Patent Foramen Ovale and Migraine: Evidence for a Link?

Recent epidemiological data suggest a bidirectional link between patent foramen ovale (PFO) and migraine with aura (MA) with a relative risk of 2 for PFO in subjects with MA and for MA in subjects with PFO. There is no evidence for a link between PFO and migraine without aura (MoA). This link is not systematic and applies only to subsets of PFO, mostly large ones, and to subsets of patients with MA. Although comorbidity cannot be ruled out, it is likely that this link is partly causal and that some large PFOs may favor MA attacks in genetically predisposed subjects, by allowing vasoactive substances, platelet emboli, or paradoxical emboli to bypass the lung filter and trigger cortical spreading depression. Even if ongoing randomized trials of PFO closure confirm the apparent benefit observed in the available retrospective studies, it would be dangerous to extrapolate from the improvement or even the cessation of symptomatic MA attacks to the treatment of migraine as a primary headache disorder.