The impact of sphenoid sinus pneumatization type on the protrusion and dehiscence of the adjacent neurovascular structures: A prospective MDCT imaging study

Rationale and objectives: Sphenoid sinus (SS) pneumatization is greatly variable. Precise determination of the pattern of SS pneumatization and its relationship to the vital neurovascular structures will provide a more comprehensive understanding of the regional SS anatomy to avoid the risk of potentially serious neural and vascular injury. We aimed to study the relationships among SS pneumatization type, extent of pneumatization, and protrusion/dehiscence of adjacent neurovascular structures using the multi-detector computed tomography.

Materials and methods: One hundred seventy healthy patients were prospectively examined by multi-detector computed tomography of the head. The type of pneumatization of the SS was determined. The protrusion/dehiscence of the internal carotid artery, optic nerve, vidian nerve, and maxillary nerve into the SS cavity was evaluated. The relationships between the SS pneumatization type and the extent of protrusion/dehiscence of the examined variables were statistically analyzed.

Results: We had 70 patients with no protrusion/dehiscence, 37 patients with unilateral protrusion/dehiscence, and 63 patients with bilateral protrusion/dehiscence. The presellar type was dominant (61.4%) in the group with no protrusion/dehiscence, the sellar type was dominant (56.8%) in the group with unilateral protrusion/dehiscence, and the postsellar type was dominant (55.6%) in the group with bilateral protrusion/dehiscence. The protrusion rates of the internal carotid artery, optic nerve, vidian nerve, and maxillary nerve in the postsellar type were 50.6%, 52.3%, 56.9%, and 54.1%, respectively (p< 0.001).

Conclusion: The prevalence of protrusion/dehiscence of the neurovascular structures is significantly related to the type of SS and increases as the degree of SS pneumatization increases.