Microsurgical Treatment of Complex Aneurysms in the Current Endovascular Era

The most commonly selected interventions for intracranial aneurysms are endovascular, often with minimal or no consideration of open microneurosurgery. Open microneurosurgery must equally be considered in the aneurysm treatment decision-making process, through the involvement of a skilled open cerebrovascular and skull base neurosurgeon. This is especially the case when assessing treatment options for aneurysms with complex morphologies, high hemodynamic stress, those that have failed prior endovascular treatments, aneurysms in patients who may not comply with the necessary endovascular anti-platelet therapy and diagnostic treatment follow-ups, and for young patients and other patients who prefer or require a definitive cure. In this chapter, we provide a guide to the decision-making for selecting open microneurosurgery. These include the following criteria: (1) aneurysms in the middle cerebral artery, (2) aneurysms located distal to the circle of Willis, (3) aneurysms with simple microneurosurgical options and difficult endovascular options, (4) multiple aneurysms that are accessible with a single surgical approach, (5) small aneurysms, (6) blood blister-like aneurysms, (7) giant aneurysms, (8) aneurysms causing mass effect, (9) ruptured aneurysms with intraparenchymal hematomas, (10) aneurysms in pediatric and young patients, (11) aneurysms with complex morphologies or difficult bifurcating or branching angles with high hemodynamic stress, (12) aneurysms that failed endovascular treatments, (13) aneurysms in patients that would not comply with follow-up, (14) aneurysms in patients that short- and/or long-term antiplatelet treatment is contraindicated or may cause potential bleeding problems, and (15) patient’s preference. The anatomy and microneurosurgical principles are reviewed with five illustrative cases.