Transient Ischemic Attack

What you need to know about "mini strokes"

A transient ischemic attack (TIA) is also often called a “mini stroke.” It is caused by the changes in the blood supply to a particular area of the brain, resulting in brief neurologic dysfunction that persists for less than 24 hours. If the symptoms persist beyond 24 hours, then it is categorized as a stroke. Symptoms vary widely from person to person, depending on the area of the brain involved. The most frequent symptoms include temporary loss of vision, difficulty speaking, weakness on one side of the body and numbness or tingling, also on one side of the body. Impairment of consciousness is very uncommon.

Patients diagnosed with a TIA are sometimes thought to have had a warning for an approaching stroke. If the time period of blood supply impairment lasts more than a few minutes, the nerve cells of that area of the brain die and cause a permanent neurologic deficit. One-third of the people with TIA later have recurrent TIAs and one-third have a stroke due to permanent nerve cell loss.

Some of the factors that increase the likelihood of subsequent attacks are:

• Age 60 or above
• Blood pressure at or above 140/90
• Unilateral weakness
• Speech disturbance without weakness
• The length of the initial attack
• Diabetes

Causes

The most common cause of a TIA is an embolus that occludes an artery in the brain. Other reasons include excessive narrowing of large vessels due to an increased blood viscosity due to some blood diseases. TIA is related with other medical conditions like hypertension, heart disease, migraine, cigarette smoking, hypercholesterolemia and diabetes mellitus.

A person who’s had one or more TIAs is more likely to have a stroke than someone of the same age and sex who hasn’t. TIAs are important in predicting if a stroke will occur rather than when one will happen. They can occur days, weeks or even months before a major stroke. In about half the cases, the stroke occurs within one year of the TIA. If you have had a transient ischemic attack, your doctor will perform tests to look at your heart and blood vessels. You may need:

• Tests that show pictures of your brain and blood vessels, such as a CT scan, an MRI, a magnetic resonance angiogram (MRA) or an angiogram.
• A test that uses sound to check your blood flow.
• An echocardiogram (echo) to check your heart’s shape and its blood flow.
• An electrocardiogram (EKG, ECG) to measure your heart rhythm.