Arterial dysplasia with ruptured basilar artery aneurysm: report of a case.

An 11 year old girl died unexpectedly as a result of spontaneous subarachnoid hemorrhage originating from a ruptured giant fusiform aneurysm of the basilar artery. The aneurysm had developed as a long standing complication of arterial fibromuscular dysplasia. This discussion describes the light and electron microscopic findings in the aneurysm and the histologic examination of abnormalities in the muscular arteries of the viscera.