High-resolution computed tomography analysis of the frontal sinus ostium: A pilot study

Purpose: Identification and exposure of the frontal sinus recess (FSR) during endoscopic sinus surgery (ESS) are challenging due to the variable anatomy, the narrow opening of the frontal sinus ostium (FSO), and the proximity of vital anatomic structures. Hence, a strong understanding of frontal sinus anatomy is required to prevent intracranial entry. Consistent and easily identifiable landmarks and measurements could assist safe entry into the FSO. In this study, we determine the distances from the columella and anterior nasal spine (ANS) to the nasofrontal beak (NFB) and anterior skull base (ASB) using high-resolution computed tomography (HRCT) scans. Methods: A radiographic analysis was performed at a tertiary care medical center. Measurements from the ANS to the NFB and ASB, and from the columella to the NFB and ASB were made using sagittal HRCT. Thirty-two HRCT scans were analyzed by three observers, and the mean distances and standard deviations were calculated. Results: The mean distance from the ANS to the NFB was 52.3 ± 3.4 mm in men and 47.7 ± 3.5 mm in women (p < 0.0001). Mean distance from the ANS to the ASB was 61.8 ± 4.1 mm in men and 56.5 ± 4.1 mm in women (p < 0.0001). Mean distance from the columella to the NFB was 58.9 ± 2.3 mm in men and 53.0 ± 3.3 mm in women (p < 0.0001), and from the columella to the ASB was 67.9 ± 3.7 mm in men and 61.3 ± 4.1 mm in women (p < 0.0001). Conclusion: While performing FSR exposure in ESS, it is recommended to stay a distance of less than 66.9 mm in men and 60.6 mm in women from the columella to minimize intracranial complications.