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What is a Stroke?

Definition  |  TIA |  Prevention |  Aspirin Therapy  |  Needed Research

picture showing an ischemic area of the brain caused by a lack of oxygen

Definition

A Stroke is an acute medical emergency. Stroke (also called "Brain Attack") is a disease of the circulatory system caused by the rupturing or the blockage of an artery. In middle aged and older women, approximately 70% of strokes are thromboembolic (caused by a blockage from a blood clot), 15% consist of intracerebral hemorrhage, and 10% of subarachnoid hemorrhage. Depending on where the rupture or blocked artery leads, this part of the brain does not get oxygen. This can result in permanent brain damage, disability and sometimes death.

When a section of the brain is deprived of oxygen, neurological symptoms result, such as loss of vision in one eye (or other vision changes), confusion, vertigo, inability to speak, numbness or weakness of one side of the body, severe headache and asymmetrical drooping of the face. These symptoms require immediate attention by emergency room doctors.

Hospitals vary as to the care given to persons with stroke. Ask your healthcare professional which area hospitals provide the best emergency treatment for stroke.

Transient Ischemic Attack (TIA)

"TIA" is a transient ischemic attack or episode that describes when part of the brain is not getting enough oxygen for a short period of time. It causes symptoms of stroke that appear, but then subside. Symptoms are focal and usually consist of weakness and numbness. Symptoms can last a few minutes or up to 24 hours before improving. According to the National Stroke Association, this is a stroke warning sign and still needs to be tended to as a medical emergency. Only a doctor can make determination as to whether a person is having a stroke, a TIA or a migraine episode.

Stroke Prevention

Controlling hypertension is the single most important consideration for stroke prevention. It is the leading risk factor for stroke in both men and women. Data from the Framingham study indicate that after the age of 45, elevations of systolic pressure are more predictive of subsequent stroke than are elevations of diastolic pressure. It is clear that the control of both systolic and diastolic blood pressure is effective in the prevention of stroke.

Treating established cardiac disease can prevent stroke. The combination of atrial fibrillation with rheumatic cardiac valvular disease presents a very high risk of subsequent stroke, and is an indication for anticoagulation. Non-rheumatic atrial fibrillation also presents a definite risk, although less than that with rheumatic disease. Warfarin is the drug of choice for treatment of atrial fibrillation, but for those unable to take warfarin, aspirin can be effective as an anticoagulant, but to a lesser degree.

Drinking low to moderate amounts of alcohol was shown to have a protective effect on the cerebral vasculature but heavy alcohol consumption predisposed individuals to hemorrhagic and non-hemorrhagic stroke, including subarachnoid hemorrhage. Stroke rate was somewhat higher in those who don't drink alcohol at all.

Avoiding estrogen therapy may be preventive. Women on birth control pills have a higher incidence of stroke, however, with the newer, low-dose pills, the risk is thought to be negligible (further study is needed). None-the-less, risk is greatest for women over 35 who take birth control pills and who smoke cigarettes. Results of the HERS trial examining estrogen replacement therapy in women with established heart disease also showed an increase rate of stroke for those taking estrogen hormone.

Other risk factors that may help prevent stroke are smoking cessation, control of diabetes and decreased obesity, however, more definitive epidemiologic studies are needed. Studies as it regards primary prevention in stroke are lacking.

Even less clear in stroke prevention is the relationship to blood cholesterol levels. Surprisingly, while having elevated serum cholesterol and other lipoproteins is a risk factor for coronary heart disease, it may not be for stroke. In the Framingham study, after age 55, there was an inverse relationship of total serum cholesterol to subsequent stroke. Thus far, data concerning the relationship between the risk of stroke and the ratio of total serum cholesterol and low-density lipoprotein to high-density lipoprotein cholesterol must be considered inconsistent and somewhat controversial.

Aspirin Therapy in Women

Study results are conflicting regarding the role of aspirin and stroke prevention in women. While aspirin appears to be beneficial for men in preventing a stroke, it's role is not as well understood in women. One study did show benefit from aspirin if combined with the drug dipyridamole, however, dipyridamole was found to be ineffective in earlier studies. Another drug - ticlopidine - if given after a TIA or small stroke, definitely reduces the subsequent rate of events in both men and women. (ref.: Canadian-American Ticlopidine Study). Whether ticlopidine is superior to aspirin is subject to debate since ticlopidine probably has more side-effects than aspirin.

Needed Research

Black women have the highest prevalence of stroke of any group. In several population studies, black women had a higher incident rate of stroke than white women in every age group. Survivorship and outcome following stroke appear to be poorer in blacks than in whites. (The relative risk for stroke associated with hypertension and diabetes mellitus was unrelated to race.) A more complete understanding of the determinants of stroke may be required to account for the excess risk of stroke among black women.

Major studies are also needed on various issues in the primary prevention of stroke in women. Among possible interventions to be studied are:

A multiple-risk-factor intervention trial of the impact of weight loss, cigarettes smoking cessation and control of diabetes mellitus in women at high risk for stroke would be of particular benefit.

Studies of secondary prevention are easier to accomplish since the event rate is higher and such studies usually have a greater power to detect meaningful difference between treatment and control groups. Studies are needed in regard to the value of rehabilitation for a woman as a form of tertiary prevention of disability after stroke.

For Dietary Approaches to Stop Hypertension, go to DASH diet. For information on the Mediterranean diet, click here. For Health Guide on Controlling High Blood Pressure, click here.


Research Note 1: A recent report published in the Journal of the American Medical Association (Mar98) showed that decreased fat in the diet of men increased the risk of stroke. The study reported that people who ate about 20% less fat than average had two to three times the risk of stroke. But those who ate more than the average amount of fat were not better off than those who ate the average amount (40 percent of total calories from fat). The latter fact is important because of the negative effect of too much fat in the diet on health problems such as heart disease and obesity. The researchers suggested that certain fats in the diet are responsible for the prevention of strokes. Two fatty acids discussed were palmitoleic acid and alpha-linolenic acids. Further research is needed to learn about the role of different kinds of dietary fat and disease prevention. 

Research Note 2: In a recent report on the HERS trial examining the risk and benefit of hormone replacement in secondary prevention of heart disease in women, study results revealed an increase in death rates from stroke and pulmonary emboli for those taking HRT (Hormone Replacement Therapy). The women in the study were given the hormones estrogen and progestin. For more information, go to HRT article.

Source: Derived from Proceedings of an NHLBI Conference: Cardiovascular Health and Disease in Women: "Stroke and Women" by Applegate,W., MD, MPH. Chap50,  p313-318. Editors: Nanette K. Wenger, MD, L. Speroff, MD, B. Packard, MD, PhD., copyright 1993, Le Jacq Communications Publishing Company. Used by persmission.

Stroke  |  What is a Stroke?  |  Stroke: Are You at Risk?  |  Stroke Warning Signs  |  Atrial Fibrillation (AF)   |  Pulse Check Twice a year to Screen for AF |  Stroke Facts

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1999-2000; updates: 2002, 2004, 2005, 2007 Women's Heart Foundation, Inc. All rights reserved. Unauthorized use prohibited. The information contained in this Women's Heart Foundation (WHF) Web site is not a substitute for medical advice or treatment, and WHF recommends consultation with your doctor or health care professional.