Ominous 'Mini-Strokes' Often Dismissed by Primary Care Doctors
The symptoms of TIA are actually the same as symptoms of stroke: sudden numbness or weakness of the face, arm, or leg -- especially if it is one-sided; confusion; trouble speaking or understanding; vision problems; difficulty walking; or sudden severe headache. But unlike stroke, the symptoms are fleeting and thus can easily be ignored by patients. Nonetheless, TIA is "an ominous sign," says S. Claiborne Johnson, MD, an assistant professor at the University of California, San Francisco. He has compiled data that back up that claim.
Johnson tells WebMD that among 1,707 people who presented to 16 Kaiser-Permanente emergency departments with symptoms of a TIA, "10.5% had a stroke within 3 months of presentation, about 2.6% died in three months, 2.5% had a cardiovascular event such as a [heart attack] or congestive heart failure, and 13.5% had recurrent TIAs. The total incident rate was 26%. And 50% of the patients who had strokes had [them] within two days of the TIA."
Given these findings on the "overlooked" nature of an important stroke marker, a report from Robert D. Brown Jr., MD, associate professor of medicine at Mayo Clinic School of Medicine, is especially compelling. Brown tells WebMD that a long-term, population-based study of all residents of Rochester, Minn., suggests that the stroke incidence among white Americans is 256 per 100,000, while the incidence of having a stroke for the first time is 183 per 100,000. "We extrapolated our data to the U.S. population of 273 million," he says. Using the figure of 256 per 100,000 for both white and Hispanic Americans and an incidence rate of 411 per 100,000 for African Americans, "a conservative estimate is that there are 750,000 strokes per year. The previous estimate was 500,000," he says.
"When you combine all strokes and TIAs, our estimate is that 1.2 million events occur each year," he says. Brown says that the data from Rochester date back to 1955. "During the 1950s and the 1960s, we saw a decline in the number of strokes," he says. The decline began to level off in the late 1960 and 1970s, and "in the 1980s and 1990s, we have seen an increase in the number of strokes." Brown says one explanation for the increase is that clinicians may "be less vigilant about detecting, treating, and controlling high blood pressure." But a more probable explanation for the increase, he says, is that "more people are surviving other ischemic events like heart attacks. That survival allows them to survive to have the stroke." He says, too, that since age itself is a risk factor for stroke, longer life expectancy carries an increased risk of stroke. "These people are [simply] living long enough to have a stroke," he says.