Natural History of Ruptured but Untreated Intracranial Aneurysms

Knowledge on a natural history of untreated ruptured intracranial aneurysms is based on a small historical cohort from 1960s. We calculated mortality rates for patients with untreated ruptured intracranial aneurysms using a more recent and relatively large hospital cohort.Patients admitted to the study hospital between 1968 and 2007 with saccular but untreated ruptured intracranial aneurysms were identified from the hospital aneurysm registry of 6850 patients. The study cohort included only patients who were followed up until death and for whom the date of symptom onset and the date of hospital admission were available.For 510 patients identified, the median survival time from symptom onset to death was 20 days. The 1-year mortality rate was 65%, but varied substantially by admission delays and clinical status on admission, being lowest (13%) for patients admitted later than a month after symptom onset and highest (89%) for poor-grade patients. The 1-year mortality rate was 75% for good-grade patients admitted within a week.Mortality rates for patients with untreated ruptured intracranial aneurysms are even worse than presented in the historical study. When discussing with subarachnoid hemorrhage patients and their relatives about treatment options, the presented natural history figures are of use.