Delay of switch from hypo- to hyperperfusion in migraine aura evidenced by arterial spin labeling (ASL): case series and pooled-data analysis

Introduction: Arterial Spin Labeling (ASL) is an MRI technique used to non-invasively assess cerebral blood flow in clinical practice. In migraine aura, previous studies have shown both cortical hypoperfusion and hyperperfusion patterns. Sequential perfusion changes with alternation of hypoperfusion and hyperperfusion has been scarcely reported, only in children. Our goal was to determine the delay of conversion between hypoperfusion and hyperperfusion at acute phase, using ASL technique, in adult patients presenting migrainous aura. Materials: and methods: Six local patients with migrainous aura presenting as stroke mimics were explored with ASL sequence. Two had repeated ASL exploration. Literature search allowed to include 9 additional patients. Mann-Whitney-U test, logistic regression and ROC curve analysis were conducted on pooled data with a total of 15 patients. Results: : Median age was 30 years (range 17-87). Hypoperfusion was present on 7 ASL acquisitions and hyperperfusion on 10. Median onset-to-MRI delay was higher in hyperperfused pattern group than in hypoperfused pattern group (17.6 vs 3.5 hours, p<0.001). Best cut-off for separating hypoperfused and hyperperfused patterns was 4.5 hrs (95% confidence interval: 3.75-8.5-hrs). Conclusion: Cerebral blood perfusion pattern in ASL switches from hypoperfusion to hyperperfusion 4.5 hours after symptom onset time in adult population. Repeated ASL exploration is an asset for the differential diagnosis between stroke and migraine.