Endoscopic Transforaminal Transchoroidal (ETTC) Approach to the Third Ventricle for Cystic and Solid Tumors

Abstract Background Endoscopic access to the third ventricleis limited by the confinements of the foramenof Monro and can be aided by opening of the choroidal fissure. Objective We describe the endoscopic transforaminal transchoroidal (ETTC) approach to the third ventriclewith opening of the choroidal fissureto enlarge the posterior foramenof Monro for treatment of various third ventricular pathologies. Methods The authors completed a retrospective review of a prospectively collected database at three tertiary academic facilities. The search included patients who underwent endoscopic transcranial procedures between 2005 and 2018. All thirteen patients included in this study were treated using the ETTC approach for lesions in the third ventricleusing a rigid 6mm working endoscope. Results There were 7 females and 6 males with a mean (standard deviation) age of 44 (16). Third ventricular pathology included colloid cyst, craniopharyngioma, anaplastic astrocytoma, subependymal giant cell astrocytoma, metastatic lung adenocarcinoma, and lymphoma. Resection was complete in 7 patients and near complete in 4. Two patients had biopsy of a thalamic tumor and third ventriculostomy. The mean (SD) follow-up time was 44 (36) with a range of 9 to 121 months. There were no intraoperative or postoperative complications related to the approach. Conclusion ETTC approach is a safe and effective method for enlargement of the foramenof Monro. The approach improves maneuverability of the endoscope and allows a broad range of movement and increased angulation within the foramenof Monro. Attention to anatomy is paramount to avoid injury to the venous structures and fornix.