Sami Al Kasab, MD
Recently, there has been increasing evidence of higher risk for stroke in patients with migraine, in particular with migraine with aura. Interestingly, patients with migraine with aura have higher rates of PFO with right to left shunt, bringing up the question: What’s the relationship between migraine with aura, PFO, and ischemic stroke?
In this study, West et al evaluate the prevalence of PFO with right to left shunt in patients with cryptogenic stroke and who had a history of migraine. This was a retrospective analysis of data on patients presenting to the UCLA comprehensive stroke center between January 2008 and November 2017. Stroke etiology was classified based on the ASCOD phenotyping. Patients’ charts were also reviewed to identify patients who carried a diagnosis of migraine. Patients with migraine auras for > 50% of the time were classified as migraine with frequent aura. A PFO with right to left shunt was identified by the presence of positive bubble contrast study with TTE, TEE, or TCD.
A total of 1255 patients between 18-60 years of age were identified during the study period. Of those, 712 were diagnosed with ischemic stroke. 127 patients of the 712 ischemic strokes were identified as cryptogenic stroke. Among the 127 patients, 68 had adequate testing to determine the presence of PFO with right to left shunt and a complete migraine history.
Of the 68 patients with cryptogenic ischemic stroke with adequate testing for PFO with right to left shunt, 47 (69%) had PFO, and 34 (50%) had migraine; 15 of those were migraine with frequent aura. Of the 34 patients with migraine, 27 (79%) had PFO. Of the other 34 patients who didn’t have migraine, 20 (59%) had a PFO. The prevalence of PFO among patients with cryptogenic stroke was significantly higher in patients with migraine compared to those without migraine (p=0.0042).
In this study, the authors found a high prevalence of PFO in patients with cryptogenic stroke (69%), and a high prevalence of migraine (50%) in patients with cryptogenic stroke. Given prior evidence of higher rates of PFO in patients with migraine, the higher risk of stroke in patients with migraine, it is thought that there might be a link between cryptogenic stroke, migraine, and PFO.
Given that ischemic strokes in patients with migraine are unlikely to be explained by the vasoconstriction theory, the authors suggest that this risk is better explained by the higher rates of PFO increasing the risk of paradoxical emboli in such patients.
The study has some limitations; first there was not adequate PFO testing given that many patients had TTE with bubble study as the screening test for PFO, which carries a high rate of false negative results. In this study, only 54% of patients with cryptogenic stroke had both sufficient PFO testing and complete migraine history performed. Second, the diagnosis of migraine in this study was based on neurology note reviews and not based on standarized ICHD criteria. Additionally, the study is limited by its observational, retrospective nature.