CINCINNATI—Approximately 14 percent of all strokes occur during sleep, preventing many from getting clot-busting treatment, according to new research from the University of Cincinnati (UC).
The study authored by Jason Mackey, MD, a second-year stroke fellow in the department of neurology and a member of the UC Neuroscience Institute, is published in the May 10, 2011, print issue of Neurology, the medical journal of the American Academy of Neurology.
"Because the only treatment for ischemic stroke must be given within a few hours after the first symptoms begin, people who wake up with stroke symptoms often can’t receive the treatment since we can’t determine when the symptoms started,” says Mackey, a member of the American Academy of Neurology.
"Imaging techniques are being developed and tested that will help us better determine when strokes occurred so that patients may receive the proper treatment.”
The study examined all cases of ischemic stroke (caused by blocked blood flow in the brain) in people age 18 and older seen in hospital emergency departments in the Greater Cincinnati/Northern Kentucky region over one year. About 87 percent of strokes are ischemic strokes, according to the American Stroke Association.
The research is part of the Greater Cincinnati/Northern Kentucky Stroke Study, begun in 1993 at the UC College of Medicine. Funded by the National Institutes of Health (NIH), the project identifies all hospitalized and autopsied cases of stroke and transient ischemic attack (TIA) in a five-county region (Hamilton and Clermont Counties in Ohio, and Boone, Kenton and Campbell counties in Kentucky). The NIH also funded the study led by Mackey.
Of the 1,854 ischemic strokes in Mackey’s study, 273, or 14 percent, were "wake-up strokes,” where the person woke up with stroke symptoms, according to the patient, a partner or a caregiver. By extrapolating that number to the general U.S. population, the researchers estimate that approximately 58,000 people in the United States go to the emergency department with a wake-up stroke in a year.
The researchers compared those with wake-up strokes to those who were awake when their stroke symptoms started. There were no differences between the two groups in terms of sex, whether they were married or were living with someone, and their stroke risk factors such as high blood pressure, diabetes, smoking or high cholesterol.
There were minor statistically significant differences in age and the severity of the stroke. People with wake-up strokes were an average of 72 years old, compared to 70 for non-wake-up strokes. Those with wake-up strokes had an average score of four on a test of stroke severity, compared to a three for those with non-wake-up strokes. Scores ranging from one to four indicate mild strokes.
The researchers also analyzed whether those with wake-up strokes would have been eligible for the clot-busting drug tissue plasminogen activator, or tPA, if the time of stroke onset had been available. Of the 273 wake-up strokes, at least 98 would have been eligible for treatment by meeting the normal criteria for treatment with tPA. (There are a number of exclusions for tPA, based on stroke severity, recent surgery and other factors.)
"This is a group of patients that should be a focus for future studies,” Mackey said. "It’s likely that some of these strokes occurred immediately prior to awakening, and people would benefit from treatment.”