Combining Retropharyngeal and Endonasal Routes to Maximize Anterior Skull Base Exposure: A Feasibility and Quantitative Anatomical Study.

BACKGROUND

The anterior craniocervical junction (CCJ) and lower clivus (LC) are challenging regions in skull base surgery because of their depth and proximity to critical neurovascular structures. The simplified retropharyngeal submandibular approach (SRSMA) provides a direct route but has only been described up to C2. This study assessed whether the SRSMA can be safely extended cranially and evaluated the anatomical feasibility and quantitative advantages of combining it with an extended endoscopic endonasal approach (EEA).

METHODS

Ten embalmed, latex-injected cadaveric specimens underwent 30 dissections, including bilateral SRSMA and EEA. Surgical exposure, corridor depth, and horizontal angles of attack were measured with intraoperative neuronavigation. A customized 3D-printed tubular retractor was used to create a standardized operative corridor for the SRSMA. Morphometric data were statistically analyzed to compare exposure and surgical freedom among approaches.

RESULTS

The SRSMA provided significantly wider exposure of the extracranial LC than the EEA (mean surgical area 35-46 cm2 vs. 23 cm2, P < 0.001). The EEA offered better visualization of the foramen magnum. When combined, the 2 approaches provided complementary access to the ventral skull base without requiring drilling of the anterior arch of C1. A new retropharyngeal landmark, the Longus Capitis Tubercle, was consistently identified. The customized 3D-printed tubular retractor proved effective and reproducible for standardizing the operative corridor.

CONCLUSIONS

The combined SRSMA-EEA strategy broadens ventral skull base exposure while preserving stability and minimizing invasiveness. This approach may be useful for selected lesions spanning regions beyond the reach of either route alone. Clinical validation is needed.