The Natural History of Aneurysms of the Basilar Bifurcation

Thirty patients with aneurysms of the basilar bifurcation were found among 1098 patients with intracranial arterial aneurysms diagnosed in the Neurosurgical Clinic of the Helsinki University Central Hospital between 1 January 1960 and 31 December 1969. Five were excluded from the series for various reasons and 25 remained for closer scrutiny. In three, the aneurysm was diagnosed at autopsy only, and in two the patient suffered a fatal haemorrhage so soon after diagnosis that no operation was thought possible. Of the remaining 20 patients, eight died 4 to 52 months after diagnosis. Thus, late mortality from aneurysms of the basilar bifurcation is considerable. The one factor that could be adduced as influencing the fate of the patient was the size of the aneurysm; those who died had on an average an aneurysm almost twice the size of the aneurysms in patients who were alive at follow-up.