Stroke

What is stroke?

Stroke is an abrupt interruption of constant blood flow to the brain that causes loss of neurological function. The interruption of blood flow can be caused by a blockage, leading to the more common ischemic stroke, or by bleeding in the brain, leading to the more deadly hemorrhagic stroke. Ischemic stroke constitutes an estimated 80 percent of all stroke cases. Stroke may occur suddenly, sometimes with little or no warning, and the results can be devastating.

It is crucial that proper blood flow and oxygen be restored to the brain as soon as possible. Without oxygen and important nutrients, the affected brain cells are either damaged or die within a few minutes. Once brain cells die, they cannot regenerate, and devastating damage may occur, sometimes resulting in physical, cognitive and mental disabilities.

Stroke Statistics

Stroke is the third leading cause of death in the United States. Statistics indicate that 157,803 people in the United States died from cerebrovascular disease in 2003. Of the more than 700,000 people affected every year, about 500,000 of these are first attacks, and 200,000 are recurrent. About 25 percent of people who recover from their first stroke will have another stroke within five years. Stroke is a leading cause of serious long-term disability, with an estimated 5.4 million stroke survivors currently alive today. The American Heart Association estimates that in 2003, stroke cost about $51.2 billion in both direct and indirect costs in the United States alone.

Understanding the factors that increase your risk of a stroke and recognizing the symptoms may help you prevent a stroke. Receiving early diagnosis and treatment may improve your chances for complete recovery.

What are the risk factors for stroke?

Although they are more common in older adults, strokes can occur at any age. Controllable or treatable risk factors for stroke include:

• Smoking: You can decrease your risk by quitting smoking. Your risk may be increased further if you use some forms of oral contraceptives and are a smoker. There is recent evidence that long-term secondhand smoke exposure may increase your risk of stroke.
• High blood pressure: Blood pressure of 140/90 mm Hg or higher is the most important risk factor for stroke. It usually has no specific symptoms and no early warning signs. That’s why it is important to have your blood pressure checked regularly. Controlling your blood pressure is crucial to stroke prevention.
• Carotid or other artery disease: The carotid arteries in your neck supply blood to your brain. A carotid artery narrowed by fatty deposits from atherosclerosis (plaque buildups in artery walls) may become blocked by a blood clot. Carotid arteries are treated by neurosurgeons through carotid endarterectomy, a procedure in which an incision is made in the neck and plaque is removed from the artery.
• History of transient ischemic attacks (TIAs ): About 30 percent of stroke patients have a history of TIAs. Common temporary symptoms include difficulty speaking or understanding others, loss or blurring of vision in one eye, and loss of strength or numbness in an arm or leg. Usually these symptoms resolve in less than 10 to 20 minutes, and almost always within one hour. Even if all the symptoms resolve, it is very important that anyone experiencing these symptoms call 911 and immediately be evaluated by a qualified physician.
• Diabetes: It is crucial to control your blood sugar levels, blood pressure, and cholesterol levels. Diabetes, especially when untreated, puts you at greater risk of stroke and has many other serious health implications.
• High blood cholesterol: A high level of total cholesterol in the blood (240 mg/dL or higher) is a major risk factor for heart disease, which raises your risk of stroke. Recent studies show that high levels of LDL (bad) cholesterol (greater than 100 mg/dL) and triglycerides (blood fats, 150 mg/dL or higher) increase the risk of stroke in people with previous coronary heart disease, ischemic stroke or TIAs. Low levels (less than 40 mg/dL) of HDL (good) cholesterol also may increase stroke risk. You can often improve your cholesterol levels by decreasing the salt and saturated fat in your diet. However, some people inherit genes associated with elevated levels of cholesterol. Although they may eat well and exercise, they still may have high cholesterol, and must take medication to control it.
• Physical inactivity and obesity: Being inactive, obese or both can increase your risk of high blood pressure, high blood cholesterol, diabetes, heart disease and stroke. Getting 30 minutes of moderate exercise, five days a week can help reduce your risk of stroke. Check with your health care provider first before starting any exercise program if you have any health problems or have been inactive.
• Recent research shows evidence that people receiving hormone replacement therapy (HRT) have an overall 29 percent increased risk of stroke, in particular ischemic stroke.

Uncontrollable risk factors include:

• Age: People of all ages, including children, have strokes. But the older you are, the greater your risk of stroke.
• Gender: Stroke is more common in men than in women. In most age groups, more men than women will have a stroke in a given year. However, women account for more than half of all stroke deaths. Women who are pregnant have a higher stroke risk. Some research has indicated that women may experience and interpret stroke symptoms differently than men, causing them to delay seeking medical care, and contributing to their higher stroke mortality rates.
• Heredity and race: You have a greater risk of stroke if a parent, grandparent, sister or brother has had a stroke. Blacks have a much higher risk of death from a stroke than Caucasians do, partly because they are more prone to having high blood pressure, diabetes and obesity.
• Prior stroke or heart attack: If you have had a stroke, you are at much higher risk of having another one. If you have had a heart attack, you are also at higher risk of having a stroke.

What are the symptoms of a stroke?

The range and severity of early stroke symptoms vary considerably, but they share the common characteristic of being sudden. Warning signs may include some or all of the following symptoms:

• Dizziness, nausea, or vomiting
• Unusually severe headache
• Confusion, disorientation or memory loss
• Numbness, weakness in an arm, leg or the face, especially on one side
• Abnormal or slurred speech
• Difficulty with comprehension
• Loss of vision or difficulty seeing
• Loss of balance, coordination, or the ability to walk

What are the effects of a stroke?

The effects of a stroke depend primarily on the location of the obstruction and the extent of brain tissue affected. One side of the brain controls the opposite side of the body, so a stroke affecting the right side will result in neurological complications on the left side of the body. A stroke on the right side may result in the following:

• Paralysis on the left side of the body
• Vision problems
• Quick, inquisitive behavior
• Memory loss

A stroke on the left side may result in the following:

• Paralysis on the right side of the body
• Speech/language problems
• Slow, cautious behavior
• Memory loss

How are strokes treated?

Rehabilitation following a stroke may involve a number of medical specialists; but the early diagnosis of a stroke, its treatment or its prevention, can be undertaken by a neurosurgeon.

Rapid and accurate diagnosis of the kind of stroke and the exact location of its damage is critical to successful treatment. Such technical advances as the use of the operating microscope (microsurgery) and the surgical laser have made it possible to treat stroke problems that were thought to be inoperable a few years ago.

Ischemic stroke is treated by removing obstruction and restoring blood flow to the brain. One treatment for ischemic stroke is the FDA-approved drug, tissue plasminogen activator (tPA), which must be administered within a three-hour window from the onset of symptoms to work best. Unfortunately, only 3 to 5 percent of those who suffer a stroke reach the hospital in time to be considered for this treatment. This medication carries a risk for increased intracranial hemorrhage and is not used for hemorrhagic stroke.

Hemorrhagic stroke usually requires surgery to relieve intracranial (within the skull) pressure caused by bleeding. Surgical treatment for hemorrhagic stroke caused by an aneurysm or defective blood vessel can prevent additional strokes. Surgery may be performed to seal off the defective blood vessel and redirect blood flow to other vessels that supply blood to the same region of the brain.
Endovascular treatment involves inserting a long, thin, flexible tube (catheter) into a major artery, usually in the thigh, guiding it to the aneurysm or the defective blood vessel, and inserting tiny platinum coils (called stents) into the blood vessel through the catheter. Stents support the blood vessel to prevent further damage and additional strokes.

The Merci Retriever, approved recently by the FDA, is a corkscrew- shaped device used to help remove blood clots from the arteries of stroke patients. A small incision is made in the patient’s groin, into which a small catheter is fed until it reaches the arteries in the neck. At the neck, a small catheter inside the larger catheter is guided through the arteries until it reaches the brain clot. The Merci Retriever, a straight wire inside the small catheter pokes out beyond the clot and automatically coils into a corkscrew shape. It is pulled back into the clot, the corkscrew spinning and grabbing the clot. A balloon inflates in the neck artery, cutting off blood flow, so the device can pull the clot out of the brain safely. The clot is removed through the catheter with a syringe.

Recovery and rehabilitation are important aspects of stroke treatment. In some cases, undamaged areas of the brain may be able to perform functions that were lost when the stroke occurred. Rehabilitation includes physical therapy, speech therapy, and occupational therapy.

• Physical therapy involves using exercise and other physical means (e.g., massage, heat) and may help patients regain the use of their arms and legs and prevent muscle stiffness in patients with permanent paralysis.
• Speech therapy may help patients regain the ability to speak.
• Occupational therapy may help patients regain independent function and relearn basic skills (e.g., getting dressed, preparing a meal, and bathing).

This information is provided courtesy of the American Association of Neurological Surgeons, www.neurosurgerytoday.org, and edited by Johnny Hudson, NP. Updated January 200