A transient ischemic attack (TIA) is a short period of symptoms similar to those of a stroke. It's caused by a brief blockage of blood flow to the brain. A TIA usually lasts only a few minutes and doesn't cause long-term damage.

However, a TIA may be a warning. About 1 in 3 people who has a TIA will eventually have a stroke, with about half occurring within a year after the TIA.

Often called a ministroke, a TIA can serve as both a warning of a future stroke and a chance to prevent it.

Transient ischemic attacks usually last a few minutes. Most symptoms disappear within an hour. Rarely, symptoms may last up to 24 hours. The symptoms of a TIA are similar to those found early in a stroke. Symptoms happen suddenly and may include:

• Weakness, numbness or paralysis in the face, arm or leg, typically on one side of the body.
• Slurred speech or trouble understanding others.
• Blindness in one or both eyes or double vision.
• Dizziness or loss of balance or coordination.

You may have more than one TIA. Their symptoms may be similar or different depending on which area of the brain is involved.

When to see a doctor

If you think you're having or have had a transient ischemic attack, get medical attention right away. TIAs most often occur hours or days before a stroke. Being evaluated quickly means healthcare professionals can pinpoint potential treatable conditions. Treating those conditions may help you prevent a stroke.

The cause of a transient ischemic attack is similar to the cause of an ischemic stroke, which is the most common type of stroke. In an ischemic stroke, a blood clot blocks the blood supply to part of the brain. In a TIA, unlike a stroke, the blockage is brief and there is no permanent damage.

The blockage that occurs during a TIA often results from a buildup of cholesterol-containing fatty deposits called plaques in an artery. This is known as atherosclerosis. The buildup also may occur in an artery's branches that supply oxygen and nutrients to the brain.

Plaques can decrease the blood flow through an artery or lead to the development of a clot. A blood clot that moves from another part of the body, such as the heart, to an artery that supplies the brain also may cause a TIA.

Some risk factors of a transient ischemic attack and stroke can't be changed. Others you can control.

Risk factors you can't change

You can't change these risk factors of a TIA and stroke. But knowing you have these risks can motivate you to change the risk factors you can control.

• 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, especially after age 55.
• Sex. Men have a slightly higher risk of a TIA and a stroke. But as women age, their risk of a stroke goes up.
• Prior transient ischemic attack. If you've had one or more TIAs, you're much more likely to have a stroke.
• Sickle cell disease. Stroke is a frequent complication of sickle cell disease, also known as sickle cell anemia. Sickle-shaped blood cells carry less oxygen and also tend to get stuck in artery walls, affecting blood flow to the brain. But with proper treatment of sickle cell disease, you can lower your risk of a stroke.

Risk factors you can control

You can control or treat a number of risk factors of a TIA and a stroke, including certain health conditions and lifestyle choices. Having one or more of these risk factors doesn't mean you'll have a stroke, but your risk increases if you have two or more of them.

Health conditions

• High blood pressure. The risk of a stroke begins to increase at blood pressure readings of 140/90 millimeters of mercury (mm Hg) and higher. Your healthcare professional can help you decide on a target blood pressure based on your age and other factors, such as whether you have diabetes.
• High cholesterol. Eating less cholesterol and fat, especially saturated fat and trans fat, may reduce the plaques in your arteries. If you can't control your cholesterol through dietary changes alone, your provider may prescribe a statin or another type of cholesterol-lowering medicine.
• Cardiovascular disease. This includes heart failure, a heart defect, a heart infection or a heart rhythm condition.
• Carotid artery disease. In this condition, the blood vessels in the neck that lead to the brain become clogged.
• Peripheral artery disease (PAD). PAD causes the blood vessels that carry blood to the arms and legs to become clogged.
• Diabetes. Diabetes speeds up and worsens the narrowing of arteries due to a buildup of fatty deposits, known as atherosclerosis.
• High levels of homocysteine. Elevated levels of this amino acid in the blood can cause the arteries to thicken and scar. This makes them more susceptible to clots.
• Excess weight. Obesity, especially carrying extra weight in the stomach, increases stroke risk.
• COVID-19. There is evidence that the virus that causes COVID-19 may raise the risk of stroke.

Lifestyle choices

• Cigarette smoking. Smoking increases the risk of blood clots, raises blood pressure and plays a part in the development of atherosclerosis. But quitting smoking lowers the risk of having a TIA or a stroke.
• Physical inactivity. Engaging in 30 minutes of moderate-intensity exercise most days helps lower risk.
• Poor nutrition. Eating less fat and salt decreases the risk of a TIA and a stroke.
• Heavy drinking. If you drink alcohol, limit yourself to up to one drink a day for women and up to two drinks a day for men.
• Use of illicit drugs. Avoid cocaine and other illicit drugs.

Knowing your risk factors and living healthfully are the best things you can do to prevent a transient ischemic attack. A healthy lifestyle includes getting 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 and trans fat, in your diet may reduce buildup of plaques in the arteries.
• Eat plenty of fruits and vegetables. These foods contain nutrients such as potassium, folate and antioxidants, which may protect against a TIA or a stroke.
• Limit sodium. If you have high blood pressure, avoid salty foods and don't add salt to food. These habits may help reduce your blood pressure. Limiting salt may not prevent high blood pressure, but excess sodium may increase blood pressure in some people.
• Exercise regularly. If you have high blood pressure, regular exercise is one of the few ways you can lower your blood pressure without medicines.
• Limit alcohol intake. Drink alcohol in moderation, if at all. The recommended limit is no more than one drink daily for women and two drinks 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. Illicit drugs such as cocaine are associated with an increased risk of a TIA or a stroke.
• Control diabetes. You can manage diabetes and high blood pressure with diet, exercise, weight control and, when necessary, medicine.

A prompt evaluation of your symptoms is vital to diagnose the cause of a transient ischemic attack. It also helps your healthcare professional determine the best treatment. To pinpoint the cause of the TIA and to assess your risk of a stroke, your healthcare professional may rely on the following:

• Physical exam and tests. Your healthcare professional performs a physical exam and a neurological exam. Tests of your vision, eye movements, speech and language, strength, reflexes, and sensory system are included.

  Your healthcare professional may use a stethoscope to listen to the carotid artery in your neck. During this exam, a whooshing sound called a bruit may mean that you have atherosclerosis. Or your healthcare professional may use an ophthalmoscope. This instrument looks for cholesterol fragments or platelet fragments called emboli in the tiny blood vessels of the retina at the back of the eye.

  You also may be checked for risk factors of a stroke. These include high blood pressure, high cholesterol levels, diabetes and sometimes high levels of the amino acid homocysteine.

• Carotid ultrasonography. If your healthcare professional suspects that a narrowed carotid artery in the neck may be the cause of your TIA, you may need a carotid ultrasound. A wandlike device called a transducer sends high-frequency sound waves into the neck. The sound waves pass through the tissue and create images on a screen. The images can show narrowing or clotting in the carotid arteries.
• Computerized tomography (CT) or computerized tomography angiography (CTA) scans. CT scans of the head use X-ray beams to create a 3D image. This allows your healthcare professional to look at the brain or the arteries in the neck and brain. A CTA scan may involve an injection of a contrast material into a blood vessel. Unlike a carotid ultrasound, a CTA scan can look at blood vessels in the neck and head.
• Magnetic resonance imaging (MRI) or magnetic resonance angiography (MRA). These tests use a strong magnetic field to create a 3D view of the brain. MRA uses technology similar to MRI to look at the arteries in the neck and brain. But an MRA may include an injection of a contrast material into a blood vessel.

• Echocardiography. This test may be done to find out if a heart issue caused fragments in the blood that led to a blockage. A traditional echocardiography is called a transthoracic echocardiogram (TTE). A TTE involves moving an instrument called a transducer across the chest to look at the heart. The transducer emits sound waves that bounce off different parts of the heart, creating an ultrasound image.

  Or you may need another type of echocardiography called a transesophageal echocardiogram (TEE). A flexible probe with a transducer is placed into the tube that connects the mouth to the stomach, known as the esophagus. Because the esophagus is directly behind the heart, a TEE can create clearer, detailed ultrasound images. This allows a better view of some things, such as blood clots, that might not be seen clearly in a traditional echocardiography exam.

• Arteriography. This procedure is used in some people to get a view of arteries in the brain not usually seen in an X-ray. A radiologist inserts a thin, flexible tube called a catheter through a small incision, usually in the groin.

  The catheter is guided through the major arteries and into the carotid or vertebral artery in the neck. Then a dye is injected through the catheter. The dye allows the arteries to be seen on X-ray images.

A transient ischemic attack often is diagnosed in an emergency situation. But if you're concerned about your risk of having a stroke, you can plan to talk about it with your healthcare professional at your next appointment.

What you can do

If you want to discuss your risk of a stroke with your healthcare professional, write down and be ready to discuss:

• Your risk factors for a stroke, such as family history of strokes.
• Your medical history, including a list of all medicines, as well as any vitamins or supplements, you're taking.
• Key personal information, such as lifestyle habits and major stressors.
• Whether you think you've had a TIA and what symptoms you experienced.
• Questions you might have.

What to expect from your doctor

Your healthcare professional may recommend that you have several tests to check your risk factors. You're given instructions on how to prepare for the tests, such as fasting before having your blood drawn to check your cholesterol and blood sugar levels.