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Undiagnosed ‘micro-strokes’ deep in the brain may impede recovery from major strokes

Monday, June 9, 2014: FOR IMMEDIATE RELEASE 12:01 am EDT

Tiny speckles on brain scans could signal need for personalized therapies

OTTAWA _ Small hidden brain injuries, or micro-strokes, may explain why people recover very differently after what appear to be similar kinds of strokes, according to research presented today at a national conference on stroke recovery.

Researchers at the University of British Columbia are tracking the number and location of micro-strokes — tiny speckles on the patient’s brain scan — to understand why some patients respond well to rehabilitation therapy while others do not.

Working with colleagues in Toronto and Waterloo, Heart and Stroke Foundation Canadian Partnership for Stroke Recovery (CPSR) researchers are measuring the impact of micro-strokes on motor function, cognitive function, or both.

“You can have a silent injury, or micro-stroke, deep in the brain and have no indication that anything has actually happened,” says researcher Dr. Angela Auriat, a postdoctoral fellow at UBC’s Brain Behaviour Research Lab.

Research has found that more than a quarter of people who experience a stroke have had micro-strokes – microscopic tissue damage caused by loss of blood supply, leaking blood vessels, or inflammation due to infection, among other causes.

“Understanding more about the way silent strokes impact recovery could eventually help shed light on the brain circuits important for recovery,” says Dr. Dale Corbett, Scientific Director and CEO of the CPSR.

“People with many micro-strokes, or silent strokes in certain parts of the brain, could require different types or duration of therapy, and require more personalized stroke rehabilitation,” says Dr. Corbett.

According to Dr. Auriat, “Silent [micro-strokes] are more common in people over 80 years old, but some studies indicate up to eight per cent of people between 40 and 45 years of age have these injuries.”

In a study presented today, researchers examined five control subjects and 10 people who’d had a stroke between one and five years previously. The goal was to assess participants’ overall cognitive function: thinking, memory, and attention.

Although all participants were high-functioning and living independently in the community, the researchers found significant cognitive deficits, particularly in memory, in the stroke group compared to the control group.

The next phase of the study will examine MRI images of participants’ brains to gain greater understanding of the relationship between micro-strokes and recovery.

Identifying silent strokes is increasingly possible thanks to advances in brain-imaging technology, including MRI techniques developed by CPSR researchers based at Sunnybrook Research Institute in Toronto.

Despite these advances in technology, however, “silent [injuries] really are under-detected in the population,” says Dr. Auriat. And micro-strokes are probably a predictor of bigger strokes to come.

“Increasing our understanding, detection and treatment of micro strokes will make a tremendous difference in the lives of affected Canadians,” says David Sculthorpe, CEO of the Heart and Stroke Foundation of Canada. ”Research such as this can go a long way in our collective prevention and treatment efforts in Canada.”

Other CPSR research has shown that exercise could be an important preventative factor.


The HSF Canadian Partnership for Stroke Recovery is a joint initiative of the Heart and Stroke Foundation and Canada’s leading stroke recovery research centres – Sunnybrook, Baycrest, Toronto Rehab, University of Ottawa, Ottawa Hospital Research Institute and Memorial University. The Partnership is restoring lives through research. Learn more at


Cathy Campbell

Heart and Stroke Foundation Canadian Partnership for Stroke Recovery


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