Supraorbital Keyhole and Superior Eyelid Transorbital Endoscopic Approaches to the Ipsilateral Opticocarotid Cistern: An Anatomical Comparative Analysis

Introduction: Neurosurgical procedures involving the skull base require precise access and techniques for optimal outcomes. The supraorbital (SO) and superior eyelid transorbital endoscopic (SL-TOE) approaches have emerged as prominent surgical routes for lesions in the anterior and middle cranial fossa. This study aimed to compare the SO and SL-TOE approaches in the context of the opticocarotid cistern.

Methods: Anatomical dissections were performed bilaterally on three de-identified cadaveric, latex-injected heads. High-resolution computed tomography scans were taken prior to dissection. Approaches were carried out sequentially on each side; the SO approach was performed first, followed by the SL-TOE approach. The area of exposure (AoE), surgical freedom (SF), and angle of attack (AoA) were measured and compared between the approaches. Four distinct anatomical landmarks were identified to delineate the region: most anterolateral point of the anterior clinoid process (AL-Clinoid), most proximal point along the carotid artery (P-Carotid), most proximal and distal points along the optic nerve (P-ON and D-ON, respectively).

Results: The mean AoE for the SO approach was 82.44 ± 31.46 mm², while for the SL-TOE approach it was 70.55 ± 23.25 mm². There was no significant difference in AoE between the approaches(p = 0.48). However, the mean SF was significantly higher for the SO approach (2,834.44 ± 522.47 mm²) compared to the SL-TOE approach (1,009.21 ± 475.91 mm²) (p < 0.001). The AoA measurements showed significantly higher values for the SO approach for the AL-Clinoid and P-Carotid landmarks (p < 0.05). The D-ON had a significantly higher AoA using the SO approach on the horizontal plane (p = 0.027) but not on the vertical plane(p = 0.47). The AoAs were comparable for the P-ON (p > 0.05).

Conclusion: The SO and SL-TOE approaches offer comparable AoE in the opticocarotid cistern. However, the SO approach provides superior surgical maneuverability based on SF and AoA measurements. Surgeons should consider these factors when comparing both surgical approaches for lesions in the opticocarotid cistern.