Complex anatomy of the sphenoid sinus: a radiographic study and literature review.

Objectives Nasal endoscopic approaches to the sphenoid sinus are challenging. Variations in septation, shape, and dimensions have a critical impact on surgical planning of the skull base. Previous anatomical studies have small numbers or a limited description of this complex structure. The present study is a radiographic analysis of the septation and dimensions of the sphenoid sinus. Design and Methods High-resolution surgical-guidance computed tomography images of the sinuses from 90 patients at a tertiary care medical center between 2002 and 2007 were studied. Multiple anatomical measurements from axial and sagittal images were obtained and analyzed with imaging and statistical software. Results Of the 90 patients studied, 9% had presellar, 37% sellar, and 54% postsellar pneumatization. In 34%, the posterior extent of the intersinus septum involved the bony covering of the carotid artery. The average presellar width of the sinus was 1.3 cm, the average midline presellar depth was 1.4 cm, and the average infrasellar midline depth was 2.6 cm. Conclusions Approaching the skull base through the sphenoid sinus requires a tailored process based on anatomy. Septal involvement of the carotid artery occurs frequently. Pneumatization patterns are potentially disorienting, and awareness of the sinus's posterior and lateral extensions is critical.