FRIDAY, Feb. 27, 2009 (HealthDay News) -- If you knew you were having a stroke, you'd seek immediate medical attention. But what if your symptoms were mild or ambiguous?

Even people who experience vague symptoms of a stroke suffer mental and physical damage that diminishes their quality of life, researchers have found.

The implicit message? Don't wait for the worst to happen before reacting. Mild, short-lived or sporadic symptoms of a brain attack should be enough to send up a red flag.

"I would suggest that people with stroke symptoms rush to the doctor," said George Howard, professor and chair of biostatistics at the University of Alabama at Birmingham School of Public Health.

Stroke -- the third-leading cause of death in the United States, behind heart disease and cancer -- occurs when a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot or bursts. When that happens, part of the brain can't get the oxygen it needs and starts to die, according to the American Stroke Association.

Strokes can also be disabling, affecting speech, memory and movement. Some 4 million Americans are living with the effects of stroke, says the National Institute of Neurological Disorders and Stroke.

What's more, it's estimated that as many as 10 million Americans have strokes without ever knowing it. These have been dubbed "silent strokes."

But what if silent strokes aren't as clandestine as experts think? Howard and his colleagues have proposed that some people with silent strokes actually do experience the effects of a stroke, even though the warnings signs escape diagnosis. He calls these "whispering strokes."

"A silent stroke is one that shows up on imaging without a clinical diagnosis. A whispering one is one that has symptoms without clinical diagnosis," he explained.

Until recently, little was known about the health of people who experienced subtle symptoms but were never diagnosed as having a stroke.

Using data from a large national study of black and white individuals over age 45, Howard found that people who had stroke symptoms, but no stroke diagnosis, scored lower on tests of mental and physical function. Their scores were 5.5 points lower for physical functioning and 2.7 points lower for mental functioning than those people who'd had no symptoms.

What does that level of decline mean, exactly?

The survey questions used to assess mental and physical function are very general. For example, a person might be asked whether he or she had troubling climbing stairs in the past month.

"We can't know from this set of questions exactly what the symptoms are that are causing trouble climbing stairs, such as loss of balance, for example," said Howard's colleague Dr. Monika Safford, assistant professor of preventive medicine at the University of Alabama at Birmingham. The questions are designed to compare deficits across populations and disease states, she explained.

To put the results into perspective, Safford cited an English study in which older people living in a community experienced a 10-point decline on a similar question set if they developed knee pain over three years. "Therefore, suffering a 'whispering stroke' may give you about half the general physical impairment of knee arthritis," she reasoned.

Howard and his team reported their findings in the journal Stroke. Since then, his team has done follow-up work, suggesting that "these silent strokes are associated with very negative outcomes."

Indeed, in a separate study involving brain MRIs, a U.S. research team reported that one in 10 healthy, middle-aged adults had suffered a silent stroke. For purposes of the study, whispering strokes were considered silent strokes.

Of these silent-stroke victims, 84 percent had a single brain "lesion," or abnormality. That may not sound serious, but such damage can't be taken lightly.

"A single lesion can cause whispering subtle symptoms and signs," explained study author Dr. Sudha Seshadri, associate professor of neurology at Boston University School of Medicine. "It also increases the risk of more strokes and of cognitive impairment," she said.

More information

Learn more about stroke from the American Stroke Association.

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