To determine the association between frontal sinus pneumatisation and concomitant anatomical variations in paranasal sinuses as seen on computed tomography.

A total of 403 patients who underwent paranasal sinus computed tomography were allocated to three groups according to the degree of frontal sinus pneumatisation (type 1 – hypoplasia; type 2 – medium size; and type 3 – hyperplasia). In this unique model, the prevalence of ipsilateral variations on paranasal sinuses on each side of the head were analysed separately within each pneumatisation group.

The type 3 frontal sinus pneumatisation group showed a greater association with ipsilateral variations of the sphenoid bone. Variations included pneumatisation of the anterior clinoid process, lateral sphenoid recess, pterygoid process and greater wing, and exposure of Vidian canal. This group also showed significant associations with male gender, and the presence of frontal and Onodi cells.

Interpretation of the paranasal sinus variations is imperative for pre-operative evaluation in functional endoscopic sinus surgery, particularly in patients with frontal sinus hyperplasia. Attention to variation on the ipsilateral side is informative.

This study aimed to examine the relationship of the accessory sphenoidal septum with surrounding vital structures and their variations.

This cross-sectional retrospective study investigated the prevalence of accessory sphenoidal septa and their relationship with variations in surrounding vital structures in coronal and axial paranasal computed tomography images.

Coronal and axial computed tomography images of 347 patients were assessed to evaluate the presence of accessory sphenoidal septa. Accessory sphenoidal septa originated from the internal carotid artery in 47.7 per cent of patients and from the optic nerve in 17.5 per cent. These structures were significantly associated with protrusion of the optic nerve, internal carotid canal or Vidian nerve canal.

Accessory sphenoidal septa can originate from the internal carotid artery or the optic nerve. Therefore, the presence of an accessory sphenoidal septum indicates an increased risk of surgical complications including internal carotid artery injury and loss of vision due to optic nerve injury.