Surgical Freedom Evaluation During Optic Nerve Decompression: Laboratory Investigation

Area of Science:

• Neurosurgery
• Surgical Anatomy
• Ophthalmology

Background:

• Surgical decompression of the intracanalicular optic nerve historically utilized transcranial approaches.
• Ventral approaches, including endonasal and transorbital routes, have emerged as alternatives, used individually or in combination.

Purpose of the Study:

• To quantitatively compare the bony optic canal removal achievable via transcranial, transorbital, and endonasal pathways.
• To analyze and compare the surgical freedom offered by each of these approaches.

Main Methods:

• Optic canals in 10 cadaveric specimens (20 canals) were decompressed using pterional (transcranial), endoscopic endonasal, and endoscopic superior eyelid transorbital corridors.
• Surgical freedom and circumferential optic canal decompression were quantitatively assessed.
• Statistical analysis was performed using a nonpaired Student t test.

Main Results:

• The transcranial approach provided significantly greater surgical freedom (109.4 cm² ± 33.6) and optic canal decompression (245.2) compared to transorbital (37.2 cm² ± 4.9; 177.9) and endonasal (10.9 cm² ± 5.2 to 11.1 cm² ± 5.6; 144.6) routes.
• These differences were statistically significant for the transcranial approach in many comparisons.

Conclusions:

• The transcranial approach yields the widest optic canal decompression and greatest surgical freedom for instrument manipulation.
• This study provides a comprehensive anatomical evaluation of surgical access to the optic canal.
• Further clinical experience is required to define the specific indications for the transorbital approach in optic canal decompression.