Cerebrospinal Fluid Output as a Risk Factor of Chronic Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage

Chronic shunt-dependent hydrocephalus is a well-known complication of subarachnoid hemorrhage. Although the risk factors have been extensively investigated, most fail to predict permanent shunt dependency. It is unknown whether the volume of cerebrospinal fluid (CSF) from external ventricular drainage and the daily volume of drainage during the acute hydrocephalus phase (first 72 hours) can predict shunt dependency. We aimed to determine whether CSF output during the acute hydrocephalus phase is a risk factor for shunt dependency. Patients with aneurysmal subarachnoid hemorrhage and hydrocephalus treated with external ventricular drainage were prospectively registered in our database between January 2017 and March 2020. Factors evaluated for predicting shunt dependency included age; sex; Hunt and Hess grade; World Federation of Neurological Surgeons grade; acute hydrocephalus; modified Fisher grade; aneurysm treatment modality; hospital length of stay; modified Rankin score; average daily overall CSF production; average CSF output for the first 24, 48, and 72 hours; external ventricular drainage days; the number of wean/clamp failures; and ventriculoperitoneal shunting. Univariate analysis identified Hunt and Hess grade; acute hydrocephalus at onset; external ventricular drainage; overall CSF output; average CSF output for the first 24, 48, and 72 hours; and CSF output until the first clamp as significant risk factors for shunt dependency (P < 0.001). In a multivariate logistic regression analysis, overall CSF output and average CSF output for the first 72 hours were significant risk factors for shunt dependency. Overall CSF output, especially during the acute hydrocephalus phase (first 72 hours), predicts the development of chronic hydrocephalus.