New Clue to Brain Bleeding After Stroke Treatment

New Clue to Brain Bleeding After Stroke Treatment
Friday, October 14, 2011
By: Steve Tokar

Steve Tokar, UCSF

The only medication currently approved for stroke treatment—tissue plasminogen activator (tPA), which dissolves blood clots—is associated with an increased risk of bleeding in the brain, particularly among patients with hyperglycemia (high blood sugar). A study led by Raymond A. Swanson, MD, chief of the neurology and rehabilitation service at the San Francisco VA Medical Center, provides a possible reason: high blood sugar fuels the formation of superoxide, a toxic form of oxygen, which in turn damages tissues, weakens blood vessels and promotes excess bleeding.

The study, which used an animal model of stroke, was published on October 14 in the online Early View section of Annals of Neurology.

“A stroke is usually caused by a blood clot lodging in a brain artery and cutting off blood flow,” said Swanson, who is also professor and vice chair of neurology at the University of California, San Francisco (UCSF). “If you can administer tPA in time and dissolve the clot, then blood flow is restored.” However, he said, “there’s a risk that when the clot is dissolved and blood suddenly flows back into the affected area of the brain, there will be bleeding. And that is a huge problem, because the bleeding can cause more damage, or even death.”