Multivariate Evaluation of Risk Factors for Hydrocephalus in Posterior Fossa Tumors.

Abstract

Introduction: This study aimed to fully analyze the hydrocephalus risk factors according to tumor characteristics and treatment protocols and their effects on patient survival.

Material and methods: We retrospectively analyzed 31 patients (13 pontine gliomas, 18 cerebellar metastases) treated from January 2019 to January 2024. The preoperative and postoperative magnetic resonance images provided volumetric measurements to determine tumor characteristics including volume and fourth ventricle distance and ventricular configuration. The treatment plan for pontine glioma patients included 50.4 Gy (1.8 Gy/fraction), while metastasis patients received 30 Gy whole-brain radiotherapy with a 9 Gy boost to the tumor bed (total 39 Gy). The analysis used univariate and multivariate Cox proportional hazards regression models to examine the relationships between tumor characteristics and hydrocephalus development as a time-to-event outcome and survival.

Results: The mean tumor volumes were 24.7 ± 5.8 cm 3 (pontine gliomas) and 17.3 ± 6.2 cm 3 (metastases), with mean fourth-ventricle distances of 1.58 ± 0.72 cm and 2.34 ± 0.81 cm, respectively. Hydrocephalus developed in 30.8% of pontine glioma patients and 27.8% of metastasis patients ( P > 0.05). Multivariate Cox proportional hazards regression analysis revealed increased hydrocephalus risk with a tumor volume >20 cm 3 (hazard ratio (HR) =3.86, 95% CI: 1.92-7.74) a fourth-ventricle distance ≤2 cm (HR = 3.42, 95% CI: 1.68-6.96), and distorted ventricular configuration (HR = 3.28, 95% CI: 1.62-6.64). Ventricle configuration distortion predominated in pontine gliomas (75% of hydrocephalus cases), while ventricle proximity predominated in metastases (80% of cases). Radiotherapy doses had no significant effect on hydrocephalus rates (HR = 1.14, 95% CI: 0.72-1.82, P = 0.568).

Conclusions: The development of hydrocephalus in posterior fossa tumors seems to be more closely related to the anatomical features of the tumor than to the doses of radiotherapy. Hydrocephalus has a negative impact on survival outcomes.