The "Dual-Port" Approach to the Posterior Incisura: A Quantitative Cadaver Study of a Combined Endoscopic Paramedian Supracerebellar Infratentorial and Occipital Interhemispheric Transtentorial Approach.

Background: The posterior incisura is a deep and surgically challenging area with complex neurovasculature. Endoscopic paramedian supracerebellar infratentorial approaches (EPSCITAs) have improved access and visualization of this region. However, endoscope and instrument conflict within this deep and narrow corridor remains a key limitation. This study evaluates the feasibility of a combined EPSCITA and endoscopic occipital interhemispheric transtentorial approach (EOIHTTA) with the aim of improving surgical freedom and visualization in this region.

Methods: Five embalmed and latex-injected cadaveric donors were dissected bilaterally (10 sides total). Measurements were taken at the EPSCITA port and then were repeated after addition of the EOIHTTA port. Measurements of surgical freedom at 3 anatomic targets, area of exposure, distance to the pineal gland, and angle at approach port, were obtained using stereotactic navigation. Statistical analyses were performed using 2-sample t-tests.

Results: Addition of the EOIHTTA port improved the vertical angle of approach from 15.07° to 58.96°, P < 0.0001, and horizontal angle of approach from 28.1° to 50.02°, P < 0.0001. The area of surgical freedom at each anatomic target increased notably, with the area at the pineal gland expanding from 663 mm to 1042 mm, P < 0.005, the superior colliculus from 806 mm to 1090 mm, P < 0.005, and the splenium from 415 mm to 902 mm, P < 0.005.

Conclusions: This dual-port approach enhances access to the posterior incisura, providing improved surgical exposure and maneuverability while reducing instrument conflict. This technique is an effective minimally invasive approach to this deep-seated region, addressing the limitations of traditional single-port techniques.