Quantitative Cadaveric Analysis of Exposure in Endoscope-Assisted Intradural Subtemporal Approach Versus Endoscopic Endonasal Transsphenoidal Transcavernous Transoculomotor Triangle Approach to the Parapeduncular Cistern

Background: The parapeduncular space, a complex region lateral to the interpeduncular fossa and medial to the temporal lobe, poses a significant challenge in skull base surgery. This area is located between the uncus-parahipoccampal gyrus and the cerebral peduncle and is directly above the dura of the oculomotor triangle. It contains critical neurovascular structures including the oculomotor and trochlear nerves, internal carotid artery, and posterior communicating artery. Access to this region remains technically demanding due to its deep location and vital neurovascular structures.

Objectives: This study compared the anatomic exposure of two minimally invasive techniques: the endoscope-assisted intradural subtemporal approach and the endoscopic endonasal transsphenoidal transoculomotor triangle approach for accessing lesions in the parapeduncular space.

Methods: This comparative anatomical study used four latex-injected fresh cadaveric head specimens (eight sides). The endoscope-assisted intradural subtemporal approach was conducted using a rigid endoscope, while the endonasal endoscopic transoculomotor triangle approach was performed via an extended endoscopic endonasal corridor. The water balloon technique was used to simulate space-occupying lesions in the parapeduncular cistern. Balloons were inflated to volumes of 0.5, 1.0, and 1.5 mL to assess the impact on surgical exposure and maneuverability. Key anatomical landmarks, including cranial nerves III and IV, posterior communicating artery, and surrounding neurovascular structures, were identified and their relationships analyzed. Measurements were taken using a stereotactic navigation system and analyzed statistically to compare the approaches.

Results: Both approaches provided access to the parapeduncular cistern, each with distinct advantages and limitations. The endonasal transoculomotor triangle approach offered a direct midline trajectory and excellent visualization of the para-peduncular fossa, particularly with larger balloon volumes. The subtemporal approach provided superior lateral exposure and a wider working corridor for manipulating simulated lesions. Increasing balloon volume significantly improved surgical exposure in both approaches, with the endonasal route potentially benefiting more from larger lesions.

Conclusion: The endoscopic subtemporal and endonasal transoculomotor triangle approaches offer complimentary access to the parapeduncular cistern. The choice between these techniques should be based on the lesion's specific location and extent. The water balloon technique is valuable in simulating dynamic surgical conditions, enhancing our understanding of approach selection and operative nuances for this challenging region.

 

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
07 February 2025