Stroke

Overview

The two main types of stroke are ischemic and hemorrhagic:

Ischemic stroke. Most strokes in the United States fall into this category. Ischemic strokes happen when a blood clot blocks the blood supply to part of the brain, preventing cells from getting oxygen and nutrients. Within a few minutes, those cells may begin to die.

The underlying cause is usually atherosclerosis, a condition in which blood vessels have become narrowed or blocked by a buildup of fatty deposits called plaque. Atherosclerosis can lead to an ischemic stroke in one of two ways:

• It can cause a cerebral thrombosis, a clot in a blood vessel leading to the brain.
• It can cause a cerebral embolism, a clot that formed in a blood vessel somewhere other than the brain (usually the heart, neck or chest) and then traveled and lodged in an artery in the brain.

Hemorrhagic stroke. This occurs when a blood vessel in the brain leaks or ruptures in one of two ways:

• Intracerebral hemorrhage. A blood vessel in the brain is bleeding into surrounding tissue. Accumulating blood can exert pressure on the brain. High blood pressure is a common cause.
• Subarachnoid hemorrhage. This is bleeding in the space between the brain and the lining that surrounds it. The cause is usually an aneurysm, a weak area in the blood vessel wall that can stretch and burst. It’s also important to be aware of a stroke-related condition called a transient ischemic attack:

Transient ischemic attack (TIA). A TIA is a stroke-like event that can cause temporary symptoms. TIAs occur when a narrowed artery or blood clot temporarily reduces the brain’s blood supply. Possible symptoms include numbness, weakness or tingling in one arm or leg and problems with speech, vision or balance.

A TIA goes away in a few minutes or hours and usually doesn’t cause permanent brain injury. However, it may be a warning sign of an upcoming stroke, so don’t ignore the symptoms. If you have symptoms of a TIA, seek immediate medical attention. There are treatments that reduce your chance of having another TIA or a stroke.

Risk factors for stroke

Anyone can have a stroke at any age, but certain factors increase the risk of having one. Some can be treated and changed, while others are beyond your control. Even if you can’t modify a risk factor, knowing about it may encourage you to take steps to reduce your overall risk.

Stroke risk factors that people can manage or modify include:

High blood pressure (hypertension). High blood pressure can damage the arteries that supply blood to the brain. Lowering it will greatly reduce your risk of having a stroke or heart attack.

Cardiovascular disease. Several heart conditions can cause blood clots and other blockages that raise stroke risk. These include coronary artery disease, a previous heart attack, congestive heart failure, a diseased aortic valve, atrial fibrillation and some congenital heart defects.

Cigarette smoking. The nicotine and carbon monoxide in cigarette smoke can damage the cardiovascular system, giving smokers almost double the risk of stroke that nonsmokers have. (Exposure to secondhand smoke also raises stroke risk.) If you smoke and take oral contraceptives, your risk of having a stroke is even higher.

Carotid artery disease. The carotid arteries supply the brain with blood. In this disorder, the vessels are narrowed by fatty deposits and can become blocked by a blood clot or produce a blood clot that leads to a stroke.

Diabetes mellitus. Having diabetes doubles the risk of stroke. Many people with diabetes also have high blood pressure, obesity and high cholesterol, all of which further raise stroke risk.

Undesirable cholesterol levels. High bloodstream levels of low-density lipoprotein (LDL) cholesterol and/or low levels of high-density lipoprotein (HDL) cholesterol can cause fatty deposits to build up in arteries, increasing stroke risk.

Obesity. Excess weight can double the risk of an ischemic stroke.

Lack of physical activity. This raises the risk of high blood pressure and therefore the risk of stroke. Being active for at least 30 minutes a day – through simple cumulative measures, such as taking the stairs instead of an elevator, or going on a daily brisk walk – can reduce your risk.

Birth control pills and hormone therapy. Women who take birth control pills, especially those who smoke and are 35 or older, have a higher risk of stroke. Women using hormone therapy for menopause are also at higher risk.

Substance abuse. Alcohol overuse can contribute to medical conditions that raise stroke risk, such as high blood pressure and diabetes. Commonly abused illicit drugs, including cocaine, amphetamines and heroin, are also associated with an increased risk, including in younger people.

Sleep apnea. A history of apnea – when breathing repeatedly stops and starts during sleep – increases the chance of having a stroke.

Risk factors that you can’t control include:

Family history. The risk of having a stroke is higher if one of your parents or siblings has had a stroke.

Age. Your risk of stroke increases as you get older, doubling every 10 years after age 55.

Sex. Before age 55, men are more likely than women to have strokes. After 55, the risk is the same for men and women. However, because women tend to live longer, they’re more likely than men to die of a stroke.

Previous stroke, TIA or heart attack. Once you’ve had a stroke, you’re at greater risk for having another one. A TIA also elevates your risk: About 1 in 3 people who experience a TIA have a stroke within one year. The risk is highest during the first 48 to 72 hours after a TIA.

Race. African Americans have a higher incidence of stroke and risk of death from stroke than white Americans. Asian Americans have a higher incidence of hemorrhagic stroke than other ethnic groups.

The Sali International Hospital offers preventive care and screening for patients at high risk of stroke, as well as the latest treatments and tools for patients who have had one. Our doctors have played key roles in developing methods for safely removing blood clots from patients experiencing a stroke. We’re also one of the premier institutions for treating patients with cerebral aneurysms (weak areas in artery walls that may rupture) and subarachnoid hemorrhage.

As a world-class stroke research program, we apply the latest study findings and technologies to developing and evaluating new treatments that might improve stroke recovery and outcomes. Interested patients may have opportunities to participate in clinical trials (studies of promising treatments).