Novel 3D volumetric and gallium casting assessment of anterior clinoidectomy for microsurgical clipping of posterior communicating artery aneurysms: an anatomical laboratory study

Abstract

Microsurgical treatment of dysmorphic, wide-neck posterior communicating artery aneurysms may require anterior clinoidectomy to improve exposure, proximal control, and clip maneuverability. Although many posterior communicating artery aneurysms are increasingly treated endovascularly, selected complex aneurysms continue to require microsurgical clipping. This anatomical laboratory study evaluates the effect of anterior clinoidectomy on the surgical corridor using 3D volumetric analysis and gallium casting. Five formalin-fixed, color latex-injected cadaveric specimens were subjected to a pterional approach. Dissection and anterior clinoidectomy were performed microscopically with neuronavigation. For each dataset, 17 Cartesian coordinates were acquired to model the volume of surgical freedom (VSF) before and/or after clinoidectomy. The resulting 3D models were compared, and gallium casting was used as a complementary physical visualization of the postclinoidectomy surgical space. Neuronavigation produced four paired pre-/postclinoidectomy datasets (left and right sides of two specimens; eight sets of 17 Cartesian coordinates) and six additional postclinoidectomy datasets, for a total of 14 coordinate sets. Mean VSF increased from 48.1 cm3 (48.1 mL) before clinoidectomy to 54.2 cm3 (54.2 mL) after clinoidectomy; this difference did not reach statistical significance ( P  = 0.304). Gallium casting provided a physical representation of the postclinoidectomy surgical field, which approximated an irregular two-based pyramid/frustum. In this cadaveric laboratory model, anterior clinoidectomy was associated with an increase in measured working volume and provided additional operative maneuverability for the microsurgical clipping corridor of posterior communicating artery aneurysms. These exploratory findings support the feasibility of 3D VSF modeling and gallium casting as complementary tools for skull-base laboratory training and future preoperative planning research.