MRI-ASL-based CBF changesduring the interictal period after anti-CGRP therapy in migraine patients

Objective: Migraine and insomnia often accompany migraine are not steady-state conditions because cerebral blood flow (CBF) autoregulation and the glymphatic system are impaired. Anti-endogenous anti-calcitonin gene-related peptide (CGRP) therapy may thus reduce the interictal CBF. Methods: Interictal magnetic resonance arterial spin labeling (ASL) was performed on 73 migraineurs before and after anti-CGRP therapy, including antibody switching, to investigate changes in CBF and predictors of treatment response. Results: Multivariate analysis revealed that the significant positive neuroradiological predictors were no migraine with cortical hyperperfusion (CHP) findings despite insomnia and no insomnia with white matter hyperintensities. Patients in this study were divided into four clinical groups according to CBF changes after anti-CGRP therapy: Group A, CHP findings before treatment and decreased CBF after treatment (27 patients); Group B, no CHP before treatment and decreased CBF after treatment (19 patients); Group C, no CHP before treatment and increased CBF after treatment (18 patients); and Group D, no change in CBF before or after treatment. Changes in CBF after therapy were appropriate in Groups A and C; in particular, Group C had the highest percentage of ³ 50% of the responders, reaching 94%. Approximately 90% of patients in Group B showed an inappropriate reduction in CBF below normal after treatment. All but 1 patient in Group D did not respond to treatment. Conclusion: Interictal CBF measurements by ASL before and after anti-CGRP therapy are clinically useful biomarkers for predicting and evaluating treatment efficacy.