Abstract
Giant intracranial aneurysms are defined by a maximal diameter of at least 25 mm. They are rare, representing only 2% to 5% of all intracranial aneurysms, and can be found throughout the cerebral vasculature, although the majority are associated with the internal carotid artery. Saccular aneurysms typically arise at bifurcation points as a result of continuous hemodynamic stress, whereas fusiform or dolichoectatic aneurysms are often secondary to atherosclerosis, traumatic dissection, or an underlying arteriopathy. The most common presenting symptoms are related to the mass effect on surrounding neural structures or raised intracranial pressure secondary to obstructive hydrocephalus. Giant aneurysms also are associated with a much greater annual rate of rupture than smaller aneurysms. As a result, treatment of these lesions is recommended to mitigate the risk of hemorrhage and ameliorate symptoms caused by mass effect.
Several treatment options exist and include direct and indirect surgical solutions as well as endovascular procedures. The location of the aneurysm dictates the appropriate surgical skull base approach, and the basic tenets of microsurgery for these lesions include proximal and distal vascular control, wide exposure with identification of branch and perforating vessels, and careful clip application. When direct clipping is not feasible, alternative indirect techniques include proximal occlusion, distal occlusion, and trapping with distal revascularization. These options require intimate knowledge of the collateral circulation and identification of potential donor and recipient arteries in the event of a bypass. Endovascular therapies should also be considered, either as adjunctive procedures to surgical techniques or as the primary method of treatment if the surgical risk is too great.