村木 睦子¹, 三神 大世², 北口 真弓¹, 徳田 耕一¹, 柏葉 武¹, 小野塚 久夫³, 菅原 智子³

Mutsuko MURAKI¹, Taisei MIKAMI², Mayumi KITAGUCHI¹, Kouichi TOKUDA¹, Takeshi KASHIWABA¹, Hisao ONOZUKA³, Tomoko SUGAWARA³

¹医療法人柏葉脳神経外科病院, ²北海道大学医療技術短期大学部, ³北海道大学大学院医学研究科循環病態内科学

¹Kashiwaba Neurosurgery Hospital, ²College of Medical Technology, Hokkaido University, ³Department of Cardiovascular Medicine, Hokkaido University, Graduate School of Medicine

キーワード : B-mode ultrasound, carotid artery, mural thrombus, spontaneous contrast echoes

症例は57歳の男性. 左上下肢の脱力などを主訴に当院を受診した. MRIでは, 右中大脳動脈領域に高信号域がみられ, MRAでは, そのM 2部の完全閉塞を認めた. 12誘導ならびにホルター心電図検査及び心エコー検査では, 心臓に異常所見を認めなかった. 右頚動脈のB モードエコー検査では, 分岐部前壁に付着する比較的低エコーのmassが, そのすぐ遠位側のわずかなモヤモヤエコーとともに検出された. 6日間のウロキナーゼ投与後には, このmassが縮小し, モヤモヤエコーの範囲が明瞭に広がった. さらなる塞栓症の再発を予防するために, 我々は頚動脈内膜剥離術を行い, プラークの遠位側にあたる分岐部前壁の非潰瘍性陥凹部に付着する新鮮血栓を確認した. 術後5日目のエコー検査で左頚動脈分岐部内腔にモヤモヤエコーがみられ, 手術後40日目までにはこの部に血栓が再発した. ワーファリンによる抗凝固療法開始後89日には, 血栓様エコーは縮小し, さらに, プロトロンビン時間 (INR) 2.0以上の厳密なコントロール下では, 血栓は消失し, モヤモヤエコーの強度も減弱した. 本例における頚動脈内モヤモヤエコーの検出が, 内膜剥離術の術前には, 新鮮血栓の存在を指摘する上で, またその術後には, その後の血栓形成を予測する上で有用であった.

A 57 year-old man was admitted to the hospital because of several neurological deficits including left hemiparesis. An area of high signal intensity was visualized in the region of the right middle cerebral artery in T2-weighted MRI, and a complete occlusion of the M2 branch was detected by MR angiography. Twelve-lead and Holter electrocardiogram showed no cardiac abnormalities. B-mode ultrasound imaging of the right carotid artery showed a low-echo mass and modest spontaneous contrast echoes just distal to the mass, which was attached to the anterior wall of the bifurcation. The mass was smaller and the extent of the spontaneous contrast echoes had increased distinctly after administration of urokinase for 6 days. We performed an endarterectomy to prevent further embolus, and then found a new thrombus attached to the nonulcerated pitting area in the anterior wall of the bifurcation just distal to plaqe. Examination with B-mode ultrasound carried out 5 days after the operation detected the distinct spontaneous contrast echoes in the lumen of the right carotid bifurcation, where a recurrence of the thrombus formation was observed on the 40th day after operation. The thrombus decreased in size for 89 days after anticoagulant therapy with warfarin potassium, and then the thrombus disappeared and the intensity of the spontaneous contrast echoes diminished with the strict control of prothrombin time (INR; more than 2.0). Detection of the spontaneous contrast echoes with B-mode ultrasound was useful in revealing a new thrombus before endarterectomy and in predicting recurrence of the thrombus after surgery.