Definition

Transient ischemic attack (TIA) refers to temporary brain dysfunction. It lasts no longer than 24 hours. TIA is due to a shortage of blood and oxygen to the brain. It sometimes is referred to as a mini-stroke. TIA is a serious condition. It serves as a warning for a stroke. About 30% of stroke patients have had a TIA at some point in the past.

Blood Supply to the Brain

© 2009 Nucleus Medical Media, Inc.

Causes

A TIA results from a temporary blockage of the blood supply to the brain. The carotid artery in the front of the neck is a major supply of blood to the brain. A build-up of plaque and hardening of this artery can slow or stop blood flow.

Reasons for the blockage may include:

  • A blood clot or a piece of plaque (called an embolus) from inside the wall of an artery breaks off and blocks blood flow to a portion of the brain.
  • A blood clot dislodges from the heart and moves to the brain.
  • Temporary low blood pressure in the brain may occur due to narrowed arteries in the neck.
  • Blood and blood-clotting disorders such as:
    • Anemia (too few red blood cells)
    • Polycythemia (too many red blood cells)
    • Hyperviscosity (abnormal thickening of the blood)
  • Vasculitis or blood vessel inflammation
  • Endocarditis (infection of the lining of the heart)

Embolus

Embolus
© 2009 Nucleus Medical Media, Inc.

Risk Factors

TIAs may be caused by high blood pressure, diabetes, atrial fibrillation, or blood clotting disorders. Factors that increase your chance for TIA and stroke are similar:

Symptoms

TIA symptoms occur abruptly. They usually last less than 10 minutes. They may persist for up to 24 hours. The effects differ depending on the location of the blockage. TIA symptoms are similar to those of a stroke. They require immediate medical attention.

Symptoms may include:

  • Blindness in one eye, often described as a window shade dropping, and/or other visual problems
  • Weakness, numbness, or tingling of the face, arm, leg, or one side of the body (usually affects one side of the body, but there are exceptions).
  • Difficulty speaking or understanding words
  • Dizziness, unsteadiness of gait, or falling
  • Trouble with balance or coordination
  • Loss of consciousness
  • Nausea
  • Vomiting
  • Sudden confusion or loss of memory

Diagnosis

The doctor will ask about your symptoms and medial history. A physical exam will be done. Particular attention will be paid to your blood pressure and nervous system. A primary goal will be to determine your stroke risk.

Tests may include:

  • Blood tests—such as a complete blood count, blood sugar (glucose), cholesterol and other fat levels, clotting factors, and a check of other elements in the blood
  • Electrocardiogram (EKG)—to measure heart rhythm (which would be irregular in, for example, atrial fibrillation) and check for other signs of heart disease
  • Doppler ultrasound—a test that uses sound waves to help determine if there is compromised blood flow in the arteries supplying the brain
  • Echocardiogram—another ultrasound test to look for blood clots and valve abnormalities within the heart
  • CT scan of the head—a type of x-ray that uses a computer to create images of structures inside the head; in this case, to look for evidence of bleeding or other damage to the brain
  • CT angiogram—a CT scan which uses dye to evaluate the blood vessels in the brain and neck.
  • MRI scan of the head—a test that uses powerful magnetic radiowaves to create images of structures inside the head; in this case, to look for evidence of bleeding or other damage to the brain
  • Magnetic resonance angiography (MRA)—generally performed prior to carotid artery surgery to determine how much the artery has narrowed
  • Arteriogram—a test in which contrast dye is injected into selected arteries and x-ray images are produced to precisely locate the blockage and to determine its extent
  • Electroencephalogram (EEG)—a test that can detect the presence of seizures by measuring brain waves (used only if a seizure is suspected)

Treatment

A TIA places you at greater risk for having a stroke. The risk is actually highest in the first week after your TIA. Therefore, rapid treatment aims to decrease stroke risk. This can be done with lifestyle changes, medication, and surgery. If the cause of the TIA is a treatable condition it must be promptly treated. Specific conditions include:

  • Atrial fibrillation
  • Severe anemia
  • Vasculitis

Lifestyle

Smokers must quit. Patient with diabetes, hypertension, and/or high cholesterol must make every effort to manage these conditions. It can be done with:

Medications

In addition, doctors often prescribe medication to lower blood sugar, blood pressure, and cholesterol. This will help lower these risk factors. To decrease the risk of clot formation your doctor may recommend:

Surgery

If the carotid artery on the same side as the TIA is 70% blocked or more, doctors may recommend:

  • A carotid endarterectomy—to remove the plaque deposits
  • Other less invasive procedures such as (intra-arterial stenting)

These procedures have risks associated with them. Talk to your doctor about your options. They are often not done if there are no symptoms and less than 70% blockage.

Prevention

The following strategies may help reduce the chance of TIAs and stroke:

  • Exercise regularly, with your doctor's approval.
  • Eat a healthful diet. It should be low in saturated fat and rich in whole grains, fruits, and vegetables.
  • Maintain a healthy weight.
  • If you smoke, quit.
  • Drink alcohol in moderation. Moderate alcohol intake is no more than two drinks per day for men and one drink per day for women.
  • Control blood pressure, high cholesterol, and diabetes with medications as needed.