The University of Illinois at Chicago has been awarded a five-year, $2.1 million grant from the National Institute of Neurological Disorders and Stroke to lead a multi-center study to assess blood flow and stroke risk.
Ischemic strokes -- the type caused by clots rather than bleeds in the brain -- account for 80 percent of all strokes and represent a major source of death and disability. They are often caused by atherosclerosis, a build-up of plaque inside the walls of blood vessels.
Advances in endovascular techniques, such as threading a catheter to open up a blockage, or placing a stent in a vessel, provide new treatment options for patients with stroke. But these interventions carry risks, and physicians don't always know which patients are appropriate candidates for these procedures.
"There's been a lot of emphasis in prior medical research on the type of stroke that affects the anterior circulation, or blood supply to the major lobes in the front of the brain," says Dr. Sepideh Amin-Hanjani, UIC assistant professor of neurological surgery and principal investigator of the study.
"But there's another set of arteries that supply the back part of the brain, including the brainstem, which is a smaller, but in some ways, a much more functionally important part of the brain with a lot of important real estate," she said.
Even a very small stroke in this area of the brain can have very devastating consequences, Amin-Hanjani said.
Until recently, it has been difficult for researchers to measure blood flow in the vertebral arteries to the back of the brain. But they hypothesize that patients with vascular disease in these arteries have low blood flow and are at higher risk of stroke.
The study will enroll 80 patients at five sites who have first-time stroke symptoms caused by 50 percent or greater blockage of the arteries leading to the back of the brain.
Patients will receive standard brain imaging with MRI or CT, imaging of the blood vessels, and possible medication therapy, which might include aspirin, anti-cholesterol medication, or blood pressure lowering medication.
As part of the study, patients will additionally undergo magnetic resonance (MR) perfusion and quantitative magnetic resonance angiography (QMRA) that measures blood flow using "NOVA" technology developed by UIC neurosurgeon Dr. Fady Charbel. The Noninvasive Optimal Vessel Analysis measures the volume of blood flow, direction, and provides a four-dimensional view of the shape and form of blood flow.
Patients will be imaged when they are first enrolled in the study and six and 12 months later. They will be monitored monthly for any recurrent symptoms that would suggest a stroke.
After following the participants for a minimum of one year, researchers will compare the blood flow of patients who had a stroke since their initial symptoms with those patients who did not have stroke.
"We hypothesize that patients who have better blood flow to their brains are going to be the ones that don't have new strokes, and those that have low blood flow on their brain scans will be at higher risk of having strokes," said Amin-Hanjani.
If this is demonstrated, then patients with low blood flow to their brain -- even when they first have stroke symptoms -- may be candidates for intervention such as stenting or angioplasty to increase blood flow, said Amin-Hanjani. At the same time, people who have stroke symptoms but normal blood flow could be reassured that their risk of stroke on medication therapy is low, and there may be no need for further intervention exposing them to unnecessary risk.
"If we know who is at highest risk, we may be able to figure out who is going to benefit the most from interventional treatment," said Amin-Hanjani. "Given that treatment such as stenting is not entirely risk free, it would be important to know that you're treating the highest risk population and offering them a benefit, rather than treating patients who may not need it."
|Contact: Sherri McGinnis Gonzalez|
University of Illinois at Chicago