Free-Floating Thrombus in the Distal Internal Carotid Artery Causing a Stroke
頸內動脈遠端的自由浮動血栓導致中風

Case Report 病例報告

A 55-year-old male with a past medical history of smoking, alcoholic cirrhosis, and sleeve gastrectomy for morbid obesity was diagnosed with colon adenocarcinoma. Upon waiting for surgical resection, he suddenly presented with left hemiparesis, walking instability, and confusion. A brain magnetic resonance imaging (MRI) scan revealed brain infracts in parietal, temporal and frontal lobes in the right side. A carotid color duplex showed a <50% stenosis at the level of the carotid bulb and thrombosis of the right ICA. A computed tomography angiography (CTAngio) revealed a FFT beginning from the carotid bifurcation and extending up to the carotid siphon, 7-cm long ( Fig. 1 ). The patient was commenced to enoxaparine 60-mg bid and acetylsalicylic acid of 100 qd. The course after the stroke was uneventful with neurological improvement and a residual paresis of the left arm. After 15 days, a CTAngio showed complete resolution of the thrombus ( Fig. 2 ). The patient continued enoxaparine 60-mg bid and underwent an uneventful subtotal colectomy 2 months after the episode. He was discharged with dual antiplatelet therapy.
一名 55 歲男性，過去有吸菸、酒精性肝硬化病史，並因病態肥胖接受袖狀胃切除術，被診斷為結腸腺癌。在等待手術切除時，他突然出現左側偏癱、行走不穩、意識不清。腦部磁振造影（MRI）掃描顯示右側頂葉、顳葉和額葉腦部梗塞。頸動脈彩色雙聯顯示頸動脈球部 <50% 狹窄，右側 ICA 有血栓。電腦斷層掃描血管攝影 (CTAngio) 顯示 FFT 從頸動脈分叉處開始，一直延伸到頸動脈虹吸管，長 7 公分（圖 1 ）。患者開始服用依諾肝素 60 mg bid 和乙醯水楊酸 100 qd。中風後的病程很順利，神經功能改善，左手臂仍有麻痺症狀。 15 天后，CTAngio 顯示血栓完全消退（圖 2 ）。患者繼續服用依諾肝素 60 mg bid，並在發作 2 個月後順利接受了結腸次全切除術。他接受雙重抗血小板治療後出院。

Discussion 討論

FFT in the carotid artery is defined as an extended thrombus stacked to the arterial wall with circumferential blood flow around its most distal part, with cyclic movement relating to the cardiac cycle. ³ The optimal treatment of patients in this setting remains uncertain. There are several case reports in the literature and small observational studies but no data from randomized trials or large clinical studies exist.
頸動脈中的 FFT 被定義為堆積在動脈壁上的擴展血栓，其最遠端周圍有圓週血流，並具有與心動週期相關的循環運動。 ³在這種情況下患者的最佳治療仍不確定。文獻和小型觀察性研究中有一些病例報告，但沒有隨機試驗或大型臨床研究的數據。

A critical analysis of the literature ends up in the following five important points:
文獻的批判性分析最終得出以下五個要點：

1. Emergency carotid endarterectomy (CEA) and thrombectomy for patients with stroke caused by acute thrombosis of the ICA are associated with a perioperative cerebral event risk of 40%. ⁴ Emergency open revascularization in case of thrombus extending distally carries the risk of clot dislocation and consequent cerebral embolization during the surgical exposure of the carotid bifurcation, placement of the vascular clamps, and removal of the thrombus by a Fogarty catheter.
   對頸動脈急性血栓形成引起的中風患者進行緊急頸動脈內膜切除術 (CEA) 和血栓切除術與 40% 的圍手術期腦事件風險相關。 ⁴在血栓向遠端延伸的情況下進行緊急開放血運重建，在手術暴露頸動脈分叉、放置血管夾以及通過 Fogarty 導管去除血栓期間，存在血栓移位和隨後發生腦栓塞的風險。

2. Regarding the thrombolysis, there are concerns about the risk of development of recurrent events due to fragmentation and dislodgement of thrombus in patients that receive intravenous tissue plasminogen activator. ² Similarly, local intra-arterial thrombolysis has the risk of intraluminal manipulation of guides and catheters in association with the lysis effect that can cause the fragmentation of clots and subsequently increase the danger of distal intracerebral embolism.
   關於溶栓，人們擔心接受靜脈注射組織纖溶酶原激活劑的患者因血栓碎裂和移位而發生復發事件的風險。 ²同樣，局部動脈內溶栓也存在管腔內操作導引器和導管的風險，其與溶解效應相關，可能導致血栓碎裂，增加遠端腦內栓塞的危險。

3. Direct aspiration of thrombus using distal and proximal balloon protection, and stent-retriever mechanical thrombectomy have been reported with encouraging results. ^{5 6} These endovascular techniques appear efficient, but their role needs to be validated in larger trials. Regarding carotid artery stenting aiming to trap the thrombus between the stent and the arterial wall, there are concerns about development of new brain infarcts if the thrombus extends distally. ¹
   據報道，使用遠端和近端球囊保護直接抽吸血栓以及支架回收器機械血栓切除術取得了令人鼓舞的結果。 ^{5 6}這些血管內技術似乎有效，但其作用需要在更大規模的試驗中得到驗證。對於旨在將血栓限制在支架和動脈壁之間的頸動脈支架置入術，人們擔心如果血栓向遠端延伸，可能會發生新的腦梗塞。 ¹

4. Several small observational studies have suggested the safety of short-term intravenous heparin or low molecular weight heparin (LMWH) in this setting. ^{7 8} Anticoagulation with or without antiplatelet therapy led to complete dissolution of thrombus up to 85% of patients in 12 to 24 weeks in one report. ³ Recent guidelines recommend the safety and usefulness of short-term anticoagulation for nonocclusive, extracranial intraluminal thrombus in the setting of acute ischemic stroke (IIb level of recommendation), and posing, however, the absence of evidence from large trials. ⁹
   幾項小型觀察性研究表明，在這種情況下短期靜脈注射肝素或低分子肝素 (LMWH) 是安全的。 ^{7 8}一份報告顯示，抗凝血聯合或不合併抗血小板治療可使高達 85% 的患者在 12 至 24 週內血栓完全溶解。 ³最近的指引建議在急性缺血性中風的情況下短期抗凝血治療非閉塞性顱外腔內血栓的安全性和有效性（IIb 級建議），但缺乏大型試驗的證據。 ⁹

5. Delayed operation: if thrombus is unchanged and the patient remains neurologically stable, a conservative management is continuing with reassessment at a later phase. If thrombus has shrinked in the carotid bulb and the underline causative stenosis or plaque has emerged, a thromboendarterectomy can be performed. It is proposed that surgery should be performed regardless of the degree of carotid stenosis. ¹⁰
   延遲手術：如果血栓沒有變化並且患者神經功能保持穩定，則繼續保守治療並在後期進行重新評估。如果頸動脈球內的血栓縮小，並且出現下線狹窄或斑塊，則可以進行血栓內膜切除術。建議無論頸動脈狹窄程度如何均應進行手術。 ¹⁰

In our case, the FFT was extending in the ICA lumen, and the operation was considered risky to provoke thrombus dislodgment and distal intracerebral embolism. We decided to start anticoagulation plus antiplatelet treatment to halt the thrombus progression, offering the opportunity for potential fibrinolysis to take place. A repeat CTAngio was performed 15 days later which confirmed the total lysis of thrombus, without any residual atheromatic stenosis. Thus, no indication for delayed intervention was set.
在我們的病例中，FFT 在 ICA 腔中延伸，該手術被認為有引發血栓移位和遠端腦內栓塞的風險。我們決定開始抗凝血加抗血小板治療，以阻止血栓進展，為潛在的纖維蛋白溶解發生提供機會。 15 天後再次進行 CTAngio，證實血栓完全溶解，沒有任何殘留的動脈粥狀硬化狹窄。因此，沒有設定延遲幹預的跡象。

Conclusion 結論

In conclusion, it appears that in patients with FFT distally extended in the ICA, anticoagulation with heparin is initially preferable. Anticoagulation may lead to resolution of thrombus in many cases while interventional or surgical options potentially can cause brain embolization from dislodgement of mobile thrombus and should be considered if there are recurrent symptoms despite medical management.
總之，對於 ICA 遠端延伸的 FFT 患者，最初優選使用肝素抗凝血。在許多情況下，抗凝血治療可能會導致血栓消退，而介入或手術選擇可能會因移動血栓的脫落而導致腦栓塞，如果儘管進行了藥物治療但症狀復發，則應考慮進行治療。