Abstract:

Objective　The aim of our study was to apply an customized three-dimensional digital model(3D-DM) to endoscopic endonasal approaches to analyze the bony anatomy of inferior third of the clivus, quantify preoperative bone removal, and optimize surgical planning.　Methods　Silicone dyes were respectively injected into the great vessels of the neck of 12 cadaveric specimens. Digital data acquired from 320-slices CT scan was imported to a 3DView system to form individual 3D-DM. With the 3D-DM support, an endoscopic endonasal dissection of the inferior clivus was completed under conditions that mimicked our operating suite. Bone removal of occipital condyle was quantified postoperatively by 3D-DM, which compared with the preoperative ones, to analyze physical percentage of bone excision.　Results　Customized 3D-DM was useful to de?ne the exact boundaries of the endoscopic endonasal approaches. The vision acquired by 3D-DM was consistent with the intraoperative findings. Preoperative measurement of related landmarks in 3D-DM showed no significant difference from the measurement data on cadaveric head specimens. Completion of a unilateral ventromedial condyle resection opened a wider lateral surgical corridor. The supracondylar groove was a reliable landmark for locating the hypoglossal canal. The transjugular tubercle approach was accomplished by drilling above the hypoglossal canal, and increasing of the vertical length of the lateral surgical corridor, which allowed for visualization of the distal cisternal segment of the lower cranial nerves.　Conclusions　The endonasal approach provides exposure of the brainstem in the ventromedial compartment. This 3D-DM is very effective in providing a depiction of surgical landmarks and visual feedback of the amount of bone removed.

Key words: Endoscopic endonasal approaches, Three-dimensional digital model, Skull base, Anatomy, Inferior clivus