New York, Feb 15 (IANS): Patients, who have low blood flow to the back of the brain, are at increased risk of recurrent stroke, a six-year-long trial has found.

"We found that patients with low blood flow had a 22 percent risk of recurrent stroke in the first 12 months, versus a four percent risk for patients whose blood flow was not low," said principal investigator Sepideh Amin-Hanjani, professor of neurological surgery at the University of Illinois' college of medicine, the US.

At 24 months, the risk for patients with low blood flow was up to 30 percent versus 13 percent for other patients.

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.

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.

Patients with VBD can have blockage ranging from partial to complete, which affects blood flow accordingly.

The 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.

For the study, adult stroke patients were assessed for low posterior blood flow and followed for one to two years, an average of 22 months.

The researchers also developed a specialised software to analyse blood flow using standard magnetic resonance imaging.

"The ultimate goal is to find what treatments might be most effective for each patient," Hanjani noted.

The researchers presented their findings at the International Stroke Conference in Nashville, Tennessee in the US.