First experience of using transcallosal interfoniceal approach in microsurgery for third ventricle tumors

Microsurgery of third ventricle tumors is a complex and relevant neurosurgical problem. Microsurgical access to the third ventricle depends on tumor size and location and can be performed using one of the following methods: transforaminal, transchoroidal, subchoroidal, infratentorial, supracerebellar, interhemispheric transtentorial, or subfrontal translaminar approach. Transforaminal and translaminar approaches are used for anterior parts of the third ventricle, while trans- and subchoroidal as well as supracerebellar infratentorial accesses are applied to its posterior regions. We present our experience with the use of interfoniceal access (IFA), which allows visualization of both anterior and posterior parts of the third ventricle. Objective: To describe IFA technique and evaluate immediate and long-term outcomes of employing transcallosal interfoniceal approach in treating third ventricle tumors. Materials and Methods. From June 2019 to December 2025, 12 patients underwent surgery at Moscow Regional Clinical Research Institute named after M.F. Vladimirsky using the transcallosal interfoniceal approach. Results. Total resection was achieved in 9 cases. Subtotal removal was performed in 3 cases. Early postoperative complications occurred in 25% of the cases. Pathohistological examination confirmed colloid cysts in 5 cases (41.7 %), pilocytic astrocytoma in 3 cases (25 %), germ cell tumors in 2 cases (16.7 %), cavernoma in 1 case (8.3 %), and ependymoma in 1 case (8.3 %). Follow-up data were available for all 12 patients, showing favorable long-term results in each case.