Right-to-left shunt and subclinical ischemic brain lesions in Chinese migraineurs: a multicentre MRI study

BACKGROUND Migraine is considered as a risk factor for subclinical brain ischemic lesions, and right-to-left shunt (RLS) is more common among migraineurs. This cross-sectional study assessed the association of RLS with the increased prevalence of subclinical ischemic brain lesions in migraineurs. METHODS We enrolled 334 migraineurs from a multicentre study from June 2015 to August 2016. Participants were all evaluated using contrast-enhanced transcranial Doppler, magnetic resonance imaging (MRI), and completed a questionnaire covering demographics, the main risk factors of vascular disease, and migraine status. RLS was classified into four grades (Grade 0 = Negative; Grade I = 1 ≤ microbubbles (MBs) ≤ 10; Grade II = MBs > 10 and no curtain; Grade III = curtain). Silent brain ischemic infarctions (SBI) and white matter hyperintensities (WMHs) were evaluated on MRI. RESULTS We found no significant differences between migraineurs with RLS and migraineurs without RLS in subclinical ischemic brain lesions.SBI and WMHs did not increase with the size of the RLS(p for trend for SBI = 0.066, p for trend for WMHs = 0.543). Furthermore, curtain RLS in migraineurs was a risk factor for the presence of SBI (p = 0.032, OR = 3.47; 95%CI: 1.12-10.76). There was no association between RLS and the presence of WMHs. CONCLUSION Overall, RLS is not associated with increased SBI or WMHs in migraineurs. However, when RLS is present as a curtain pattern, it is likely to be a risk factor for SBIs in migraineurs. TRIAL REGISTRATION No. NCT02425696 ; registered on April 21, 2015.