Incidence of Hydrocephalus and Permanent Shunt Dependency Following Posterior Fossa Surgery: A Retrospective Study

Abstract

Background: Posterior fossa lesions are an important cause of obstructive hydrocephalus in both children and adults. Objectives: This study evaluated the incidence and timing of hydrocephalus and the need for permanent ventriculoperitoneal (VP) shunting after surgical treatment of posterior fossa lesions. Secondary outcomes included preoperative and postoperative hydrocephalus and temporary cerebrospinal fluid (CSF) diversion. Methods: We retrospectively reviewed 69 consecutive pediatric and adult patients who underwent surgical management of posterior fossa lesions at our institution between 2019 and 2024. The primary endpoints were the incidence and timing of hydrocephalus and the need for subsequent permanent VP shunting. Results: Hydrocephalus was present in 32 patients (46.4%). In 28 of these patients (87.5%), hydrocephalus was evident before the index operation, whereas 4 patients (12.5% of the hydrocephalus group) developed de novo postoperative hydrocephalus. Overall, 26 of the 32 patients with hydrocephalus (81.3%) required some form of CSF diversion; however, half were managed with temporary external ventricular drainage alone. Permanent VP shunt placement was required in 13 patients overall (18.8% of the entire cohort and 40.6% of those with hydrocephalus). In univariate analysis, neoplastic lesion type (OR = 3.67, 95% CI, 1.06 - 12.70), preoperative hydrocephalus (OR = 5.15, 95% CI, 1.30 - 20.40), and midline location (OR = 4.75, 95% CI, 1.32 - 17.10) were associated with increased odds of permanent shunt dependency. Owing to the small sample size, multivariable adjustment was not feasible; these findings should be considered exploratory and hypothesis-generating. Conclusions: Permanent shunting was required in 18.8% of the overall cohort and 40.6% of patients who developed hydrocephalus. The small number of pediatric patients (n = 3) precludes meaningful inference in children; therefore, these findings are primarily applicable to adults and should be considered hypothesis-generating. Follow-up data were complete for 95.7% of patients over 6 months. Larger prospective studies are needed to confirm these observations and clarify the role of endoscopic third ventriculostomy versus traditional shunting in this population.