Anatomical variations of the sphenoid sinus and its adjacent structures: a review of existing literature

The sphenoid sinus, one of the posterior groups of sinuses, has long been regarded as a 'neglected sinus' due to the anatomical location, poor understanding and poor accessibility, till the advent of endoscopes and modern imaging techniques. Increasing knowledge and greater understanding of this sinus has permitted an evolution in surgical practices and boundaries. Various literatures of the past report a great variety of rates of pneumatization, rates of optic nerve protrusion and dehiscence, as well as internal carotid artery (ICA) protrusion and dehiscence. One similarity noted among these studies is that the rates vary according to the ethnicity of the patients. Recommendations have also been made along the way with regard to modified surgical techniques. This review aims to describe the pneumatization of sphenoid sinus and the topographical relation of the optic nerve and ICA in different populations.