Introduction: The transorbital endoscopic approaches (TOEAs) recently emerged as alternatives for accessing the various aspects of the skull base. Anatomical awareness is a skull base surgeon’s best ally for safe and successful surgery. The anatomy of TOEAs from a ventral viewpoint remains to be fully elucidated.
Methods: Lateral TOEAs to the middle cranial fossa were carried out in 20 adult cadaveric heads (40 sides). The presence of the crista ovale (COv; previously described transcranially as the mid-subtemporal ridge) was assessed under endoscopic visualization. The relationship between the COv and key anatomical structures was evaluated with neuronavigation. Its presence was also examined in 30 cadaveric head computed tomographic (CT) scans (60 sides).
Results: The COv was identified on the skull base, in 98% (39/40) of cadaveric sides (right and left), shortly upon accessing the middle cranial fossa, as either one of three major configurations (single, bifid or extended). It was found just anterolateral to the FO and FS (mean distance: 9.2 ± SD 2.4 mm and 12.3 ± SD 2.6 mm, respectively) and in line or slightly anteromedial to the petrous apex (PA; mean distance: 26.2 ± SD 2.6 mm), at a mean 47.6 ± SD 4.7 mm from the lateral orbital portal. The COv was also readily recognized in 95% (57/60) of right and left side CT scans.
Conclusions: The COv can be readily identified during TOEAs to the middle and posterior skull base and on CT imaging, serving as a constant landmark for the FO, FS, and PA. Clinical studies are necessary to confirm its surgical significance and further applications in transorbital skull base procedures.
Patient Care: Anatomical awareness during transorbital skull base procedures may minimize the risk of neurovascular injury
Learning Objectives: Assess the anatomy of the “Crista Ovale” (COv; known transcranially as the mid-subtemporal ridge) from a ventral transorbital perspective and evaluate its role as a landmark during TOEAs to the middle and posterior skull base.
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