Differentiation between Posterior Sinuses Using the Medial Orbital Floor as a Landmark

Camila Degen Meotti; Otávio Bejzman Piltcher; Bruno Netto; Jaqueline Lemieszek; Michelle Lavinsky-Wolff; Felipe Marques do Rego Monteiro; Gustavo Rassier Isolan

doi:10.1055/s-0035-1571203

Differentiation between Posterior Sinuses Using the Medial Orbital Floor as a Landmark

J Neurol Surg B Skull Base. 2017 Apr;78(2):152-157. doi: 10.1055/s-0035-1571203. Epub 2016 Nov 17.

Authors

Camila Degen Meotti¹, Otávio Bejzman Piltcher², Bruno Netto², Jaqueline Lemieszek², Michelle Lavinsky-Wolff³, Felipe Marques do Rego Monteiro⁴, Gustavo Rassier Isolan⁵

Affiliations

¹ Department of Otolaryngology, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil.
² School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Department of Radiology, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil.
³ Department of Otolaryngology, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil; School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
⁴ Ceanne-Neurosurgery, Rua Vicente de Fontoura, Porto Alegre, Rio Grande do Sul, Brazil.
⁵ Department of Neurosurgery, Universidade Federal do Rio Grande do Sul-Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil; Hospital Moinhos de Vento-Skull Base and Brain Tumor Center, Porto Alegre, Rio Grande do Sul, Brazil.

Abstract

Objectives This study aims to evaluate the difference in height between the floors of the posterior ethmoid and sphenoid sinuses with respect to the medial orbital floor (MOF) to confirm this difference as a landmark for identification of the posterior sinuses. It also aims to describe this difference regarding the type of pneumatization of the sphenoid sinus (conchal, presellar, and sellar). Design A cross-sectional study was conducted. Study Center The study was conducted at the Department of Radiology of Hospital de Clínicas de Porto Alegre, a tertiary care university hospital in Southern Brazil. Materials and Methods A standardized and computerized analysis of 100 tomography scans of sinuses (200 sides), in patients older than 18 years, was carried out. Results Mean vertical distance (height) from the MOF to the floor of the posterior ethmoid and sphenoid sinuses was 0.72 ± 1.85 mm and 9.48 ± 3.81 mm, respectively. There was no statistically significant difference as compared with sex and side. We found conchal-type sphenoid sinus pneumatization in 1.5% (n = 3), presellar in 13.5% (n = 27), and sellar in 85% (n = 170), whereas the vertical distance between the MOF and the floor of the sphenoid sinus was 2.04 ± 0.81 in the conchal-type sinuses, 5.71 ± 2.49 in the presellar sinuses, and 10.21 ± 3.52 in the sellar sinuses. No sphenoid sinus showed its floor above the MOF, regardless of the type of pneumatization. Discussion and Conclusion The present study demonstrates that there is a difference between the floor of the posterior sphenoid and ethmoid sinuses in adults, which is more evident when the sphenoid sinus is well pneumatized. These data suggest that the difference in height between the floors of the sinus investigated in our study may be considered during endoscopic sinus surgery to guide adequate localization, but the surgeon should be aware of the type of pneumatization of the sphenoid sinus to use this landmark.

Keywords: endoscopic sinus surgery; landmarks; medial orbital floor; posterior ethmoid sinus; sphenoid sinus.