TRANSIENT ISCHEMIC ATTACK

TRANSIENT ISCHEMIC ATTACK

You may download this file. Download

A stroke occurs when blood flow to a part of the brain is interrupted or severely reduced. This deprives part of the brain of oxygen and nutrients, which can destroy brain cells and result in some degree of permanent disability. Stroke symptoms may include trouble walking and speaking, as well as paralysis or numbness on one side of the body. Prompt treatment is essential. The longer a stroke goes untreated, the greater the risk of permanent disability.

definition

Rushing through the grocery store, you suddenly lose some of the feeling in your right arm and leg. You grab some shelves to steady yourself. You try to talk to a fellow shopper, but your words sound garbled and listeners seem confused by your speech. Then, after a few minutes, your signs and symptoms disappear and you go on with your shopping.

You may have experienced a temporary or intermittent neurological event called a transient ischemic attack (TIA). Ignoring this episode could have serious consequences for your health.

Even though a transient ischemic attack doesn't last very long and leaves no permanent effects, it's far from an insignificant event. About one in three people who have a transient ischemic attack eventually have a stroke, with about half occurring during the year after the transient ischemic attack.

A transient ischemic attack can serve as both a warning and an opportunity — a warning of an impending stroke and an opportunity to take steps to prevent it.

Symptoms

Transient ischemic attacks usually last for a few minutes. Most signs and symptoms disappear within an hour, and, by definition, all effects disappear within 24 hours. The signs and symptoms of TIA resemble those found early in a stroke and may include:

• Sudden weakness, numbness or paralysis in your face, arm or leg, typically on one side of your body
• Slurred or garbled speech or difficulty understanding others
• Sudden blindness in one or both eyes or double vision
• Dizziness, loss of balance or loss of coordination

You may have more than one TIA, and the recurrent signs and symptoms may be similar or different depending on which area of the brain is involved. If signs and symptoms last longer than 24 hours, it's considered a stroke.

Causes

The cause of a transient ischemic attack is a temporary decrease in blood supply to part of your brain. Most attacks last just a few minutes.

A transient ischemic attack has the same origins as that of an ischemic stroke. In ischemic strokes, which are the most common type of stroke, a clot blocks the blood supply to part of your brain. But in contrast to a stroke, which involves a more prolonged lack of blood supply and causes some permanent damage to your brain tissue, a TIA doesn't leave lasting effects to your brain.

The underlying cause of a TIA often is a buildup of cholesterol-containing fatty deposits called plaques (atherosclerosis) in an artery or one of its branches that supply oxygen and nutrients to your brain. Plaques can decrease the blood flow through an artery or lead to the development of a clot. Other causes include a blood clot moving to your brain from another part of your body, most commonly from your heart.

Risk factors

You can't change the following risk factors for transient ischemic attack and stroke. But knowing you're at risk can motivate you to change your lifestyle to reduce other risks.

• Family history. Your risk may be greater if one of your family members has had a TIA or a stroke.
• Age. Your risk increases as you get older.
• Sex. Men generally have a higher incidence of TIA and stroke than women do, but when it comes to deaths from stroke, the gender difference reverses. More than half of total deaths from stroke occur in women.
• Race. Blacks are at greater risk of dying of a stroke than are people of other races. The reason is partly because of their higher prevalence of high blood pressure and diabetes.

You can control the following risk factors:

• High blood pressure. Having high blood pressure — 140/90 millimeters of mercury or higher — increases your risk of TIA or stroke. Poor diet, lack of exercise and being overweight contribute to this risk factor.
• Cardiovascular disease. Conditions including a previous heart attack, heart valve abnormalities, a patent foramen ovale, acute heart valve disease and atrial fibrillation — an irregular and, often, rapid heartbeat — increase your risk. Your heart doesn't pump blood as efficiently with these conditions, or it beats irregularly, allowing blood clots to form in the chambers of your heart that can break off and travel to the brain.
• Cigarette smoking. Smoking contributes to development of cholesterol-containing fatty deposits in your arteries (atherosclerosis). Nicotine increases your heart rate and blood pressure. The carbon monoxide in cigarette smoke replaces some of the oxygen in your blood, decreasing the amount of oxygen delivered to your tissues, including your brain. Smoking also increases the risk of blood clots.
• Diabetes. Diabetes increases the severity of atherosclerosis — narrowing of the arteries due to accumulation of fatty deposits — and the speed with which it develops.
• Undesirable levels of blood cholesterol. High blood levels of low-density lipoprotein (LDL) cholesterol — the "bad" cholesterol — and triglycerides, or low levels of high-density lipoprotein (HDL) cholesterol — the "good" cholesterol — increase your risk of narrowed or blocked arteries.
• Elevated homocysteine level. Homocysteine — an amino acid and a building block of proteins — naturally occurs in your blood. Elevated levels of homocysteine can cause arteries to thicken and scar, making it more likely that cholesterol will clog arteries. B complex vitamins — B-6, B-12 and folic acid — have been shown to reduce blood levels of homocysteine. However, it isn't known whether taking supplements will reduce the likelihood of a stroke.
• Blood disorders. Some blood disorders, such as sickle cell anemia, increase the risk of stroke because blood abnormalities can cause blood cells to be stickier and more likely to cling to artery walls, blocking them.
• Sleep apnea. People with this sleep disorder seem to have a higher risk of stroke, which may be because people with sleep apnea also seem to have an increased risk of high blood pressure, a known risk factor for stroke.
• Migraine. Some studies have found that people who have chronic headaches have an increased risk of stroke. However, since not all studies have found this association, additional research is needed to confirm this finding.
• Sedentary lifestyle. People with limited physical activity are at increased risk of stroke. A brisk walk or some other exercise, if done on a regular basis, may lessen your risk of stroke.
• Obesity. Your risk of stroke increases if you're overweight. Obesity can also increase your blood pressure and your risk of diabetes.
• Carotid artery disease. Your doctor may hear a noise (bruit) over the arteries in the front part of your neck (carotid arteries) and then may recommend some studies of these arteries. If your doctor detects moderate to severe narrowing, your risk of stroke may be elevated, even though you haven't had signs or symptoms. You may need additional treatment to prevent a stroke from occurring.
• Peripheral artery disease. In peripheral artery disease, fatty deposits build up on the artery walls in the legs and arms, narrowing the arteries. Anyone with peripheral artery disease has an increased risk of carotid artery disease, which increases stroke risk.
• Heavy drinking. While moderate drinking — up to two drinks daily for men and one drink daily for women — is associated with a reduced risk of stroke, drinking more than this appears to increase stroke