What Is Stroke? 

Stroke  is literally a "brain attack", caused  when the vital supply of  blood and oxygen is cut off  to part of the brain. If a portion of the  brain loses its supply of nutrient-rich blood and oxygen, the bodily functions controlled by that part of the  brain (vision, speech, walking, etc.)  are impaired. Like a heart attack, every minute counts in getting a stroke victim emergency medical treatment so that brain damage and possible future disability will be minimized. 

Stroke is the third leading killer in the U.S. (after heart disease and cancer) and a primary cause  of disability in adults. Each year more than 500,000 people in the U.S. have strokes, killing almost 150,000 of them and dramatically changing the lives of those who survive. Currently, three million Americans are permanently disabled because of  stroke. However, new methods of stroke diagnosis and treatment are available, and they are dramatically increasing a person's chance of recovery after a stroke. 

The National Stroke Association uses the term "brain attack" to describe stroke and to say that: 

• Stroke affects the brain, perhaps the body's most vital organ 
• Stroke strikes suddenly, often with no warning 
• Stroke  is a medical emergency and requires immediate care 

What Causes a Brain Attack? 

Stroke results from disease of the blood vessels supplying the brain with blood. Commonly, stroke is  caused by atherosclerosis (deposits of cholesterol, fats, and other matter inside the vessel walls) of the left or right carotid artery of the neck. For example, turbulent blood flow through the carotid bifurcation (point where the common carotid artery splits into the internal and external carotid artery branches) dislodges material from the atherosclerotic narrowing and carries it to the brain, where it may form  a plug in the arteries. 

The main types of stroke are ischemic stroke and hemorrhagic stroke: 

• ischemic stroke happens when an artery leading to the brain becomes blocked by a  blood clot (cerebral embolism) and circulation is obstructed 
• ischemic stroke is also caused when a plaque  or other fatty deposits (cerebral thrombosis) blocks an artery, significantly reducing blood flow (for example, to less than one fourth of the normal flow level) 
• hemorrhagic stroke is caused by  a rupture of the  blood vessels which feed the brain 
• Roughly 80% of strokes are caused by clots (ischemic stroke) while the remaining 20% are caused by hemorrhage. In addition to disease of the carotid arteries, ischemic stroke can also be caused from clots originating from the heart, vessels of the legs or elsewhere  in the body. Heart attack victims are susceptible to  stroke, more than 20% of ischemic strokes are  caused by clots from the heart. 

Transient ischemic attack (TIA) is as  a mild stroke (also called "mini-stroke") where the attack lasts for only a few minutes to less than 24 hours, followed by complete recovery. A TIA is a warning sign that a sufficient supply of  blood is not reaching part of the brain. People who have suffered a TIA are at significant risk of having an acute stroke. Recognizing a "mini-stroke" is important because if appropriate treatment is begun, major strokes can be prevented. 

Stroke is A Medical Emergency! 

Like a heart attack, stroke demands immediate medical attention. Emergency medical treatment can make all the difference in the world for someone who is having a stroke . . . it can be the difference between life and death . . . the difference between brain cells  that are saved  and brain cells that are damaged forever . . .  the difference between recovery and lifelong impairment. For each minute that brain cells are deprived of oxygen, brain damage increases and more of the brain is injured. 

Medical research shows that  when a stroke happens, brain cells in  the area of the stroke set off a sort of chain reaction of chemical and electrical signals, possibly leading  to secondary injury. This secondary injury can damage or even kill brain cells in a much larger area surrounding  the original stroke. The faster a stroke is diagnosed, the faster treatment can occur, thus lowering the risk of permanent  brain damage and disability. However, nationwide only about 15% of stroke patients get to the hospital during the window of time where the most effective therapy can be delivered (within three to six hours of the onset of symptoms). In fact, most people wait anywhere from six to 24 hours after experiencing the first symptoms of a stroke before seeking medical care. This  is too late!

Neurologists and other emergency physicians involved in the treatment  of stroke/brain attack have come up with the saying "Time is brain!" as a direct way of conveying the message that  stroke is a medical emergency. This simply means that as more time elapses after the onset of stroke, more brain damage will occur. Conversely, if the stroke is treated immediately, brain damage will be minimized. Stroke is a brain attack. 

People at high risk of stroke, especially those that have experienced mini-stroke or TIA (transient ischemic attack) should research the location of nearby hospitals that have established emergency room teams to handle stroke/brain attack. These hospitals will have neurologists, radiologists/neuro-radiologists and other healthcare professionals who  are able to diagnose and treat a stroke during the critical three-hour window in which tissue plasminogen activator (TPA) must be delivered. Those medical centers and hospitals with dedicated stroke treatment programs should have experience in the administration of TPA clot busting agents or other thrombolitic and neuro-protective agents, as well as dedicated specialists and imaging protocols for diagnosing stroke and mapping the best course of therapy. 

What are the Warning Signs and Risk Factors for Stroke? 

• Numbness, weakness or paralysis  of face, arm, leg: especially  on only one side of the body
• Sudden blurry  or decreased eyesight  in one or both eyes
• Difficulty speaking  or understanding simple sentences 
• Sudden and severe headache with no apparent cause
• Unexplained loss of balance, dizziness, or loss of coordination, with particular concern if combined with another of the above symptoms 

What Are the Risk Factors for Stroke? 

• Age (the incidence  of stroke rises steeply with age, especially over 55) 
• Previous stroke or transient ischemic attack (brief episode of stroke symptoms) 
• High blood pressure 
• Heart disease (especially atrial fibrillation) 
• Carotid artery disease or other atherosclerosis (narrowed arteries) 
• Diabetes mellitus 
• Smoking  
• Family history of stroke 
• High cholesterol (or hyperlipidemia, a high level of fatty substances in the blood) 
• Obesity  
• Excessive consumption of alcohol 
• Polycythemia (a raised level of red blood cells in the blood) 
• Lack of exercise 

Diagnosing Menopause 

Before menopause, the female body produces the hormones estrogen and progesterone in the ovaries. Estrogen works  to regulate a woman’s monthly menstrual cycle and secondary sexual characteristics (such as breast development and function), and also prepares the body for fertilization and reproduction. Progesterone is released each month during menstruation  to prepare the uterus for possible pregnancy and to prepare the breasts for lactation (milk production). As a woman reaches menopause, typically around 50 years old, her body produces less and less estrogen and progesterone. 

This loss of estrogen and progesterone usually results in irregular periods and other symptoms such as hot flashes, vaginal changes, sleep disturbances, etc. At this time, a woman’s physician will usually test her follicle stimulating hormone (FSH) level. FSH is a hormone that is secreted by the body’s pituitary gland to stimulate growth of ova (female reproductive eggs). As the ovaries produce less estrogen, the pituitary gland increases production of FSH to try to stimulate the ovaries into producing more estrogen. 

While FSH levels can help determine a woman’s stage of menopause, FSH levels do tend to fluctuate from month-to-month during peri-menopause. Women who take oral contraceptive pills will have to temporarily stop taking them so that their FSH levels can be measured accurately. In addition, as a woman nears menopause, the walls of her vagina will become thinner and dryer. At this time, the physician may take a sample of the vaginal wall when performing a Pap smear. However, it is also important for a woman to keep track of her menstrual periods when they  begin to become irregular to help her physician know 

What Causes a Brain Attack? 

For the best, most effective treatment of  stroke, a person with a suspected stroke must be given immediate medical attention. It is during the critical first 3 to 6 hours following stroke that today's growing stroke therapy options have the highest curative potential. Doctors can now administer an injection of tissue plasminogen activator (TPA) to dissolve the clots that block  blood flow to the brain. If the blockage can be removed with administration of TPA and sufficient blood flow is recovered within a three hour period following the stroke, the severity of permanent  brain damage (neurological disability) is minimized or eliminated. However, medical imaging  is a critical component in determining the course of  stroke treatment. 

Important Note: Some of the methods of acute stroke diagnosis and treatment described herein are new and are still not widely available  in the U.S. People who are at high risk of stroke should investigate which medical centers in their  area have active stroke diagnosis and treatment capabilities. Those medical centers and hospitals with dedicated stroke treatment programs should have experience in  the administration of tissue plasminogen activator (TPA) or other thrombolitic  and neuro-protective agents, as well as dedicated specialists and imaging protocols for diagnosing stroke and mapping the best course of therapy. Particularly in rural areas, which may not have large medical centers with the needed neurology specialists and emergency room staffing, access  to these new methods of stroke diagnosis and therapy may be limited for some time (some predict it may be five years before TPA treatment of stroke becomes routine). 

How Can Stroke be Prevented? 

Not having a stroke in the first place is vastly better than relying on medical science to undo the damage of stroke after it has been done. Keeping cholesterol levels down decreases the risk of atherosclerosis and blood clots, both  major causes of stroke. Treating high blood pressure drastically reduces the risk of bleeding (hemorrhagic) strokes. Eliminating smoking also improves a person's chances of not having a stroke. Exercise, proper diet and elimination of smoking are among the best prescriptions to minimize the health conditions that cause stroke and heart disease. 

Medical care for patients at high risk of stroke may include the administration of one adult aspirin daily (to thin the blood) and aggressive management of modifiable risk factors, such as counseling to help them stop smoking and treatment for high blood pressure, high cholesterol, and diabetes when indicated. These treatments may involve the use of drugs to lower cholesterol and blood pressure. 

Steps to reduce risk of stroke and heart attack 

• reduce weight 
• control high blood pressure 
• reduce sodium 
• quit smoking 
• exercise regularly 
• control cholesterol 
• eat less fat 
• reduce stress 

Surgery of the carotid arteries to help prevent stroke (carotid endarterectomy) 

Carotid artery surgery (carotid endarterectomy) can prevent stroke in carefully selected individuals who have no outward sign of disease but are at risk for stroke from a severe narrowing of the carotid artery in the neck. A carotid endarterectomy  is a surgical procedure in which  a vascular surgeon or neurosurgeon removes fatty deposits and plaque from one of the two main arteries  in the neck supplying blood to  the brain.

Carotid artery disease is more common in elderly people.  The disease process that causes the buildup of fat and other material on the artery walls is called atherosclerosis, popularly  known as "hardening of the arteries." Narrowing of an artery  is called stenosisand the degree of stenosis is usually expressed as  a percentage of  the normal diameter of the opening. Carotid stenosis can be measured using high resolution ultrasound, magnetic resonance angiography, CT angiography  and other techniques. Click here to learn about  the use  of medical imaging to diagnose vascular disease before a stroke occurs. 

In 1992, the most recent year for which statistics  are available from the National Hospital Discharge Survey, there were about 91,000 carotid endarterectomies performed in the United States. The average cost of carotid endarterectomy including diagnostic test, surgical procedure, hospitalization, and follow-up care is about $15,000. 

Two large clinical trials have identified specific individuals for whom the carotid surgery is highly beneficial when performed by surgeons and in institutions that  can match the standards set in those studies. Carotid surgery has been found highly beneficial for persons who have already had  a stroke or experienced the warning signs of  a stroke and have a severe stenosis  of 70 percent to 99 percent. In this group, surgery reduces  the estimated two-year risk  of stroke by more than 80 percent,  from greater than 1 in 4  to less than 1 in 10. In a second trial, the carotid surgery has also been found highly beneficial for persons who are have no symptoms but have a  severe carotid stenosis of 60 percent to 99 percent. In this group, the surgery reduces the estimated 5-year risk of stroke by more than one-half, from about 1 in 10 to less than 1 in 20. 

Carotid angioplasty  and stenting 

Other methods of treating carotid artery disease  include the use of angioplasty  and stenting to open the stenosis (narrowing). Stenting I 

Notes: DrJMinor

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EditText of this page (last edited December 24, 2009)