Prevalence of Onodi Cells in Korean Based on Computed Tomography / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: The Onodi cell is the posterior-most ethmoid air cell that lies superior to the sphenoid sinus, and has intimate relationship with the optic nerve. The aim of this study was to evaluate Onodi cell prevalence, protrusion and bony dehiscence of the optic nerve in Korean population using computed tomography (CT). SUBJECTS AND METHOD: A retrospective analysis was performed on 129 Korean patients who consecutively underwent CT between January 2014 and December 2014. The presence of Onodi cells and protrusion and bony dehiscence of the optic nerve were analyzed using 3-dimensional CT images. RESULTS: A total of 70 males and 59 females were studied. Onodi cells were present in 61 (47.3%) patients but in 88 CT slides (34.1%); this consisted of 27 Onodi cells found bilaterally (44.3%), 18 on the right side only (29.5%), and 16 on the left only (26.2%). Of the total 61 patients with Onodi cells, the optic nerve protrusion and dehiscence were present in 34.4% and 23.8% of the studied CT slides. There was no statistically significant relationship between the presence of Onodi cells and protrusion and bony dehiscence of the optic nerve. CONCLUSION: In our study, Onodi cells were found in almost half of the patients. This prevalence is higher than previously reported in the literature. In patients with Onodi cells, the optic nerve protrusion and dehiscence were present in about 1/3 and 1/5 of the total slides, respectively. Therefore, the identification of these cells is essential prior to endoscopic sinus and skull base surgery to prevent potential complications.