It is an established fact that migraine, and especially migraine with aura increases the risk of strokes. The increase in the risk is small, but according to a new study published in the British Medical Journal, it is higher during and after surgery.
The researchers examined records of 124,558 surgical patients at the Massachusetts General and two other hospitals. Among these, 8.2% or 10,179 patients had a history of migraines with 1,278 or 12.6% having migraine with aura. The risk of stroke during or within 30 days after surgery was 1-2 in 1,000 among patients without migraine history, 4 in 1,000 in those who had migraines and 6 in 1,000 in patients who had migraine with aura. So, the absolute risk of a stroke is still very small, but the relative risk is statistically much higher. They also discovered that strokes were more common in patients who during surgery needed medications to increase their blood pressure. Most of the strokes occurred within the first two days after surgery.
We do not know why migraine carries an increased risk for strokes, so the only recommendation the authors offer is for migraine diagnosis to be included in the preoperative risk assessment of patients. I would add that according to another study, taking high doses of magnesium and potassium supplements could possibly reduce this risk. Magnesium alone was shown to reduce the risk of strokes in another review of studies involving 6,477 patients. Our own research and that of others have shown the beneficial effect of magnesium on the prevention of migraines as well. Here is one of a dozen posts on magnesium on this blog that provides dosing recommendations.