Page 18 - Migraine, the heart and the brain

Chapter 1
the left (arterial) circulation. Several structural abnormalities can cause right-to-left shunting. The most frequent cause is a patent foramen ovale (PFO),37 a remnant from the fetal period located in the atrial septum of the heart. Other causes of RLS are actual defects of the cardiac septum (atrial septum defect, ASD) and pulmonary arteriovenous malformations (PAVM) or stulas.38 Most imaging studies that evaluated the presence of RLS in migraine patients, however, only aimed for detecting PFO or ASD but did not include the pulmonary causes. A systematic review reported that PFO was more prevalent in migraine with aura patients than in the general population. The reported pooled risk was increased more than two times (OR 2.54, 95%CI 2.01-3.08).39 Following that study, two case-control studies evaluating PFO prevalence were published and found no increased PFO prevalence in migraine with aura.40;41 Due to technical limitations (low sensitivity of trans-thoracic echo and short evaluation time) small PFOs could have been missed in these studies, which may be an explanation for a lower prevalence. Non-cardiac causes of RLS like PAVM generally are not detected with cardiac echography. No studies in migraineurs and controls have been done evaluating the prevalence of PAVM.
In healthy subjects 71% were found to have a RLS (38% had a PFO, 28% had a PAVM, 5% had evidence of both using trans-thoracic echo (TTE)42 In this study, any appearance of left-sided heart micro-cavitations was considered positive for a RLS, which is the lowest threshold possible and explains the rather high prevalence of RLS. It was shown that patients with hereditary haemorragic teleangiectasia who had PAVM more frequent had migraine with aura compared to patients without PAVM.43 The prevalence of migraine without aura was not increased in subjects with a PAVM.
To summarize, RLS detected by transcranial doppler was associated with migraine with aura in case-control studies.33;36 More speci c, PFO detected by cardiac echography was associated with migraine with aura39 and PAVM patients more frequent had migraine with aura than subjects with no PAVM.43 However, a population based study evaluating the presence of all types of RLS in migraineurs and non-migraine controls was lacking up to this moment. In Chapter III, I describe the prevalence of RLS in migraineurs and controls in a population based study. I hypothesized that RLS is more frequent in migraine with aura.
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