Fig. 2

Intraoperative finding of the visualized case in a–c. The vertebral artery runs from caudal to rostral, while the (a) PICA runs in an upward loop close to the surface of the medulla and the root entry zone of the cranial nerves IX and X (b) inducing a neurovascular compression at this site. Adequate decompression was (c) achieved by insertion of Teflon. The intraoperative findings correspond very clearly to the results of the 3D visualization