Cerebral revascularization: extracranial-intracranial bypass.

Extracranial-intracranial (EC-IC) bypass remains an important revascularization technique for management of complex cerebrovascular disease. Despite evolving endovascular techniques, the role of bypass for the purpose of flow replacement prior to planned vessel sacrifice remains relevant for treatment of complex and fusiform aneurysms. The role of bypass for purposes of flow augmentation in the setting of cerebral ischemia is limited based on current data, but remains an important option for selected cases of athero-occlusive disease, in addition to a primary treatment for symptomatic moyamoya disease. An objective flow-based approach to EC-IC bypass can enhance decision-making in preoperative patient selection, intraoperative graft assessment, and postoperative follow-up.