DOI: 10.1227/ons.0000000000002166 ISSN: 2332-4252

Quantitative Anatomic Comparison of Microsurgical Transcranial, Endoscopic Endonasal, and Transorbital Approaches to the Orbit and Surrounding Skull-Base Regions

Edoardo Agosti, Marco Valentini, Karen Mapelli, Ludovico Agostini, Barbara Buffoli, Vittorio Rampinelli, A. Yohan Alexander, Maria Peris-Celda, Marco Ravanelli, Amedeo Piazza, Pier Paolo Panciani, Lena Hirtler, Rita Rezzani, Mario Turri-Zanoni, Marco Maria Fontanella, Francesco Doglietto
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BACKGROUND AND OBJECTIVE:

Microsurgical transcranial approaches (MTAs) to the orbit and surrounding skull-base region lesions have been progressively complemented by endoscopic endonasal approaches (EEAs) and endoscopic transorbital approaches (ETOAs). This study provides the first quantitative, navigation-based comparison of working volumes and exposure areas of major approaches to the orbit and surrounding skull-base regions.

METHODS:

Five alcohol-fixed specimens were dissected. Twenty-six subregions grouped into the orbit, midline, spheno-orbital, and cavernous regions were segmented. Nineteen approaches, including anterior MTAs, anterolateral MTAs, EEAs, and ETOAs, were performed. Exposure areas and working volumes were quantified.

RESULTS:

Endoscopic endonasal transpterygoid approach (EETPA) provided the greatest exposure of the optic foramen (67.98%, P = .03 vs EEA to the medial orbit). The superior eyelid approach with lateral orbitotomy achieved the widest access to the lateral orbital wall, reaching 98.56% in the middle and 99.42% in the temporal portions ( P < .05 vs the orbitozygomatic approach [OZA]). The transcaruncular approach better exposed medial wall (99.41%, P = .04 vs EETPA), and the inferolateral approach gained largest orbital floor exposure (99.18%, P < .001). The extended transbasal approach maximally exposed the planum sphenoidale (99.28%, P = .03 vs orbitozygomatic approach with anterior clinoidectomy [OZA + AC]), while the EETPA the chiasmatic sulcus and the tuberculum sellae (98.76% and 96.47%, P < .001). The OZA + AC dominated most subregions, including greater wing, optic canal roof, and superior orbital fissure (98.49%, 98.18%, and 98.68%, P < .05). The superior eyelid approach with lateral orbitotomy better exposed foramen ovale at 88.89% ( P < .01), foramen rotundum at 88.78% ( P < .001), intracranial V3 at 92.92% ( P = .04), and petrous apex at 93.85% ( P < .01), while OZA + AC maximized intracranial V1 and V2 (87.94% and 90.74%, P < .05). The MTAs had largest working volumes (extended transbasal approach 59.35 cm 3 ; OZA + AC 53.69 cm 3 ).

CONCLUSION:

ETOAs provide unmatched access to the lateral orbit and cavernous regions, while EEAs excel medially and MTAs, especially OZA + AC, remain indispensable for broad spheno-orbital exposure and maximal working volumes.

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