The relation between right-to-left shunt and migraine: Focus on pulmonary arteriovenous malformations

Migraine is a common and disabling disorder. Pulmonary arteriovenous malformations (PAVMs) cause a right-to-left shunt (RLS). An increased prevalence of migraine, particularly migraine with aura (MA+), has been shown in patients with a RLS of both pulmonary and cardiac origin. The prevalence of PAVM in patients with hereditary hemorrhagic telangiectasia (HHT) is 15-45%. Therefore, the HHT population provides a unique opportunity to study the RLS-migraine hypothesis. Embolization of PAVMs might reduce the prevalence of migraine, and an association between PAVM in HHT patients and MA+ was shown recently in a prospective study. The current review focuses on the evidence of a real association between an intrapulmonary RLS and migraine, and summarizes the possible underlying pathogenesis.