Compromised cerebrovascular reactivity in migraineurs with right-to-left shunts: a potential mechanism of white matter hyperintensities

Our study aims to explore the changes of cerebrovascular reactivity (CVR) in migraineurs with right-to-left shunts (RLS), and further evaluate the association between CVR and the occurrence of the white matter hyperintensities (WMHs).RLS was diagnosed based on a contrast enhancement transcranial Doppler (c-TCD) examination. The breath holding index (BHI), which represents CVR, was measured from the middle cerebral artery (MCA) using a TCD with the breath-holding method. WMHs was defined as clearly hyperintense areas in 3 T magnetic resonance imaging (MRI). All migraineurs underwent a standardized questionnaire for family and personal history and detailed migraine features.Three hundred and ninety-seven migraineurs and 100 controls were included in our study. The BHI was significantly lower in migraineurs than controls (0.527 ± 0.709 vs. 0.674 ± 0.489, P = 0.016). Moreover, migraineurs with RLS had lower BHI than those without RLS (0.504 ± 0.671 vs. 0.674 ± 0.721, p = 0.024). Migraineurs with WMHs had lower BHI than those without (0.47 ± 0.71 vs. 0.75 ± 0.49, p = 0.035). The reduced BHI was an independent influencing factor for WMHs in our study (OR = 0.338; 95% CI = 0.142-0.806, p = 0.014).Our results indicated that BHI was reduced in migraineurs, and the reduced BHI was associated with RLS. Moreover, the reduced CVR in migraineurs with RLS might be related to the occurrence of WMHs.