A substantial body of evidence supports the idea that CSF diversion could prevent VS, even if this issue is still much debated. External ventricular drainage (EVD) is the recommended procedure for posthemorrhagic hydrocephalus.
VS occurred in 8.75% of cases (7 patients) in the first groups, while in 22.95% (14 patients) in the second group. In addition, patients not treated with EVD display a prevalence of VS in lower Fisher grades compared to the other group.
This data indicate that CSF drainage reduces the risk of vasospasms in patients with endovascular treatment for aneurysmal SAH
Della Pepa GM, Scerrati A, Albanese A, Marchese E, Maira G, Sabatino G. Protective effect of external ventricular drainage on cerebral vasospasm. A retrospective study on aneurysmal SAH treated endovascularly. Clin Neurol Neurosurg. 2014 Sep;124:97-101. doi: 10.1016/j.clineuro.2014.06.030. Epub 2014 Jun 28. PubMed PMID: 25019459.