Role of High-Resolution Computed Tomography in the Evaluation of Anatomical Variations of Sphenoid Sinus and Its Clinical Importance in FESS.

ABSTRACT

Sphenoid sinus of all sinuses is generally the most inaccessible sinus to the surgeons. The trans-sphenoid route is considered to be the standard approach for surgery of pituitary adenomas. Knowing the details of the anatomy of sphenoid sinus and the extent of pneumatization can guide the surgeon through difficult corners of the approach. We wanted to evaluate the incidence of the different anatomical variations of sphenoid sinus as detected by HRCT scan and their impact on related neurovascular structures for the safe removal of inter sphenoid and pituitary lesions.METHODSThis prospective study was conducted in Sree Gokulam Medical College & Research Foundation, Trivandrum. Study population included 150 cases who were referred for HRCT of the paranasal sinuses to the Department of Radiodiagnosis, over a period of 12 months (from November 2018 to October 2019). After obtaining a written informed consent and history, all the patients underwent HRCT axial section of PNS. Once the axial sections were obtained through the paranasal sinuses, these images were reconstructed into coronal sections by multiplanar reconstruction (MPR) technique without exposing the patient.RESULTSOnodi cells were found predominantly in female patients with malefemale ratio 27. Optic nerve protrusion and dehiscence had male predominance. Rest of the variations had no significant gender difference and few variations were seen equally distributed among both males and females. The most common variation observed in our study was pterygoid process pneumatization. Of the total 150 patients, pterygoid process pneumatization was identified in 76 patients including bilateral in 54 patients. Next common variation observed was vidian nerve protrusion, identified in 62 patients along with dehiscence of wall in 38 patients. Maxillary nerve protrusion was present in 42 patients and its dehiscence of wall in 10 patients. Optic nerve protrusion was identified in 41 patients and dehiscence of wall was noted in only 6 patients.CONCLUSIONSSphenoid sinuses are the most inaccessible paranasal sinuses and are surrounded by significant anatomical structures such as the orbit and its contents, cavernous sinus, internal carotid artery (ICA) and the anterior cranial fossa. HRCT of sphenoid sinus for the demonstration of the anatomical variations and its relation to the vital adjacent crucial anatomical structures helps in reducing the complications during trans-sphenoidal surgeries and functional endoscopic sinus surgery. Our study of HRCT findings delineates most of the anatomical variations in sphenoid sinus and thus helps the surgeons in appropriate surgical planning and helps them to reduce the intraoperative complications.