The Displacement Patterns of Petrous Internal Carotid Artery and Its Morphometric Relations with Vidian Canal in Petroclival Chondrosarcomas Relevant to Extended Endoscopic Endonasal Approaches: A Radiological Study

Abstract

PurposeExtended endoscopic endonasal approaches (EEAs) to petroclival chondrosarcomas (PCs) require a thorough understanding of skullbase anatomy, especially the anatomy of petrous ICA (pICA), as ICA injury is the most dreaded complication of extended EEAs. We conducted this study to determine the displacement patterns of pICA in patients with PCs. MethodsCECT & angiography images of patients with PCs were analyzed for following parameters -antero-posterior (AP), cranio-caudal (CC), medio-lateral (ML) & direct distances between anterior genu of pICA (AGpICA) and posterior end of vidian canal (pVC). pICA encasement/ narrowing by tumor was noted on MRI images. ResultsWe studied 11 patients with histopathologically proven PCs. pICA encasement/narrowing & pVC destruction were observed in one patient each. The mean AP & CC distances on tumor side/normal side were 7.7±1.9/6.4±1.0mm & 4.5±1.5/3.4±0.9mm, respectively. The overall displacement was posterior & superior. ML displacement was seen in 4 patients (lateral in 3 & medial in 1). In rest, AGpICA was centered on pVC. The mean direct distance was 9.4±2.5 mm. In 3 patients with displacement seen in all three axes, direct distance was measured by the “cuboid method”. Overall, posterior-superior-lateral, posterior-superior & anterior-inferior were the common displacement patterns of AGpICA relative to pVC. ConclusionsThe displacement patterns of AGpICA in PCs are variable. An individualized approach with meticulous analysis of preoperative imaging can help in determining the relation between AGpICA & pVC. This detailed morphometric information can facilitate better orientation to altered anatomy, which can be helpful in preventing pICA injury during extended EEAs.