Assessment of Internal Carotid Artery Invasion With the Endoscopic Endonasal Approach: Implications of a New Grading System and Security Strategy

Internal carotid artery (ICA) injury during the endoscopic endonasal approach (EEA) for ventral cranial base tumors is rare but fatal.The aim of this study was to investigate the relationship between ventral cranial base tumors and corresponding ICA using quantitative means to improve the safety of surgery.In this retrospective study, a total of 46 patients with ventral cranial base tumors undergoing surgery with the EEA were enrolled. Preoperative imaging features and clinical data were recorded. The influencing factors of the gross total resection (GTR) rate were analyzed. A new grading system and security strategy were developed.Postoperative enhanced magnetic resonance imaging showed a GTR of 61.7%. There was a significant correlation between the GTR rate and tumors surrounding the ICA, the tumor site, the involved ICA segment, and the blood supply (P < 0.05). We included preoperative radiotherapy as supplementary data in the grading system. Each variable involved the letter "S"; (surround, site, segment, blood supply, supplementary data); hence, the system was named the 5S ICA grading scale.We recommend a safety assessment through the 5S ICA grading scale and the ICA grading strategy to obtain the maximum total resection rate while ensuring patient safety.