[Giant anterior communicating artery aneurysm (author's transl)]

A case of giant aneurysm arising from the anterior communicating artery, 24 X 28 X 30 mm in diameter was found in a 30 year old man. About ten years ago he became blind and recently developed right anosmia and diencephalic seizures. No subarachnoid hemorrhage, however, was found. Radiograms and tomograms of the cranium showed a ring-like calcification, but by angiography it couldn't be recognized as a giant aneurysm. The right frontal craniotomy and partial resection, therefore, was performed. A histological study of the resected material revealed that it was a spontaneously thrombosed giant aneurysm. The inner layer of its wall had neither endothelium nor elastic lamina, but had deposits of calcium salt. The outer layer was composed of collagen fibers without cell infiltration. The aneurysm was thrombosed except for its neck but its organization occurred incompletely. We want to emphasize the importance of a correct preoperative diagnosis, as an erroneous operative procedure can result in disaster. Volume, viscosity and tension of flowing blood into the aneurysm as well as the size of its neck and dome regulate dynamic properties. These properties may determine the enlargement rate or growth of the aneurysm. The dynamic characteristics and features of the inner surface of the aneurysmal wall may regulate the formation of thrombosis in the aneurysm. The intraluminal thrombosis and strength of aneurysmal wall, for example, calcium deposits, may prohibit aneurysm from its rupture.