Surgical Decision-Making for Managing Complex Intracranial Aneurysms

The treatment of complex intracranial aneurysms remains a therapeutic challenge. These lesions are frequently not amenable to selective clipping or coiling or other endo-vascular procedures and surgery still has a predominant role. We illustrate our "surgical decision making" for managing complex intracranial aneurysmal lesions. The best strategy is decided on the basis of pre-operative neuroradiological and intra-operative main determinants such as anatomical location, peri-aneurysmal angioanatomy (branch vessels, critical perforators), broad neck, intraluminal thrombosis, aneurysmal wall atherosclerotic plaques and calcifications, absence of collateral circulation, and previous treatment. The surgical strategy encompasses one of the following treatment possibilities: (1) Direct clip reconstruction; (2) Complete trapping ("classic" or "variant"); (3) Partial trapping (proximal "inflow" or distal "outflow" occlusion). Because the goal of any aneurysm treatment is both (1) aneurysm exclusion and (2) blood flow replacement, cerebral revascularization represents a major management option whenever definitive or temporary vessel occlusion is needed. Cerebral revascularization can therefore be used temporarily as a "protective" bypass, or definitively as a "flow replacement" bypass. Complete and partial trapping strategies are associated with flow "replacement" bypass surgery, to preserve blood flow into the territory supplied by the permanently trapped vessel. The construction of the "ideal" bypass depends on several factors, the most important of which are amount of flow needed, recipient vessel, donor vessel, and microanastomosis technique. The choice between "complete" or "partial" trapping depends on angioanatomical criteria as well. A complete trapping is always favored, as it has the advantage of immediate aneurysm exclusion. When perforating vessels arise from the aneurysmal segment or when the inspection of all the angioanatomy of the aneurysm is considered inadvisable and risky, "partial trapping" strategies are of interest. Partial trapping may consist either of proximal or distal occlusion. We discuss the rationale behind these treatment modalities and illustrate it with a case series of seven patients successfully treated for complex intracranial aneurysmal lesions (location: 1 ICA, 1 ACom, 3 MCA, 2 PICA).