Spontaneous subarachnoid hemorrhage is a bleeding in to the subarachnoid space without trauma. Aneurysms are the underlying cause in 80% of the cases. Among other causes are: arteriovenous malformations, anticoagulation, vasculitis or brain tumor. Spontaneous subarachnoid hemorrhage is a serious disease, where up to half of the patients die. Of those who survive, only half return to work and many have a reduced quality of life. To prevent rebleeding the aneurysm is closed either with endovascular coiling or neurosurgical clipping.