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

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 cm3; OZA + AC 53.69 cm3).

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.