Supracerebellar infratentorial inverted subchoroidal approach to lateral ventricle lesions: Anatomical study and illustrative case.

Background: This study provides an anatomical description of a novel supracerebellar infratentorial inverted subchoroidal (SIIS) approach to the lateral ventricle. An illustrative case is presented in which this approach was used to simultaneously resect two tumors residing in the posterior fossa and lateral ventricle.

Methods: The SIIS approach was performed on five cadaveric heads using microsurgical and endoscopic techniques. Target points were defined in the lateral ventricle, and quantitative analysis was performed to assess limits of exposure within the lateral ventricle. Two coronal reference planes corresponding to the anterior and posterior margins of the lateral ventricle body were defined. Distances from target points to reference planes were measured, and an imaging-based predicting system was provided according to obtained measurements to guide preoperative approach selection.

Results: Mean (standard deviation) distances between the predefined target points indicating the anterior limits and the anterior plane were 9 (7.0) mm, 11 (5.8) mm, and 7 (5.1) mm; posterior limits had distances of 8 (3.0) mm, 17 (9.2) mm, 15 (9.2) mm, and 9 (7.2) mm to the posterior plane. Limiting factors of the choroidal fissure dissection were the venous angle anteriorly and thalamocaudate vein posteriorly. The position of the venous angle had a high negative correlation with the anterior exposure limit ( = -0.87, < 0.001; = -0.92, < 0.001).

Conclusion: A step-by-step anatomical description of a new SIIS approach is given, and a quantitative description of the limits of the exposure is provided to evaluate the application of this approach.