Studies: Brain imaging gives doctors more time to treat strokes

Advanced brain imaging technology may give doctors an additional 10 hours or more to respond to some strokes, researchers said Wednesday, a development that may soon bring major changes to the way hospitals treat one of the leading causes of disability and death.

The research is upending doctors’ long-held belief that they have just six hours to save threatened brain tissue from lack of blood flow when a major vessel to the brain is blocked. Wednesday’s research suggests they may have as long as 16 hours in many cases; a study published three weeks ago with a different group of stroke victims put the outer limit at 24 hours for some.

Together, the two studies are expected to be responsible for new guidelines for stroke treatment that were scheduled to be released Wednesday. Both studies showed such dramatic results that they were cut short to speed up reporting information to physicians.

“The big news is that we were all wrong in how we were thinking about how strokes evolve,” said Gregory Albers, a professor of neurosurgery at Stanford University Medical Center and lead author of the new paper. While some brain tissue dies in a stroke, collateral blood vessels temporarily take over feeding a larger area that is also starved for blood and oxygen, giving doctors many more hours to save that tissue than they previously believed, he said.

“We are quadrupling the stroke treatment window today,” Albers said. “It’s going to have a massive impact on how stroke is triaged and assessed.”

Walter Koroshetz, director of the National Institute of Neurological Disease and Stroke, which funded the new study, said in a news release: “These striking results will have an immediate impact and save people from life-long disability or death. I really cannot overstate the size of this effect.”

Strokes were the fifthleading cause of death in the United States in 2016, when they killed 142,142 people. About 800,000 people have strokes every year, most of which are first-time events.

The vast majority of strokes are “ischemic”: a clot or mass blocks a vessel, cutting off the flow of blood to a portion of the brain. Those strokes kill some brain tissue and threaten more in many people.

Doctors can respond with clot-dissolving drugs within the first few hours, and within six hours have been reaching into the blood vessel with clot-removing devices.

But the studies show they may have more time to save brain tissue where the blood supply is being choked off but the tissue has not yet died.

Both studies were published in the New England Journal of Medicine. Albers’ study was presented at a meeting of the American Heart Association meeting in Los Angeles.