Migraine Elevates the Risk of Perioperative Stroke

ASHEVILLE, NC—The 30 days after surgery are a period of exceptionally high risk for ischemic stroke, and the risk is greater for patients with migraine, compared with patients without migraine, according to a lecture at the Eighth Annual Scientific Meeting of the Southern Headache Society.

Timothy T. Houle, PhD

“When we send individuals with migraine to surgery who do not have classical risk factors [for stroke], they may, in fact, still be at risk for stroke during the perioperative period,” said Timothy T. Houle, PhD, Associate Professor of Anesthesia at Massachusetts General Hospital and Harvard Medical School in Boston.

Dr. Houle described a hospital-based registry study that he and his colleagues published in BMJ. They found that the rate of ischemic stroke within 30 days of surgery was about 240 strokes per 100,000 patients without migraine, whereas among migraineurs, the rate was 430 strokes per 100,000 patients. Among patients with migraine without aura, the rate was 390 strokes per 100,000 patients, and among patients with migraine with aura, the rate was 630 strokes per 100,000 patients. “If you have migraine with aura, your risk of having a stroke is appreciably elevated and not trivial,” Dr. Houle said. “This is something to take seriously.”

The Migraine–Stroke Connection

Researchers consistently have found that migraine is associated with an increased risk of ischemic stroke in the general population, but the relationship has been challenging to study.

Possible mechanisms underlying the relationship between migraine and stroke include comorbidities (eg, higher BMI and increased cardiovascular risk factors) and medication use. In addition, research suggests that cortical spreading depression might make migraineurs’ brains more susceptible to stroke, Dr. Houle said. Patent foramen ovale, arterial dissection, coagulation dysfunction, endothelial dysfunction, or a genotype that increases the risk of migraine and stroke are other potential pathways.

Spector et al conducted a meta-analysis of 21 studies and concluded that migraine appears to be independently associated with a twofold increased risk of ischemic stroke. A meta-analysis by Schürks et al found that the relative risk of stroke was about 1.73 for patients with migraine and 2.16 for patients with migraine with aura. Migraine without aura was associated with a relative risk of 1.23, but this result was not statistically significant.

Dr. Houle and colleagues hypothesized that focusing on the perioperative period, when stroke is more prevalent, “could yield unique insights into the migraine–stroke connection,” he said.

Ischemic stroke in the perioperative period occurs at a rate of about 100 strokes per 100,000 individuals for the lowest-risk surgeries. After major cardiac and vascular surgery, the risk may be between 600 and 7,400 strokes per 100,000 individuals. “We have … a risk period that is intensely elevated for patients about to receive surgical insult,” Dr. Houle said. The increased risk may result from the indication for the surgery, as well as factors related to surgery itself, such as surgical stress, inflammatory responses, and intraoperative hypotension.

A Retrospective Cohort Study

Based on the increased risk of stroke in the general population, the investigators hypothesized that individuals with migraine also would have an elevated risk of stroke in the 30 days after surgery. They analyzed data from 124,558 patients (mean age, 52.6; 54.5% women) who underwent surgery between 2007 and 2014 at Massachusetts General Hospital and two satellite campuses. They included patients who had surgery under general anesthesia with mechanical ventilation and were successfully extubated. They used ICD-9 codes to identify patients with migraine. The primary outcome was ischemic stroke within 30 days. They identified strokes using ICD-9 codes and confirmed strokes by reviewing brain scans and medical records.