Transient Ischemic Attack (Encyclopedia of Medicine)
A transient ischemic attack, or TIA, is often described as a mini-stroke. Unlike a stroke, however, the symptoms can disappear within a few minutes. TIAs and strokes are both caused by a disruption of the blood flow to the brain. In TIAs and most strokes, this disruption is caused by a blood clot blocking one of the blood vessels leading to the brain. The blockage produces symptoms such as sudden weakness or numbness on one side of the body, sudden dimming or loss of vision, and difficulty speaking or understanding speech. If the symptoms are caused by a TIA, they last less than 24 hours and do not cause brain damage. Stroke-associated symptoms, on the other hand, do not go away and may cause brain damage or death. TIAs can serve as an early warning sign of stroke and require immediate medical attention.
Strokes are the third leading cause of death in the United States and the leading cause of disability. Approximately 500,000-600,000 people have strokes each year, and more than 160,000 die as a result. About 85% of these strokes are classified as ischemic. In ischemic stroke, a blood vessel leading to the brain becomes blocked and an area of the brain is deprived of oxygenated blood. (The other 15% of strokes are caused by bleeding from a blood vessel that has ruptured.) Without the blood supply, the...
(The entire section is 2042 words.)
Want to Read More?
Subscribe now to read the rest of this article. Plus get complete access to 30,000+ study guides!
Transient Ischemic Attack (Encyclopedia of Neurological Disorders)
A transient ischemic attack (TIA), or "mini-stroke," is a neurologic episode resembling a stroke but resolving completely within a short period of time. By definition, symptoms of TIA resolve within 24 hours, and symptoms lasting longer than that are termed a stroke. A TIA is caused by brief interruption of the blood supply to a specific brain region, and it may warn of impending stroke.
Symptoms of TIA begin suddenly and are similar to those of stroke, but leave no residual damage. By definition, symptoms of TIA resolve within 24 hours, but typically they last less than five minutes, or about one minute on average.
The symptoms of TIA vary depending on what part of the brain is affected. Anterior circulation TIAs interrupt the blood supply to most of the front part of the brain known as the cerebrum, including the frontal, parietal, and temporal lobes.
Symptoms suggesting anterior circulation TIAs may include difficulty speaking or understanding speech. Blindness in one eye suggests amaurosis fugax, a type of TIA caused by decreased blood flow through the carotid artery. This large artery in the neck supplies blood to the optic nerve responsible for vision in the eye on the same side as the artery.
Posterior circulation TIAs involve the...
(The entire section is 3977 words.)
Transient Ischemic Attacks (Encyclopedia of Public Health)
Transient Ischemic Attacks (TIAs) are transient neurological deficits, such as temporary blindness of one eye (amaurosis fugax), hemiparesis, or aphasia. Most typically, these symptoms last for periods of minutes or even hours, and they may persist for up to twenty-four hours. TIAs frequently result from platelet aggregates forming and then dislodging to embolize peripherally, or from significant atherosclerotic disease of extracranial carotid arteries, especially at the carotid bifurcation.
Because TIAs due to extracranial carotid stenosis (constriction) were recognized to be harbingers of larger and even devastatingly severe strokes, efforts to eliminate these offending lesions resulted in widespread carotid endarterectomies (CEA) being performed in the expectation of averting strokes. To scientifically assess the value of CEAs, three large-scale prospective randomized studies were undertaken, and the results were published in 1991. In patients with TIAs in the carotid distribution, and showing significant extracranial disease (greater than 70% diameter stenosis at the carotid bifurcation), carotid endarterectomy in competent surgical hands was shown to reduce stroke recurrence significantly. In these patients, control of risk factors for atherosclerosis should also be instituted, such as those for hypertension, smoking, diabetes mellitus, elevated cholesterol, stress, and, perhaps, sedentary lifestyle. In nonsurgical candidates, in addition to risk factor reduction, aspirin and other antiplatelet drugs can prevent subsequent strokes.
(SEE ALSO: ; Cardiovascular Disease; Stroke)