Extensive maxillary sinus pneumatization.

Aim: To determine the incidence of variations of maxillary sinus pneumatization especially when it is extensive and the associated anomalies.

Study Design: Two hundred consecutive direct coronal paranasal sinus computed tomography (CT) scans were reviewed retrospectively. Extensive maxillary sinus pneumatization (EMSP) was defined as one in which the largest horizontal and/or vertical dimension of the maxillary sinus equalled or exceeded 90% of the corresponding diameter of the orbit. Further subtype I, II & III were defined depending on whether the pneumatization was extensive in one dimension (horizontal or vertical), two dimensions (horizontal & vertical) and by the presence of sphenomaxillary plate, intermaxillary plate or extension into frontal recess.

Results: EMSP was found in 8%, of these 7% were bilateral and 1% was unilateral. (Subtype I, II and III constituting 1%, 3% & 4% respectively).

Conclusion: EMSP has been defined as a group and a classification proposed. EMSP will result in an atypical clinical picture, has a role in the pathogenesis of frontal sinusitis in some cases and may predispose injury to the orbit during endoscopic sinus surgery (ESS).