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Original research
Endovascular treatment of fusiform intracranial vertebral artery aneurysms using reconstructive techniques
  1. Guilherme Dabus,
  2. Eugene Lin,
  3. Italo Linfante
  1. Division of NeuroInterventional Surgery, Baptist Cardiac and Vascular Institute and Baptist Neuroscience Center, Miami, Florida, USA
  1. Correspondence to Dr G Dabus, Division of NeuroInterventional Surgery, Baptist Cardiac and Vascular Institute, 8900 N Kendall Drive, Miami, FL 33176, USA; guilhermed{at}baptisthealth.net

Abstract

Objective To report our single center experience in the treatment of fusiform aneurysms involving the intracranial vertebral arteries using reconstructive endovascular techniques.

Patients and methods The neurointerventional database of our institution was retrospectively reviewed from June 2010 to February 2013. Patients who underwent endovascular treatment of fusiform intracranial vertebral artery aneurysms using reconstructive techniques were included in the analysis. Clinical presentation, size, reconstructive technique used, procedural complication, and clinical and angiographic follow-ups were included in the analysis.

Results Nine patients, aged 41–76 years (mean 54.8 years), were included. Mean angiographic diameter of unruptured aneurysms was 8.4 mm (range 4–14) while ruptured aneurysms averaged 6 mm (range 5–7 ). Two patients (two women) presented with acute subarachnoid hemorrhage (SAH). One patient with a large partially thrombosed aneurysm was treated with stent reconstruction requiring deployment of two stents (no coiling). There was one asymptomatic procedural complication (non-flow limiting cervical vertebral dissection). All patients had good clinical outcomes (modified Rankin Scale score of 0 or ≤1) including the two patients that presented with SAH (Hunt and Hess grades 2 and 3). There were no late hemorrhages at a mean clinical follow-up of 12 months (6–24 months). Eight patients had angiographic follow-up (6–18 months, mean 10.5 months) and six demonstrated aneurysm occlusion with complete vessel reconstruction at the angiographic follow-up.

Conclusions The use of reconstructive techniques in the endovascular treatment of unruptured fusiform intracranial vertebral artery aneurysms is feasible, safe, and effective in the mid term. In patients presenting with SAH, however, the safety and effectiveness of these techniques remain unclear.

  • Aneurysm
  • Stent
  • Intervention
  • Coil
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Introduction

Fusiform intracranial aneurysms affecting the intradural vertebral arteries are very uncommon lesions that occur secondary to atherosclerosis or dissection.1–3 Although unclear, the natural history of patients with fusiform aneurysms in the posterior circulations has been associated with increased morbidity and mortality.4–6 Endovascular treatment of these lesions is complex and includes a deconstructive technique with parent vessel sacrifice and reconstructive techniques using stents alone or in conjunction with coils.2 ,7–9 We report our single center experience in the treatment of fusiform aneurysms involving the intracranial vertebral arteries using reconstructive endovascular techniques.

Patients and methods

After institutional review board approval was obtained, the neurointerventional database of our institution was retrospectively reviewed from June 2010 to February 2013. A total of 12 patients with fusiform intracranial vertebral artery (VA) aneurysms were identified. Nine patients (five men and four women) who underwent endovascular treatment of fusiform intracranial VA aneurysms using reconstructive techniques were included in the analysis. Clinical presentation, size, reconstructive technique used, procedural complications, and clinical and angiographic follow-up were included in the analysis. Three patients were treated with parent vessel sacrifice (deconstructive technique) because they were considered not appropriate candidates for reconstructive techniques. Of these patients excluded from the analysis, one presented with a poor clinical status due to a mass effect and brainstem strokes from giant partially thrombosed aneurysms; the second had a hypoplastic distal VA; and the third patient had bilateral V3/V4 dissections with pseudoaneurysm formation and occlusion of the distal VAs bilaterally.

All procedures were performed under general anesthesia using biplane angiographic equipment. The treatment performed included stent assisted coil embolization (SACE) or the use of self-expanding stents alone. Patients were pretreated with clopidogrel (600 mg loading dose in acute cases and 75 mg every day for 5 days in elective cases) and aspirin 325 mg every day. The procedures were performed with systemic heparinization (target activated clotting time target 250 s). Heparinization was discontinued at the end of the procedure. After the procedure, patients were kept on dual antiplatelet therapy for 3 months, and after that on aspirin only indefinitely.

Results

Among the patients with a fusiform intracranial VA aneurysm treated in our neurointerventional database, nine met the inclusion criteria for our study (table 1). Seven (78%) had right VA aneurysms and two patients (22%) had left VA aneurysms. Patient age ranged from 41 to 76 years (mean 54.8). Mean angiographic diameter of unruptured aneurysms was 8.4 mm (range 4–14) while ruptured aneurysms averaged 6 mm (range 5–7). Two patients (two women) presented with acute subarachnoid hemorrhage (SAH) and were treated with SACE. Seven patients had unruptured aneurysms, with six patients treated by SACE. One patient with a large partially thrombosed aneurysm was treated with stent reconstruction requiring deployment of two stents (no coiling). There was one asymptomatic procedural complication (non-flow limiting cervical vertebral dissection).

Table 1

Clinical data of patients with fusiform intracranial vertebral artery aneurysms

All patients had good clinical outcomes (modified Rankin Scale scores <1), including the two patients that presented with SAH (Hunt and Hess grades 2 and 3). There were no late hemorrhages at a mean clinical follow-up of 12 months (6–24). Eight patients had angiographic follow-up (6–18 months, mean 10.5 months). One patient with SAH was lost to angiographic follow-up only. Of these eight patients with angiographic follow-up, six demonstrated aneurysm occlusion with complete vessel reconstruction at the angiographic follow-up. One patient that presented with SAH and was treated with SACE had aneurysm regrowth at 1 month and was retreated with further coil embolization and deployment of a third stent with no complications. A 6 month angiographic follow-up on this patient revealed complete occlusion of the aneurysm. In the other patient, follow-up angiography revealed partial remodeling of the vessel; however, the most prominent aneurysmal component was occluded. Five patients had two stents placed, three patients had one, and one patient had three (average stents per case 1.7).

Discussion

VA aneurysms account for 0.5–3% of all intracranial aneurysms and 15% of posterior circulation aneurysms.3 ,10 Fusiform aneurysms are uncommon lesions.1–3 Approximately 25% of fusiform aneurysms are located in the vertebrobasilar system and can vary in spectrum from a small fusiform aneurysmal dilatation of a single vessel to a giant dolichoectatic aneurysm filled with thrombus (giant serpentine aneurysm).11 In addition, fusiform aneurysms have different hemodynamics and natural histories, with etiologies ranging from dissection and atherosclerosis to disorders of collagen and elastin metabolism.1 ,12 Indeed, Nakatomi divided fusiform aneurysms into two subcategories: dissecting aneurysms and chronic fusiform aneurysms.1 In dissecting aneurysms, there is disruption of the internal elastic lamina associated with intramural hemorrhage acutely whereas with chronic fusiform aneurysms, there is fragmentation of the internal elastic lamina, intimal hyperplasia, neoangiogenesis within the intima, and intramural hemorrhage.1 It is also thought that severe atherosclerosis results in lipid deposition in and beneath the intima infiltrating the muscular wall with disruption of the internal elastic membrane. Due to persistent intravascular pressure, there is an increase in vessel tortuosity and the whole vessel segment becomes ectatic. Furthermore, fusiform aneurysms have been found to have a male predominance, and some may become symptomatic in younger patients compared with saccular aneurysms.6 ,13 ,14 Our selected patients support this general trend with slightly more men than women who were found to have fusiform VA aneurysms with a mean age of presentation of 56 years.

The presentation of fusiform VA aneurysms spans a wide range of symptoms, ranging from asymptomatic to stroke, hemorrhage, cranial nerve deficits, and symptoms related to mass effect.5 ,6 ,13 ,15 When the pathophysiology is acute dissection, these patients may present with acute headache and dizziness, with or without SAH.1 ,2 However, when fusiform VA aneurysms are symptomatic, the most common presentation seems to be related to cerebral infarction.6 The risk of rupture in fusiform aneurysms has not been well established.5 ,6 ,15 Indeed, the risk of hemorrhage has been shown to be lower than the risk of recurrent cerebral infarction.5 ,6 Flemming et al6 showed a 10 year risk of cerebral infarction of 16%. In this study, the risk of recurrent stroke was almost 7% per patient per year.6 On the other hand, the prospective risk of hemorrhage in patients with fusiform vertebrobasilar aneurysms was shown to be 2.3% carrying significant mortality.5 In our series, the likely underlying cause for the fusiform aneurysms was dissection in eight of the nine patients. In three patients the aneurysms were found incidentally. Two patients presented with acute SAH and the other four had acute onset of new neurological symptoms found to be related to their aneurysms. One patient that presented with acute onset of dizziness had a large partially thrombosed aneurysm diagnosed. In this case, considering the patient's age (mid 60s) and presentation, the underlying case for the aneurysm may have been atherosclerosis resulting in a chronic fusiform aneurysm, as described by Nakatomi.1 No patients in our series presented with ischemic stroke.

Endovascular reconstructive techniques for repair of VA aneurysms include SACE, use of stents alone, flow diversion, and covered stents. Covered stents have been proposed but their placement is limited by their inflexibility, insufficient data for long term efficacy, and occlusion of side branches and perforators arising from the covered segment which may result in a catastrophic ischemic event.16

Flow diversion through the use of a high density, low porosity to modify the flow between the parent vessel and the aneurysmal sac has also been proposed. Alteration of flow then induces embolization of the aneurysm with reconstruction of the parent vessel by the device. This is often the goal when treating fusiform and giant aneurysms. However, its use in the posterior circulation is controversial. Recent case series and reports have demonstrated the efficacy of flow diversion in the treatment of these aneurysms with preservation of the side branches and patency of the stents with appropriate use of antiplatelet agents.17–20 A recent study, however, demonstrated that the outcomes of patients presenting with large or giant fusiform aneurysms treated with flow diverters are poor.21

The use of stents that are not specifically designed for flow diversion alone without coils in the treatment of fusiform aneurysms has been described.9 As seen with one of our patients and in other case reports, stent alone treatments can alter hemodynamics and create favorable flow conditions to enhance thrombosis. Placement of multiple stents across the neck of the aneurysm has been angiographically shown to profoundly reduce aneurysmal inflow to the aneurysm.22 SACE was the main technique used in our series. When combined with placement of coils within the aneurysm, stents allow greater packing density within the aneurysmal sac, serve as a scaffold for endothelial growth, and support coils within wide necked aneurysms to preserve the patency of the parent vessel. The use of SACE for treatment of fusiform aneurysms has been described with good results for unruptured fusiform aneurysms.2 ,7–9 ,23 ,24 The results of this technique in ruptured cases are not clear. Wakhloo et al2 described a series of 28 patients of whom three had VA fusiform aneurysms. Of these three patients, two presented with SAH. No recanalization was noted on follow-up and all three patients had favorable outcomes. In contrast, other studies demonstrated a higher incidence of complications and poor outcomes using SACE for the treatment of fusiform aneurysms presenting with SAH.7 ,8 In our series, two patients presented with SAH and were treated with SACE. One patient required retreatment after a 1 month follow-up angiography revealed recurrence. In this patient, a 6 month follow-up revealed complete aneurysm occlusion with vessel reconstruction. The other patient that presented with SAH could not return for follow-up angiography; however, this patient has been contacted by phone and is completely asymptomatic at 16 months after the initial presentation. Our experience also indicated that using multiple stents (two or three) enhanced occlusion of the aneurysmal dilatations and reconstruction of the artery (figures 1, 2). This benefit, in our opinion, outweighs the possible increase in procedural risks with placement of multiple devices. This may be the result of slight changes in the angulation of the parent vessel which seems to facilitate aneurysm thrombosis and vessel reconstruction (figure 3). Improved occlusion rates with double stenting have also been demonstrated in the literature.23 In our series, despite suboptimal immediate angiographic occlusion rates, follow-up angiography revealed that in six out of eight patients the aneurysms were completely occluded and the vessel reconstructed (figure 2). One patient had partial occlusion of the aneurysmal dilatation which has been stable on two consecutive follow-up angiographies. One patient required retreatment (the patient that presented with SAH and was described above).

Figure 1

Patient in their early 40s presenting with acute onset of severe occipital headaches and nausea. Workup revealed an irregular fusiform dissecting aneurysm of the intradural right vertebral artery (A) that was treated with stent assisted coil embolization using two stents. (B) The 13 month angiographic follow-up.

Figure 2

Patient in their late 60s with an incidental/asymptomatic fusiform right vertebral artery aneurysm. Immediate post treatment angiography (A, B) and 16 month follow-up (C, D), demonstrating progressive vessel remodeling and aneurysm occlusion.

Figure 3

Patient in their mid 40s presenting with acute onset of severe occipital headaches. Workup revealed an irregular fusiform dissecting aneurysm of the intradural right vertebral artery (A, B) that was treated with stent assisted coil embolization using two stents. The 18 month follow-up (C, D) demonstrating progressive vessel remodeling and complete aneurysm occlusion. Note the change in the angle of the vessel (red lines B, D) after placement of the stents.

Our experience demonstrates that, in this limited small series, the use of reconstructive techniques in the endovascular treatment of unruptured fusiform intracranial VA aneurysms is feasible, safe, and effective in the mid term. In patients presenting with SAH, however, the safety and effectiveness of these techniques remain unclear.

References

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Footnotes

  • Contributors Study concept and design, and study supervision: GD and IL. Acquisition of the data, and analysis and interpretation of the data: GD, EL, and IL. Drafting of the manuscript, critical revision of the manuscript for important intellectual content, and administrative, technical, and material support: EL and GD.

  • Competing interests GD is a consultant for Codman Neurovascular, Covidien Neurovascular, and Reverse Medical. IL is a consultant for Covidien Neurovascular, Stryker, and Codman Neurovascular.

  • Ethics approval The study was approved by the hospital institutional review board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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