Twisted internal carotid arteryを呈する内頚動脈狭窄に対する頚動脈内膜切除術

A Case of Carotid Endarterectomy for the Internal Carotid Artery Stenosis Associated with Twisted Internal Carotid Artery

Ⅰ．はじめに

　通常，頚部内頚動脈（internal carotid artery：ICA）と外頚動脈の位置関係は内頚動脈が外側に位置しているが，稀にICAが内側に位置することがあり，Twisted ICAといわれる^7,8)．頚動脈内膜切除術（carotid endarterectomy：CEA）に際して問題となることがある．症例を提示し，発生機序や手術時の注意点などについて検討した．

　Twisted carotid artery bifurcation is a variant in which the internal carotid artery（ICA）courses mediall to the external carotid artery（ECA). Here, we report a case of ICA stenosis, which is a complication of twisted ICA, treated with carotid endarterectomy（CEA). A 75-year-old woman was brought to our hospital with left-sided hemiparesis. MRI diffusion-weighted image revealed right frontal lobe infarction and high-grade stenosis at the origin of the right ICA. The ICA was located inside in relation to the ECA, manifesting as twisted ICA. We diagnosed her with cerebral infarction, caused by the ICA stenosis, and performed CEA. Afcer administering general anesthesia, the bifurcation of the right common carotid artery was exposed. ICA was located inside, and ECA was located outside. The superior thyroid artery originated from ECA and coursed in front of the ICA. After arteriotomy, internal shunting was performed. The plaque was removed en bloc and the arteriotomy was closed. Throughout the operation, the position of the arteries was retained while the procedures were performed. The postoperative course was uneventful, and the imaging study revealed that the stenosis was resolved. It is important to confirm which artery is an ICA in a case of twisted ICA during CEA. The etiology can be congenital or acquired. In conclusion, CEA was performed safely for ICA stenosis that manifested as twisted ICA with some tips.