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That risk was higher for those who had migraine with aura, but was elevated regardless of whether patients had aura or not (aOR 2.61 and aOR 1.62, respectively), Matthias Eikermann, MD, PhD, of Massachusetts General Hospital (MGH), and colleagues reported online in The BMJ.
"There are 60 million surgeries every year, and the baseline stroke risk is one in 1,000," Eikermann told MedPage Today. "If migraine [with aura] increases that risk almost three-fold ... you're talking about thousands of strokes each year. This is a relevant observation that needs to be explored further."
Richard Lipton, MD, of Albert Einstein College of Medicine in New York, a migraine specialist who was not involved in the study, called it "well-designed" and suggested that migraineurs needing surgery should not panic about the findings.
"The study suggests that, in patients with migraine with aura undergoing surgery, steps should be investigated to reduce the heightened risk of stroke," Lipton told MedPage Today. "People with migraine undergoing surgery should be reassured that although the relative risk is high, the absolute risk of post-operative stroke is modest."
Migraine is already a known risk factor for ischemic stroke, especially if a patient has aura. Eikermann and colleagues wanted to investigate whether that risk also carries to the perioperative period.
They looked at data on nearly 125,000 surgical patients (mean age 53; 55% female) who had surgery at MGH, or two satellite sites, from January 2007 to August 2014. About 8% of the patients had any migraine diagnosis, and 13% of migraineurs had aura.
Overall, there were 771 cases of perioperative ischemic stroke (0.6%). About 12% of these patients had a diagnostic code for migraine.
In controlled analyses, the researchers found that patients with migraine were at an increased risk of perioperative ischemic stroke compared with patients without migraine (aOR 1.75, 95% CI 1.39-2.21), and that risk was higher in those who had aura (aOR 2.61, 95% CI 1.59-4.29), though it was still elevated for migraineurs without aura (aOR 1.62, 95% CI 1.26-2.09).
The researchers calculated a predicted absolute risk of 2.4 perioperative ischemic strokes for every 1,000 surgical patients, which rises to 4.3 for every 1,000 patients with any migraine diagnosis.
That separates into rates of 3.9 per 1,000 patients for migraine without aura, and 6.3 per 1,000 for migraine with aura, they added.
Eikermann's group also found a higher rate of hospital readmission within 30 days of discharge among those with migraine (aOR 1.31, 95% CI 1.22-1.41).
"We see that patients with migraine are not only readmitted for stroke, but for other conditions associated with migraine, such as GI symptoms like nausea and vomiting, and pain," he told MedPage Today. "We should not only look at stroke, but other factors that contribute to more frequent readmission in migraine patients. Those things may be just as important to focus on."
Migraine patients may have a genetic predisposition that puts them at heightened risk of stroke during surgery, as well as an increased perioperative vulnerability to cerebral ischemia. One major mechanism may be an increased susceptibility to spreading depolarization, particularly in migraine with aura, they noted.
Eikermann said there are "two things that we feel pretty certain about" with regard to managing perioperative stroke risk in migraineurs: use of vasopressors, and right-left shunt, such as patent foramen ovale (PFO).
"High-dose vasopressin puts them at higher risk, and the same is true for right-left shunt, blood flowing from the right part of the heart to the left part," he said, noting that much more work would need to be done before recommending something like PFO closure to lower the risk of perioperative stroke in migraineurs.
He added that his group plans to use their data to create a new prediction instrument for perioperative stroke, which includes migraine and other risk factors, and that they would ultimately like to do an intervention study to see if that tool could decrease the risk of perioperative stroke.
Matthew Robbins, MD, of Montefiore Medical Center, who was not involved in the study, said it would “lead me to counsel patients with migraine differently.”
“Common sense measures include stroke education to such patients to promote awareness, early stroke diagnosis and treatment,” Robbins told MedPage Today. “Surgeons and anesthesiologists should also take note of this study’s results as the use of higher doses of vasopressors in patients with migraine could be a modifiable perioperative stroke risk factor, as the authors suggest.”
He noted that open questions still remain — “Does having chronic migraine or a higher migraine attack frequency elevate the perioperative stroke risk? Do those with more optimally treated migraine have a diminished risk?” — but concluded that the study “should further heighten our awareness that having migraine is not ‘benign.’”
Eikermann disclosed relevant relationships with Calabash Bioscience, Merck, and the Buzen Fund. Co-authors disclosed relevant relationships with Merck, Depomed, Anesthesiology, Annals of Surgery, and Headache, the NIH, the Else-Kröner-Fresenius-Stiftung/German Scholars Organization, the French National Research Agency, Amgen, BMJ, Cephalalgia, and the International Headache Society.