Why do people with similar strokes experience completely different recoveries? Why do some people respond well to rehabilitation therapy, while others do not?

Dr. Lara Boyd and her team at the University of British Columbia think the answers may be found in the number and location of vascular lesions, or injuries, that appear as tiny speckles on the patient’s brain scan.

“As stroke researchers we like to make the assumption that we have this one big stroke and we can attribute all the deficits to that, ” says Dr. Boyd, who runs UBC’s Brain Behaviour Research Lab, Vancouver Coastal Health. “But I’ve always felt that’s not quite the whole story.”

The idea to track these small lesions, also known as silent or covert strokes, partly came out of her work as a physical therapist, when she realized that patients with seemingly very similar strokes were responding very differently to therapy.

“Variability from patient to patient is really hard to understand,” she explained. “We started thinking in my group that some of that might be attributable to these smaller lesions,” which are classically found in the deep part of the brain.

Working with colleagues in Toronto and Waterloo, the team of HSF Canadian Partnership for Stroke Recovery (CPSR) researchers hopes to understand whether these tiny lesions are playing a big role in motor function, cognitive function, or both.

“Understanding and characterizing the extent of these [small] lesions as thoroughly as possible will help us understand capability for recovery and sets us on a course to think about more personalized health care,” Dr. Boyd said. “So maybe the person with lots of micro-lesions needs a much different kind of intervention than a person without.”

The group is currently recruiting more participants, and data analysis will take place over the next year.

Supported by CPSR, the research has the potential to impact the quality of life of Canadians. The team is aware that the small lesions are probably a predictor of bigger strokes to come.

Exercise could also be an important preventative factor. Other research has shown that dementia patients with vascular cognitive lesions were able to lessen the effect with exercise.

“The end goal [would be], if we understand that a patient like this [with this many micro-lesions] has a different outcome than a patient who has a stroke who doesn’t have that – we would treat them differently,” Dr. Boyd said.

“Maybe those rehab courses look very different. Maybe one’s longer, maybe one’s more intense, we’re not really sure yet. But that’s the kind of information we’re trying to get out of it.”