Surgical Decision-Making for Managing Complex Intracranial Aneurysms

Abstract

The treatment of complex intracranial aneurysms remains a therapeutic challenge. These lesions are frequently not amenable to selective clipping or coiling or other endovascular 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). ABSTRACTThe treatment of complex intracranial aneurysms still remains a therapeutic challenge. These lesions are frequently not amenable to selective clipping or coiling or other endovascular 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 t...

Intraoperative tools for cerebral bypass surgery

“…The role of a flow-preservation bypass is to replace the blood flow provided by a major intracranial vessel, the occlusion of which is necessary for treating an underlying disease (such as complex aneurysms). The role of a flowaugmentation bypass is to restore flow to hypoperfused brain territories (in patients with steno-occlusive diseases) [1][2][3].…”

Distal outflow occlusion with bypass revascularization: last resort measure in managing complex MCA and PICA aneurysms

“…The rationale behind Binflow^and Boutflow^occlusion is to obtain a reduction/ change of flow within the aneurysm, with a subsequent a-m antero-medullary segment of the PICA, ELANA Excimer laser-assisted non-occlusive anastomosis, l-m latero-medullary segment of the PICA, MCA middle cerebral artery, M1-M5 segments of the MCA, ICA internal carotid artery, PICA posterior inferior cerebellar artery, t-m tonsillo-medullary segment of the PICA decrease in hemodynamic stress [1,2,9,10,23,30]. The concept is to manipulate the flow in order to induce hemodynamic change and favor intra-aneurysmal thrombosis and reduce the risk of rupture [10]. A major limitation of partial trapping strategies remains, however: the incapacity to reliably predict/control the extent and the speed of the aneurysmal thrombosis.…”

“…A major limitation of partial trapping strategies remains, however: the incapacity to reliably predict/control the extent and the speed of the aneurysmal thrombosis. Rapid and complete thrombosis may carry the risk of aneurysm rupture or lead to occlusion of the perforating arteries [9,10,13,16,23,31]. Both complete and partial trappings are commonly performed in combination with flow-replacement bypass to revascularize the territory of the occluded artery [4, 6-10, 12, 14-17, 20, 21, 25-27, 29-31].…”

“…For complex aneurysms not amenable to selective clip or endovascular reconstruction, complete trapping of the aneurysm is the recommended treatment option [9,10,13,22,26,27,31]. Partial trapping may be a reasonable option when total trapping is contraindicated because of the cortical branches or perforator arteries arising from the aneurysmal sac [4, 8-10, 21, 31].…”

“…Since the goal of aneurysm treatment is both aneurysm exclusion and blood flow maintenance, trapping strategies are often performed in combination with a flow-replacement bypass [10,20,22,26]. Trapping strategies comprise both Bcomplete^and Bpartial^trapping.…”