Endoscopic posterior transchoroidal approach for biopsy and fenestration of lesions of the posterior tentorial incisura: a case series and review of the literature.

Objective. To describe the anatomical rationale, surgical technique, and outcomes of a purely endoscopic posterior transchoroidal approach (EPTCA) to lesions of the tentorial incisura, and to contextualise these results within the existing literature on endoscopic transchoroidal procedures. Methods. We retrospectively reviewed all patients who underwent EPTCA for lesions of the posterior tentorial incisura at our institution between 2012 and 2024. All procedures were performed via a single frontal burr hole, combining ETV when indicated with a posterior transchoroidal opening at the body–atrium junction to access the quadrigeminal cistern and tentorial incisura. A literature review of PubMed and Scopus was conducted to identify series reporting purely endoscopic transchoroidal approaches. Results. Twenty-two patients (13 females, 9 males; mean age 23.4 years) were included. Adjuvant ETV was performed in 20 patients (90.9%) and intralesional stenting in 8 (36.3%). Cystic lesions (n = 11) underwent fenestration with clinical success in 90.9%; solid lesions (n = 14) underwent biopsy, which was diagnostic in all cases. There were no deaths, no permanent cognitive decline and no venous injuries. Overall, 86.7% of patients achieved a good outcome (mRS 0–2) and 13.6% a fair outcome (mRS 3). Procedure-related complications included 3 intraventricular haemorrhages, 1 transient memory impairment, and 1 transient diplopia. The literature review identified 7 studies (49 patients) on endoscopic transchoroidal approaches, predominantly using anterior intraventricular routes; none described a posterior variant for extraventricular lesions. Conclusions. The EPTCA provides a safe, minimally invasive corridor to extraventricular lesions of the posterior tentorial incisura and posterior third ventricle, enabling effective biopsy, cyst fenestration, and adjuvant CSF diversion with low morbidity when applied in appropriately selected patients. Our series represents the first description of the posterior endoscopic transchoroidal route and the largest cohort of endoscopic transchoroidal procedures to date, supporting its inclusion in the contemporary surgical armamentarium for deep midline lesions.