What Is a Stroke?

Stroke, also called brain attack, occurs when blood flow to the brain is disrupted. This disruption in blood flow occurs when either a blood clot blocks one of the vital blood vessels in the brain (ischemic stroke) or when a blood vessel in the brain bursts, spilling blood into surrounding tissues (hemorrhagic stroke).

The blood supply to the brain is very important. The brain needs a constant supply of the oxygen and nutrients carried by the blood in order to function, and even a brief interruption in blood supply can cause major problems. After only a few minutes without blood or oxygen, brain cells begin to die, and when this happens, a stroke results. Due to both the physical and chemical changes that occur in the brain with stroke, damage can continue to occur for several days.

When brain cells die, that particular area of the brain loses function. Because different areas of the brain control different bodily functions, this may lead to impairments involving movement, speech, thinking and memory, bowel and bladder control, eating, emotional control and other vital body functions. The specific abilities affected and likelihood of recovery depend on the size and location of the stroke. A small stroke may result in only minor problems such as weakness in an arm or leg. Larger strokes may cause paralysis (inability to move part of the body), loss of speech or even death.

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Stroke survivor teams up with Norton Neuroscience Institute to support others

A Stroke of Grace, a nonprofit organization, offers virtual support groups twice a month along with education and awareness for stroke prevention.

What Are the Different Types of Strokes?

Strokes fall into several major categories based on whether the disrupted blood supply is caused by a blocked blood vessel or a hemorrhage. Since each type of stroke has a different type of treatment, it is very important for the physician to determine the cause of the stroke, as well as the location, as quickly as possible.

Ischemic strokes occur when a blood vessel within the brain tissue is clogged, typically by a blood clot (also called a cerebral embolism or thrombus). Over 80 percent of all strokes are ischemic.

Ischemic strokes are divided into two groups:

  • Thrombotic strokes are caused by a blood clot that develops in the blood vessels inside the brain. This type of stroke usually occurs in older persons, especially those with high-cholesterol levels and atherosclerosis (a buildup of fat and lipids inside the walls of blood vessels). Symptoms of a thrombotic stroke often occur suddenly, most often during sleep or in the early morning. On occasion, a thrombotic stroke may occur gradually over a period of hours or even days — this is called a “stroke-in-evolution.”
  • Embolic strokes are caused by a blood clot that develops somewhere in the body outside of the brain and then travels to one of the blood vessels in the brain via the bloodstream. This type of stroke often results from heart disease or heart surgery and occurs rapidly without any warning signs. About 15 percent of embolic strokes occur in people with atrial fibrillation, a type of abnormal heart rhythm in which the upper chambers of the heart do not beat effectively.

Hemorrhagic strokes occur when a blood vessel that supplies the brain ruptures and bleeds into surrounding brain tissue. When an artery bleeds into the brain, the affected brain cells and tissues do not receive necessary oxygen and nutrients. In addition, pressure builds up in surrounding tissues, and irritation and swelling occur. About 20 percent of strokes are caused by hemorrhage.

Hemorrhagic strokes are divided into two main categories:

  • Intracerebral hemorrhage is caused when an abnormal artery within the brain bursts, flooding the surrounding brain tissue with blood. Intracerebral hemorrhage is usually caused by hypertension (high blood pressure), and bleeding occurs suddenly and rapidly. There are usually no warning signs and bleeding can be severe enough to cause coma or death.
  • Subarachnoid hemorrhage is caused by bleeding in the subarachnoid space (the space between the brain and the skull). This type of hemorrhage is often due to an aneurysm (an abnormal “bulging” of a blood vessel in the brain) or cerebral vascular malformation (a cluster of abnormal blood vessels in the brain). In the case of an aneurysm, the weak spot in the vessel wall can be stretched out over the course of years, often by high blood pressure, which eventually causes it to rupture.

Transient ischemic attacks (TIAs) are minor or warning strokes that may indicate the possibility of a major ischemic stroke to come. About one-third of all strokes are preceded by one or more of these “mini-strokes” which can occur days, weeks or even months before. TIAs are caused by a temporary disruption in the brain’s blood supply. Although TIAs usually clear up naturally and are short lived, a TIA should be taken very seriously, and medical attention should be sought immediately.

Following a TIA, the body soon returns to normal, so it is easy to ignore it and believe that the problem has disappeared. This is extremely dangerous, however, because the underlying problem that caused the TIA continues to exist; the TIA is often an early warning sign of a more serious and debilitating stroke in the future.

What Are Some Conditions That Cause Strokes?

  • Carotid stenosis – A condition caused by a blockage or narrowing of the carotid arteries in the neck. This blockage is caused by a buildup of plaque or fatty materials in the walls of the arteries, and as a result, blood flow to the brain is disrupted.
  • Aneurysm – A weakened, ballooned area on an artery wall. As this area continues to stretch out over time, it is at high risk for rupturing. Aneurysms may be congenital (present at birth) or may develop later in life due to such factors as hypertension (high blood pressure) or atherosclerosis (build up of fatty materials on artery walls).
  • Arteriovenous malformation (AVM) – A congenital disorder that consists of a disorderly, tangled web of arteries and veins in the brain or spinal cord. These abnormal clusters often bleed into the brain, causing a cerebral hemorrhage.

What Are the Risk Factors of Stroke?

The most common risk factors for stroke are listed below. They include some conditions that can be changed by modifying your lifestyle or seeking medical treatment, as well as conditions that cannot be changed, such as hereditary factors.

Risk factors for stroke that can be changed, treated or medically managed include:

  • High blood pressure (hypertension) is the most important risk factor for stroke. Even mild hypertension, if not adequately treated, increases your risk for stroke. Generally, a blood pressure of 120/80 or lower is ideal. Controlling blood pressure, whether by a low-sodium diet, weight control, regular exercise, stress management and/or medication is an important means of reducing your risk of stroke.
  • Heart disease is the second most important risk factor for stroke and the major cause of death among stroke survivors. Having regular medical checkups is important so that your physician can monitor this factor. Heart disease, including such conditions as irregular heart rhythms, heart attacks and heart valve disorders can be helped by seeking appropriate medical treatment.
  • High red blood cell count thickens the blood and makes clots more likely, thus increasing the risk for stroke. Even a moderate increase in red blood cells can increase stroke risk.
  • High blood cholesterol and lipids increase the risk for brain attack, but can be controlled by proper medical treatment and appropriate diet and lifestyle modifications.
  • Lack of exercise and physical inactivity increase stroke risk by promoting excess fat storage in the body. Physical inactivity is also linked to higher levels of atherosclerosis, which also increases stroke risk.
  • Obesity and being overweight strain the heart and blood vessels and are associated with high blood pressure. Obesity also predisposes a person to diabetes and heart disease, both of which increase the chances of stroke.
  • Cigarette smoking greatly increases stroke risk, especially when combined with the use of oral contraceptives. The good news is that stroke risk declines dramatically within a few years of stopping smoking.
  • Excessive alcohol use (more than two drinks per day) raises blood pressure, and binge drinking increases stroke risk even further. Healthy young adults who are heavy drinkers are just as susceptible to the risk of stroke as are older people.
  • Intravenous drug abuse carries a high risk of stroke from cerebral embolisms (blood clots). Cocaine use has been closely linked to strokes, heart attacks and a variety of other cardiovascular complications; some of them, even among first-time cocaine users, have been fatal.
  • Use of oral contraceptives,especially those with high levels of estrogen, appear to increase the risk of blood clots, including clots that cause stroke. Women over age 30 are especially at risk. The risk is even higher in women who smoke.
  • Diabetes increases stroke risk due to the circulatory problems caused by the disease. However, good control of diabetes seems to reduce the cardiovascular complications.
  • Stress tends to increase blood pressure, so it indirectly increases one’s risk of stroke. Stress management, including relaxation techniques, exercise, biofeedback and/or counseling, tends to be helpful in the treatment of high blood pressure, thus lowering the risk of stroke.

Risk factors for stroke that cannot be changed include:

  • Age  For each decade of life after age 55, the chance of having a stroke more than doubles. Two-thirds of all strokes occur in people over age 65.
  • Race  African Americans have a much higher risk of death and disability from stroke than Caucasians, in part because the African-American population has a greater incidence of high blood pressure. Furthermore, they are more likely to suffer strokes at an earlier age.
  • Gender  For reasons that remain unclear, stroke is 25 percent more common in men than in women.
  • Family or individual history of stroke or TIAs  A history of cerebrovascular disease in a family appears to place an individual at a higher risk for stroke. In addition, if you have experienced a stroke or transient ischemic attack (TIA) in the past, you are at a greatly increased risk for having a stroke in the future. A person who has had one or more TIAs is almost 10 times more likely to have a stroke than someone of the same age and sex who has not had a TIA.

Other risk factors of stroke to consider include:

  • Where a person lives  Strokes are more common among people living in the southeastern United States than in other areas. This may be due to regional differences in lifestyle, race, cigarette smoking and diet.
  • Temperature, season and climate  Stroke deaths occur more often during periods of extreme temperatures.
  • Socioeconomic factors  There is some evidence that strokes are more common among low-income people than among more affluent people.

What Are the Warning Signs of Stroke?

Stroke warning signs include:

  • Sudden weakness, numbness or paralysis of the face, arm or leg – especially on one side of the body
  • Difficulty talking or understanding language
  • Sudden loss of vision or double vision, particularly in only one eye
  • Severe headache with no apparent cause
  • Unexplained dizziness, loss of balance or coordination — especially if associated with any of the above symptoms

Not all of these warning signs occur with every stroke, so if you experience any combination of these symptoms, seek help immediately. When symptoms of a stroke occur and then resolve on their own in a short period of time, an individual may have experienced a transient ischemic attack (TIA). Although TIAs usually go away within minutes, they should be taken very seriously because they are major warning signs of an impending stroke to come; one out of every 10 major stroke victims first experiences a warning TIA. The lag between a TIA and a major stroke may be hours, days or even months. However, one-fifth of all strokes that follow a TIA occur within the month and half occur within the same year.

What Should I Do If I Suspect I Am Having a Stroke?

According to the National Stroke Association, it is important to learn the three R’s of stroke:

  • Reduce the risk.
  • Recognize the symptoms.
  • Respond by calling 911.

Stroke is an emergency and should be treated as such. The greatest chance for recovery from stroke occurs when emergency treatment is started immediately. The sooner a brain attack victim seeks medical attention, the better. New and emerging therapies are showing promise, but all must be started in the first few hours following the onset of symptoms.

If you or someone you know should experience stroke symptoms, call 911 immediately — do not wait!

Care That’s Focused on You

It’s part of Norton Neuroscience Institute’s goal to care for the whole person, not just the condition.

  • Norton Neuroscience Institute Resource Centers offer ways to improve your access to care, provide valuable information on managing your disease and address your quality of life issues. The Norton Healthcare Foundation funds this important service, so patients don’t need to pay.
  • Dedicated patient navigators provide assistance securing transportation to and from Norton Healthcare facilities, schedule follow-up appointments, coordinate prescription assistance, create customized diet plans and provide guidance on disability benefits, housing, financial and employment concerns and more.
  • Patients can access support groups, exercise classes and other educational events to connect with others and learn how to make the most of life while managing a neurological condition. 
  • Access an on-demand video library of educational content across a variety of condition related topics is available.
  • We want to help prevent illness. Get help quitting smoking and learn the signs of stroke.
  • Communicate with your provider, manage appointments, refill prescriptions and more anytime from a computer or mobile device with a free MyNortonChart account.

Award-winning Stroke Care

  • Norton Healthcare’s four adult service hospitals in Louisville are certified by DNV Healthcare, representing the highest level of care.
    • Norton Brownsboro Hospital is recognized as a Comprehensive Stroke Center.
    • Norton Audubon Hospital and Norton Hospital are Primary Stroke Centers.
    • Norton Women’s & Children’s Hospital is an Acute Stroke Ready Hospital.
  • Norton Brownsboro Hospital and Norton Hospital have been nationally recognized for their quality of advanced stroke care by the American Heart Association/American Stroke Association Get With the Guidelines – Stroke Quality Achievement Awards.
    • Norton Brownsboro Hospital received a Gold Plus designation.
    • Norton Hospital received Silver designation.
  • Norton Healthcare adult-service hospitals in Louisville ranked as “high performing” for stroke on the 2022-23 U.S. News & World Report annual list of the best hospitals across the country.

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