Relationship of sphenoid sinus to adjacent structures in South India: a retrospective cross sectional study

Abstract

Abstract Background Sphenoid sinus is one of the most inaccessible paranasal sinuses. Advent of minimally invasive trans-nasal trans-sphenoidal approach over the past few years has provided an additional armament in the hands of skull-base surgeons to access pathologies adjoining base of skull. Close relationship of vital neurovascular structures with sphenoid sinus and variability of their protrusions into the sinus make these structures more vulnerable to iatrogenic trauma during surgical procedures. Preoperative assessment of such variations is imperative to avoid unintentional damage. The present study is a retrospective study conducted on CT scan records of 140 patients with an aim to evaluate prevalence of vital structures invaginating into sphenoid sinus and their clinical implications. The internal carotid artery (ICA), optic nerve (ON), maxillary nerve (MN), and Vidian nerve (VN) were assessed for protrusion into the sphenoid sinus and their dehiscence. Attachment of septum to protruding structures was also assessed. Data was statistically analyzed in the form of frequency and percentage to evaluate the prevalence of neurovascular invaginations into sphenoid sinus and their clinical implications. Results ICA invagination was observed in 16% of males and 12% of females with males showing higher frequency on left side. Protrusion of ON was seen in 13% of males and 10% of females with higher prevalence in bilateral category. Twenty-four percent of study population had MN prominences which included 13% of males and 11% of females with higher reflection of bilateral presentation. Highest prevalence of 44% was observed in VN protrusions with equal distribution (22%) among each sex. Majority of these were bilaterally located. Dehiscence of ICA was observed in 9%, ON in 29%, MN in 10%, and VN in 30% of study population. Dehiscence brings these structures closure to sinus mucosa with increased risk of involvement in sinus disease. Septal attachment to ICA and ON was present in 7% and 15% cases respectively. Conclusion Preoperative assessment of anatomical configuration of sphenoid sinus and associated neurovascular structures is mandatory to minimize per-operative complications. This study provides statistical data on anatomical variations in neurovascular structures protruding into the sphenoid sinus, their dehiscence, and septal attachments in South Indian population.