MONDAY, Dec. 21, 2015 (HealthDay News) -- People who have a stroke in the back of the brain and continue to have reduced blood flow to this area have a higher risk of having another stroke within two years, a new study reveals.
But researchers say people with low blood flow to the back of the brain can be identified with a new MRI-based technology. And, identifying areas with low blood flow is crucial, the study authors explained.
"Having a blockage present in a blood vessel doesn't always correlate to low blood flow," lead investigator Dr. Sepideh Amin-Hanjani, a professor of neurological surgery at the University of Illinois at Chicago College of Medicine, said in a university news release.
"There can be a blockage and flow can be normal, if other nearby blood vessels are able to compensate," Amin-Hanjani added.
Once areas with low blood flow have been identified, patients might benefit from angioplasty, a procedure to open blocked arteries, the researchers said.
Findings from the study were published in the Dec. 21 issue of JAMA Neurology.
Up to 40 percent of all strokes occur in the area of the back of the brain responsible for movement and balance. Strokes in this area can result in partial or total paralysis, the study authors said.
The study included 72 adults who had a stroke or mini-stroke in the back of the brain. The adults were treated at five academic medical centers in the United States and Canada. The stroke patients had at least a 50 percent blockage of the arteries in that part of their brain. Their health was tracked for an average of 22 months, according to the report.
The blood flow to the back of the patients' brains was assessed using noninvasive optimal vessel analysis -- a program that can quantify the volume, speed and direction of blood flowing through any major vessel in the brain using standard MRI equipment.
The study revealed that 25 percent of the stroke patients had reduced blood flow in the back of the brain. These people had 12-month stroke-free survival rates of 78 percent, the researchers said. Those with normal blood flow to the back of their brains had a 96 percent stroke-free survival rate at 12 months.
People with low blood flow had 24-month stroke-free survival rates of 70 percent, compared to 87 percent for patients with normal blood flow, the investigators found.
"At one year, the risk for patients with low blood flow was about five times as high as risk for patients without low flow in the back of the brain," Amin-Hanjani said. For these high-risk patients, the benefits of angioplasty likely outweigh the risks of the procedure, the researchers advised.
The study authors pointed out that as many as three-quarters of people in the study didn't have low blood flow to the back of the brain. "Other arteries are doing the job of ensuring that proper blood flow is reaching that area -- and these patients would not benefit from treatments aimed at opening the vessels, such as angioplasty -- in fact, the procedure would put these patients at unnecessary risk," Amin-Hanjani said.
The National Stroke Association has more about stroke.