Microembolic Air Load During Contrast-Transcranial Doppler: A Trigger for Migraine With Aura?

Background.-There is a well-known association between migraine with aura (MA) and right-to-left shunt (RILES) because of patent foramen ovale (PFO). The occurrence of MA attacks after microbubble (MB) injection during contrast-enhanced transcranial Doppler (ce-TCD) has been recently described. Objectives.-The aim of this study was to analyze the prevalence of RILES in a consecutive cohort of MA patients and to characterize the occurrence of MA attacks after diagnostic ce-TCD. Methods.-A total of 159 consecutive MA patients underwent ce-TCD with air-mixed saline to disclose RILES. RILES was characterized in terms of MB amount (small-moderate or large) and occurrence at rest and/or during Valsalva maneuver (permanent or latent). Results.-RILES was revealed in 79/159 patients (similar to 50%). Permanent RILES were detected in 56/79 (71%) and latent RILES in 23/79(29%) MA patients. The occurrence of a typical MA attack was overall observed in 12/159 patients (7.5%; 95% CI: 4-12.8%), but arose only in RILES-positive ones, immediately after ce-TCD (12/79; 15.2%; P<.001). All 12 patients had permanent RILES (12/56; 21.4%; P =.015) and MA attack was mostly observed in large RILES-positive patients, even without statistical significance (P=.118). Conclusions.-Microembolic air load could act as a trigger of MA attack. According to recent studies and to the clinical characteristics observed in our patients, microembolization because of MB injection might provoke a decrease in cerebral oxygen saturation, thus triggering cortical spreading depression and, thereafter, MA attack. Larger and prospective studies will be necessary to confirm our data and observe a wider correlation.