Nearly 15 per cent of strokes happen while people are sleeping, a new study finds, which means most can't benefit from a potentially brain-saving clot busting treatment.
The key treatment for stroke is a blood clot-busting drug called tPA, but it must be offered within three hours of the onset of stroke symptoms for it to be effective. That's why doctors always urge people who think they might be having a stroke to get to a hospital quickly.
But when patients wake up with symptoms of a stroke, it's impossible to tell how long ago the stroke began.
To study how prevalent "wake-up strokes" are, researchers from the University of Cincinnati looked at the medical records of 1,854 adults who were treated at emergency rooms in the Cincinnati area for ischemic strokes in a one-year period.
Ischemic strokes are by far the most common kind of stroke and involve a blockage, usually a blood clot, in a blood vessel entering the brain.
The researchers determined that in 14 per cent of the cases, people had a wake-up stroke, meaning they woke up with stroke symptoms.
The doctors could find few distinguishing characteristics of those patients who had wake-up strokes compared to those who had strokes later in the day. There were no gender differences between the two groups, their stroke risk factors such as high blood pressure, diabetes, smoking or high cholesterol were generally the same, nor did it matter whether they were married, living with someone, or living alone.
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. Anything between one and four indicates a mild stroke.)
The results appear in the journal Neurology.
Of 273 people who had "wake-up strokes," at least 98 would have been eligible for treatment with a blood clot-busting drug called tPA if doctors had known when the stroke had begun. Doctors can't use tPA if they don't know when the stroke began because after the four-hour window, the drug can actually cause bleeding that will extend and enlarge the stroke.
Study author Dr. Jason Mackey, of the University of Cincinnati's Department of Neurology, said more study should be done on wake-up strokes, since it's likely that some of these strokes occurred immediately prior to awakening, meaning the patients would benefit from treatment.
"Imaging studies are being conducted now to help us develop better methods to identify which people are most likely to benefit from the treatment, even if symptoms started during the night," he said in a news release.
Doctors advise that even those having a wake-up strokes should seek medical attention immediately, because even though they might not qualify for tPA, there are other treatments that can mean the difference between recovery and lasting brain damage.
Health Canada has approved tPA to be used within three hours from the time symptoms begin. However, since new research shows the drug can be effective up to 4.5 hours after symptom onset, it is up to emergency room doctors to determine when tPA should be administered.
The symptoms of a stroke include:
- sudden paralysis or weakness in the face or limbs, especially on one side of the body
- sudden problems with balance or walking
- sudden vision problems
- slurred speech
- sudden confusion or problems speaking or understanding simple statements
- sudden severe headache with no apparent cause
