Classification of aneurysms of the internal carotid system.

Microsurgery has improved the treatment of cerebral aneurysms techically and by more detailed knowledge of the topographic relations, the variations, and the anomalies of the involved arteries. A personal study of 450 aneurysms formed the basis of a modified and more detailed classification of aneurysms of the carotid system. It was confirmed that aneurysms originate at the junctions of arteries, and generally project according to the course of the vessel involved. The origins and projections aneurysms and their different sites were analyzed with the aid of angiography, angiotomography, magnification angiography, operative drawings, photographs, and films, which permitted the establishment of a special classification for every particular form. Preoperative knowledge of the types of aneurysms facilitates the surgical procedures and results in lowered morbidity.