International Journal of Neuroscience
ISSN: 0020-7454 (Print) 1543-5245 (Online) Journal homepage: http://www.tandfonline.com/loi/ines20
Treatment of unruptured vertebral dissecting aneurysms: internal trapping or stent-assisted coiling Hui Li, Xi-Feng Li, Xin Zhang, Xu-Ying He, Chuan-Zhi Duan & Yan-Chao Liu To cite this article: Hui Li, Xi-Feng Li, Xin Zhang, Xu-Ying He, Chuan-Zhi Duan & YanChao Liu (2016) Treatment of unruptured vertebral dissecting aneurysms: internal trapping or stent-assisted coiling, International Journal of Neuroscience, 126:3, 243-248, DOI: 10.3109/00207454.2015.1010648 To link to this article: https://doi.org/10.3109/00207454.2015.1010648
Published online: 22 May 2015.
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International Journal of Neuroscience, 2016; 126(3): 243–248 Copyright © 2015 Taylor and Francis ISSN: 0020-7454 print / 1543-5245 online DOI: 10.3109/00207454.2015.1010648
ORIGINAL RESEARCH
Treatment of unruptured vertebral dissecting aneurysms: internal trapping or stent-assisted coiling Hui Li, Xi-Feng Li, Xin Zhang, Xu-Ying He, Chuan-Zhi Duan, and Yan-Chao Liu
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Department of Neurosurgery, Southern Medical University, Zhujiang Hospital, 253# Industry Road, Guangzhou, Guangdong, RP China Purpose: Endovascular treatment is an attractive approach for the treatment of unruptured vertebral dissecting aneurysms, and includes internal trapping and stent-assisted coil embolization. However, the optimal therapy remains debatable. We reviewed our experience with both endovascular treatment modalities and compared the safety, efficacy, and short-term outcomes for each approach. Materials and Methods: We retrospectively reviewed 65 consecutive patients with unruptured vertebral dissecting aneurysms who underwent endovascular treatment between January 2003 and January 2014. 24 patients underwent endovascular internal trapping (group A) while 41 patients underwent stent-assisted coiling (group B). Thirteen patients underwent single stent with coiling while 28 patients underwent double or three stent-assisted coiling. Short-term outcomes were evaluated using the modified Rankin Scale. Results: A favorable clinical outcome was achieved in 58 of 65 patients. Procedure-related complications included ischemic symptoms (n = 6) and recurrence (n = 4). There was no statistical difference in modified Rankin Scale scoring between groups. Group A patients had more ischemia symptoms compared with group B patients (p = 0.043), Group B patients had higher recurrence rates compared with group A patients, but the difference had no statistical significance (p = 1.00). However, recurrence only occurred in patients who underwent stent-assisted coiling alone (p = 0.046). Conclusion: Stent-assisted coiling for unruptured vertebral dissecting aneurysms may maintain artery patency. Multilayer disposition of stents with coils may decrease complications and facilitate aneurysm occlusion. Larger, prospective studies are necessary to determine the long-term outcomes of reconstructive therapy. KEYWORDS: endovascular treatment, internal trapping, stent-assisted coiling, outcomes
Introduction With advances in imaging techniques and increased clinical awareness, vertebral dissecting aneurysm has become a recognized etiology of subarachnoid hemorrhage and ischemic stroke. It accounts for 28% of vertebral artery aneurysms and 11% of posterior circulation aneurysms [1]. The incidence of aneurysm rebleeding may be as high as 30%–70 % [2–4], with mortality rates ranging from 19% to 83% [5]. Given these statistics, early surgical or endovascular treatment is warranted to reduce morbidity and mortality. Endovascular treatment has become promising due to its minimally invasive characteristics. It involves proximal occluReceived 21 October 2014; revised October xxxx; accepted 19 January 2015; publish online 16 December 2015 Correspondence: Director and Professor Chuan-Zhi Duan, Department of Neurosurgery, Southern Medical University, Zhujiang Hospital, 253# industry road, 510282, Guangzhou, Guangdong, China. Tel: +86-013539962233; Fax: +86-020-61643269. E-mail: doctor [email protected]
sion of the parent artery, internal trapping, stent-only placement, and stent-assisted coil embolization. Internal trapping and stent placement with or without coiling are typically adopted by neurologists; however, most reports have focused on a single endovascular treatment method, procedural complications, and short-term outcomes. We aimed to compare these two common endovascular treatment modalities with regards to safety, efficacy, and short-term outcomes of patients.
Materials and Methods Patients This retrospective study was approved by our institutional review board; informed consent was required prior to study participation. We conducted a retrospective review of 65 consecutive patients with unruptured vertebral dissecting aneurysms who underwent endovas243
244
Hui Li et al.
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cular treatment between January 2003 and January 2014. The diagnosis of dissecting aneurysm was based on clinical manifestations and radiographic findings, including CT, MRI, and conventional angiography. All patients were evaluated by two neurosurgeons and two neuroradiologists. Patients with extracranial vertebral artery dissecting aneurysms were not included in our study. The type of therapy was not randomized, nor did it follow a specified protocol; it was determined by the neurosurgeon’s discretion. Twenty-four patients underwent endovascular internal trapping (group A) while 41 patients underwent stent-assisted coil embolization (group B). Thirteen patients underwent single stent with coiling while 28 patients underwent double or three stent-assisted coiling.
percentage of obliteration was based on angiographic results at the final follow-up visit. Complete obliteration was defined as 100% obliteration of the aneurysm; partial obliteration was defined as a small residual aneurysm in the neck or fundus; and recurrence was defined as an increase in size of the aneurysmal sac.
Statistical methods Analyses of continuous variables were performed by two independent t-tests or the Wilcoxon two sample test. Categorical variables were compared using the Pearson’s chi-squared test, as appropriate. A p-value of less than 0.05 was considered statistically significant. Statistical analysis was performed using SPSS statistical software (SPSS13.0 Chicago, IL, USA).
Endovascular procedures Balloon test occlusion was not performed in our center. All patients underwent endovascular treatment under general anesthesia. After a 6-French introducer sheath was placed in the right femoral artery, a 5-French guiding catheter was advanced into the vertebral or subclavian artery, proximal to the lesion. Full systemic heparinization was then performed, by administering a 5000 IU bolus, followed by a continuous infusion of 1000 IU/h. Throughout the procedure, the activated clotting time was maintained two to three times above baseline. After an optimal angiographic projection was achieved, a microcatheter was directed into the lesion through the guidewire. For internal trapping, coils were placed through a microcatheter into the dissecting aneurysm and parent artery. For stent-assisted coiling, the microcatheter was advanced into the dissecting aneurysm through the interstices of the stent. Several types of coils were used (GDC or Matrix, Boston Scientific Corporation, Natick, MA; EDC, eV3 Neurovascular, Irvine, CA), and consisted of either the LEO stent (Balt Extrusion, Montmorency, France), the Neuroform stent (Boston Scientific Corporation, Fremont, CA, USA), or the Enterprise stent (Cordis Corporation, Miami Lake, FL, USA). After the procedure, all patients were continuously monitored for 24 h in our neurosurgery intensive care unit. Patients who underwent stent-assisted coiling received clopidogrel and aspirin for 3 months; after 3 months, aspirin alone was administered for 1 year.
Clinical assessment and follow-up Follow-up was performed between 3 and 27 months after treatment. Clinical outcomes were evaluated using the modified Rankin Scale (mRS) score, which was measured by neurologic examination or a structured telephone interview. Each patient’s clinical status at the follow-up visit was defined as the final outcome. The
Results Patient population and Angiographic follow-up Our study cohort had a marked male preponderance (34 males versus 31 females, age range 37 to 70 years, mean age 51.7 years). Headache and limb weakness were the most common clinical presentations. In group B, 28 patients underwent double stent-assisted coiling; 13 patients underwent stent-assisted coiling alone. During the follow-up period, recurrence occurred in three patients, and these three patients all received single-stent coiling, later required repeat treatment (Figure 2). Patients who underwent multiple stents had no recurrence. In group A, One aneurysm recurred by the 6-month follow-up visit, the remnant aneurysms were stable without recurrence.
Clinical follow- up Favorable outcomes (mRS0-1) were in 58 patients of 65. In group A, two patients developed postoperative blurred vision, two patients developed dysphagia after 3 month, and MRI showed pontine infarction (Figure 1); one patient developed ataxia 2 months postoperatively without improvement in the follow-up period. In group B, one patient developed dizziness, and the symptom disappeared before discharge, there was no bleeding event during follow-up period.
Comparability of the study groups There was no statistically significant difference between groups with regards to age, gender, size, or site of the aneurysms (Table 1). During the follow-up period, there was no significant difference in mRS score between International Journal of Neuroscience
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FIGURE 1. 44-year-old male with right vertebral artery dissecting aneurysm. A: The right angiogram demonstrates an irregular dilation which involved PICA in the right vertebral artery. B: anteroposterior view, showing total occlusion of the dissecting aneurysm and proximal parent artery after internal trapping; C: MRI shows pontine infarction during 3-month follow-up.
groups (1.2 vs. 0.79, p = 0.24). Group A patients had more ischemia symptoms compared to group B patients (20.8% vs. 5.3% p = 0.043). Group B patients also trended towards higher recurrence rates compared with group A patients (7.3% vs.4.1 %,) although this difference did not reach statistical significance (p = 1.00, Table 2). In group B, follow-up angiography demonstrated complete obliteration of 26 aneurysms, partial obliteration of 12 aneurysm, and recurrence in three aneurysms. Recurrence was found only in patients who underwent stent-assisted coiling alone (p = 0.046, Table 3).
Discussion Vertebral dissecting aneurysms are a well-known cause of stroke and subarachnoid hemorrhage. Due to their infrequency, there have been no randomized controlled studies to guide treatment standards. Unruptured vertebral artery dissections usually have a benign course, with conservative therapy such as anticoagulation and antiplatelet medications recommended as the first line treatment. There is no consensus on the preferred approach to treat unruptured vertebral dissecting aneurysms. Iihara et al. reported seven patients who developed progressive aneurysmal dilatation during the C
2015 Taylor and Francis
59-year-old male with right vertebral artery dissecting aneurysm. A: The right angiogram shows a 5 × 6 mm right vertebral artery dissecting aneurysm B: DSA shows total occlusion of the aneurysm after the procedure C: The angiogram shows regrowth of the aneurysm during 3-month follow up. D: Additional stent was placed again to occlude the aneurysm E: The aneurysm stays stable without recurrence during 6-month follow-up.
FIGURE 2.
follow-up period [6]. Naito et al. reported a higher potential risk of rupture than previously thought [7]. In our experience, interventional treatment is mandatory in patients with progressive ischemia after medical management and those with aneurysms susceptible to rupture. The surgical approaches to treat unruptured vertebral artery dissecting aneurysms include open surgery and endovascular treatment. Endovascular treatment has evolved as an alternative to surgical clipping due to its minimally invasive characteristics. So far, endovascular internal trapping has been utilized and long-term outcomes have been described [8–10], it is considered one of the most reliable techniques to prevent rebleeding. Compared with proximal occlusion, internal trapping can prevent retrograde flow from the contralateral
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TABLE 1. groups.
Population and aneurysm characteristics of both
Variable
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Sex Male Female Age(y) Diameter (mm) Site LVA RVA
Group A (n = 24)
Group B (n = 41) 24 (58.5%) 17 (41.5%) 51.1 ± 2.0 7.80 ± 0.4
13 (54.2%) 11(45.8%)
18(43.9%) 23 (56.1%)
0.703 0.986
TABLE 2. Univariate statistical models comparing the outcomes of both groups.
mRS score Ischemia Yes No Recurrence Yes No ×
§
Group A (n = 24)
Group B (n = 41)
1.2±0.3
0.8±0.2
5 (20.8%) 19 (79.2%)
1 (2.4%) 40 (97.6%)
1 (4.2%) 23 (95.8%)
3 (7.3%) 38 (92.7%)
Student’s t-test
Pearson’s chi-squared test
Variable
Single stent (n = 13)
Multiple stents (n = 28)
Recurrence Yes No
3 (23.1%) 10 (76.9%)
0 (0%) 28 (100%)
p 0.046 §
§ Pearson’s chi-squared test
0.424
vertebral or basilar arteries into the dissecting aneurysm, effectively precluding aneurysm re-expansion [11]. Although coil occlusion of the affected segments is one strategy, there are some drawbacks to this method. After occlusion the parent artery, some vital perforating branches are at risk of becoming occluded. For vertebral dissecting aneurysms of the posterior inferior cerebellar artery (PICA), after obliteration of the parent vessel, lateral medullary or cerebellar infarction will likely occur. Therefore, this approach is unsuitable for vertebral vessels that involve the dominant vertebral artery with poor collateralization, or the segment bordering the origin of the PICA. In our study cohort, five patients developed ischemic symptoms; three aneurysms were located distal to the origin of the PICA and two aneurysms were located proximal to the PICA. There are several reasons for the development of ischemic symptoms. Rhoton et al. reported that the segment of the vertebral artery distal to the origin of the PICA gives rise to more perforating arteries than in the segment proximal to the origin of the PICA [12]. Therefore, if the dissecting aneurysm is located distal to the PICA, it is highly likely that most of the perforators would become occluded by internal trapping. Other than occlusion of perforators, migration of throm-
Variable
Recurrence of data in stent-assisted coiling group.
p 0.189
10(41.7%) 14 (58.3%) 52.3± 2.1 7.80 ± 0.5
TABLE 3
p 0.240× 0.043§ 1.00§
bus forming within the coils and hemodynamic ischemia can also lead to infarction. For bilateral vertebral dissecting aneurysms, there is another consideration. Occlusion of one vertebral artery may overload flow in the contralateral vertebral vessel, leading to enlargement of the contralateral, preexisting dissecting aneurysm [13]. Rabinov reported a case of one patient who developed contralateral vertebral dissection after occlusion of the dominant vertebral artery, and died of a brainstem infarct. The explanation for this may be that after occlusion of one vertebral artery, normal hemodynamics were accordingly altered, resulting in increased flow and pressure in the contralateral vertebral artery. For vertebral dissecting aneurysms that are not amenable to internal trapping, stent placement is an attractive reconstructive alternative. There is no need to consider whether collateral blood flow will be sufficient to allow parent artery sacrifice without neurologic deficit. Once aneurysm thrombosis has occurred, the spouting of the neointima along the stent struts can lead to remodeling of the stented arterial segment [5]. The favorable outcomes of this approach have been reported by many investigators [14,15]. In our series, only one patient developed dizziness postoperatively; compared with internal trapping, the incidence of ischemic symptoms was lower (2.4% vs.20.8% p = 0.043). This finding suggested maintaining parent artery patency may effectively decrease the prevalence of ischemia. It has been hypothesized that if the press gradient across the perforators is maintained and the perforator is covered less than 50% by stent struts, the vessels will remain patent [16]. Although the stent technique has the advantage of preserving the parent vessel, there are some limitations to be considered. Because of the high porosity of current generations of stents, stent-assisted coiling sometimes has the risk of aneurysm recurrence [17]. Therefore, in order to decrease the porosity of stent constructs, the stent-within-a-stent approach may be promising. While further diverting the inflow of the aneurysm and promoting immediate thrombosis, this approach also provides more endoluminal matrix for endothelial growth. Suh et al. reported ten patients with vertebrobasilar dissecting aneurysms who were treated International Journal of Neuroscience
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How to treat unruptured vertebral dissecting aneurysms
with stent-assisted coiling, followed by the stent-withina-stent technique; outcomes were excellent, with no instent stenosis or occlusion of the perforating arteries [18]. Kim et al. reported that placement of a single stent may produce a new, concentrated, jet-like inflow which was more likely to cause rupture by continued impact on the aneurysm wall [19]. It is well known that hemodynamic changes are proportionate to the number of overlapping stents, and that compared with single stent, multiple stent-assisted coiling can modify hemodynamic effects by straightening the curvature of the parent artery. In our study cohort, the three patients who underwent stent-assisted coiling alone developed recurrence; the three angiographic recurrences occurred in patients with incomplete obliteration, there was no recurrence in patients who received double stents (p = 0.046). We concluded that multi-stents with coil may enhance radial force and prevent recurrence through increasing the immediate obliteration grade. Park reported that, compared with the single-stent group, angiographic improvement was more frequently observed in the multiple-stent group [20]. Recently, a new endovascular reconstruction with flow diverting stents (FDS) has been adopted in the treatment of vertebral dissecting aneurysms. It not only effectively decreases porosity and increases the surface area of the devices, but also maintains parent artery patency, especially when preserving side branches such as the PICA or anterior spinal artery is important. Yeung reported four unruptured vertebral dissecting aneurysms that were successfully occluded with FDS without recurrence and side-branch occlusion [21]. Narata reported two ruptured vertebral dissecting aneurysms that were completely occluded; there was no recanalization or rebleeding during the followup period [22]. Therefore, multilayer disposition of may be an attractive alternative to surgery in these cases and the effect need to be evaluated in long-term follow-up. There were several limitations in our study. First, because of its retrospective nature, inherent bias could not be avoided. Second, the limited period of analysis may not be long enough to draw definitive conclusions. Third, because of the short-term follow-up period, some complications may have been underestimated.
Conclusion Internal trapping for unruptured vertebral dissecting aneurysms has a higher risk for ischemia. Stent-assisted coiling for unruptured vertebral dissecting aneurysms may maintain artery patency. Multilayer disposition of stents with coils may decrease the risk of recurrence and C
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facilitate aneurysm occlusion. Larger, prospective studies are necessary to determine long-term outcomes of this therapy.
Disclosure The authors have no personal financial or institutional interest in any of the drugs, materials, devices described in this article.
Acknowledgements None.
Declaration of Interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.
References 1. Yamaura A. Diagnosis and treatment of vertebral aneurysms. J Neurosurg 1988;69:345–49. 2. Aoki N, Sakai T. Rebleeding from intracranial dissecting aneurysm in the vertebral artery. Stroke 1990;21: 1628–31. 3. Kurata A, Ohmomo T, Miyasaka Y, et al. Coil embolization for the treatment of ruptured dissecting vertebral aneurysms. AJNR Am J Neuroradiol 2001;22:11–18. 4. Mizutani T, Aruga T, Kirino T, et al. Recurrent subarachnoid hemorrhage from untreated ruptured vertebrobasilar dissecting aneurysms. Neurosurgery 1995;36:905–11, 912–13. 5. Santos-Franco JA, Zenteno M, Lee A. Dissecting aneurysms of the vertebrobasilar system. A comprehensive review on natural history and treatment options. Neurosurgical Rev 2008;31:131–40, 140. 6. Iihara K, Sakai N, Murao K, et al. Dissecting aneurysms of the vertebral artery: a management strategy. J Neurosurg 2002;97:259–67. 7. Naito I, Iwai T, Sasaki T. Management of intracranial vertebral artery dissections initially presenting without subarachnoid hemorrhage. Neurosurgery 2002;51:930–37, 937–38. 8. Sugiu K, Tokunaga K, Watanabe K, et al. Emergent endovascular treatment of ruptured vertebral artery dissecting aneurysms. Neuroradiology 2005;47:158–64. 9. Peluso JP, van Rooij WJ, Sluzewski M, et al. Endovascular treatment of symptomatic intradural vertebral dissecting aneurysms. AJNR Am J Neuroradiol 2008 29:102–106. 10. Su W, Gou S, Ni S, et al. Management of ruptured and unruptured intracranial vertebral artery dissecting aneurysms. J Clin Neurosci 2011;18:1639–44. 11. Jin SC, Kwon DH, Choi CG, et al. Endovascular strategies for vertebrobasilar dissecting aneurysms. AJNR Am J Neuroradiol 2009;30:1518–23. 12. Rhoton AJ. The cerebellar arteries. Neurosurgery 2000; 47:S29–S68.
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13. Shin YS, Kim BM, Kim SH, et al. Endovascular treatment of bilateral intracranial vertebral artery dissecting aneurysms presenting with subarachnoid hemorrhage. Neurosurgery 2012;70:75–81, 81. 14. Ahn JY, Han IB, Kim TG, et al. Endovascular treatment of intracranial vertebral artery dissections with stent placement or stent-assisted coiling. AJNR Am J Neuroradiol 2006;27:1514–20. 15. Mehta B, Burke T, Kole M, Bydon A, Seyfried D, Malik G. Stent-within-a-stent technique for the treatment of dissecting vertebral artery aneurysms. AJNR Am J Neuroradiol 2003;24:1814–18. 16. Lieber BB, Gounis MJ. The physics of endoluminal stenting in the treatment of cerebrovascular aneurysms. Neurolog Res 2002;24(Suppl 1):S33–S42. 17. MacKay CI, Han PP, Albuquerque FC, et al. Recurrence of a vertebral artery dissecting pseudoaneurysm after successful stent-supported coil embolization: case report. Neurosurgery 2003;53:754–59, 760–61.
International Journal of Neuroscience
ISSN: 0020-7454 (Print) 1543-5245 (Online) Journal homepage: http://www.tandfonline.com/loi/ines20
Treatment of unruptured vertebral dissecting aneurysms: internal trapping or stent-assisted coiling Hui Li, Xi-Feng Li, Xin Zhang, Xu-Ying He, Chuan-Zhi Duan & Yan-Chao Liu To cite this article: Hui Li, Xi-Feng Li, Xin Zhang, Xu-Ying He, Chuan-Zhi Duan & YanChao Liu (2016) Treatment of unruptured vertebral dissecting aneurysms: internal trapping or stent-assisted coiling, International Journal of Neuroscience, 126:3, 243-248, DOI: 10.3109/00207454.2015.1010648 To link to this article: https://doi.org/10.3109/00207454.2015.1010648
Published online: 22 May 2015.
Submit your article to this journal
Article views: 151
View related articles
View Crossmark data
Citing articles: 2 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ines20 Download by: [University of Florida]
Date: 05 December 2017, At: 05:49
International Journal of Neuroscience, 2016; 126(3): 243–248 Copyright © 2015 Taylor and Francis ISSN: 0020-7454 print / 1543-5245 online DOI: 10.3109/00207454.2015.1010648
ORIGINAL RESEARCH
Treatment of unruptured vertebral dissecting aneurysms: internal trapping or stent-assisted coiling Hui Li, Xi-Feng Li, Xin Zhang, Xu-Ying He, Chuan-Zhi Duan, and Yan-Chao Liu
Downloaded by [University of Florida] at 05:49 05 December 2017
Department of Neurosurgery, Southern Medical University, Zhujiang Hospital, 253# Industry Road, Guangzhou, Guangdong, RP China Purpose: Endovascular treatment is an attractive approach for the treatment of unruptured vertebral dissecting aneurysms, and includes internal trapping and stent-assisted coil embolization. However, the optimal therapy remains debatable. We reviewed our experience with both endovascular treatment modalities and compared the safety, efficacy, and short-term outcomes for each approach. Materials and Methods: We retrospectively reviewed 65 consecutive patients with unruptured vertebral dissecting aneurysms who underwent endovascular treatment between January 2003 and January 2014. 24 patients underwent endovascular internal trapping (group A) while 41 patients underwent stent-assisted coiling (group B). Thirteen patients underwent single stent with coiling while 28 patients underwent double or three stent-assisted coiling. Short-term outcomes were evaluated using the modified Rankin Scale. Results: A favorable clinical outcome was achieved in 58 of 65 patients. Procedure-related complications included ischemic symptoms (n = 6) and recurrence (n = 4). There was no statistical difference in modified Rankin Scale scoring between groups. Group A patients had more ischemia symptoms compared with group B patients (p = 0.043), Group B patients had higher recurrence rates compared with group A patients, but the difference had no statistical significance (p = 1.00). However, recurrence only occurred in patients who underwent stent-assisted coiling alone (p = 0.046). Conclusion: Stent-assisted coiling for unruptured vertebral dissecting aneurysms may maintain artery patency. Multilayer disposition of stents with coils may decrease complications and facilitate aneurysm occlusion. Larger, prospective studies are necessary to determine the long-term outcomes of reconstructive therapy. KEYWORDS: endovascular treatment, internal trapping, stent-assisted coiling, outcomes
Introduction With advances in imaging techniques and increased clinical awareness, vertebral dissecting aneurysm has become a recognized etiology of subarachnoid hemorrhage and ischemic stroke. It accounts for 28% of vertebral artery aneurysms and 11% of posterior circulation aneurysms [1]. The incidence of aneurysm rebleeding may be as high as 30%–70 % [2–4], with mortality rates ranging from 19% to 83% [5]. Given these statistics, early surgical or endovascular treatment is warranted to reduce morbidity and mortality. Endovascular treatment has become promising due to its minimally invasive characteristics. It involves proximal occluReceived 21 October 2014; revised October xxxx; accepted 19 January 2015; publish online 16 December 2015 Correspondence: Director and Professor Chuan-Zhi Duan, Department of Neurosurgery, Southern Medical University, Zhujiang Hospital, 253# industry road, 510282, Guangzhou, Guangdong, China. Tel: +86-013539962233; Fax: +86-020-61643269. E-mail: doctor [email protected]
sion of the parent artery, internal trapping, stent-only placement, and stent-assisted coil embolization. Internal trapping and stent placement with or without coiling are typically adopted by neurologists; however, most reports have focused on a single endovascular treatment method, procedural complications, and short-term outcomes. We aimed to compare these two common endovascular treatment modalities with regards to safety, efficacy, and short-term outcomes of patients.
Materials and Methods Patients This retrospective study was approved by our institutional review board; informed consent was required prior to study participation. We conducted a retrospective review of 65 consecutive patients with unruptured vertebral dissecting aneurysms who underwent endovas243
244
Hui Li et al.
Downloaded by [University of Florida] at 05:49 05 December 2017
cular treatment between January 2003 and January 2014. The diagnosis of dissecting aneurysm was based on clinical manifestations and radiographic findings, including CT, MRI, and conventional angiography. All patients were evaluated by two neurosurgeons and two neuroradiologists. Patients with extracranial vertebral artery dissecting aneurysms were not included in our study. The type of therapy was not randomized, nor did it follow a specified protocol; it was determined by the neurosurgeon’s discretion. Twenty-four patients underwent endovascular internal trapping (group A) while 41 patients underwent stent-assisted coil embolization (group B). Thirteen patients underwent single stent with coiling while 28 patients underwent double or three stent-assisted coiling.
percentage of obliteration was based on angiographic results at the final follow-up visit. Complete obliteration was defined as 100% obliteration of the aneurysm; partial obliteration was defined as a small residual aneurysm in the neck or fundus; and recurrence was defined as an increase in size of the aneurysmal sac.
Statistical methods Analyses of continuous variables were performed by two independent t-tests or the Wilcoxon two sample test. Categorical variables were compared using the Pearson’s chi-squared test, as appropriate. A p-value of less than 0.05 was considered statistically significant. Statistical analysis was performed using SPSS statistical software (SPSS13.0 Chicago, IL, USA).
Endovascular procedures Balloon test occlusion was not performed in our center. All patients underwent endovascular treatment under general anesthesia. After a 6-French introducer sheath was placed in the right femoral artery, a 5-French guiding catheter was advanced into the vertebral or subclavian artery, proximal to the lesion. Full systemic heparinization was then performed, by administering a 5000 IU bolus, followed by a continuous infusion of 1000 IU/h. Throughout the procedure, the activated clotting time was maintained two to three times above baseline. After an optimal angiographic projection was achieved, a microcatheter was directed into the lesion through the guidewire. For internal trapping, coils were placed through a microcatheter into the dissecting aneurysm and parent artery. For stent-assisted coiling, the microcatheter was advanced into the dissecting aneurysm through the interstices of the stent. Several types of coils were used (GDC or Matrix, Boston Scientific Corporation, Natick, MA; EDC, eV3 Neurovascular, Irvine, CA), and consisted of either the LEO stent (Balt Extrusion, Montmorency, France), the Neuroform stent (Boston Scientific Corporation, Fremont, CA, USA), or the Enterprise stent (Cordis Corporation, Miami Lake, FL, USA). After the procedure, all patients were continuously monitored for 24 h in our neurosurgery intensive care unit. Patients who underwent stent-assisted coiling received clopidogrel and aspirin for 3 months; after 3 months, aspirin alone was administered for 1 year.
Clinical assessment and follow-up Follow-up was performed between 3 and 27 months after treatment. Clinical outcomes were evaluated using the modified Rankin Scale (mRS) score, which was measured by neurologic examination or a structured telephone interview. Each patient’s clinical status at the follow-up visit was defined as the final outcome. The
Results Patient population and Angiographic follow-up Our study cohort had a marked male preponderance (34 males versus 31 females, age range 37 to 70 years, mean age 51.7 years). Headache and limb weakness were the most common clinical presentations. In group B, 28 patients underwent double stent-assisted coiling; 13 patients underwent stent-assisted coiling alone. During the follow-up period, recurrence occurred in three patients, and these three patients all received single-stent coiling, later required repeat treatment (Figure 2). Patients who underwent multiple stents had no recurrence. In group A, One aneurysm recurred by the 6-month follow-up visit, the remnant aneurysms were stable without recurrence.
Clinical follow- up Favorable outcomes (mRS0-1) were in 58 patients of 65. In group A, two patients developed postoperative blurred vision, two patients developed dysphagia after 3 month, and MRI showed pontine infarction (Figure 1); one patient developed ataxia 2 months postoperatively without improvement in the follow-up period. In group B, one patient developed dizziness, and the symptom disappeared before discharge, there was no bleeding event during follow-up period.
Comparability of the study groups There was no statistically significant difference between groups with regards to age, gender, size, or site of the aneurysms (Table 1). During the follow-up period, there was no significant difference in mRS score between International Journal of Neuroscience
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FIGURE 1. 44-year-old male with right vertebral artery dissecting aneurysm. A: The right angiogram demonstrates an irregular dilation which involved PICA in the right vertebral artery. B: anteroposterior view, showing total occlusion of the dissecting aneurysm and proximal parent artery after internal trapping; C: MRI shows pontine infarction during 3-month follow-up.
groups (1.2 vs. 0.79, p = 0.24). Group A patients had more ischemia symptoms compared to group B patients (20.8% vs. 5.3% p = 0.043). Group B patients also trended towards higher recurrence rates compared with group A patients (7.3% vs.4.1 %,) although this difference did not reach statistical significance (p = 1.00, Table 2). In group B, follow-up angiography demonstrated complete obliteration of 26 aneurysms, partial obliteration of 12 aneurysm, and recurrence in three aneurysms. Recurrence was found only in patients who underwent stent-assisted coiling alone (p = 0.046, Table 3).
Discussion Vertebral dissecting aneurysms are a well-known cause of stroke and subarachnoid hemorrhage. Due to their infrequency, there have been no randomized controlled studies to guide treatment standards. Unruptured vertebral artery dissections usually have a benign course, with conservative therapy such as anticoagulation and antiplatelet medications recommended as the first line treatment. There is no consensus on the preferred approach to treat unruptured vertebral dissecting aneurysms. Iihara et al. reported seven patients who developed progressive aneurysmal dilatation during the C
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59-year-old male with right vertebral artery dissecting aneurysm. A: The right angiogram shows a 5 × 6 mm right vertebral artery dissecting aneurysm B: DSA shows total occlusion of the aneurysm after the procedure C: The angiogram shows regrowth of the aneurysm during 3-month follow up. D: Additional stent was placed again to occlude the aneurysm E: The aneurysm stays stable without recurrence during 6-month follow-up.
FIGURE 2.
follow-up period [6]. Naito et al. reported a higher potential risk of rupture than previously thought [7]. In our experience, interventional treatment is mandatory in patients with progressive ischemia after medical management and those with aneurysms susceptible to rupture. The surgical approaches to treat unruptured vertebral artery dissecting aneurysms include open surgery and endovascular treatment. Endovascular treatment has evolved as an alternative to surgical clipping due to its minimally invasive characteristics. So far, endovascular internal trapping has been utilized and long-term outcomes have been described [8–10], it is considered one of the most reliable techniques to prevent rebleeding. Compared with proximal occlusion, internal trapping can prevent retrograde flow from the contralateral
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TABLE 1. groups.
Population and aneurysm characteristics of both
Variable
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Sex Male Female Age(y) Diameter (mm) Site LVA RVA
Group A (n = 24)
Group B (n = 41) 24 (58.5%) 17 (41.5%) 51.1 ± 2.0 7.80 ± 0.4
13 (54.2%) 11(45.8%)
18(43.9%) 23 (56.1%)
0.703 0.986
TABLE 2. Univariate statistical models comparing the outcomes of both groups.
mRS score Ischemia Yes No Recurrence Yes No ×
§
Group A (n = 24)
Group B (n = 41)
1.2±0.3
0.8±0.2
5 (20.8%) 19 (79.2%)
1 (2.4%) 40 (97.6%)
1 (4.2%) 23 (95.8%)
3 (7.3%) 38 (92.7%)
Student’s t-test
Pearson’s chi-squared test
Variable
Single stent (n = 13)
Multiple stents (n = 28)
Recurrence Yes No
3 (23.1%) 10 (76.9%)
0 (0%) 28 (100%)
p 0.046 §
§ Pearson’s chi-squared test
0.424
vertebral or basilar arteries into the dissecting aneurysm, effectively precluding aneurysm re-expansion [11]. Although coil occlusion of the affected segments is one strategy, there are some drawbacks to this method. After occlusion the parent artery, some vital perforating branches are at risk of becoming occluded. For vertebral dissecting aneurysms of the posterior inferior cerebellar artery (PICA), after obliteration of the parent vessel, lateral medullary or cerebellar infarction will likely occur. Therefore, this approach is unsuitable for vertebral vessels that involve the dominant vertebral artery with poor collateralization, or the segment bordering the origin of the PICA. In our study cohort, five patients developed ischemic symptoms; three aneurysms were located distal to the origin of the PICA and two aneurysms were located proximal to the PICA. There are several reasons for the development of ischemic symptoms. Rhoton et al. reported that the segment of the vertebral artery distal to the origin of the PICA gives rise to more perforating arteries than in the segment proximal to the origin of the PICA [12]. Therefore, if the dissecting aneurysm is located distal to the PICA, it is highly likely that most of the perforators would become occluded by internal trapping. Other than occlusion of perforators, migration of throm-
Variable
Recurrence of data in stent-assisted coiling group.
p 0.189
10(41.7%) 14 (58.3%) 52.3± 2.1 7.80 ± 0.5
TABLE 3
p 0.240× 0.043§ 1.00§
bus forming within the coils and hemodynamic ischemia can also lead to infarction. For bilateral vertebral dissecting aneurysms, there is another consideration. Occlusion of one vertebral artery may overload flow in the contralateral vertebral vessel, leading to enlargement of the contralateral, preexisting dissecting aneurysm [13]. Rabinov reported a case of one patient who developed contralateral vertebral dissection after occlusion of the dominant vertebral artery, and died of a brainstem infarct. The explanation for this may be that after occlusion of one vertebral artery, normal hemodynamics were accordingly altered, resulting in increased flow and pressure in the contralateral vertebral artery. For vertebral dissecting aneurysms that are not amenable to internal trapping, stent placement is an attractive reconstructive alternative. There is no need to consider whether collateral blood flow will be sufficient to allow parent artery sacrifice without neurologic deficit. Once aneurysm thrombosis has occurred, the spouting of the neointima along the stent struts can lead to remodeling of the stented arterial segment [5]. The favorable outcomes of this approach have been reported by many investigators [14,15]. In our series, only one patient developed dizziness postoperatively; compared with internal trapping, the incidence of ischemic symptoms was lower (2.4% vs.20.8% p = 0.043). This finding suggested maintaining parent artery patency may effectively decrease the prevalence of ischemia. It has been hypothesized that if the press gradient across the perforators is maintained and the perforator is covered less than 50% by stent struts, the vessels will remain patent [16]. Although the stent technique has the advantage of preserving the parent vessel, there are some limitations to be considered. Because of the high porosity of current generations of stents, stent-assisted coiling sometimes has the risk of aneurysm recurrence [17]. Therefore, in order to decrease the porosity of stent constructs, the stent-within-a-stent approach may be promising. While further diverting the inflow of the aneurysm and promoting immediate thrombosis, this approach also provides more endoluminal matrix for endothelial growth. Suh et al. reported ten patients with vertebrobasilar dissecting aneurysms who were treated International Journal of Neuroscience
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How to treat unruptured vertebral dissecting aneurysms
with stent-assisted coiling, followed by the stent-withina-stent technique; outcomes were excellent, with no instent stenosis or occlusion of the perforating arteries [18]. Kim et al. reported that placement of a single stent may produce a new, concentrated, jet-like inflow which was more likely to cause rupture by continued impact on the aneurysm wall [19]. It is well known that hemodynamic changes are proportionate to the number of overlapping stents, and that compared with single stent, multiple stent-assisted coiling can modify hemodynamic effects by straightening the curvature of the parent artery. In our study cohort, the three patients who underwent stent-assisted coiling alone developed recurrence; the three angiographic recurrences occurred in patients with incomplete obliteration, there was no recurrence in patients who received double stents (p = 0.046). We concluded that multi-stents with coil may enhance radial force and prevent recurrence through increasing the immediate obliteration grade. Park reported that, compared with the single-stent group, angiographic improvement was more frequently observed in the multiple-stent group [20]. Recently, a new endovascular reconstruction with flow diverting stents (FDS) has been adopted in the treatment of vertebral dissecting aneurysms. It not only effectively decreases porosity and increases the surface area of the devices, but also maintains parent artery patency, especially when preserving side branches such as the PICA or anterior spinal artery is important. Yeung reported four unruptured vertebral dissecting aneurysms that were successfully occluded with FDS without recurrence and side-branch occlusion [21]. Narata reported two ruptured vertebral dissecting aneurysms that were completely occluded; there was no recanalization or rebleeding during the followup period [22]. Therefore, multilayer disposition of may be an attractive alternative to surgery in these cases and the effect need to be evaluated in long-term follow-up. There were several limitations in our study. First, because of its retrospective nature, inherent bias could not be avoided. Second, the limited period of analysis may not be long enough to draw definitive conclusions. Third, because of the short-term follow-up period, some complications may have been underestimated.
Conclusion Internal trapping for unruptured vertebral dissecting aneurysms has a higher risk for ischemia. Stent-assisted coiling for unruptured vertebral dissecting aneurysms may maintain artery patency. Multilayer disposition of stents with coils may decrease the risk of recurrence and C
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facilitate aneurysm occlusion. Larger, prospective studies are necessary to determine long-term outcomes of this therapy.
Disclosure The authors have no personal financial or institutional interest in any of the drugs, materials, devices described in this article.
Acknowledgements None.
Declaration of Interest The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.
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International Journal of Neuroscience
