The anterolateral triangle as window on the foramen lacerum from transorbital corridor: anatomical study and technical nuances

Abstract

Objective Neurosurgical indications for the superior eyelid transorbital endoscopic approach (SETOA) are rapidly expanding over the last years. Nevertheless, as any new technique, a detailed knowledge of the anatomy of the surgical target area, the operative corridor, and the specific surgical landmark from this different perspective is required for a safest and successful surgery. Therefore, the aim of this study is to provide, through anatomical dissections, a detailed investigation of the surgical anatomy revealed by SETOA via anterolateral triangle of the middle cranial fossa. We also sought to define the relevant surgical landmarks of this operative corridor. Methods Eight embalmed and injected adult cadaveric specimens (16 sides) underwent dissection and exposure of the cavernous sinus and middle cranial fossa via superior eyelid endoscopic transorbital approach. The anterolateral triangle was opened and its content exposed. An extended endoscopic endonasal trans-clival approach (EEEA) with exposure of the cavernous sinus content and skeletonization of the paraclival and parasellar segments of the internal carotid artery (ICA) was also performed, and the anterolateral triangle was exposed. Measurements of the surface area of this triangle from both surgical corridors were calculated in three head specimens using coordinates of its borders under image-guide navigation. Results The drilling of the anterolateral triangle via SETOA unfolds a space that can be divided by the course of the vidian nerve into two windows, a wider “supravidian” and a narrower “infravidian,” which reveal different anatomical corridors: a “medial supravidian” and a “lateral supravidian,” divided by the lacerum segment of the ICA, leading to the lower clivus, and to the medial aspect of the Meckel’s cave and terminal part of the horizontal petrous ICA, respectively. The infravidian corridor leads medially into the sphenoid sinus. The arithmetic means of the accessible surface area of the anterolateral triangle were 45.48 ± 3.31 and 42.32 ± 2.17 mm2 through transorbital approach and endonasal approach, respectively. Conclusion SETOA can be considered a minimally invasive route complementary to the extended endoscopic endonasal approach to the anteromedial aspect of the Meckel’s cave and the foramen lacerum. The lateral loop of the trigeminal nerve represents a reliable surgical landmark to localize the lacerum segment of the ICA from this corridor. Nevertheless, as any new technique, a learning curve is needed, and the clinical feasibility should be proven.

A New Perspective on the Cavernous Sinus as Seen through Multiple Surgical Corridors: Anatomical Study Comparing the Transorbital, Endonasal, and Transcranial Routes and the Relative Coterminous Spatial Regions

“…The lacerum segment of the ICA, at its transition zone from the horizontal petrous segment to the ascending cavernous segment, located medially to the petrolingual ligament, along with the related carotid sympathetic plexus, can be also exposed ( Figure 5 b). As recently already described by our group [ 37 ], it is possible to appreciate a space limited by the inferior border of V2 superiorly, the superior border of V3 posteriorly, the line crossing the most anterior limit of exposure of the Vidian nerve and joining the foramen rotundum and the point where the greater wing joints the body of the sphenoid bone anteriorly, and the line between this last point and the foramen ovale posteriorly (red dotted line). This area includes two windows divided by the course of the Vidian nerve until where it blends into the cartilaginous tissue of the FL under the trigeminal nerve, and which unfold different corridors: A wider superior window (“supravidian”) that discloses two corridors in relationship to the lacerum segments of the ICA: a “medial supravidian corridor” leading to the lower clivus, and a “lateral supravidian corridor” leading, after gentle lateralization of the Gasserian ganglion, to the medial aspect of the Meckel’s cave and the terminal portion of the horizontal petrous ICA (pICA).…”

“…The opening of the anterolateral triangle through SETOA [ 37 ] reveals a space that can be divided into a wider superior window (“supravidian”) and a narrow inferior window (“infravidian”). The supravidian window allows direct access to the lacerum segment of the ICA and the related carotid sympathetic plexus; furthermore, this space reveals two different corridors: the medial supravidian corridor leading to the lower clivus, and the lateral supravidian corridor leading to the Meckel’s cave and the terminal portion of the horizontal petrous ICA, medial and lateral to the lacerum ICA, respectively.…”

“…At this point, once the zygomatic body and the intraorbital part of the greater sphenoid wing (including the sagittal crest [ 35 ]) were drilled until the exposure of the temporal pole dura mater, an interperiosteal-dural dissection via the meningo-orbital band (MOB) [ 21 ] was performed to unlock the lateral wall of the CS up to the Gasserian ganglion (GG). After cutting the middle meningeal artery (MMA), the temporal pole was elevated in an extradural fashion and, once the mid-subtemporal ridge and the trigeminal lateral loop were identified [ 36 ], the anterolateral triangle of middle fossa was opened [ 37 ]. Finally, an extradural anterior clinoidectomy [ 38 ] completed the surgical procedure.…”

Spheno-Orbital Meningiomas: The Rationale behind the Decision-Making Process of Treatment Strategy

“…The endoscopic endonasal technique affords great visualization of the orbital apex and optic canal and allows for the resection of tumors extended medially to the optic canal, pterygopalatine fossa, and the infratemporal fossa. The endoscopic transorbital approach (ETOA), first mainly adopted by ophthalmologists, allows for lesions affecting the paramedian aspect of the anterior and middle cranial fossae to be accessed [ 47 , 63 , 64 , 65 , 66 , 67 ]. This route addresses a similar anatomical target of the OC to the microsurgical transcranial approach, including lateral orbitotomy, but with different angles of attack, surgical freedom, and carrying peculiar benefits and limits [ 15 ].…”

Endoscopic transorbital resection of the temporal lobe: anatomic qualitative and quantitative study

“…The endoscopic transorbital approach has now entered the skull base neurosurgeon's armamentarium for the management of selected skull base lesions (Somma et al, 2021 ; Yoo et al, 2021 ; Han et al, 2023 ). Starting from anatomic studies that demonstrated the feasibility of exploring via the transorbital route, the anterior (Di Somma et al, 2018 ; Nannavecchia et al, 2021 ; Lim et al, 2022 ), middle (Chibbaro et al, 2021 ; Guizzardi et al, 2022 ; Corvino et al, 2023 ), and posterior cranial fossae (De Rosa et al, 2022 ), many applications of this approach in the management of extradural lesions have been published (Dallan et al, 2018b ; Zoia et al, 2018 ; Park et al, 2020a ; Corvino et al, 2022 ; Lee et al, 2022 ; Lim et al, 2022 ; Noiphithak et al, 2022 ; Di Somma et al, 2023a ; Zoli et al, 2023 ), demonstrating the possibility of overcoming many concerns attributed to this approach in terms of poor maneuverability and intraoperative complications' management (Kim W. et al, 2021 ; Di Somma et al, 2023b ).…”