Postoperative hydrocephalus in patients with infratentorial brain metastases may be influenced by preoperative treatment: a single-center cohort study.

Abstract

Purpose: Infratentorial brain metastases (BM), particularly those causing obstruction of the fourth ventricle, are associated with a significant risk of postoperative hydrocephalus. This complication remains poorly understood, especially regarding its predictors beyond mechanical obstruction. This study aims to identify clinical predictors of postoperative hydrocephalus in patients undergoing surgery for infratentorial BM.

Methods: We performed a single-center retrospective analysis of 235 adult patients surgically treated for infratentorial BM between 2009 and 2025. Patients with leptomeningeal disease were excluded. Pre- and postoperative hydrocephalus were defined based on imaging and clinical criteria. Logistic regression and multivariate modeling were used to evaluate predictors, including clinical presentation, treatment history, and imaging features.

Results: Postoperative hydrocephalus occurred in 18.45% of patients. Breast cancer patients exhibited the highest incidence (30.61%), significantly more than those with lung cancer (15.66%, p = 0.042). Preoperative hydrocephalus (p = 0.005), and prior chemotherapy (p = 0.001) or radiotherapy (p = 0.004) were significantly associated with postoperative hydrocephalus. Imaging variables, including tumor volume or proximity to the fourth ventricle, were not predictive. Multivariate regression confirmed preoperative hydrocephalus, and systemic treatment as independent risk factors.

Conclusion: Postoperative hydrocephalus in infratentorial BM is influenced not only by mechanical factors but also by preoperative clinical and therapeutic variables. Breast cancer patients, particularly those who received prior systemic or local therapy, are at higher risk. These findings suggest the need for individualized risk assessment and raise the question of whether prophylactic interventions could mitigate complications and treatment delays in high-risk cohorts.