MRI can help decide therapy in patients with unclear-onset stroke

	Tweet

Among patients who have had strokes but aren’t sure when symptoms began, magnetic resonance imaging (MRI) can help distinguish who might benefit from clot-busting drugs while facing acceptable risk, according to research presented at the American Stroke Association’s International Stroke Conference 2011.

Researchers used MRI techniques to screen 430 patients with unclear-onset stroke at six university hospitals in South Korea. Strokes are categorized as unclear-onset, or “wake-up,” strokes if patients or witnesses don’t know when symptoms began, or woke up already in the throes of a stroke.

It is a key issue because clot-busting drugs have proven effective at reducing disability up to 4.5 hours after symptom onset.

“Wake-up, or unclear-onset, strokes account for a quarter of all ischemic strokes but have been automatically excluded from clot-busting techniques because the onset time cannot be known. Our study shows that such patients could also be treated safely and effectively,” said Dong-Wha Kang, M.D., Ph.D., lead author and associate professor in the Department of Neurology at Asan Medical Center at the University of Ulsan College of Medicine in Seoul, South Korea. 

All the patients arrived at one of six emergency rooms within six hours of detecting symptoms. Using diffusion-perfusion MRI, which shows tissue death and blood flow in the brain, the researchers looked for sizable areas where tissue remained alive even though it lacked blood flow. To limit the risk of serious bleeding in the brain from clot-busting therapy, patients were excluded if they had extensive tissue death in the brain area supplied by a major artery, the middle cerebral artery, or if other MRI techniques, such as those called FLAIR or T2, showed that the time of tissue death had elapsed.

More than 80 patients (median age 67 and classified as having severe stroke) were found eligible for clot-busting therapy, which included intravenous administration of the drug tissue plasminogen activator (tPA), direct administration of the drug urokinase – which is not available in the United States – to the blocked vessels in the brain or both. Some patients also had their clots removed mechanically or underwent stenting.

Among those who received the drug therapy, about 45 percent had at least a “good” clinical outcome—ranging from no symptoms to slight disability with curtailed activities—on the modified Rankin scale, which measures degree of impairment and its impact on stroke patients’ daily activities. Almost 29 percent had an excellent clinical outcome, meaning they were able to carry out all their usual activities with little or no impairment.

A key limitation of the study is it didn’t include a comparison group of patients who did not receive the clot busting treatment. Still, Kang said, “This study should trigger follow-up studies to develop the best available treatment strategies for this important but neglected group of stroke patients.”

The study also found that female patients were likely to fare more poorly with treatment, as were patients who had a more severe initial assessment of their stroke impairment, and those treated at the two centers lacking previous experience in thrombolysis for unclear-onset stroke.

Because researchers in the study treated patients with strokes of various origins, it’s likely that the findings would also apply to non-Korean populations, said Kang. But patient outcomes are likely to vary among medical centers, due to the availability of MRI facilities as well as interventionists to deliver clot-busting drugs directly to the brain blood vessels.

This work received the Emergency Medicine Award from the International Stroke Conference committee – which recognizes outstanding research in the field by a young investigator.

The research team next plans to compare the outcomes from their study population with those of comparable but untreated patients listed in stroke registries. “Although this study provides some important clues to treat wake-up, or unclear-onset, stroke patients, we still have a long way to go to find the best way to treat them,” Kang said.

###

Co-authors are Sung-Il Sohn, M.D., Ph.D.; Kyung-Ho Yu, M.D., Ph.D.; Yang-Ha Hwang, M.D.; Moon-Ku Han, M.D., Ph.D.; Jun Lee, M.D., Ph.D.; Jong-Moo Park, M.D., Ph.D.; A-Hyun Cho, M.D., Ph.D.; Dong-Eog Kim, M.D., Ph.D.; Yong-Jin Cho, M.D., Ph.D.; Jaseong Koo, M.D., Ph.D.; Keun-Sik Hong, M.D., Ph.D.; Sun U Kwon, M.D., Ph.D.; Juneyoung Lee, Ph.D.; Hee-Joon Bae, M.D., Ph.D.; and Jong S Kim, M.D., Ph. Author disclosures are on the abstract. The Korean Health Ministry of Health & Welfare, Republic of Korea funded the study.

Statements and conclusions of study authors that are presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position. The association makes no representation or warranty as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing science content. Revenues from pharmaceutical and device corporations are available at http://www.heart.org/corporatefunding.

(Note: Actual presentation time is 11:16 a.m. PT/2:16 p.m. ET, Thursday, Feb. 10, 2011)

Additional resources:
Multimedia resources (animation, audio, images and video footage & interviews) are available in our newsroom at ISC 2011 Multimedia. This will include audio or video interview clips with AHA/ASA experts offering perspective on the news releases. Video clips with researchers (if available) will be added to this link after each embargo lifts.

###

Contact: ASA News Media Office in Dallas

214-706-1396
American Heart Association

RELATED STORIES:
Test for blocked neck arteries only necessary for people with stroke risk factors   Estrogen and Stroke Risk   Blueberry and green tea containing supplement protects against stroke damage   More-vigorous workout may cut men’s stroke risk   Is Clot-Busting Drug Safe for Kids with Strokes?   Stroke risk higher in less well-educated women   Increased prevalence of stroke hospitalizations seen in teens and young adults   Chocolate lovers have fewer strokes, study finds   Few African-Americans call 911 immediately for stroke symptoms   Smokeless tobacco may increase stroke risk   Taking AIM at post-stroke depression   Faster stroke care when patients come by ambulance

Comments

[ + Post Your Own ]

Now you're in the public comment zone. What follows is not Armenian Medical Network's stuff; it comes from other people and we don't vouch for it. A reminder: By using this Web site you agree to accept our Terms of Service. Click here to read the Rules of Engagement.

There are no comments for this entry yet. [ + Comment here + ]