Surgical Management of Giant Intracranial Aneurysms

Abstract

Giant aneurysms are commonly defined as those with a diameter larger than 2.5 cm. In the past, it was customary to assess this by angiography, but much more accurate assessment of aneurysmal size is now available by the use of computerised tomography or magnetic resonance imaging. These two techniques further present the advantage that the proportion of the aneurysmal sac filled by fluid blood and the proportion filled by clot are more easily assessed, and a true appreciation of the difficulties of approach, therefore, made available. Giant aneurysms present considerable problems because of their bulk, their compression of neighouring structures, and their adhesion both to the parent vessel, a considerable proportion of whose wall they may, at least apparently, take up, and to the important perforating vessels in the region of the base. Overall, aneurysms arise from the bifurcation or trifurcation of major vessels; giant aneurysms are no exception. Therefore, the complexity of their adhesion to the branches of their parent artery may be considerable, and the problems which they present in management may be considerably greater than those presented by a smaller lesion of similar origin. The age distribution of cases of giant aneurysm shows that these patients are generally older than the average age of patients presenting with aneurysmal rupture and subarachnoid hemorrhage. This consorts well with the observation that the majority of these lesions present with space-occupying and compressive effects, though a certain number of them have caused subarachnoid hemorrhage in the recent or remote past. Indeed, in a number of circumstances, false aneurysms or organizing clots without the true aneurysmal wall may increase the apparent size of such aneurysms.