Compromised Dynamic Cerebral Autoregulation in Patients with a Right-to-Left Shunt: A Potential Mechanism of Migraine and Cryptogenic Stroke

Background and Purpose: The relationship between right-to-left shunts (RLS) and migraine and cryptogenic stroke is not well understood. In this study, we investigated whether RLS are associated with impairment of dynamic cerebral autoregulation (dCA), which may play a role in migraine and cryptogenic stroke. Methods: Sixty-six migraineurs were enrolled in the study, including 36 non-RLS patients and 30 RLS patients. Non-invasive continuous cerebral blood flow velocity and arterial blood pressure were recorded simultaneously from each patient by using transcranial Doppler and servo-controlled plethysmograph, respectively. Transfer function analysis was applied to derive autoregulatory parameters of gain, phase difference (PD), and autoregulation index. Results: The PD in migraineurs with RLS was 50.6 +/- 22.9 degrees, which was significantly lower than that observed in the non-RLS group (67.2 +/- 18.2 degrees, P < 0.001). The PD in the large RLS group (45.4 +/- 22.6 degrees) was significantly lower than that of the small RLS group (64.9 +/- 17.1 degrees, P < 0.01) and non-RLS group (P < 0.001); however, the PD in the small RLS group was similar to that of the non-RLS group. The PD in the permanent group (48.8 +/- 19.9 degrees) was similar to that of the latent group (52.6 +/- 26.1 degrees), and both were significantly lower than that of the non-RLS group (P < 0.05). The autoregulation index results were similar to the PD findings. Conclusions: dCA is impaired in migraineurs with large RLS, and this may represent a potential mechanism linking RLS, migraine, and cryptogenic stroke.