Endovascular treatment of V3 segment vertebro-vertebral arteriovenous fistula with Willis covered stent: Case report and literature review

Abstract

A 46-year-old male presented to our hospital suffering from right mastoid pulsatile tinnitus secondary to traffic trauma. Digital subtraction angiography was remarkable for a vertebro-vertebral arteriovenous fistula fed by the right vertebral artery at the C1 level. Dual platelet therapy was administrated before and after the operation, then a Willis covered stent was deployed at the orifice of the fistula. Post-operative angiography showed proper stent localization but some contrast agent leaking from the fistula. Angiography performed 6 months post-operatively demonstrated no leak from the fistula and the patency of the right vertebral artery. This case demonstrated that an intracranial covered stent could be used as an alternative, successful treatment for vertebro-vertebral arteriovenous fistula.

Introduction

Vertebro-vertebral arteriovenous fistula (VVAVF) is a shunt created by abnormally high blood flow between the extracranial vertebral artery (VA), or its branches, and adjacent veins such as the vertebral venous plexus, lakes, and jugular veins, excluding capillaries.¹ This condition can lead to tinnitus, palpable pulsating masses, neurologic deficits, heart failure, and some even ocular symptoms.^2,3 Immediate treatment of the fistula is the mainstream medical protocol.

Here, we present a case of successful treatment of cervical VVAVF using a covered stent, specifically a Willis covered stent (WCS), delivered to the intracranial arteries with a transarterial approach.

Case presentation

A 46-year-old male presented to our hospital suffering from pulsatile tinnitus of the right mastoid secondary to traffic trauma 2 months prior. Upon examination the murmur sounded like a passing train and continued to be unbearable for the patient in addition to bruits at the right mastoid. Magnetic resonance imaging revealed a dilated right paravertebral vein without cervical vertebral fracture (Figure 1). Considering that the patient may require a stent during surgery, high dose aspirin (300 mg) and 150 mg of clopidogrel was administered orally the day before the operation.

Figure 1.

(a, b) T2-weighted sagittal and (c) axial magnetic resonance imaging (MRI) revealed dilated paravertebral veins, as indicated by the white arrows, with paravertebral and epidural vein drainage.

Digital subtraction angiography (DSA) was then performed and was indicative of VVAVF between the right VA and the surrounding venous plexus at the C1 level, and the V3 segment of VA. Intracranial arteries were not seen when the catheter was put into the right VA, indicative of a complete arterial steal. The orifice was also fed by backward flow from the left VA at the same location, and the left VA compensated for this posterior circulation well (Figure 2).

Figure 2.

Digital subtraction angiography (DSA) demonstrated a vertebro-vertebral arteriovenous fistula (VVAVF) between the right vertebral artery (VA) and the surrounding venous plexus at the C1 vertebral level. (a–b) Intracranial arteries did not develop when catheter was put into the right VA; (a) the white arrow indicates the location of fistula. (c) The orifice was fed by the backward flow of the left VA at the same location, and the left VA compensated well for posterior circulation; the white arrow indicates the fistula at the same location.

Under general anesthesia, a 6-F guiding catheter was advanced into the right VA and a 5-F angiography catheter into the left VA. WCS (4.5*13 mm, MicroPort, Shanghai, China) was delivered via the right VA until it covered the orifice of the fistula, which was confirmed by repeated bilateral VA injection. The balloon was inflated deploying the covered stent at a maximum inflation pressure of 7 atm. Post-stenting angiography demonstrated proper location of the stent as well as some contrast agent still leaking from the fistula into the drainage veins. Blood flow was observed to be moving into the posterior circulation on the right VA angiography and backward flow was no longer observed on the left VA angiography (Figure 3).

Figure 3.

During treatment, super-selective angiography was performed to ensure the location of the orifice point. (a) A Willis covered stent (WCS) was advanced via the right vertebral artery (VA) until it covered the orifice of the fistula; the covered stent was observed to be well deployed (b–c); white arrows show the deployed WCS. (d) Post-stenting digital subtraction angiography (DSA) showed contrast agent leakage, but the volume of blood flow was decreased. The white arrow indicates the leakage point. (e) Backward flow disappeared within the left VA angiography. (f) Posterior circulation developed when right VA angiography was performed.

The patient had no bruit immediately after the intervention and was discharged from hospital 4 days after operation. He was prescribed high dose aspirin (300 mg) and clopidogrel (75 mg) orally every day for the first 3 months after the operation. The aspirin was dosage was then reduced to a low dose (100 mg) per day for the following 3 months. Angiography 6 months after the operation demonstrated no leak from the fistula and patency of right VA with no recurrence of the fistula (Figure 4). Finally, the patient was taken off dual antiplatelet therapy. Then 3 years after operation, the patient was confirmed to still have no symptoms.

Figure 4.

Digital subtraction angiography (DSA) 6 months after the operation demonstrated no leak from the fistula and the patency of the right vertebral artery (VA), with no recurrence of the fistula.

Discussion

VVAVF is a rare disease, therefore its morbidity and mortality are not yet established.² The most common cause of VVAVF is neck trauma, as well as iatrogenic injuries such as percutaneous internal jugular vein cannulation, pedicle screw fixation after vertebral fracture, etc.^1,4,5,6 Spontaneous VVAVF is often accompanied by some diseases that may lead to dysplasia of the arterial smooth muscle, such as neurofibromatosis type I and Ehler-Danlos syndrome.^4,7 Spontaneous VVAVF are most commonly found at or above the C2 level, whereas traumatic fistula is at or below this level.⁸

At present, there are reports on the possibility of spontaneous obliteration of VVAVF, which may be due to the compression of the surrounding tissues that promotes spontaneous repair of blood vessels in addition to reduced blood flow into the VA due to the transcervical approach used.^{9, 10} However, for asymptomatic fistula, some have suggested that the advantages and disadvantages of treatment and non-treatment should be carefully evaluated.¹⁰ However, most published reports suggest that treatment should recommended as this condition will further develop and produce corresponding neurological dysfunction.² For patients with clinical symptoms, treatment is especially essential.

Ligature of the fistula orifice and venous graft bypass were the earliest methods used to effectively treat VVAVF. However, due to the chance of serious post-surgical complications such as bleeding and serious damage to the surrounding tissues, surgical operation is rarely used in clinical practice recently.¹ Endovascular occlusion of VVAVF has become the preferred method of treatment.¹¹ There are many types of skill necessary for this surgery, including balloon-assisted coil embolization, liquid embolic agent embolization, detachable balloon occlusion, and covered stent placement, etc.^8,12 However, in many cases, it is difficult to achieve complete embolization due to the high blood flow rate of the fistula, or hemodynamic changes that occur due to embolization, which can lead to vascular-related events. Therefore, nearly half of VA are occluded in the nidus segment. Patients with such a situation are at risk for vertebrobasilar ischemic events due to future contralateral VA stenosis.¹³

In previous reports, successful VVAVF embolization with covered stents has been recorded.¹³ These researchers also proposed that a single orifice in the V1-V2 segment of the vertebral artery can be safely and effectively treated with a stent graft, which is conducive to maintaining the patency of the vertebral artery. However, it is thought that fistula embolization by covered stent in the V3-4 segments should be considered doubtful because of the tortuosity and flexibility of this segment. Additionally, the placement and opening of the covered stent can be difficult and high risk. Moreover, the disadvantage of using a covered stent is that there may be thrombosis in the stent and incomplete closure of the fistula due to malposition. Therefore, it is necessary for the patient to be treated with anti-platelet therapy after operation.

WCS is designed specifically for use in intracranial aneurysms and pseudoaneurysms, and its use has been approved by the China Food and Drug Administration.¹⁴ This stent has demonstrated good flexibility and efficacy, as well as safety, in the treatment of intracranial vascular diseases, even when detached in the internal carotid siphon.¹⁵ A previous study has also shown that WCS is an alternative treatment option for traumatic carotid-cavernous fistulas, because the deployment of WCS is technically successful with few complications.¹⁶ Zhu et al. successfully treated V3 and V4 segment aneurysms with WCS, which demonstrated good flexibility and efficacy of Willis covered stent to deploy in those areas.¹⁷ In some reports and in our experience, WCS also works well to promote the regeneration of the vascular intima.¹⁸

This is the first case report published on WSC in the treatment of VVAVF. In this example, the fistula was successfully treated by the placement of WCS and the patency of the VA was well maintained. In our experience, this method is an effective way to address V3-4 segment VVAVF. Finally, dual platelet therapy is necessary to prevent ischemic events. To ensure that aspirin and clopidogrel was taken at an effective dose before surgery, we chose to double their dose before embolization.

Although the contrast agent was observed to be leaking from the orifice on the angiography performed immediately after treatment, the disease was totally resolved in follow-up DSA. This spontaneous resolution seems to correlate with slowed blood flow leading to thrombosis of the fistula.

VVAVF is often characterized by a high-flow shunt between the VA and adjacent venous plexus or lakes, which may lead to serious clinical symptoms. The clinical case described herein suggests that intracranial covered stents should be considered effective and safe for use in the treatment of extracranial VVAVF, which may maintain the patency of VA. For a single orifice fistula, a covered stent can be used as a first-line treatment. However, formulation of targeted therapies for different types of VVAVF requires further clinical classification for individualized treatment modalities.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This paper is supported by the National Key R&D program of China (2016YFC1300800) and Beijing Municipal Science and Technology Commission (D161100003816001).

Patient consent

All patients have consented to the submission of the case report for submission to the journal.