Sphenoid Sinus Pneumatization, Septation, and the Internal Carotid Artery: A Computed Tomography Study

BACKGROUND: The air spaces of the nasal cavity and the sphenoid sinus (SS) constitute a convenient corridor to access lesions of the skull base using the endoscopic endonasal transsphenoidal approach (EETA). Safe EETA depends on the SS and skull base anatomy of the patient. Individual variations exist in the degree and pattern of SS pneumatization. This study aims to examine the variations in SS pneumatization, the inter-sphenoid septum (ISS), and their relationship with the internal carotid artery (ICA) among adult Nigerians. MATERIALS AND METHODS: We reviewed computerized tomography (CT) images of 320 adult patients that had imaging for various indications. This excluded those with traumatic, inflammatory, or neoplastic process that may alter anatomical landmarks. The images were evaluated for the types of SS pneumatization, number and insertion of ISS, and the protrusion of ICA into the sinus cavity. RESULTS: Prevalence of SS pneumatization types: 1.9% conchal, 1.2% presellar, 56.6% sellar, and 40.2% postsellar. The lateral extension of SS occurred into the pterygoid in 138 patients (45.1%), greater wing 112 (35%), lesser wing 37 (11.6%), the full lateral type was seen in 97 (30.3%) patients. One ISS occurred in 150 (46.9%) patients, 162 (50.6%) had multiple, and 8 (2.5%) had none. ISS insertion into ICA bony covering occurred in 101 (31.6%) patients, whereas protrusion of ICA into SS cavity occurred in 110 (34.4%) patients. CONCLUSION: Variations of the SS, ISS, and ICA anatomy are present among native Africans. Detailed imaging evaluation of each patient is considered for EETA is mandatory.