Transorbital Routes to the Skull Base: A Comparative Anatomical Study

Objective: Transorbital approaches, have been popularized as minimally invasive alternatives to traditional skull base approaches. The exact indications for each variant have not been adequately studied in a comparative manner. In the current study, we sought to compare four approaches: (1) the lateral orbitotomy through a lateral canthus incision (LatOrb), (2) the modified orbitozygomatic approach through a palpebral incision (ModOzPalp), (3) the modified orbitozygomatic approach through an eyebrow incision (ModOzEyB), and (4) a supraorbital craniotomy through an eyebrow incision (SupraOrbEyB).

Methods: Cadaveric dissections were performed in the neuroanatomy lab of our department. A total of 4 formalin-fixed heads were used, with two sides for each approach (eight sides). Working corridors were assessed via image guidance analysis and the anatomical points on the cranial base were mapped and illustrated accordingly.

Results: The LatOrb is an approach which proves to be quite versatile in the middle fossa ([Fig. 1]). The anterior cranial fossa exposure is limited to a smaller area above the sphenoid ridge. An anterior clinoidectomy is possible; however, the exposure of the roof of the optic canal is limited. The ModOzPalp provides extensive exposure of both the anterior and middle cranial fossae ([Fig. 2]). The trajectory of the exposure is from inferior to superior providing an advantageous angle of attack for superiorly extending lesions or for pathology in the interhemispheric fissure. However, it provides limited exposure of the middle anterior skull base (olfactory groove). An anterior clinoidectomy is feasible with improved exposure compared to the LatOrb, but the exposure of the roof of the optic canal is limited. The ModOzEyB also provides extensive exposure of the anterior and middle cranial fossae but has a more superior to inferior trajectory compared to the ModOzPalp, making it more appropriate for pathology extending in the middle anterior skull base ([Fig. 3]). The anterior clinoidectomy is performed with improved visualization of the optic canal. This approach is less versatile in the middle fossa than both the LatOrb, and ModOzPalp. The SupraOrbEyB provides mainly anterior cranial base exposure, with minimal middle fossa ([Fig. 4]). An anterior clinoidectomy can be performed but without any direct observation of the superior orbital fissure. The inferior to superior trajectory is more hindered by the orbital rim, requiring more brain retraction relative to the ModOzPalp.

Conclusions: Each of the four approaches described has advantages and limitations in the exposure and the surgical trajectory they provide. For this reason, appropriate case selection is critical for the effective and safe completion of the surgical goals.

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Artikel online veröffentlicht:
05. Februar 2024