Introduction: During the decades the orbit has evolved from surgical target to serving as a corridor
to various skull base regions. Several surgical approaches have been developed to
access and pass through the orbit, including microsurgical orbitotomies (MOs), cranio-orbitotomies
(MCOs), endoscopic transorbital (ETOAs), and endoscopic endonasal approaches (EEAs).
However, there is no consensus on the best approach for specific orbital portions
and surrounding skull base regions. This study aims to quantitatively compare these
approaches in a preclinical setting.
Methods: Six formalin-fixed, latex-injected cadaveric head specimens were dissected, performing
the following approaches in each specimen: ETOAs (preseptal lower eyelid approach,
lateral cantotomy, precaruncular approach, and superior eyelid crease approach), EEAs
(transethmoidal sphenoidotomy to the medial orbital wall and optic canal, and medial
maxillectomy to the inferior orbital wall), Caldwell-Luc approach, MOs (lateral cantotomy
orbitotomy), and MCOs (fronto-orbital and orbito-zygomatic approaches; [Figs. 1 ]
[2 ]
[3 ]). High-resolution CT scans were obtained for all specimens, and ITK-Snap software
rendered the target regions. An optic neuronavigation system (ApproachViewer, part
of GTx-Eyes II, University Health Network, Toronto, Canada) quantified the working
volume and exposed area for each approach. Statistical analyses were conducted using
mixed linear models with random intersections.
Results: Twenty-four target regions of the orbit and surrounding skull base areas were identified.
MOs provided direct access to the lateral orbital wall and superior orbital fissure,
offering the maximum exposure of the lateral orbital wall (78%; p = 0.02) compared to ETOAs (55%). MCOs extended this access, allowing a broader view
of the orbital apex and posterior orbit, including the superior and inferior orbital
fissures, with significantly greater exposure compared to MOs (84 vs. 62%; p = 0.01).
ETOAs provided access to the medial and inferior orbital walls, offering a minimally
invasive route to the lamina papyracea and optic canal, with a 25% gain in exposure
compared to MCOs (67 vs. 42%; p = 0.03). ETOAs also facilitated exposure of the anterior cranial fossa, including
the planum sphenoidale and cribriform plate, with a 32% gain in exposure compared
to EEAs (74 vs. 42%; p = 0.02). Additionally, ETOAs enabled access to the sphenoid sinus and lateral recess
of the sphenoid, critical for addressing lesions in the parasellar region, with a
significant gain compared to MOs (63 vs. 28%; p = 0.01).
EEAs uniquely facilitated access to the medial orbit and optic canal, particularly
useful for decompression procedures, providing 55% exposure of the optic canal compared
to 32% by ETOAs (p = 0.04), though they provided limited access to lateral orbital structures. Each
approach had distinct advantages: MOs and MCOs excelled in lateral (78 vs. 55%; p = 0.02) and posterior orbital exposure (84 vs. 62%; p = 0.01), while ETOAs and EEAs were superior for accessing medial (67 vs. 42%; p = 0.03) and deep orbital structures (55 vs. 32%; p = 0.04).
Conclusion: MOs and MCOs are preferred for lateral and posterior orbital exposure and lateral
skull base interventions, while ETOAs and EEAs are superior for accessing medial and
deep orbital structures and medial skull base.
