Transient Ischemic Attack (TIA)
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.
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.
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.
You can control the following Risk Factors:
- 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.
When to seek medical advice:
- 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 risk.
See your doctor if you suspect you may have had signs or symptoms of a transient ischemic attack. You'll need an immediate medical evaluation to determine what caused the problem. This may require a visit to the emergency department of your nearest hospital. It's important to identify the cause so that you can take steps to prevent a stroke.
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:
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.
- 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
Characteristics of a transient ischemic attack include its rapid onset, short duration and your body's return to its normal state. Your doctor may diagnose a TIA based just on the medical history of the event rather than on anything found during a general physical and neurological examination.
In some people who've experienced a TIA, a physical examination may reveal evidence that suggests the presence of arterial plaques. Your doctor may hear a sound (bruit) over the carotid artery in your neck during an examination. Or your doctor may observe cholesterol fragments (emboli) in the tiny blood vessels of your retina, at the back of your eye, during an eye examination using an ophthalmoscope.
These tests also may help diagnose the cause of a transient ischemic attack:
- Carotid ultrasonography. A wand-like device (transducer) sends high-frequency sound waves into your neck. After the sound waves pass through your tissue and back, your doctor can analyze images on a screen to look for narrowing or clotting in the carotid arteries.
- Computerized tomography (CT) scanning. CT scanning of your head uses X-ray beams to assemble a composite, three-dimensional look at your brain.
- Computerized tomography angiography (CTA) scanning. Scanning of the head may also be used to noninvasively evaluate the arteries in your neck and brain. CTA scanning uses X-rays, similar to a standard CT scan of the head, but may also involve injection of a contrast material into a blood vessel.
- Magnetic resonance imaging (MRI). This procedure, which uses a strong magnetic field, can generate a composite, three-dimensional view of your brain.
- Magnetic resonance angiography (MRA). This is a method of evaluating the arteries in your neck and brain. It uses a strong magnetic field, similar to MRI.
- Transesophageal echocardiography (TEE). During this procedure, a flexible probe with a transducer built into it is placed in your esophagus — the tube that connects the back of your mouth to your stomach. Because your esophagus is directly behind your heart, very clear, detailed ultrasound images can be created, allowing a better view of some things, such as blood clots, that might not be seen clearly in a traditional echocardiography exam.
- Arteriography. This procedure gives a view of arteries in your brain not normally seen in X-ray imaging. A radiologist inserts a thin, flexible tube (catheter) through a small incision, usually in your groin. The catheter is manipulated through your major arteries and into your carotid or vertebral artery. Then, the radiologist injects a dye through the catheter to provide X-ray images of the arteries in your brain.
Once your doctor has determined the cause of your transient ischemic attack, the goal of treatment is to correct the abnormality and prevent a stroke. Depending on the cause of your TIA, your doctor may prescribe medication to reduce the tendency for blood to clot or may recommend surgery or a balloon procedure (angioplasty).
Doctors use several medications to decrease the likelihood of a stroke after a transient ischemic attack. The medication selected depends on the location, cause, severity and type of TIA. Two frequently prescribed types of drugs are:
Surgery and angioplasty (stenting)
- Anti-platelet drugs. These medications make your platelets, one of the circulating blood cell types, less likely to stick together. Clot formation is started by sticky platelets when there's an injury to blood vessels. The process is then completed by clotting proteins in blood plasma. The most frequently used anti-platelet medication is aspirin. Aspirin is also the least expensive treatment with the fewest potential side effects. An alternative to aspirin is the anti-platelet drug clopidogrel (Plavix). Your doctor may also consider prescribing Aggrenox, a combination of low-dose aspirin and the anti-platelet drug dipyridamole, to reduce blood clotting. The way dipyridamole works is slightly different from aspirin. Ticlopidine (Ticlid) is another anti-platelet medication that doctors occasionally recommend.
- Anticoagulants. These drugs include heparin and warfarin (Coumadin). They affect clotting-system proteins instead of platelet function. Heparin is used short term and warfarin over a longer term. These drugs have a strong anticoagulation effect and therefore require careful monitoring.
If you have a moderately or severely narrowed neck (carotid) artery, your doctor may suggest carotid endarterectomy (end-ahr-tur-EK-tuh-me). This preventive surgery clears carotid arteries of fatty deposits (atherosclerotic plaques) before another TIA or stroke can occur. An incision is made to open the artery, the plaques are removed, and the artery is closed.
In selected cases, a procedure called carotid angioplasty, or stenting, is an option. This procedure involves using a balloon-like device to open a clogged artery and placing a small wire tube (stent) into the artery to keep it open.
Knowing your risk factors and living healthfully are the best things you can do to prevent a TIA. Included in a healthy lifestyle are regular medical checkups. Also:
- Don't smoke. Stopping smoking reduces your risk of a TIA or a stroke.
- Limit cholesterol and fat. Cutting back on cholesterol and fat, especially saturated fat, in your diet may reduce buildup of plaques in your arteries.
- Eat plenty of fruits and vegetables. These foods contain such nutrients as potassium, folate and antioxidants, which may protect against a TIA or a stroke.
- Limit sodium. If you have high blood pressure, avoiding salty foods and not adding salt to food may reduce your blood pressure. Avoiding salt may not prevent hypertension. But excess sodium may increase blood pressure in people who are sensitive to sodium.
- Exercise regularly. If you have high blood pressure, regular exercise is one of the few ways you can lower your pressure without drugs.
- Limit alcohol intake. Drink alcohol in moderation, if at all. The recommended limit is no more than one drink daily for women and two a day for men.
- Maintain a healthy weight. Being overweight contributes to other risk factors, such as high blood pressure, cardiovascular disease and diabetes. Losing weight with diet and exercise may lower your blood pressure and improve your cholesterol levels.
- Don't use illicit drugs. Drugs such as cocaine are associated with an increased risk of a TIA or a stroke.
- Control diabetes. You can manage both diabetes and high blood pressure with diet, exercise, weight control and, when necessary, medication.