We report a case of emergency extra- intracranial microanastomosis in a patient with acute thrombosis of the internal carotid artery, formed on the first day after classical carotid endarterectomy using a temporary by-pass under conditions of contralateral occlusion. The causes of the complication are analyzed. A set of instrumental examinations was demonstrated, including multispiral computed tomography with angiography of the brain and extracranial arteries, as well as multispiral computed tomography with the study of parameters of cerebral perfusion after acetazolamide. The main stages of surgical correction, the dynamics of clinical indicators are presented. The conclusion was made about the effectiveness and safety of the chosen revascularization strategy.