Transient ischemic attack (TIA)

Definition
Transient ischemic attack (TIA) is a temporary episode of brain dysfunction that occurs when blood flow to the brain is reduced or blocked. TIAs may also be referred to as mini-strokes.

Causes/associated factors
The temporary reduction or blockage in blood flow to the brain is typically caused by a buildup of plaque in the arteries, an arterial spasm, a blood clot or an embolism (blockage of a blood vessel by a blood clot, air bubble, fat deposit or other foreign substance). The risk of TIA increases with age, especially after age 65. Also, men have considerably more TIAs than women.
Other risk factors for TIA include:

high blood pressure
high red blood cell count
certain blood diseases, such as polycythemia or sickle cell disease
cigarette smoking
untreated atrial fibrillation (AF, a condition in which the atrial or upper heart chamber beats rapidly and irregularly, causing a quivering sensation) and some other heart diseases, if they're left untreated
high levels of fat and cholesterol in the blood
obesity
diabetes
excessive alcohol consumption
drug abuse, such as using cocaine or other recreational intravenous drugs
sedentary lifestyle
carotid arterty disease
Studies show more than one-third of all people who experience TIAs will later suffer a stroke.


Signs/symptoms
The symptoms of TIA develop without warning and typically last from one to 15 minutes, but episodes lasting a few hours are possible. By definition, all symptoms disappear within 24 hours. Symptoms depend on the area of the brain affected by the lack of blood.
Because TIA and stroke symptoms are similar, people who have the following symptoms should seek immediate medical care to identify the cause of the symptoms and determine appropriate treatment.

Common symptoms include:

weakness, tingling or numbness on one side of the body
vision loss, typically in one eye
dizziness or lightheadedness
difficulty speaking or loss of speech
loss of balance and/or coordination
headache, usually sudden and severe
confusion

Diagnosis
The symptoms of TIA can also be similar to those of migraine headaches, seizures and low blood sugar, so a careful evaluation is important.
Initially, the doctor will ask about your medical history and current symptoms. He or she will want an account of the attack or episode. Remember, a complete and accurate description of symptoms can be a tremendous help in diagnosis. If you had weakness in just one arm or leg, for example, it may indicate a problem somewhere in the internal carotid artery (the main artery that carries blood to the head and neck).

A physical exam may include measuring blood pressure and listening to the flow of blood through various arteries through a stethoscope. (When flow is restricted, a specific sound can sometimes be heard.)

The doctor may also suggest diagnostic tests that provide images of the arteries or brain.

Computed tomography (CT scan) is a noninvasive test that uses an ultra thin X-ray beam to produce a computer-generated, cross-sectional picture of internal body parts. A CT scan may be done while symptoms are present to help rule out a stroke.

Doppler ultrasound is a high-frequency sound technique that helps the doctor detect blockage of the main arteries carrying blood to the head and neck.

Digital subtraction angiography (DSA) uses a computer to track the flow of dye injected into a vein. With this test, the doctor may be able to detect severe carotid stenosis (a narrowing or obstruction of the coronary arteries).

With arteriography, a catheter (a small, flexible tube) is inserted through a major artery. The catheter is passed through the artery until it reaches the carotid or vertebral artery. Once in position, a dye is injected and X-ray images are taken.

Magnetic resonance imaging (MRI) is a noninvasive imaging technique based on the body's response to a magnetic field.
Several lab tests, such as complete blood cell count, prothrombin time (a test that measures blood clotting time), and tests to measure levels of glucose and fat in the blood, may be done. You may also need other tests, including heart monitoring, an electrocardiogram (a recording of the electrical activity of the heart), a chest X-ray and ultrasound (using sound waves to create images of internal body parts).


Treatment
Treatment of TIA has three goals: to prevent further TIA episodes, improve circulation, and prevent a stroke. During treatment, it's crucial to manage medical risk factors.
Medication
Antiplatelet medications may be prescribed to keep blood platelets (substances in the blood cells that help blood to clot) from clumping together. Aspirin is the most common treatment. Ticlopidine hydrochloride (brand name Ticlid) and dipyridamole (Persantine) are also used. When necessary, clopidogrel bisulfate (Plavix) can be substituted for aspirin.

Depending on certain factors, anticoagulant medications such as warfarin sodium (Coumadin) and heparin sodium may be prescribed to reduce the tendency of the blood to clot.

If you have high blood cholesterol, a statin medication such as pravastatin (Pravachol) may be prescribed.

Surgery
Carotid endarterectomy (the surgical removal of plaque from inside a blood vessel) with or without the placement of a stent may be recommended if you have ongoing symptoms and narrowing of the arteries greater than 50 percent. You must be an appropriate surgical candidate, as determined by your doctor. This procedure is not recommended for everyone, especially if you have coronary artery atherosclerosis (hardening of the arteries that carry blood to the heart caused by a buildup of cholesterol).


Complications
Complications may include:
impending or progressive stroke
trauma from falls associated with weakness
seizures

Pregnancy-specific information
During pregnancy, childbirth and the postpartum period, your blood clots more easily. Although strokes are uncommon during pregnancy, the risk of stroke is higher during pregnancy. This may also mean an increased risk of TIAs during pregnancy. If you experience any neurological symptoms, contact your doctor immediately.

Senior-specific information
The risk of stroke increases with age and is considered highest after age 65. In the senior population, TIA is often preceded by atrial fibrillation. Make sure you know the symptoms of TIA and stroke, and seek emergency care when needed. If you have any heart conditions, establishing an ongoing treatment plan is vital.
As you age, it's especially important to:

control TIA risk factors
learn early warning signs
avoid recreational drugs
exercise regularly
avoid overeating, malnutrition or exhaustion
treat any blood disorders

Prevention
Many of the risk factors for stroke and TIA are treatable and controllable. The National Stroke Association has established the following guidelines for controlling risk factors:
Know your blood pressure. If it's elevated, work with your doctor to keep it under control.
Find out if you have atrial fibrillation. If you have AF, work with your doctor to manage it.
If you smoke, quit.
If you drink alcohol, do so in moderation.
Know your cholesterol numbers. Work with your doctor to control your cholesterol.
If you have diabetes, follow your doctor's recommendations carefully to control your diabetes.
Include exercise in the activities you enjoy in your daily routine.
Follow a lower-sodium (salt), lower-fat diet.
Ask your doctor if you have circulation problems that increase your risk for stroke.
If you have any stroke symptoms, seek immediate medical attention.