Cooperative study of intracranial aneurysms and subarachnoid hemorrhage: a long-term prognostic study. III. Subarachnoid hemorrhage of undetermined etiology
H. Nishioka, J. C. Torner, C. J. Graf, N. F. Kassell, A. L. Sahs and L. C. Goettler
Among 6,638 cases reported to the Cooperative Study of Intracranial
Aneurysms and Subarachnoid Hemorrhage were 477 cases in which the cause of
hemorrhage could not be determined after carotid and vertebral angiography.
These patients were followed up for up to 24 years after hemorrhage. Twenty
patients were subsequently found to have an aneurysm or arteriovenous
malformation missed by the first angiographic survey. After six-month
survival, the rate of recurrent hemorrhage was a maximum 0.86% per year.
Survival was significantly better than that of patients with verified
ruptured aneurysms managed conservatively in this cooperative study. For
normotensive patients who survived the first six months, the life
expectancy for the next 20 years equaled that of an age- and sex-matched US
population. Hypertensive patients had a higher mortality than normotensive
patients.
