Pneumatization of the sphenoid sinus in Chinese: the differences from Caucasian and its application in the extended transsphenoidal approach

In recent years, the transsphenoidal approach has been extensively used surgically to treat parasellar, suprasellar, clival, and even petrous lesions. Extended pneumatization of the sphenoid sinus (SS) is considered an indispensable element for the extended transsphenoidal (ETS) approach. Because most anatomical studies of the ETS approach use Caucasian subjects, the present study aims to clarify the pneumatic extension types in Chinese individuals as well as any differences from those in Caucasians and analyze these differences with respect to the application of the ETS approach. A total of 200 computed tomography (CT) images of SSs and 18 adult cadaveric heads were selected for observation and measurement. The conchal, presellar, and sellar types comprised 6, 28.5, and 65.5% of subjects, respectively; according to the extra extension, the prevalence of the lateral, clival, lesser wing, and combined extension sinus types was 11.4, 21.4, 0.8, and 48.1% of subjects, respectively. The percentages of pneumatization of the anterior and posterior clinoid processes, pterygoid process, and optic strut were 5.0, 1.0, 22.3, and 7.0%, respectively. Onodi cells were observed in 61.1% of the sides of the cadaveric heads, including 30.6% with good pneumatization with identifiable optical or ICA bulges. These features were related to poor lateral and clival gasification in Chinese compared with Caucasians, which might make extended surgery more dangerous. However, the anterior pneumatization, especially the higher presentation of Onodi cells, ensures that the anterior ETS approach can be performed safely in Chinese patients. In general, measurements showing smaller sinus volumes and thicker bones with identifiable bone landmarks that are hard to find compared with those in Caucasians suggest increased surgical risks in the Chinese population. In this situation, carefully analysis of presurgical CT and magnetic resonance imaging scans is important. Furthermore, in the ETS approach, the use of stricter intraoperative technological devices such as neuronavigation and ultrasound Doppler is advisable.