People who suffer migraines are at a higher risk of stroke after surgery, researchers said on Wednesday. This means that a history of migraines, which affect about one in five people, should be taken into account when weighing the pros and cons of undergoing an operation, said a study in The BMJ medical journal.
"Given the high prevalence of migraine in the general population, the association (with stroke) carries public health importance," the authors wrote.
A research team from the United States, Denmark and Germany analysed the records of nearly 125,000 surgical patients at Massachusetts General Hospital and two satellite campuses between January 2007 and August 2014.
Of the group, 771 (0.6 percent) suffered a stroke within 30 days of surgery.
Just over eight percent (10,179) of the surgery group had a history of migraine, compared to 11.5 percent (89) of the 771 who suffered a stroke.
The team calculated the risk of stroke at 2.4 attacks for every 1,000 surgeries - a number which rose to 4.3 in 1,000 for migraine patients.
The risk was highest for those whose migraines had an "aura" - described as flashing lights or other warning signals experienced before an attack.
According to the World Health Organisation, about 6.7 million people died of stroke in 2012. Survivors often suffer long-term disability.