Anatomical variations of the main septum of the sphenoidal sinus and its importance during transsphenoidal approaches to the sella turcica

Abstract Background There are numerous variations reported regarding anatomy of the sphenoidal sinuses that include e.g. their pneumatisation, septation and relation to neurovascular structures. The following study aimed to examine the height of the MS in the sphenoidal sinuses, as well as its type (bony, membranous or mixed) and its course amongst the adult Polish population. Materials and methods A retrospective analysis of 296 computed tomography (CT) images (147 females, 149 males) of the paranasal sinuses was conducted. Images in axial, coronal, and sagittal planes were visualised and analysed. Results The average height of the MS was 2.1 ± 0.41 cm for the entire research group. Completely bony MS was found in 32.77% of the patients, partially membranous in 63.85%, and solely membranous in 3.38% of the patients. The course of the MS that changed from the anterior to the posterior section of the sinuses predominated (83.78%). The MS had the shape of the letter ‘C’ in 22.29% of the cases (C-shaped in 11.82% and inverted ‘C’ in 10.47%). The rarest was the MS resembling letter ‘S’, which only appeared in 11.48% of the patients (S-shaped in 5.74% and inverted ‘S’ in 5.74%). Only 16.22% of the patients had the MS that shifted neither its course nor its shape. Conclusions The MS might be an intraoperative marker of the midline, providing surgeons with good spatial orientation. Notwithstanding, the MS changed its course in the majority of the studied here patients, hence more careful transsphenoidal approach is needed to avoid iatrogenic neurovascular injuries.