Shunt-dependency After aSAH - Role of Early Hyperglycaemia in CSF and Blood

The goal of this study is to confirm the association of early increased glucose levels in cerebro-spinal fluid (CSF) and ventriculo-peritoneal-shunt (VPS)-dependency also evaluating the influence of blood glucose on VPS dependency in patients suffering from an aneurysmal subarachnoid haemorrhage (aSAH). The main questions we aim to answer are: * Is there an association of glucose levels on VPS dependency in patients requiring extra-ventricular-drain (EVD) placement for aSAH? * In addition, if there is, what is the influence the course of glucose levels has on VPS dependency? Glucose levels in CSF and serum will be measured on admission, or in case of CSF, upon EVD placement. Glucose in CSF will then be measured every day until EVD removal together with serum glucose. Follow-up will be conducted in person after 3 and 6 months.