Prevalence of High-riding Vertebral Artery in Chiari Malformation Type-1

Objective:The aim of this study is to analyze the patients operated on for Chiari malformation type 1 for the presence of a high-riding vertebral artery (HRVA) and to investigate the effect of this parameter on surgery. Materials and Methods:Patients who underwent surgery for Chiari malformation type 1 between 2018 and 2020 in our clinic were retrospectively evaluated with patient files and preoperative cervical spine computed tomography (CT) imaging.A total of 15 patients were included in the study.Lateral mass internal height and isthmus height measurements were performed to investigate the presence of HRVA.Results: One (3.3%) of 30 C2 lateral mass internal height measurements showed a high-riding vertebral artery on the right side.A high-riding vertebral artery was found in 13 of 30 C2 isthmus height measurements (43.3%).Of these, 3 were right-sided, 2 were left-sided, and 4 were bilateral.A total of 9 patients had unilateral or bilateral HRVA.None of these patients experienced any surgical morbidity related to HRVA. Conclusion:Although HRVA was detected at a relatively high rate in CM-1 patients in our series, it did not affect the surgical outcome.We conclude that investigating the presence of HRVA in the preoperative planning of CM-1 patients could be helpful in avoiding possible complications.