Neuroendoscopic Paramedian Supracerebellar Infratentorial Approach for Pineal Region and Posterior Incisural Lesions: A Technical Case Series of 24 Patients.

Abstract

To report technical nuances, clinical efficacy, and exploratory risk stratification of the neuroendoscopic paramedian supracerebellar infratentorial approach (PSCI) for pineal region and posterior incisural lesions. A retrospective technical case series was conducted on 24 consecutive patients between February 2019 and March 2025. Operative parameters, clinical outcomes, and pathological findings were recorded. Receiver operating characteristic (ROC) analysis explored tumor volume thresholds potentially influencing subtotal resection (STR) risk. Gross total resection (GTR) was achieved in 17 cases (71%) and STR in 7 cases (29%). Mean operative time was 214 minutes, and median blood loss was 100 ml. No permanent neurological deficits or surgical mortality occurred. Predominant pathologies included germinoma (42%) and mature teratoma (21%). ROC analysis identified an exploratory volume cutoff of 8.2 cm³ (AUC=0.752, 95% CI: 0.528-0.976, P=0.023). The large-volume group (>8.2 cm³, n=11) had significantly prolonged operative time, increased blood loss, higher venous involvement, and a higher STR rate compared to the small-volume group (≤8.2 cm³, n=13). At median follow-up of 26 months, KPS improved in 20 patients (83%) at 3 months and no overt recurrence occurred; two patients with STR had stable residual lesions without progression. The neuroendoscopic PSCI is a safe and effective corridor for managing pineal region and posterior incisural lesions. Exploratory analysis suggests that tumor volume >8.2 cm³ may be associated with greater surgical complexity and residual risk, indicating a potential utility for preoperative planning.