Although it's known that 0.5 percent of over-65s suffer a stroke that is immediately recognized after surgery, many more will have a 'silent stroke' that is never diagnosed.
Researchers at McMaster University reckon it affects around 7 percent—or one in 14—of older people who have non-emergency and non-cardiac surgery. With 50 million people over the age of 65 worldwide having elective (non-emergency) surgery every year, around 3.5 million could be suffering a 'silent stroke'.
This type of stroke doubles the risk of cognitive decline and can also cause delirium or a TIA (transient ischemic attack), during the 12 months after surgery.
The researchers used MRI scans to assess the health of 1,114 patients from around the world nine days after they had undergone elective surgery. The procedure can damage the veins and arteries in the brain, so increasing the risk of a stroke, the researchers found.