1 Introduction
However, the International Subarachnoid Aneurysm Trial (ISAT) has proven that the endovascular treatment of cerebral aneurysms with detachable coils is a superior alternative to open microsurgery in terms of survival free of disability at 1 year, the recanalization rate of endovascular treatment is higher than the open microsurgery which is still a serious problem to be solved.[1,2] [3–5]
A novel stent was deployed in the parent artery to exclude the ICA aneurysm from circulation. Willis covered stent (MicroPort, Shanghai, China), a specifically designed balloon-expanded stent used in the intracranial vasculature, consists of 3 parts: a bare stent, an expandable polytetrafluoroethylene (ePTFE) membrane, and a balloon catheter.[6–9] stenosis is not rare, as covered stents are more thrombogenic than others. In our center, 20 patients with ICA aneurysm received the treatment of Willis covered stent from August 6, 2014 to December 23, 2015 and only 2 were diagnosed with in-stent stenosis . One was asymptomatic with about 20% stenosis who received conservative treatment and the other was about 80% stenosis after digital subtraction angiography (DSA) diagnosis who used stent to resolve this problem. Written informed consent was obtained from both patients for the publication of their case reports and relevant images.
2 Case report
2.1 Case 1
A 57-year-old female with 2-week history of headache and vomiting before admission. Her physical examination showed neck stiffness, Glasgow Coma Scale (GCS) score was 15 points, head computed tomography (CT) revealed subarachnoid hemorrhage and DSA demonstrated left internal carotid C6 aneurysm (Fig. 1 ).
Figure 1: The white arrow demonstrated the aneurysm located at internal carotid artery C6.
An endovascular reconstruction with Willis covered stent was scheduled. A Willis covered stent (3.5 mm × 10.0 mm, MicroPort) was deployed in the left internal carotid C6 segment. Intraoperative angiography demonstrated the collapse of the aneurysm and satisfactory stent positioning (Fig. 2 ).
Figure 2: The white arrow showed the collapse of the aneurysm and satisfactory stent (a 3.5 mm × 10.0 mm Willis covered stent, MicroPort, Shanghai, China) positioning.
Three months later since operation, her DSA showed about 20% stenosis in the position where Willis stent was deployed (Fig. 3 ). As she was asymptomatic, we did not deal with it. Now she is still under our observation.
Figure 3: About 20% of stenosis in the site where deployed the Willis covered stent (white arrow) 3 months ago.
2.2 Case 2
A 23-year-old male with skull base fracture, subarachnoid hemorrhage, right femoral fracture for 14 days and epistaxis for 9 hours caused by a car accident. Gauze packing and blood transfusion were used to prevent epistaxis. His physical examination revealed right leg movement restriction due to binding up his leg, his GCS score was 15 points, head CT demonstrated skull base fracture and subarachnoid hemorrhage, and X-ray showed right femoral fracture. After his admission to our center, his DSA demonstrated left internal carotid paracliniod pseudoaneurysm (Fig. 4 ).
Figure 4: The white arrow showed the left internal carotid paracliniod pseudoaneurysm.
Before surgery, we gave him 225 mg clopidogrel and 300 mg aspirin for oral administration. Under the condition of general anesthesia and full heparinization, a Willis covered stent (3.5 mm × 13 mm) was deployed in the left internal carotid paracliniod segment. Intraoperative angiography showed the collapse of the pseudoaneurysm and a satisfactory stent positioning (Fig. 5 ). Three days later, this patient discharged.
Figure 5: Intraoperative angiography showed the collapse of the pseudoaneurysm and a satisfactory stent (a 3.5 mm × 13 mm Willis covered stent, MicroPort, Shanghai, China) positioning (white arrow).
One year later, he went to our center again as he had headache and dizziness for 6 months. His physical examination showed no abnormality and DSA diagnosis found about 80% stenosis in the position where Willis covered stent was deployed (Fig. 6 ). Everolimus-Eluting Coronary stent (4.0 mm × 12 mm, Boston Scientific, Marlborough, Massachusetts) was used to solve this problem. Intraoperative angiography demonstrated the stenosis disappeared and the left ICA kept patency (Fig. 7 ).
Figure 6: About 80% of stenosis in the position where deployed the Willis covered stent (white arrow).
Figure 7: Intraoperative angiography demonstrated that the stenosis disappeared and that the left internal carotid artery kept patency after the stent deployed (Everolimus-Eluting Coronary stent 4.0 mm × 12 mm, Boston Scientific, Boston, USA).
3 Discussion
Although the Wills novel covered stent has advantages in treating the complicated, wide necked, large, or giant aneurysms in ICA, its disadvantages should also be considered. Compared with other stents, in-stent stenosis is not rare, particularly in this reconstruction treatment technique (Table 1 ).[2,10,11] stenosis .[11,12] stenosis might be the reendothelialization of the stent area. Stent covering may lead to a prolonged process for reendothelialization as the middle of the stents had to be reached from stent edges. This longer time needed for reendothelialization could be a stimulus for more and higher proliferation of smooth muscle cell at stent edges because this process lasts as long as the endothelial layer is incomplete.[13,14]
Table 1: The stenosis rate of Willis covered stent compare with other kinds of stents.
As in-stent stenosis may spontaneously resolve along with the progress of natural history, the patient in the first case who had asymptomatic stenosis received conservative treatment.[11] [11]
According to the literature review, it was found that postprocedure irregular antiplatelet therapy and cerebrovascular arteriosclerosis, diabetes and lesion length, multiple stents, and smaller final minimal lumen diameter are associated with increased risk of in-stent stenosis .[2,15,16] stenosis .
The patient in Case 1 received regular antiplatelet therapy, but she still developed in-stent stenosis . Prabhakaran et al[17] [18] [19]
4 Conclusion
In-stent stenosis after treated with Willis covered is uncommon, but not rare. Operators should pay more attention to the in-stent stenosis in the follow-up observation period and monitor the PRU in the antiplatelet period, especially for the Willis covered stent. What is more, the treatment of stenosis ought to be carefully considered.
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