As many as three million people over the age of 65 might experience something called “silent stroke” after surgery, every year. Also known as covert strokes, these are medical events that are not immediately obvious—except in a brain scan—and are actually more common than strokes that typically present visible symptoms quickly.
The Canadian researchers who initiated the study now saw that one in 14 post-operative patients experienced one of these silent strokes in a survey that examined more than 1,000 people across both North and South America as well as Asia, Europe, and New Zealand. The study was led by the Population Health Research Institute of Hamilton Health Sciences and McMaster University, in Hamilton, Ontario, Canada.
According to co-principal investigator Dr. PJ Devereaux, the NeuroVISION study found that “silent” covert strokes are probably far more common than overt strokes among people older than 65 who have undergone surgery. Dr. Devereaux is a cardiologist at Hamilton Health Sciences (HHS), as well as a professor in the health research methods, evidence, and impact, and medicine at McMaster University and a senior scientist at the Population Health Research Institute of McMaster University.
Of the 1,114 patients examined—who were amid elective, non-cardiac surgery (between March 2014 and July 2017), seven percent of patients were found to have experienced a covert stroke. From this, the research team further tracked patients—for the next year—to more accurately assess their cognitive capabilities.
Sure enough, those who experienced a covert (silent) stroke after surgery were found to be at least 13 percent more likely to experience cognitive decline, delirium, overt stroke, or “mini” stroke resulting from the temporary disruption in the blood supply to the brain.
Canadian Institutes of Health Research (CIHR) scientific director of the Insttitue of Circulatory and Respiratory Health, Dr. Brian Rowe, explains that both overt and covert vascular brain injuries continue to be more frequently being detected, recognized, and prevented. He adds, “The NeuroVISION Study provides important insights into the development of vascular brain injury after surgery, and adds to the mounting evidence of the importance of vascular health on cognitive decline. The results of NeuroVISION are important and represent a meaningful discovery that will facilitate tackling the issue of cognitive decline after surgery.”
The results of the NeuroVISION study were published this week in The Lancet.