Dec. 12, 2000 -- The symptoms can be so fleeting, it's easy to ignore them. Yet, a new study shows the subtle, temporary signs of transient ischemic attacks -- or TIAs -- should be taken more seriously by both patients and doctors.
TIA, like a stroke, results from a blood clot in the blood vessels leading to the brain or in the brain itself. The clot temporarily impairs some aspect of brain function, causing stroke-like symptoms such as weakness, numbness in the limbs, difficulty speaking, and double vision. Yet, the symptoms often last only a few minutes to a few hours.
However, "these patients are at substantial risk of stroke, death, heart failure, heart attack, or another TIA," says lead researcher S. Claiborne Johnston, MD, MPH, assistant professor of neurology at the University of California at San Francisco. His study is published in this week's issue of the Journal of the American Medical Association.
"Anyone with symptoms, no matter how transient, should get to the hospital immediately," he tells WebMD. "The risk of stroke is quite high in the first few days, first few months after a TIA."
Johnston's study is the first large-scale analysis of these "mini strokes," a common disorder that affects from 300,000 to 1 million people in the U.S. every year.
Because of their very fleeting nature, TIAs are not only difficult to diagnose, but the effect on stroke risk has been unclear, Johnston says. "Many go undetected," he tells WebMD. "Largely, physicians have had to rely on their own experience in determining which [patients] were at greater risk for stroke." Only two previous studies of TIA have been performed, both involving small numbers of patients, the last study dating back 15 years.
In his study, Johnston analyzed data on more than 1,700 TIA patients with an average age of 72. During the 90 days after the first TIA, more than 10% of patients returned to the emergency room with a stroke; half of those strokes occurred in the first two days after the TIA.
Moreover, the strokes were fatal for 21% of patients and disabling for another 64%.
In fact, one-quarter of the TIA patients in his study suffered some type of serious medical problem -- whether stroke, death, heart failure, heart attack, or another TIA -- in the first three months following the TIA, Johnston says.
The researchers also were able to pinpoint specific risk factors for stroke after a TIA: age over 65, diabetes, a TIA spell lasting longer than 10 minutes, and temporary weakness or speech impairment during the TIA, Johnston tells WebMD. "Each of these symptoms doubled their risk of stroke," he says.
"It's what we've been saying all along -- that if you have symptoms of stroke, get to the hospital," Johnston says. "Now we're saying if your symptoms go away, you still need to get to the hospital."
His study also points to the need for more effective drugs to treat TIA, Johnston tells WebMD. "Ninety-two percent of patients in this study got medications that have been shown to reduce stroke risk, but the medications didn't work. The drugs obviously are not strong enough."
In addition, most patients in the study were given aspirin -- "which is known to reduce stroke risk after TIA," Johnston says. "But it worked in only 20% of cases." He plans future studies of more aggressive treatments.
Calling the study "a major contribution," Jeffrey Saver, MD, neurology director of University of California-Los Angeles Stroke Center, tells WebMD, "This revises our understanding of how frequently TIA leads to stroke. It also suggests that if you have had a TIA, you got lucky, you dodged a bullet this time. But there's no guarantee you will get lucky the next time. If you have a TIA, you need to get to the hospital ER or contact your doctor and be seen -- preferably that same day.
"The study also indicates that people who experience TIA symptoms -- especially those considered to be at high risk -- should be admitted to the hospital so that treatment can get under way to avoid stroke, while those at lower risk may be adequately managed as outpatients," Saver says.