Subtotal Tumor Resection is an Important Predictor of Post-Resection Hydrocephalus and Enhances the Modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH)

Introduction: The Modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH) predicts the need for permanent CSF diversion after resection of posterior fossa tumors in children. External validation has demonstrated moderate utility, but the results have been variable. This study aims to optimize the utility of the mCPPRH by modifying its components.

Methods: We conducted a retrospective analysis of pediatric patients who underwent primary resection of posterior fossa tumors at our institution (January 2016–June 2024). Multivariable logistic regression with bidirectional stepwise selection identified predictors of CSF diversion (VP shunt, endoscopic third ventriculostomy) within 6 months of resection. The mCPPRH was modified accordingly, and its performance was compared to the original using receiver operating characteristics curve analysis.

Results: We included a total of 112 patients. Regression analysis identified age < 5 (OR 3.18, 95% CI: 1.28–8.11, p=0.01), transependymal edema on preoperative MRI (OR 4.08, 95% CI: 1.25–16.49, p=0.03), and subtotal resection (3.60, 95% CI: 1.43–9.49, p< 0.01) as independent predictors of CSF diversion. Tumor diagnosis, GCS, WHO grade, EVD placement, hemorrhagic tumor, midline tumor location, postoperative intraventricular blood, and intraoperative blood loss were not significant. The new tool replaced tumor diagnosis with subtotal resection and increased the age cutoff from < 2 to < 5 years. It assigned points for age < 5 (3), metastases (3), moderate/severe hydrocephalus (2), transependymal edema (1), and subtotal resection (1). The AUC was 0.784 (vs. 0.701 for mCPPRH). Using the same ≥5-point cutoff, sensitivity was 71.4% (vs. 57.1%), specificity 74.0% (vs. 65.4%), positive predictive value 55.6% (vs. 42.6%), and negative predictive value 85.1% (vs. 77.3%).

Conclusion : Subtotal tumor resection is an independent predictor of post-resection permanent CSF diversion in pediatric patients with posterior fossa tumors. Modifying the mCPPRH by substituting subtotal resection for tumor diagnosis and adjusting the age cutoff to under 5 years substantially improved its predictive performance in this U.S. cohort.