Strokes are preceded by a mild "warning stroke", scientifically called a transient ischemic attack (TIA), in one out of every eight cases, according to a new study.
"These results illustrate the need for better risk assessment tools for preventing strokes before they occur. Other studies have shown that up to 80 percent of strokes after TIA can be prevented when risk factors are managed intensively," said study author Dr. Daniel G. Hackam, of the University of Western Ontario in London, ON.
For the study, the researchers identified all people at Ontario hospitals with a diagnosis of stroke over four years.
They observed that 2,032 of the 16,400 patients (12.4 percent) had a TIA prior to the stroke.
The researchers also observed that, during a TIA, stroke symptoms last for less than 24 hours and then resolve.
According to them, people who had no warning strokes were more likely to have a more serious stroke, compared to those who did have the warning stroke.
The team said that people with no warning were more likely to die while at the hospital, more likely to have a heart arrest while in the hospital, and less likely to be able to go home after the hospital stay, rather than to a nursing home or rehabilitation centre.
People with the warning stroke were typically older than those without warning strokes.
They were also more likely to have diabetes, high blood pressure and heart problems.
"It's possible that the blood vessels of those with warning strokes were preconditioned to the lack of blood flow, which protected them from the full result of the larger stroke. Any person who experiences even a minor stroke should get to the emergency room immediately," wrote the authors
A research article on the study has been published in the journal Neurology.