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

BACKGROUND: Endoscopic access to the third ventricle is limited by the confinements of the foramen of Monro and can be aided by opening of the choroidal fissure. OBJECTIVE: We describe the endoscopic transforaminal transchoroidal (ETTC) approach to the third ventricle with opening of the choroidal fissure to enlarge the posterior foramen of Monro for treatment of various third ventricular diseases. METHODS: We completed a retrospective review of a prospectively collected database at 3 tertiary academic facilities. The search included patients who underwent endoscopic transcranial procedures between 2005 and 2018. All 13 patients included in this study were treated using the ETTC approach for lesions in the third ventricle using a rigid 6-mm working endoscope. RESULTS: There were 7 women and 6 men with a mean age of 44 years (standard deviation, 16 years). Third ventricular diseases 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 follow-up time was 44 months (standard deviation, 36 months; range, 9-121 months). There were no intraoperative or postoperative complications related to the approach. CONCLUSIONS: ETTC approach is a safe and effective method for enlargement of the foramen of Monro. The approach improves maneuverability of the endoscope and allows a broad range of movement and increased angulation within the foramen of Monro. Attention to anatomy is paramount to avoid injury to the venous structures and fornix.