Transient ischemic attacks (TIA) are caused by temporary disturbance of blood supply to a restricted area of brain and cause recurrent and brief (less than 24 hours) neurologic dysfunctions. If there are neurological symptoms persisting for more than 24 hours, it is classified as a cerebrovascular accident (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 (typically amaurosis fugax), difficulty speaking (dysphasia), weakness on one side of the body hemiparesis, numbness usually on one side of the body and loss of consciousness.
Patients diagnosed with a TIA are sometimes said to have had a warning for an approaching cerebrovascular accident. If the time period of blood supply impairment lasts more than a few minutes, the nerve cells of that area of the brain die permanently and cause 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.
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 or from a thrombus 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.
The mainstay of treatment following acute recovery from a TIA should be to diagnose and treat the underlying cause.
Electrocardiogram (EKG) may show atrial fibrillation.
Echocardiogram is useful in detecting thrombus within the heart chambers. Such patients benefit from anticoagulation.
If the TIA affects an area supplied by the carotid artery, ultrasound scan may demonstrate carotid stenosis. For people with a greater than 70% stenosis within the carotid artery, removal of atherosclerotic plaque by surgery (carotid endarterectomy ) may be recommended.
The majority of patients are given aspirin. Some patients may also be given modified release dipyridamole.