A 52-year-old male was admitted because of right hemiparesis. Computed tomography scan showed a low-density area in the basal ganglia on the left side. Left carotid angiography showed an aneurysm of the extracranial internal carotid artery at the level of the C1-C2 vertebral body. Right carotid angiography also showed an aneurysm of the extracranial internal carotid artery. Because there were neither steno-occlusive changes in the intracranial vessels nor abnormality in the heart, the right hemiparesis seemed to be due to embolism from the extracranial aneurysm. Aneurysmectomy and end-to-end anastomosis of the left internal carotid artery were performed. Extracranial carotid aneurysms are rare conditions. In surgery on these aneurysms, ischemic changes of the brain during arterial clump must be detected and treated. Hypothermia, induced hypertension, and/or internal shunting have been used during arterial clump. The pathogenesis, symptoms, prognosis, and surgical treatments of these aneurysms are discussed.
