Risk factors for aneurysmal subarachnoid haemorrhage: pieces of the puzzle

Rupture of an intracranial aneurysm causes aneurysmal subarachnoid haemorrhage (aSAH), which is an important subtype of stroke. The risk of aSAH consists of three different components, namely the risk factors for developing an unruptured intracranial aneurysm (UIA), risk factors for aneurysmal rupture and trigger factors, which cause the actual rupture. The aim of the present thesis was to identify risk factors for the different components that make up the risk of aSAH and to develop a prognostic model based on these risk factors. A systematic review and meta-analysis was performed to estimate the prevalence of unruptured intracranial aneurysms (UIAs). The prevalence of UIAs in persons without co-morbidity was estimated to be 3.2% and is higher in women, patients with polycystic kidney disease or family history of aSAH or UIAs. Patients