Transient ischemic attack overview
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Differentiating Transient Ischemic Attack from other Diseases |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Aysha Anwar, M.B.B.S[2]
Overview
A transient ischemic attack is caused by the temporary disturbance of blood supply to a restricted area of the brain, resulting in brief neurologic dysfunction that usually persists for less than 24 hours.
Discontinuation of the use of the term transient ischemic attack has been proposed[1].
Causes
The most common cause of a TIA is an embolus (a small blood clot) that occludes an artery in the brain. This most frequently arises from an atherosclerotic plaque in one of the carotid arteries (i.e. a number of major arteries in the head and neck) or from a thrombus (i.e. a blood clot) in the heart due to atrial fibrillation. Other reasons include excessive narrowing of large vessels due to an atherosclerotic plaque and increased blood viscosity due to some blood diseases. TIA is related with other medical conditions like hypertension, heart disease (especially atrial fibrillation), migraine, cigarette smoking, hypercholesterolemia, and diabetes mellitus.
Diagnosis
History and Symptoms
Symptoms vary widely from person to person depending on the area of the brain involved. The most frequent symptoms include temporary loss of vision (typically amaurosis fugax), difficulty speaking (dysarthria), weakness on one side of the body (hemiparesis), numbness usually on one side of the body, and loss of consciousness. If there are neurological symptoms persisting for more than 24 hours, it is classified as a cerebrovascular accident (stroke).
Electrocardiogram
An electrocardiogram (ECG) may show atrial fibrillation, a common cause of TIAs, or other arrhythmias that may cause embolisation to the brain.
CT
TIAs do not show brain changes on CT scans. (Most strokes do show changes on such tests).
MRI
TIAs do not show brain changes on MRI scans. (Most strokes do show changes on such tests).
Echocardiography
An echocardiogram is useful in detecting thrombus within the heart chambers. Such patients benefit from anticoagulation.
Ultrasound
If the TIA affects an area supplied by the carotid artery, an ultrasound (TCD) scan may demonstrate carotid stenosis.
Treatment
Surgery
For people with a greater than 70% stenosis within the carotid artery, removal of atherosclerotic plaque by surgery, specifically a carotid endarterectomy, may be recommended.
Primary Prevention
Prevention of TIAs includes controlling risk factors, such as high blood pressure, diabetes, heart disease, and other associated disorders. Smoking should be stopped.