15% strokes occur during sleep making treatment difficult: Study

By Dr. Ananya Mandal, MDMay 10 2011

According to a new study nearly 15 percent of people who have a stroke are not eligible for clot-busting treatment because the stroke happened while they slept. These clot breaking drugs can prevent permanent disability after a stroke - but the treatment must be given within a four-and-a-half-hour window after the stroke symptoms begin say experts. Since people who have a stroke while asleep can't know when it occurred, they can't get the treatment if they slept for more than four and a half hours, explained study author Dr. Jason Mackey at the University of Cincinnati. “They can't get the drug,” he said. “That's a big issue.”

When Mackey and his colleagues compared these so-called “wake-up” strokes to strokes that occur during the day, they saw no major differences between the two types, indicating that the same advice for preventing and treating daytime strokes applies to those that take place while asleep. He called the strokes while people are asleep or awake “largely indistinguishable”. He said thus people concerned about either type should focus on staying generally healthy, controlling their blood pressure, eating well, exercising, and checking their cholesterol. He added that a stroke needs to be treated quickly and anyone who wakes up with typical signs - such as trouble speaking or walking, or weakness on one side in the arm, face or leg - should work fast. “If you suspect anyone is having a stroke, the important thing is to call 911 immediately,” he said. Stroke is the third leading cause of death in the United States, after heart disease and cancer.

The team reviewed medical records from people who came to emergency rooms in Ohio and Kentucky in 2005. They identified 1,854 people who had experienced the most common kind of stroke, in which blood flow to the brain becomes blocked. Of those stroke patients, 273 (almost 15 percent) said they woke up with symptoms. If 15 percent of strokes happen during sleep, an estimated 58,000 Americans each year come to an emergency room because they woke up with stroke symptoms, the authors report in the journal Neurology.

None of the patients who woke up with symptoms received the clot-busting drug known as tPA (short for “tissue plasminogen activator”). But what if some of them had their strokes right before they woke up, instead of many hours earlier? That could have made them eligible for treatment. This becomes an issue, the authors say. Indeed, one-third of the people who experienced wake-up strokes could have received the drugs if time had not been an issue. They didn't have any other features that would disqualify them from receiving tPA, such as high blood pressure or a recent surgery. “A substantial proportion of these patients do not have any reason why they could not get the drug,” said Mackey.

The reason doctors hesitate to administer tPA after that crucial time window, he explained, is that it comes with a risk of bleeding in the brain, and research has not shown any benefits if it's administered long after symptoms began. Mackey added that the next step is to investigate how to estimate when wake-up strokes actually occurred, so clinicians can determine which people who wake up with symptoms can receive tPA, “so we can give them a chance.”

Newer imaging technologies at some hospitals can help doctors determine whether urgent treatments can still help a patient who's had a stroke while slumbering, says Ausim Azizi, professor and chair of the department of neurology at Temple University School of Medicine in Philadelphia. “There are imaging technologies that can show if there's brain tissue left that is not completely dead and can be salvaged,” he says. There is also a catheter procedure that can help remove clots seen on scans. At least 98 of the people in the study who had wake-up strokes would have been eligible for tPA, researchers said. “No matter what, still the best thing to do is to go to the hospital,” says Azizi — and by ambulance. He explained not all emergency rooms have tPA on hand or a stroke expert on call and if an ambulance team realizes a person is having a stroke, they'll be able to reroute to the nearest emergency room equipped to treat stroke patients.