“…Twenty-six studies compared CVR to hypercapnia in the anterior circulation between migraineurs and controls with mixed results; 10 studies found migraineurs to have higher CVR to hypercapnia, 16,21,30,32,35,50,51,54,58,59 five studies found migraineurs to have lower CVR to hypercapnia 19,37,43,44,56 and nine studies found no difference in CVR to hypercapnia in the anterior circulation between migraineurs and controls. 12 , 24,28,34,38,52,55,60 In Gonzalez-Quintanilla et al.…”