Warning signs of a stroke (search) may start up to a week before the actual attack, a new study suggests.
Researchers found that almost one out of every three ischemic stroke survivors suffered “ministrokes,” known as transient ischemic attacks (search), prior to the actual event, and most of these ministrokes occurred within the preceding seven days.
Ischemic strokes account for 80 percent of all strokes and are caused by blockage of a blood vessel supplying the brain. The remaining 20 percent of strokes are caused by a burst blood vessel.
Researchers say they have known for some time that TIAs, which produce symptoms similar to a stroke such as numbness or tingling, often precede a major stroke. These ministrokes typically last less than five minutes and do not cause permanent injury to the brain.
"What we haven't been able to determine is how urgently patients must be assessed following a TIA in order to receive the most effective preventive treatment,” says researcher Peter M. Rothwell, MD, PhD, of the department of clinical neurology at Radcliffe Infirmary in Oxford, England, in a news release. “This study indicates that the timing of a TIA is critical, and the most effective treatments should be initiated within hours of a TIA in order to prevent a major attack."
Stroke Warning Signs Start Early
In the study, which appears in the current issue of Neurology, researchers evaluated 2,416 people who had an ischemic stroke.
They found 23 percent of the stroke patients reported experiencing a ministroke prior to their stroke. Of those who experienced a TIA, 17 percent had it on the day of the stroke, 9 percent on the previous day, and 43 percent at some point during the week leading up to the stroke.
Researchers say given the short time window between TIA and stroke, all people with TIA should be treated urgently to prevent permanent brain damage caused by a stroke.
In many countries, people with TIA are referred to outpatient clinics and often not seen for up to two weeks. But researchers say to be most effective, preventive treatment would need to be started within hours of a ministroke and clinical guidelines should be revised accordingly.
According to the National Institute of Neurological Disorders and Stroke, about one-third of people who suffer a TIA will have a full-fledged stroke in the future.
High blood pressure, cigarette smoking, diabetes, and heavy use of alcohol have been linked to stroke risk. Lifestyle changes reduce these risks.
SOURCES: Rothwell, P. Neurology, March, 8, 2005; vol 64: pp 817-820. News release, American Academy of Neurology.