Related Experiment Video
Updated: Jul 16, 2026
Endoscopic Approach for Colloid Cyst Resection
Published on: May 23, 2025
Determining the Optimal Site of Entry for Colloid Cyst Resection Using an Expandable Tubular Retractor in a
John Na1, Marissa Koscielski1, Aaron Kakazu1
1University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
Background And Objectives:
Expandable tubular retractors have enabled microsurgical colloid cyst resection with minimal transcortical footprint, even in patients with a nondilated ventricular system. We investigated anatomic reference points to guide ideal site of transcortical entry.
Methods:
Operative windows were compared in 4 cadaveric specimens using 2 sites of entry: (1) at the Kocher point and (2) at an anterolateral point located 4 cm anterior and 1 cm lateral to the Kocher point. Visualization of the third ventricular roof from both entry sites was qualitatively compared. Virtual 3-dimensional reconstructions of the ventricular system of 6 specimens were subsequently segmented using computed tomography imaging. To optimize the trajectory, the anterolateral points were shifted medially until the third ventricle roof was visible without caudate obstruction; these optimized coordinates were designated as virtual adjusted points (VAPs). Mean VAP distance from the midline was then calculated.
Results:
The caudate head obstructed visualization of the foramen of Monro in 5 of 8 (62.5%) anterolateral entry sites, whereas no obstructions secondary to the caudate were encountered using the Kocher point. In the absence of caudate obstruction, anterolateral entry sites provided superior visualization with less line-of-sight obstruction from forniceal structures relative to Kocher entry sites. In virtual reconstruction, the VAPs offered superior visualization compared with all other entry sites, with a mean distance from the midline of 3.2 ± 0.1 cm.
Conclusion:
Both Kocher and anterolateral entries may encounter visual obstruction of the third ventricular roof in nondilated ventricles. Visualization can be optimized case-by-case as follows: (1) translation anterior, as delimited by the hairline, to minimize sagittal angle and maximize line of sight to the third ventricle roof and (2) once anterior extent is determined, use of neuronavigation to guide mediolateral transcortical access; specifically, movement of the entry site laterally until further translation would introduce visual obstruction by the caudate.