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S285: COMPREHENSIVE COMPUTED TOMOGRAPHIC ANALYSIS OF THE SPHENOID OSTIUM FOR ENDOSCOPIC TRANSSPHENOIDAL SURGERY PLANNING
Jonathan Ortiz- Rafael; Isaac Jair Palacios-Ortiz, MD; Arturo Sotomayor-Gonzalez, MD; University Hospital "Dr. José Eleuterio Gonzalez", UANL

Background: Sellar anatomy understanding is crucial to surgical planning in endoscopic transsphenoidal surgery. The sphenoid sinus ostium plays a critical role in in endoscopic transsphenoidal surgery as it represents the first visible entry point to the sphenoid sinus, presurgical analysis of the sphenoid ostium using computed tomography is helpful to predict the amount of bone removal required for an adequate exposition of the sella

Methods: Thirty sagittal paranasal sinus computed tomography scans (<1mm slices) were analyzed bilaterally (60 sides).  Lengths measured included: From the inferior sphenoid ostium border to the anterior nasal spine and to the lowest point of its anterior wall; from the superior sphenoid sinus ostium border to the highest point of its anterior wall and to the anterior wall of the sella. Angles measured were: Between the posterior bony palate and inferior sphenoid ostium margin, with the anterior nasal spine as a vertex; Between the anterior nasal spine and sellar floor, with a vertex at the inferior sphenoid ostium margin; Between the anterior nasal spine and tuberculum sellae, with the vertex at the inferior sphenoid ostium margin. Statistical descriptive analysis and Pearson/Spearman tests were performed to correlate these findings

Results: mean angles were tubercular 168.48° (SD±9.64), inferior sellar 155.49°(SD±12.29), nasal spine-ostium 37.00°(SD±3.23), mean lengths were: nasal spine-ostium 54.85mm (SD±8.14), ostium-ceiling 8.96mm (SD±3.23), ostium-floor 6.79mm (SD±2.29), ostium-sella 13.29mm (SD±2.89). Longer ostium-ceiling lengths corresponded to reduced tuberculum angles (p=0.03) and greater sellar angles (p<.01), greater nasal spine-ostium angles correlated to lesser sellar angles (p<.01), larger ostium-sella lengths correlated to greater sellar angles (p<.01)

Conclusions: Sphenoid sinus ostium is one of the most important structures to take in consideration in presurgical transsphenoidal surgery, the lengths and angles presented in this study provide valuable guidance for surgical planning, particularly the angles of the tuberculum and sellar floor; when these angles approach 180° in the sagittal plane, the corresponding structures are more likely to be easily identifiable during transsphenoidal surgery. Conversely, a reduced tubercular angle may require more extensive drilling of the posterior ethmoidal cells, whereas a decreased sellar angle may involve increased drilling of the sphenoidal rostrum to achieve adequate surgical exposure.

Fig 1-Lenghts measured. A. Anterior nasal spine to inferior border of ostium. B. superior margin of ostium to sellar ceiling. C. inferior margin of ostium to sellar floor. D. Superior margin of ostium to anterior wall of sella

Fig 2- Angles measured: a: from anterior nasal spine to tuberculum sellae, vertex at inferior sphenoid ostium margin. b: from anterior nasal spine to sellar floor, vertex at inferior sphenoid ostium margin. c: from posterior bony palate to inferior sphenoid ostium margin, vertex at anterior nasal spine.

Fig 3. High sella with reduced tubercular angle. Might require extensive posterior ethmoidal cell removal

Fig 4. Low sella with a near straight tubercular angle. Might requiere extensive rostrum drilling

 

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