Fig. 3

The patient’ headache severity was measured by numerical rating scale (NRS) every day. The inner diameter of the affected PICA was measured using cross-sectional view of T1-weighted HRVWI and the outer diameter was measured using original data of T2-weighted HRVWI (BPAS). Two weeks later after the onset of headache, the dissected vessel’s diameter grew up to the maximal, though NRS score of the patient’s headache improved steeply on the eighth day. Since then, NRS scores had been kept within 2. The maximum inner and outer diameters shrunk gradually to normal size