NASHVILLE, Feb. 6 -- Concerns about excessive bleeding in the brain -- a consequence of using a clot-dissolving drug in some stroke patients -- have led researchers to develop a 10-point system that neurologists may be able to use to take the guesswork out of when to use this drug.
The clot-busting drug TPA (tissue plasminogen activator) must be administered within three hours of onset of a stroke. If given after that time period, there is increased risk for life-threatening bleeding in the brain. Before TPA can be safely and effectively administered, the stroke patient must undergo a brain scan, called a computed tomography (CT) scan, to verify that he or she is having a stroke.
The scan helps determine whether the stroke was caused by a blood clot, in which case, TPA can help dissolve it. Strokes caused by a blood clot -- ischemic strokes -- are the most common type of stroke.
"With TPA, we worry about three things -- getting people treated in time, determining those most likely to benefit, and not giving it to the people it may hurt," says the studys senior author, Alastair M. Buchan, M.D., of the University of Calgary, Alberta, Canada. "We think this scale can help increase the confidence of physicians to use TPA."
"In the future, with more sophisticated imaging tools, we will pick people for clot-busting therapy depending on the state of their brain, rather than whether they get to the hospital within three hours. Essentially, we wanted to develop a way of helping people use the brain scans and pick the patients who might benefit from clot-busting therapy and provide other treatment to those who might not benefit."
Researchers from the University of Texas, Houston and the University of Calgary in Alberta, Canada, presented their research findings here today at the 24th American Heart Association International Conference on Stroke and Cerebral Circulation.
The scientists base their system on the cardiograms that cardiologists and other doctors use to determine damage in the heart following a heart attack. Cardiograms divide the heart into segments, and each segment is examined separately to determine the extent of damage.
"We've created a cardiogram for the brain," says Buchan.
Buchan and his fellow researchers developed a system which divides the brain into 10 sections. Each of the 10 sections is examined and given a score of 1 if there is little or no damage, or 0 if excessive damage has occurred.
"Instead of just eye-balling the brain, we wanted to develop a system that looks at the structures likely to be injured during stroke and look at the brain systematically from front to back," says Buchan. "If there is a small amount of damage or no damage, then fine, we can use the therapy. If its widespread, then its too late."
If a patient with an ischemic stroke scores 8 or higher, he or she would probably be a candidate for clot-dissolving therapy, according to Buchan. If the patient scores 7 or lower, clot-dissolving therapy may be unsafe because of greater risk for bleeding in the brain.
"Because brain scanners are more sensitive and doctors eyes are more attuned to identifying changes, we're seeing stroke damage on the scans much earlier than we used to see it," says Buchan. "Doctors seem to do better when they have a system or scale to follow. By looking at 10 regions of the brain, they will more closely examine what is going on in the brain."
The researchers utilized the scale in 101 stroke patients treated with TPA. They found that 63 percent of patients who scored 7 or less on the scale had either bleeding in the brain or died from their stroke. In contrast, only 7 percent of patients who scored 10 died of their stroke, and none developed bleeding in the brain.
"When there are bad changes on the brain scan within a few hours of symptom onset, and the person scores 7 or less, we found that the risks of the therapy far outweigh the benefits of helping patients," says Buchan. "The risk of hemorrhage is way too high. This system provides the confidence to look at the scan, examine it and reduce the risk of bleeding."
The system is being used currently in Canada in clinical trials of TPA. Buchan says he hopes that once more research data is collected on the usefulness of the scale, it can be more broadly used in both Canada and the United States.
Co-authors are Andrew M. Demchuk, M.D.; James C. Grotta, M.D., both of the University of Texas, Houston; and Hasneen Karbalai, M.S., of the University of Calgary, Alberta, Canada.
Media advisory: Dr. Buchan can be reached by phone at 403-670-1581 or by fax at 403-670-1602 or by e-mail at buchan@ucalgary.ca. (Please do not publish numbers.)