Fig. 2

Intraoperative exploration and separation of the PPTAv and AICA. A, B, At initial view, the AICA was closely related to the V, and an artery of unknown source above the latter, possibly indicating the presence of a PPTAv. C, D, Exploring the tentorium edge, the SCA was found to have no contact with the V. E, F, In front of the root of the V, the unknown artery (?) continued as the AICA, twisting around and compressing the V, which led us to consider the unknown artery to be a PPTAv. G-J, Exploration of Meckel’s cavity confirmed that the unknown artery (?) was a PPTAv that passed Meckel’s cavity, forming a loop on the surface of the pons. K, L, Teflon felts (✡) were placed as separation agents between the V and PPTAv. PPTAv, persistent primitive trigeminal artery variant; AICA, anterior inferior cerebellar artery; V, trigeminal nerve; SCA, superior cerebellar artery