Cancer Drug May Prevent Stroke-Related Brain Injury
Jan. 31, 2001 -- Each year some 750,000 people in the U.S. suffer strokes, and two-thirds of those who survive the initial attack will develop moderate to severe permanent disability due to brain injury. While drugs designed to break up blood clots can reduce permanent injuries in many patients, they must be given within three hours of a stroke to be effective.
Now, very preliminary mouse studies from a California research center suggest that a new approach to treating strokes, in which a drug is given to prevent the brain from swelling, may dramatically reduce permanent injury. And the drug appears to be effective for up to six hours following a stroke, doubling the window of therapeutic opportunity for patients.
"For people who have just had a stroke, that extra time is critical," study author David A. Cheresh, PhD, of Scripps Research Institute in La Jolla, Calif., tells WebMD. "Right now, many, many people don't make it to the hospital in time to receive the clot-busting drugs. Our study showed that a single dose of this drug, given for up to six hours after an event, gave a significant level of protection against brain injury." Cheresh and colleagues published their results in the February issue of Nature Medicine.
As the U.S. population ages and stroke incidence rises, the discovery of drugs that limit stroke-related brain damage and work for longer periods following an event is more critical than ever, American Stroke Association advisory committee chairman Edgar Kenton, MD, tells WebMD. He says these researchers, and others evaluating therapies that protect the brain immediately after a stroke, appear to be on the right track. Kenton is a professor of clinical neurology at Philadelphia's Thomas Jefferson University.
"The drugs that are now available are OK if given within this three-hour period, but studies have shown that the majority of people are not reaching the hospital during that time," Kenton says. "The average is closer to 22 hours, so the more we can extend that treatment window the better. Eventually, we may be able to use these neuroprotectors as much as 24 hours or more after a stroke."
A stroke is a sudden loss of brain function, most often prompted by a blood clot that blocks blood flow to the brain and, therefore, deprives it of oxygen. Patients may experience loss of vision, balance, coordination, speech, or the ability to understand speech.
Initially, oxygen deprivation tends to occur in a small area of the brain, but further injury often occurs when a molecule known as vascular endothelial growth factor, or VEGF, becomes active. VEGF exists throughout the body to repair tissue damage due to oxygen deprivation by enhancing the growth of new blood vessels. When VEGF is produced in the brain, usually beginning around three hours following a stroke, brain swelling and further injury often occur.