Fig. 2From: Post-angiography headachesRelation of headache diagnosis 6 months after the procedure to previous headache history; X axis: headaches the 6 months revaluation; H free: headache-free without headaches; M: missing data; Z axis: recurrent headaches before the procedure; P H free: previously headache free; P secondary: previous secondary headache; P tension-type: previous tension-type headache; P migraine: previous migraine, M: missing; Y axis: number of patients in groups, as depicted in the gray-shaded legendBack to article page