to determine mental and verbal capacities. If you're on your own, don't ignore any sudden symptoms. A stroke feels different for everyone, but we can offer a few descriptions of how others have described it. One stroke victim felt that she'd been given a shot of Novocain to the left side of her body, while another person couldn't recognize the alphabet [source: Meadows]. Though this may not be typical, one woman said she reached nirvana during her stroke because her spirit felt so free from her body [source: Kaufman].
In the case of a stroke, it's better to be safe than sorry. People with these symptoms should be driven to the nearest stroke center, which is not necessarily the closest emergency room. Certified stroke centers will have the equipment and personnel that can make a quick decision about the patient's condition, which may be prohibitively expensive in smaller hospitals. In 2007, however, only 322 of the 4,280 accredited hospitals in the United States were certified as stroke centers [source: Kolata]. If a patient does end up in an emergency room, it's important to be aggressive about being seen by a doctor as soon as possible, even if the symptoms don't seem dramatic.
What happens when you arrive at a stroke center, and why is time so important? Find out about diagnosing and treating a stroke on the next page.
When it comes to treating a stroke, every second counts. Yet time is lost when a patient ignores symptoms in the hopes they'll go away, or when a person sits in a waiting room as patients with more dramatic symptoms are admitted. As a result, a group of neurologists are promoting the term "brain attack" for a stroke, which emphasizes the urgency with which a stroke victim should be seen
Stroke victims need to be seen quickly because "time is brain," and with each passing moment, more brain cells might be lost. And doctors can't immediately administer treatment, either. They have the tricky task of deciding whether the symptoms are actually those of a stroke. About 25 percent of patients with stroke symptoms aren't having a stroke [source: Kolata]. Migraines are one condition with similar symptoms, and weakness in the body could also indicate a nerve injury or a brain tumor. Doctors also have to decide whether the stroke is ischemic or hemorrhagic because the treatment goals of the two are completely different. The most effective tool in diagnosing a stroke is a brain imaging test -- a CT scan detects hemorrhaging, while an MRI is used to spot clots.
To treat an ischemic stroke, doctors want to break up the blood clots and restore blood flow. The only drug approved by the FDA for this purpose is known as tissue plasminogen activator or tPA (you may also know it as Activase). The drug dissolves clots, hopefully restoring blood flow and minimizing brain damage. Yet only one in five stroke victims who would benefit from tPA receives it [source: Brody]. There's a three-hour window in which tPA has been shown to be effective, and many patients just don't make it in time. That's why every minute counts when stroke symptoms start.
There's another reason why doctors are hesitant to administer tPA. In testing the drug, about 6 percent of patients experienced excessive bleeding in the brain, and after three hours, the risk increases [source: Kolata]. If the patient is suffering a hemorrhagic stroke, tPA would only compound the bleeding in the brain. The decision to administer tPA has been further complicated in recent years as doctors learn more about microbleeds, or tiny drops of blood on the brain, leaked from blood vessels. Microbleeds may be present in as many as one in five people over the age of 60 [source: Kolata]. Administering tPA or any other anticlotting drug could unleash a hemorrhagic stroke, which is what happened to Israeli prime minister Ariel Sharon in 2005 [source: Kolata].
Other treatments for an ischemic stroke include controlling the patient's blood pressure, so that it's not so high that it damages organs, but also not so low that blood flow to the brain is slowed. Doctors will work to reduce any signs of fever, which increases the chance of brain damage. Anticoagulants, or drugs that ward off future clots, like heparin, may eventually be introduced, as well as drugs that could aid the heart's function, if the stroke was caused by an atrial fibrillation.
Surgery is rare in treating ischemic strokes, but it might be an option for hemorrhagic strokes. To treat a hemorrhagic stroke, the doctor's goal is to relieve pressure on the brain and stop the bleeding. The first step is lowering a patient's blood pressure so there's less opportunity for blood to build up in the brain. Then, the doctor administers drugs that reduce swelling and considers surgical options, such as clipping an aneurysm or draining a pool of blood.
That's the immediate treatment, but what are the long-term actions? Find out about stroke recovery on the next page.
Depending on the length of the stroke and the parts of the brain that were injured, the effects can be severe. There may be lasting damage to a person's behavior, speech, senses, motor skills or thought processes. While about 10 percent of stroke victims survive with no lasting effects, about 25 percent will experience minor impairments, 40 percent will experience moderate-to-severe impairments and 10 percent will require a long-term care facility or nursing home for the rest of their lives [source: Meadows]. About 15 percent of stroke victims die soon after the stroke [source: Meadows].
Rehabilitation begins soon after a stroke. Currently, many doctors believe that most healing occurs in the first three months [source: Wartik]. Patients may undergo a mix of therapies, depending on their state of health, but the basic goals usually include attempting to regain lost function and developing strategies to compensate for shortcomings. Speech, physical and occupational therapies are all common prescriptions. Many skills, such as walking and speaking, can be relearned, and new therapeutic methods are emerging all the time. Robotic therapy has been used to help incapacitated patients regain use of their limbs, and constraint-induced movement therapy is a means of focusing on an injured limb by restraining the functional limb.
But whichever method is used, it can be a long, hard path to recovery, repeating the same actions and words numerous times in an attempt to get the neurons to relearn basic functions. Studies have also shown that there's a discrepancy between a therapist's goals, which may involve small steps and helping the individual adjust to a disability, and the patient's goals, which usually involve a return to before-stroke functionality [source: Hafsteinsdottir and Grypdonck]. It's important to reconcile these goals so that rehabilitation is successful. Sometimes a goal may have to be as simple as learning how to use a wheelchair properly [source: Wartik].
One major hindrance to a successful recovery is depression. Depression occurs in 35 percent of stroke victims age 65 or older [source: Appel and Llinas]. It may be an effect triggered by the stroke or an emotional response to the other effects of the stroke. Depression can stall the recovery process because the patient gives up and feels hopeless. As a result, anti-depressants and therapy may be another component of stroke recovery.
About one quarter of those who recover from their first stroke will suffer another within five years [source: Meadows]. To prevent another stroke, patients might start taking anticoagulants, which thin the blood so that it doesn't clot as easily. Antiplatelet drugs may also prevent clotting by slowing down the blood cells that cause clots to form. This drug regimen may be as simple as taking an aspirin a day, though prescription medications such as Coumadin and Plavix are also used. Surgery to open clogged arteries may be considered, and again, patients should work to keep any modifiable stroke risk factors in check.
To learn more about brain attacks and the human body, see the links on the next page.
Related HowStuffWorks Articles
More Great Links
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- Appel, Lawrence and Rafael Llinas. "Hypertension and Stroke." Johns Hopkins White Papers. 2005.
- Brody, Jane E. "With Strokes, Knowledge is a Lifesaver." New York Times. Dec. 12, 2006. (July 8, 2008) http://www.nytimes.com/2006/12/12/health/12brody.html
- Gerber, Carolyn S. "Stroke: Historical Perspectives." Critical Care Nursing Quarterly. October-December 2003.
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- Sternberg, Steve. "Strokes in Children: A Medical Dilemma." USA Today. May 4, 2006. http://www.usatoday.com/news/health/2006-05-03-strokes-kids_x.htm
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- Wheatcraft, Dean. "On the Offensive against Brain Attack." Science & Technology Review. June 1997. (July 8, 2008) https://www.llnl.gov/str/Fitch.html