Risk of recurrent stroke is higher in patients who have low blood flow to the back of the brain, a new study has found.
Researchers at the University of Illinois at Chicago also found that the condition can be visualised using specialised software that analyses blood flow using standard magnetic resonance imaging (MRI).
Patients with blockage of the blood vessels that supply blood to the back of the brain - a condition known as vertebrobasilar disease, or VBD - are at risk of having a stroke or temporary symptoms of a stroke known as transient ischemic attack (TIA).
These posterior-circulation strokes account for 30 per cent to 40 per cent of all ischemic strokes.
The risk of a repeat stroke associated with VBD may be tied to several factors, including the degree to which the blockage reduces the blood flow to the brain, researchers said.
Patients with VBD can have blockage ranging from partial to complete, which affects blood flow accordingly. Some patients with VBD can also have normal blood flow to the back of the brain.
A six-year, multi-centre trial sought to identify patients with VBD and low blood flow to see if they had a higher risk of recurrent stroke than those with normal blood flow to the back of the brain.
A quarter of the enrolled patients were identified as having low posterior blood flow.
"We found that patients with low blood flow had a 22 per cent risk of recurrent stroke in the first 12 months, versus a 4 per cent risk for patients whose blood flow was not low," said Dr Sepideh Amin-Hanjani, professor of neurological surgery at the UIC College of Medicine and principal investigator on the study.
At 24 months, the risk for patients with low blood flow was up to 30 per cent versus 13 per cent for other patients.
"If you can establish that there is a proportion of people who have reduced blood flow, then you can consider them for treatments that might actually increase it - for example, [by] surgery or stents or other procedures that might open up the blood vessels," Hanjani said.
Just as importantly, if you find a group of people whose blood flow is not reduced, Hanjani said, there would be no need to subject them to a procedure and its associated risks.
NOVA technology, a computer-based system used to visualise brain anatomy and quantify blood flow developed at UIC by Dr Fady Charbel, professor and head of neurological surgery, made it possible to easily identify patients with reduced posterior blood flow using standard MRI.
With help from the UIC Office of Technology Management, NOVA was transferred to a newly formed company, VasSol, where the technology was further developed into a product with an improved user interface, adding functionality and applicability.
