Pneumatization of the sphenoid sinus and its surrounding neurovascular structures

Kim, Hyun Ung; Kang, Ji Won; Chung, In Hyuk; Yoon, Joo Heon; Lee, Jeung Gweon

Abstract

BACKGROUND AND OBJECTIVES: Sphenoid sinus faces the cavernous sinuses in which neurovascular structures such as the cavernous segment of the internal carotid arteries (ICA), optic nerve, and trigerminal nerve are located. In addition, it separates the pituitary gland from the nasal cavity. Therefore, surgeons are required to understand its detailed anatomy for transsphenoidal approach (TSA) or optic nerve decompression. This study is aimed to investigate the surgical anatomy of the sphenoid sinus and its clinical application using Korean adult cadaveric heads. MATERIAL AND METHODS: One hundred sagittally-divided adult cadaveric heads were used. After removing the sinus mucosa meticulously, careful examination and photodocumentation were done serially. The analysed items were the pneumatization type of the sphenoid sinus, the relationship between the pneumatization type of the sphenoid sinus and the incidence of bulging of the optic canal, segment 1 and 3 of ICA, maxillary nerve, and pterygoid nerve, and the incidence of bony dehiscence and thickness of bone at the bulging site of various neurovascular structures. RESULT: The sellar type was found in 90% of the subjects. The incidence of bulging of neurovascular structures were from 34% to 65%, and the incidence of bony dehiscence at the bulging site were from 0% to 9.6%. The more pnermatized the sphenoid bone was, the higher the prevalence of bulging became. The average thickness of bone was less than 0.5 mm. In the complete sellar type, the distances from the anterior wall of the sphenoid sinus to the bulging site at the optic canal, and to segment 1 and 3 of ICA were about 1.9 mm, 19.3 mm, and 9.5 mm, respectively. The distances from the superior wall of the sphenoid sinus to the bulging site at the optic canal and to the maxillary nerve were about 3.7 mm and 17.3 mm, respectively. Bulging of the optic canal attached to the anterior and the superior walls of the sphenoid sinus was 45% and 34%, respectively.
CONCLUSION
By elucidating the relationship between the sphenoid sinus and surrounding vital neurovascular structures, this study might be able to provide essential anatomical knowledge for surgeons to reduce surgical complication in applying to the sphenoid sinus.