The cause and symptoms of a TIA are the same as those of an ischemic stroke.
TIAs differ from ischemic strokes because symptoms usually resolve within 1 hour and no permanent brain damage occurs.
Symptoms suggest the diagnosis, but brain imaging is also done.
Other imaging tests and blood tests are done to diagnose the cause of the TIA.
Controlling high blood pressure, high cholesterol levels, and high blood sugar levels and stopping smoking are recommended.
Drugs to make blood less likely to clot and sometimes surgery (carotid endarterectomy) or angioplasty plus stenting are used to reduce the risk of stroke after a TIA.
(See also Overview of Stroke Overview of Stroke A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction) and symptoms that... read more and Ischemic Stroke Ischemic Stroke An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery. Ischemic stroke... read more .)
TIAs may be a warning sign of an impending ischemic stroke. People who have had a TIA are much more likely to have a stroke than those who have not had a TIA. The risk of stroke is highest during the first 24 to 48 hours after the TIA. Recognizing a TIA and having the cause identified and treated can help prevent a stroke.
TIAs are most common among middle-aged and older people.
TIAs differ from ischemic strokes because TIAs do not seem to cause permanent brain damage. That is, TIA symptoms resolve completely and quickly, and few or no brain cells died—at least not enough to cause any changes that can be detected by brain imaging or a neurologic examination Neurologic Examination When a neurologic disorder is suspected, doctors usually evaluate all of the body systems during the physical examination, but they focus on the nervous system. Examination of the nervous system—the... read more .
Causes of TIAs
Causes of TIAs and ischemic strokes Causes An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery. Ischemic stroke... read more are mostly the same. Most TIAs occur when a piece of a blood clot (thrombus) or of fatty material (atheroma, or plaque) due to atherosclerosis breaks off from the heart or from the wall of an artery (usually in the neck), travels through the bloodstream (becoming an embolus), and lodges in an artery that supplies the brain.
If the arteries to the brain are already narrowed (as in people with atherosclerosis), other conditions occasionally cause symptoms similar to those of TIAs. These conditions include a very low oxygen level in the blood (as may result from a lung disorder), a severe deficiency of red blood cells (anemia Overview of Anemia Anemia is a condition in which the number of red blood cells is low. Red blood cells contain hemoglobin, a protein that enables them to carry oxygen from the lungs and deliver it to all parts... read more ), carbon monoxide poisoning Carbon Monoxide Poisoning Carbon monoxide is a colorless, odorless gas that is produced when many materials are burned and can be toxic when breathed in large amounts Carbon monoxide poisoning is common. Symptoms may... read more , thickened blood (as in polycythemia Polycythemia Vera Polycythemia vera is a myeloproliferative neoplasm of the blood-producing cells of the bone marrow that results in overproduction of all types of blood cells. Polycythemia vera is due to mutations... read more ), or very low blood pressure Low Blood Pressure Low blood pressure is blood pressure low enough to cause symptoms such as dizziness and fainting. Very low blood pressure can cause damage to organs, a process called shock. Various drugs and... read more (hypotension).
Risk factors for TIAs are also the same as those for ischemic stroke Risk factors An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery. Ischemic stroke... read more .
Some of these risk factors can be controlled or modified to some extent—for example, by treating the disorder that increases risk.
The major modifiable risk factors for TIAs are
Insulin resistance (an inadequate response to insulin), which occurs in type 2 diabetes
Obesity Obesity Obesity is excess body weight. Obesity is influenced by a combination of factors, which usually results in consuming more calories than the body needs. These factors may include physical inactivity... read more , particularly if the excess weight is around the abdomen
Consumption of too much alcohol
Lack of physical activity
Heart disorders that increase the risk of blood clots forming in the heart, breaking off, and traveling through the blood vessels as emboli (such as a heart attack Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) Acute coronary syndromes result from a sudden blockage in a coronary artery. This blockage causes unstable angina or a heart attack (myocardial infarction), depending on the location and amount... read more or an abnormal heart rhythm called atrial fibrillation Atrial Fibrillation and Atrial Flutter Atrial fibrillation and atrial flutter are very fast electrical discharge patterns that make the atria (upper chambers of the heart) contract very rapidly, with some of the electrical impulses... read more )
Infective endocarditis Infective Endocarditis Infective endocarditis is an infection of the lining of the heart (endocardium) and usually also of the heart valves. Infective endocarditis occurs when bacteria enter the bloodstream and travel... read more (infection of the heart's lining and usually of the heart valves)
Use of cocaine Cocaine Cocaine is an addictive stimulant drug made from leaves of the coca plant. Cocaine is a strong stimulant that increases alertness, causes euphoria, and makes people feel powerful. High doses... read more or amphetamines Amphetamines Amphetamines are stimulant drugs that are used to treat certain medical conditions, but are also subject to abuse. Amphetamines increase alertness, enhance physical performance, and produce... read more
Use of estrogen therapy, including oral contraceptives
Risk factors that cannot be modified include
Having had a stroke previously
Having relatives who have had a stroke
Symptoms of TIAs
Symptoms of a TIA develop suddenly. They are identical to those of an ischemic stroke Symptoms An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery. Ischemic stroke... read more but are temporary and reversible. They usually last 2 to 30 minutes, then resolve completely.
People may have several TIAs in 1 day or only two or three in several years.
Symptoms may include
Sudden weakness or paralysis on one side of the body (for example, half of the face, one arm or leg, or all of one side)
Sudden loss of sensation or abnormal sensations on one side of the body
Sudden difficulty speaking (such as slurred speech)
Sudden confusion, with difficulty understanding speech
Sudden dimness, blurring, or loss of vision, particularly in one eye
Sudden dizziness or loss of balance and coordination
Diagnosis of TIAs
Rapid resolution of symptoms
Computed tomography and, when available, magnetic resonance imaging
Tests to determine the cause
People who have a sudden symptom similar to any symptom of a stroke, even if it quickly resolves, should go immediately to an emergency department. Such a symptom suggests a TIA. However, other disorders, including seizures, brain tumors, migraine headaches, and abnormally low levels of sugar in the blood (hypoglycemia), cause similar symptoms, so further evaluation is needed.
Doctors suspect a TIA if symptoms of a stroke develop, particularly if they resolve in less than 1 hour. Doctors may be unable to tell a stroke from a TIA before symptoms resolve. They evaluate people who have symptoms of a TIA or stroke rapidly. People who have had a TIA are usually admitted in the hospital, at least for a short time, to do tests and to be able to treat them rapidly if a stroke occurs soon after the TIA. Risk of a stroke is highest during the first 24 to 48 hours after a TIA.
Doctors check for risk factors for stroke by asking people questions, reviewing their medical history, and doing blood tests.
Imaging tests, such as computed tomography (CT) or magnetic resonance imaging (MRI), are done to check for evidence of a stroke, bleeding, and brain tumors. A specialized type of MRI, called diffusion-weighted MRI Diffusion-weighted MRI In magnetic resonance imaging (MRI), a strong magnetic field and very high frequency radio waves are used to produce highly detailed images. MRI does not use x-rays and is usually very safe... read more , can show areas of brain tissue that are severely damaged and not functioning. Diffusion-weighted MRI can often help doctors differentiate a TIA from an ischemic stroke. However, diffusion-weighted MRI is not always available.
Tests are done to determine what caused the TIA. Tests may include
Electrocardiography Electrocardiography Electrocardiography (ECG) is a quick, simple, painless procedure in which the heart’s electrical impulses are amplified and recorded. This record, the electrocardiogram (also known as an ECG)... read more (ECG), including continuous ECG monitoring Continuous Ambulatory Electrocardiography A standard electrocardiograph (ECG) records the heart's electrical activity for only a few seconds. This can detect abnormalities that are constant; however, sometimes abnormal heart rhythms... read more , to look for abnormal heart rhythms
Echocardiography to check the heart for blood clots, pumping or structural abnormalities, and valve disorders
Other imaging tests
Blood tests to check for disorders such as anemia and polycythemia and for risk factors such as high cholesterol levels or diabetes
Other imaging tests help determine whether an artery to the brain is blocked, which artery is blocked, and how complete the blockage is. These tests provide images of the arteries that carry blood through the neck to the brain (the internal carotid arteries and the vertebral arteries) and the arteries of the brain (such as the cerebral arteries). They include color Doppler ultrasonography Color Doppler ultrasonography Ultrasonography uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. A device called a transducer converts electrical current into sound waves... read more (used to evaluate blood flow through arteries), magnetic resonance angiography Magnetic resonance angiography (MRA) , and CT angiography CT angiography .
Did You Know...
Treatment of TIAs
Control of risk factors for TIAs
Drugs that make blood less likely to clot
Sometimes surgery or angioplasty with a stent
Treatment of TIAs is aimed at preventing a stroke. It is the same as treatment after an ischemic stroke Treatment An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery. Ischemic stroke... read more .
The first step in preventing a stroke is to control, if possible, the major risk factors for it:
People may be given a drug to make blood less likely to clot (an antiplatelet drug or an anticoagulant).
Taking an antiplatelet drug, such as aspirin, a combination tablet of low-dose aspirin plus dipyridamole, clopidogrel, or clopidogrel plus aspirin, reduces the chance that clots will form and cause TIAs or ischemic strokes. Antiplatelet drugs make platelets less likely to clump and form clots. (Platelets are tiny cell-like particles in the blood that help it clot in response to damaged blood vessels.)
Taking clopidogrel plus aspirin appears to reduce the risk of future strokes more than taking aspirin alone, but only for the first 3 months after a stroke. After that, the combination has no advantage over taking aspirin alone. Also, taking clopidogrel plus aspirin increases the risk of bleeding by a small amount.
If a blood clot from the heart caused the TIA, anticoagulants, such as warfarin, are given to make blood less likely to clot. Dabigatran, apixaban, and rivaroxaban are new anticoagulants that are sometimes used instead of warfarin. These newer anticoagulants are more convenient to use because they, unlike warfarin, do not require regular monitoring with blood tests to measure how long it takes blood to clot. Also, they are not affected by foods and are unlikely to interact with other drugs. But the new anticoagulants have some disadvantages. Dabigatran and apixaban must be taken twice a day. (Warfarin is taken once a day.) Also, people must not miss any doses of the newer drugs for the drugs to be effective, and these drugs are significantly more expensive than warfarin.
The degree of narrowing in the carotid arteries helps doctors estimate the risk of a stroke or subsequent TIAs and thus determine the need for further treatment. If people are thought to be at high risk (for example, if the carotid artery is narrowed at least 70%), an operation to widen the artery (called carotid endarterectomy Surgery ) may be done to reduce the risk. Carotid endarterectomy usually involves removing fatty deposits (atheromas, or plaques) due to atherosclerosis and clots in the internal carotid artery. However, the operation can trigger a stroke because the operation may dislodge clots or other material that can then travel through the bloodstream and block an artery. However, after the operation, the risk of stroke is lower for several years than it is when drugs are used. The procedure can result in a heart attack because people who have this procedure often have risk factors for coronary artery disease.
If people are not healthy enough to have surgery, angioplasty with stenting (see figure Understanding Percutaneous Coronary Intervention (PCI) Understanding Percutaneous Coronary Intervention (PCI) ) may be done. For this procedure, a catheter with a balloon at its tip is threaded into the narrowed artery. The balloon is then inflated for several seconds to widen the artery. To keep the artery open, doctors insert a tube made of wire mesh (a stent) into the artery.
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