Microsurgical Anatomy of the “True” Petrous Apex: Anatomical Considerations and Technical Nuances in Endoscopic Endonasal Surgery

Objectives: The “true” petrous apex is a hidden region through transcranial skull base approaches due to its concealment by multiple vital neurovascular structures. However, the endoscopic endonasal approach offers a direct route to this region. Nonetheless, a thorough understanding of the “true” petrous apex from an endoscopic endonasal viewpoint remains elusive. This study aims to elucidate the complex microsurgical anatomy of the “true” petrous apex and evaluate the viability of accessing it through the endoscopic endonasal approach.

Methods: A detailed microsurgical dissection of 10 lightly embalmed post-mortem human specimens (20 hemispheres) was undertaken, utilizing an endoscopic endonasal medial and lateral petrosectomy approach. Key anatomical landmarks, critical neurovascular structures, and parameters were systematically measured and evaluated in a stepwise manner.

Results: The “true” petrous apex is a dense osseous structure situated lateral to the petroclival fissure, posterior to the lacerum and petrous segment of the internal carotid artery (ICA), and is enveloped by Meckel’s Cave. The endoscopic endonasal petrosectomy approach, categorized into two variants based on its relationship with the ICA, facilitates access to this anatomically intricate region ([Fig 1]). The medial approach, often referred to as the translacerum approach, provides exposure to the “true” petrous apex, measuring an average width of 5±1 mm. The lateral approach, which accesses through the space between paraclival ICA and Meckel’s Cave, can achieve an enhanced exposure width of 9 ± 1 mm. The lingual process, mandibular strut, sympathetic, abducens and trigeminal nerves stand out as the vital intraoperative landmarks when employing the endoscopic endonasal lateral petrosectomy ([Fig. 2]).

Conclusions: The current study offers a comprehensive and meticulous anatomical assessment and technical nuances of the endoscopic endonasal petrosectomy, which is demonstrated as an efficient surgical alternative for accessing lesions situated at the “true” petrous apex.

Fig. 1 Microsurgical anatomy of “true” petrous apex and two variants of endoscopic endonasal petrosectomy approach.

Fig. 2 Stepwise dissection of endoscopic endonasal petrosectomy.

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Artikel online veröffentlicht:
05. Februar 2024