In 1877 cohnheim described a case of stroke death due to paradoxical embolism of the patent foramen ovale (PFO), and in 1885 zahn introduced the concept of paradoxical embolism: systemic arterial embolism caused by emboli from the venous system entering the body circulation through intracardiac anatomic channels. The association of PFO with unexplained stroke (CS) and migraine has received increasing attention in recent years. The detection rate of PFO in the population is about 20-30%, and PFO is the pathological and anatomical basis for paradoxical embolism. I. PFO and unexplained stroke About 10%-40% of ischemic strokes have an unknown cause and are presumed to be associated with paradoxical embolism of the PFO, whereas several publications have identified large thrombi across the PFO by echocardiography or surgery. lechat reported a 54% detection rate of PFO in CS in stroke patients <55 years of age, and 21% of stroke PFOs with a definite cause, compared with 10% in control populations. The PICSS study found PFO-mediated paradoxical embolism to be an independent risk factor for CS. Oral anticoagulation and antiplatelet agents are routinely used for secondary prevention of CS, but the risk of recurrent stroke or TIA within one year is 3.4%-12%, with anticoagulants being preferred to antiplatelet agents. Potential disadvantages of drug therapy: increased risk of bleeding; poor efficacy of recurrence prevention; poor compliance. Transcatheter occlusion of PFO is more effective in preventing CS recurrence. A meta-analysis showed that the incidence of stroke or TIA after transcatheter occlusion of PFO was lower than with drug therapy (1.3% vs 5.2%). 980 patients with CS combined with PFO were randomized to PFO occlusion and conventional drug therapy in the RESPECT trial, a large prospective randomized controlled clinical study, with a mean follow-up of 2.2 years and a maximum of 8 years, with results published in 2012. The RESPECT study established that patients with CS combined with PFO should be treated with PFO occlusion as early as possible. The prevalence of PFO and unexplained migraine is 30%-40% in migraine patients and 48%-70% in patients with migraine with aura (MA), both higher than the normal population. PFO occlusion may reduce migraine attacks, as shown in a single-center study by Tsimika, which showed a 55% cure and 42% improvement in migraine after PFO occlusion.The MIST trial was a multicenter randomized controlled study looking at 432 patients with frequent and treatment-naïve MA, 163 with moderate to massive shunts in the PFO, randomized to Interventional occlusion of the PFO resulted in a significant reduction in migraine attacks. Because of the complex mechanism of migraine, the relationship between PFO and migraine as well as the efficacy of occlusion still deserves further study. Indications for PFO occlusion Unexplained stroke or TIA, age 18-60 years (excluding lacunar infarction) Migraine with aura combined with PFO Decompression sickness Oblique prone dyspnea - upright hypoxemia IV. Major exclusion criteria (RESPECT study)