Endoscopic Anatomy of the Skull Base.

Presently, endoscopic skull base surgery has undergone significant advancements since its inception over two decades ago. Nevertheless, it is imperative to underscore that the fundamental basis of all surgical procedures lies in the meticulous understanding of anatomy, with particular emphasis on the ventral anatomy. This facet has recently garnered increased attention.Following the advancements in endoscopic skull base surgery techniques, this chapter will concentrate on the pertinent anatomical considerations that serve as key foundations for successful procedures. These considerations are categorized into two planes: the sagittal plane and the coronal plane.The sagittal plane is further subdivided into five distinct approaches, namely,(1) the transcribriform approach, (2) the transplanum approach, (3) the transsellar approach, (4) the transclival approach, and (5) the transodontoid approach.On the other hand, the coronal plane is delineated into seven specific zones to facilitate comprehension and potential applications: (1) the petrous apex approach, (2) the intrapetrous approach, (3) the suprapetrous approach, (4) the cavernous sinus approach, (5) the infratemporal approach, (6) the medial condyle approach, and (7) the jugular foramen approach.By organizing the anatomical aspects in this systematic manner, the information provided becomes more accessible, fostering a comprehensive understanding of the subject matter for potential future application.

Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Approach to the Sellar and Parasellar Regions.

Introduction Surgery of the sellar and parasellar regions can be challenging due to the complexity of neurovascular relationships. The main goal of this study is to develop an educational resource to help trainees understand the pertinent anatomy and procedural steps of the endoscopic endonasal approaches (EEAs) to the sellar and parasellar regions. Methods Ten formalin-fixed latex-injected specimens were dissected. Endoscopic endonasal transsphenoidal transsellar, transtuberculum-transplanum, and transcavernous approaches were performed by a neurosurgery trainee, under supervision from the senior authors and a PhD in anatomy with advanced neuroanatomy experience. Dissections were supplemented with representative case applications. Results Endoscopic endonasal transsphenoidal approaches afford excellent direct access to sellar and parasellar regions. After a wide sphenoidotomy, a limited sellar osteotomy opens the space to sellar region and medial portion of the cavernous sinus. To reach the suprasellar space (infrachiasmatic and suprachiasmatic corridors), a transplanum-prechiasmatic sulcus-transtuberculum adjunct is needed. The transcavernous approach gains access to the contents of the cavernous sinus and both medial (posterior clinoid and interpeduncular cistern) and lateral structures of the retrosellar region. Conclusion The anatomical understanding and technical skills required to confidently remove skull base lesions with EEAs are traditionally gained after years of specialized training. We comprehensively describe EEAs to sellar and parasellar regions for trainees to build knowledge and improve familiarity with these approaches and facilitate comprehension and learning in both the surgical anatomy laboratory and the operating room.