Development of a Four-Parameter Preoperative Pilot Risk Score for Predicting Postoperative Shunt Dependency After Endoscopic Resection of Symptomatic Third Ventricular Colloid Cysts.

Abstract

Persistent hydrocephalus may develop after surgery for symptomatic third ventricular colloid cysts (TVCC), requiring ventriculoperitoneal (VP) shunting. No existing scoring system predicts this outcome. We developed a four-parameter preoperative pilot risk score to predict postoperative shunt dependency. In this retrospective study, 29 symptomatic TVCC patients who underwent endoscopic surgery (16 males, 13 females; median age 40, range 11-66) were evaluated using preoperative MRI. Four risk factors were identified: cyst location (Zone I or III), cyst volume ≥6.0 cm³, third ventricular volume ≥7.8 cm³ (ROC-derived thresholds), and T2-weighted hypointensity. Each factor was assigned 1 point, yielding an exploratory pilot risk score (0-4) intended for hypothesis-generating risk stratification rather than as a definitive clinical scoring system. VP shunt was required in 4/29 (14%). Using a cutoff of ≥2, the pilot risk score correctly identified all four shunt cases (sensitivity 100%), with a specificity of 56%, a positive predictive value (PPV) of 27%, a negative predictive value (NPV) of 100%, and an Area Under the Curve (AUC) of 0.800. In this pilot study, our findings suggest that the clinically derived pilot risk score, despite the lack of statistical significance for individual predictors, may serve as a hypothesis-generating tool to support clinical decision-making pending external validation. Patients with a pilot risk score of ≥2 represent a high-risk group in whom adjunctive endoscopic third ventriculostomy (ETV) or early shunt preparation may be considered. External validation in larger prospective cohorts is warranted.