Background: Many neurovascular structures are in critical proximity to the sphenoid sinus margins.  The purpose of the study is to establish a simple classification for the relation of the paraclival carotid canal to sinus margins using computed tomography to minimize surgical risks.
Methods: This retrospective study included 168 patients who were referred to the Diagnostic Radiology Department for computed tomography scans on paranasal sinuses from June 2019 to June 2020. We evaluated the sphenoid sinus pneumatization pattern, the relation of the paraclival internal carotid artery canal to its margins, and the variations of the intersinus septum.  
Results: Type 2 canal was the commonest in the midsellar pattern, type 3 canal was the commonest in the sellar pattern whereas type 4 canal was absent in conchal, presellar, and midsellar patterns. We found a highly significant association between type 4 canal and sellar and postsellar patterns of pneumatization on both sides (p <.001).
Conclusion: The establishment of a simple and applicable standard classification for the types of paraclival internal carotid artery by computed tomography can help to minimize vital surgical complications.