Inter Palatovaginal Canal corridor- Proposing a Safe Landmark to Approach Clival Region of Sphenoid Sinus.

Internal carotid artery injury is one of the most feared intraoperative complications of endoscopic sinus surgery and endoscopic skull base surgery. Vidian canal is used as a landmark to identify laceral genu of ICA. But, this structure leads to the lateral aspect of the genu and so, there is still a possibility of injuring the genu, if we blindly follow this landmark. So, to find out a more reliable landmark to locate ICA, we conducted a computed tomography-based study in our institution. The aim was to evaluate the anatomical variations in position of palatovaginal canal in relation to laceral genu of ICA. The primary objective was to know the anatomical relation of medial opening of PVC to laceral genu of ICA, and the secondary objective was to measure the distance between these two structures. CT paranasal sinus images of 105 patients were collected and axial cuts evaluated to find out the anatomical relation between PVC and ICA. In 97.1% of the scans, laceral genu of ICA was found lateral to medial opening of PVC, and in the rest 2.9%, both structures were found to lie in the same line. In 62.9% of the patients, the distance between the two structures was found to be between 3.1 and 6 mm. The inter-palatovaginal canal corridor can possibly be considered as a safe corridor to clival region of sphenoid sinus. This corridor can be easily identified intraoperatively during endoscopic skull base surgeries So, if the surgeon limits the instrumentation to the inter-palatovaginal canal corridor, iatrogenic injury to ICA, one of the most dreaded complications, can be avoided, while working in the clival region of sphenoid sinus.