Clinical and MR Predictors of Retro-Odontoid Pseudotumor Regression Following Posterior Fixation in Patients with Atlantoaxial Instability

Abstract

Purpose To identify clinical and MR predictors of retro-odontoid pseudotumor (ROP) regression after posterior fixation in patients with atlantoaxial instability. Materials and Methods We included patients who had undergone posterior fixation for atlantoaxial instability and preoperative and postoperative MR imaging. Patients were classified into two groups according to the degree of ROP regression after posterior fixation: regression (≥ 10% reduction) and no regression ( 5 mm exhibited ROP regression. The other variables were not significantly associated with ROP regression. Conclusion Older age and thicker preoperative ROP are associated with ROP regression after posterior fixation in patients with atlantoaxial instability.

Keywords

• retro-odontoid pseudotumor
• atlantoaxial instability
• magnetic resonance imaging