Each year, as many as 500,000 Americans experience mini strokes called transient ischemic attacks (TIAs).
Symptoms quickly go away, usually within an hour, and many people don't seek treatment. But 10 to 15 percent of people who experience TIAs will experience full-blown strokes within three months, and 40 percent of these strokes will occur in the first 24 hours, according to an article by three Loyola University Medical Center neurologists in the journal Expert Review of Neurotherapeutics.
Rapid evaluation and treatment of TIA patients, either in the emergency room or in specially designed TIA clinics, can reduce the risk of subsequent strokes, according to authors Farrukh Chaudhry, MD, Jose Biller, MD and Murray Flaster, MD, PhD.
A TIA is caused by a temporary blockage, typically a blood clot, in a blood vessel in the brain. Symptoms are similar to that of a stroke, including numbness or paralysis on one side of the body, vision changes, trouble speaking, difficulty with balance or walking, sudden severe headache, etc.
Blood clots that trigger TIAs can arise from atherosclerosis (hardening of the arteries), heart attacks and abnormal heart rhythms.
Advances in imaging techniques such as MRIs have improved diagnostic accuracy in patients. And rapid treatment following TIAs can reduce the risk of stroke by about 80 percent, according to two studies, one in Britain and one in France. These studies "are suggestive but not fully conclusive," the authors write. "Better study designs are needed to prove this vital point."
A 2006 study in the journal Stroke found that only 44.1 percent of TIA patients – mostly those with motor symptoms – seek medical attention. "One factor may be minimization or ignorance on the part of TIA patients, relatives and friends, or on the other hand, under-diagnosis or under-prioritization by physicians," Chaudhry, Biller and Flaster write.
And even when patients do seek treatment and are correctly diagnosed, some may resist hospitalization because their symptoms have gone away.
Factors that help predict whether a TIA patient is at especially high risk for subsequent stroke include age over 60, high blood pressure, weakness on one side of the body, isolated speech difficulties, diabetes and symptoms lasting an hour or more.
Chaudhry is a stroke fellow, Biller is a professor and chair and Flaster is an associate professor in the Department of Neurology of Loyola University Chicago Stritch School of Medicine.
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