The natural history of untreated, ruptured cerebral aneurysms
Data on ruptured cerebral aneurysms left unsecured are from the 1960s. This month in the journal Stroke, a group of researchers from Helsinki in Finland published their findings in a more recent cohort. The authors identified 510 patients out of 6850 in their registry that had an untreated, but ruptured cerebral aneurysm between 1968 and 2007.
Overall, the 1, 5, and 10 year mortality rates in these patients were 65%, 69%, and 76%, respectively. About 90% of patients admitted with poor grade were deceased at 1 year. Good grade patients admitted within 7 days of symptom onset had a 75% 1-year mortality. Patients with delayed admission had a notably lower mortality rate, possibly indicating a natural selection process.
While there are several limitations of the study that include the change of definition of poor grade over the years, change in neurosurgical management of aneurysmal subarachnoid hemorrhage over time, referral bias, and exclusion of patients that may have died prior to coming to any medical attention, it does illustrate the high mortality in not treating ruptured aneurysms. And the data are even worse than those from the 1960s.