副中大脳動脈に関連した塞栓性脳梗塞に対して急性期血行再建術を施行した1例

A Case of Embolic Infarction Associated with Accessory Middle Cerebral Artery and Treated Using Mechanical Thrombectomy

Ⅰ．はじめに

　副中大脳動脈（accessory middle cerebral artery：AMCA）は，中大脳動脈におけるanomalyの一種であり，前大脳動脈より分岐し，シルビウス裂内を本来の中大脳動脈と並行して走行する血管である²⁾．その血管走行から，hemodynamic stressによるものと考えられる分岐部動脈瘤の報告^12,20)は散見されるが，AMCAに関連する脳梗塞に対して急性期血行再建術を施行した報告は極めて稀である．今回われわれは，AMCAに関連した塞栓性脳梗塞に対して経皮的血栓回収術を施行した1例を経験した．症例を提示し，AMCAにおける脳梗塞の特徴や血管内治療に対する注意点について，文献的考察を加えて報告する．

　The accessory middle cerebral artery（AMCA）is an anatomical variant of the MCA. It originates from the anterior cerebral artery, reaches the sylvian fissure, and supplies the territory of the middle cerebral artery. We report a case of embolic infarction associated with the AMCA that was treated using mechanical thrombectomy. An 82-year-old man with chronic atrial fibrillation experienced a sudden onset of left hemiparesis and was brought to our hospital. Magnetic resonance imaging showed a right temporal lobe, parietal lobe, and basal ganglion infarction, and indicated right internal carotid artery（ICA）occlusion. Mechanical thrombectomy using a Penumbra system was performed with complete recanalization. Final angiography revealed the existence of the AMCA, and the thrombus was located at the right ICA C2 portion to the main MCA. There have been twelve reported cases of ischemic stroke associated with the AMCA, including the present case. We summarized the data from the reported cases of ischemic stroke with an AMCA and evaluated their clinical characteristics and the pitfalls of endovascular treatment. These cases suggest that the AMCA may play a role in collateral flow around the main MCA occlusion, but provides insufficient collateral blood supply. Owing to the anatomical characteristics of the AMCA, we should pay attention to possible complications of endovascular treatment.