Anatomic Variations of Sphenoid Sinus and Related Neurovascular Structures: A Study of CT Analysis

Lee, Seung Kyun; Park, Yong Soo; Cho, Jin Hee; Park, Yong Jin; Kang, Jun Myung; Jeon, Eun Ju; Kim, Sung Won; Yoon, He Ro

Abstract

BACKGROUND AND OBJECTIVES
Anatomic variations of the sphenoid sinus and the related neurovascular structures are common. Because it is a rule that may complicate surgery in such a place, these variations should be known preoperatively. The aim of this study was to delineate the relationship between the pneumatization of the sphenoid sinus and the related neurovascular structure variations including carotid artery and optic nerve.
SUBJECTS AND METHOD
A review of 100 paranasal sinus tomographic scans was made to investigate the anatomic variations of the sphenoid sinus and the related structures. The analyzed items were the pneumatization of the sphenoid bone including anterior clinoid process (ACP) and pterygoid process (PP), the relationship between the pneumatization of the sphenoid sinus and the incidence of bulging of the internal carotid artery (ICA), optic nerve (ON), maxillary nerve and pterygoid nerve. The patterns of intersinus septum and accessory septum were also assessed.
RESULTS
The most prevalent type of the pneumatization of the sphenoid sinus was the sellar type (90%). Midline location of the septum was found in 32 patients. Accessory septum was found in 52 patients. The bulging of ICA into the sphenoid sinus was found in 52 patients (retrosellar segment) and 67 patients (presellar segment). ON bulging was found in 52 patients. Patients showing pneumatization of ACP and PP were 20 and 34, respectively. There was a statistically significant relationship between the pneumatization of ACP, PP and the bulging in ICA and ON. Number of patients showing bulging of the maxillary nerve and pterygoid nerve was 36 and 49, respectively.
CONCLUSION
Accurate evaluation of the pneumatization of the sphenoid sinus and the variations of the related neurovascular structures is possible with preoperative CT scans of the sinus. Numerous variations of the related neurovascular structures are related with degrees of pneumatization of the sphenoid sinus. For safe sphenoid sinus surgery, a thorough analysis of the preoperative CT scans as well as the precise anatomic knowledge is required.