Percutaneous transluminal angioplasty for suspected vertebral artery stump syndrome

Abstract

Vertebral artery stump syndrome is a rare disease associated with a posterior circulation stroke after vertebral artery origin occlusion. However, few reports have addressed its management. We herein present a case involving a patient with vertebral artery stump syndrome who underwent successful intravascular intervention. We also present a literature review of previous cases of this rare disease. The present case involved a 91-year-old man with acute onset of vertigo and disturbance of consciousness. Diffusion-weighted imaging showed an acute ischaemic stroke in the bilateral cerebellar hemispheres. Magnetic resonance angiography revealed left vertebral artery origin occlusion. Angiography detected a nearly occluded left vertebral artery site, with distal antegrade collateral flow via the deep cervical artery at the C6 level. We observed intravascular stasis at the proximal end of the left vertebral artery via the collateral flow. We performed percutaneous transluminal angioplasty towards the occluded left vertebral artery site. The flow from the left vertebral artery was significantly improved. This is the first report of percutaneous transluminal angioplasty performed for vertebral artery stump syndrome. Although vertebral artery stump syndrome has a high risk of recurrence and a poor prognosis, endovascular intervention showed a better outcome than pharmacotherapy in our patient. However, such cases are rare and further investigations are needed.

Introduction

Carotid artery stump syndrome is reportedly an embolic source for ischaemic stroke.^1,2 Previous reports have stated that ischaemic stroke following carotid artery occlusion can be caused by an embolism from the contralateral carotid artery via the circle of Willis, the distal limit of the propagated thrombus, and an embolism from the carotid bifurcation via the external carotid artery; collateral flow via the external carotid artery branches can carry proximal or distal emboli to the intracranial internal carotid artery.³

Some reports have described a similar syndrome causing stroke in the posterior circulation after vertebral artery (VA) origin occlusion, which has been termed vertebral artery stump syndrome (VASS).^4,5 However, few reports have addressed the management of VASS. Moreover, no published reports have provided a detailed effective treatment strategy. We herein present a case involving a patient with VASS who underwent successful intravascular intervention. We also present a literature review of previous cases of this rare disease.

Case presentation

A 91-year-old man presented to our institute with acute onset of vertigo and disturbance of consciousness. He had no significant medical history such as hypertension, diabetes, dyslipidaemia, or prior stroke. He also had no significant smoking or drinking history. Diffusion-weighted imaging on admission showed an acute ischaemic stroke in the bilateral cerebellar hemispheres. Magnetic resonance angiography (MRA) revealed an occlusion at the origin of the left VA (Figure 1(a) and (b)). Angiography detected a nearly occluded site of the left VA (Figure 2(a)), with distal antegrade collateral flow via the deep cervical artery at the C6 level, about 2.5 cm above the occlusion site (Figure 2(b)). We found opacification of the cervical collaterals and distal VA occlusion (Figure 2(c)). Transthoracic echocardiography and electrocardiography monitoring revealed no cardiac embolic sources. Blood examination findings, including coagulation test results, were within the reference ranges. We also confirmed the absence of a central embolic source on angiography. We decided to perform endovascular treatment towards the left VA occlusion. A 8-Fr FlowGate balloon guide catheter (Stryker Neurovascular, Fremont, CA, USA) was positioned as the guiding catheter at the left origin of the subclavian artery through right common femoral artery access under local anaesthesia. Left subclavian angiography showed intravascular stasis at the proximal end of the left VA via the collateral flow, which indicated haemodynamic occlusion (Figure 2(d)). After microcatheter insertion, we performed percutaneous transluminal angioplasty (PTA) towards the occluded site at the left VA. The flow from the left VA was significantly improved (Figure 3). The duration from symptom onset to revascularisation was 4 hours. The patient was treated with argatroban and 200 mg of aspirin per day as secondary prophylaxis 24 hours after the intravascular treatment. He developed no recurrence of stroke progression. The patency of the left VA two months after PTA was preserved, and no recurrence was observed (Figure 4).

Figure 1.

(a) Diffusion-weighted imaging showed an acute ischaemic stroke in the bilateral cerebellar hemispheres. (b) Magnetic resonance angiography revealed occlusion at the origin of the left vertebral artery.

Figure 2.

Angiography detected a nearly occluded site at the origin of the left vertebral artery (white arrow) with distal antegrade collateral flow via the deep cervical artery at the C6 level (black arrow). Opacification of the cervical collaterals and distal vertebral artery occlusion was observed. Intravascular stasis was present at the proximal end of the left vertebral artery via the collateral flow (white arrowhead).

Figure 3.

The flow from the left vertebral artery was significantly improved after percutaneous transluminal angioplasty (black arrowhead).

Figure 4.

Patency of the left vertebral artery two months after percutaneous transluminal angioplasty.

Discussion

Vertebral artery stump syndrome

VASS was first described in 2008 in two patients with posterior circulation strokes after VA origin occlusion; both patients were treated with endovascular embolisation.⁵ Kawano et al.⁶ retrospectively investigated the mechanism, prevalence and recurrence of ischaemic stroke in 3463 patients. The diagnostic criteria for VASS are: (a) acute ischaemic stroke in the posterior circulation; (b) occlusion at the VA origin identified on MRA, duplex ultrasonography, computed tomography angiography and/or conventional angiography; (c) the presence of distal antegrade flow in the ipsilateral VA; and (d) the absence of other causes of ischaemic stroke. The pathogenetic mechanism of ischaemic stroke in patients with VASS might be explained as follows. First, VASS following ipsilateral VA origin occlusion can be caused by the distal limit of the expanded thrombus. Second, it has been suggested that the occurrence of ischaemic events after VA origin occlusion is associated with emboli of the stagnating clot fragment and a low-flow state caused by the collateral flow via the deep cervical arteries. In the present case, the intravascular stasis at the proximal end of the VA via the collateral flow detected on conventional angiography suggested a low-flow state or turbulent flow in the culprit VA. A low-flow state or turbulent flow might cause the formation of thrombi that can lead to distal embolism.⁶ The prevalence of VASS is about 14%, the overall rate of recurrence of ischaemic stroke is about 25% and the incidence of an unfavourable outcome (defined as a modified Rankin scale score of 3–5 at discharge) may reach 25%. These data suggest that VASS has a high risk of recurrence and a poor prognosis.⁶ Previous reports have suggested several treatments such as antiplatelet therapy, anticoagulant therapy and endovascular intervention.^2,4–7 However, the most effective treatment for VASS has not been established.

Literature review

Four case reports involving seven patients with VASS have been published to date (Table 1).^4,5,7,8 Six patients were men and one patient was a woman. The mean age at the time of presentation was 64 years. Most neurological findings involved the posterior lobe and cerebellar symptoms such as quadrantanopia, gait instability and vertigo. The patients’ symptoms appeared to have no relationship with a history of stroke, but three of the seven patients had hypertension as a risk factor. Most patients had distal antegrade collateral flow via the deep cervical artery from C1 to C6. Among these seven patients, two were treated with endovascular embolisation followed by warfarin or clopidogrel and aspirin, four were treated with anticoagulant or thrombolytic therapy as the initial treatment and one was treated with antiplatelet therapy only. In five patients, warfarin therapy was continued as secondary prevention, whereas two patients received antiplatelet therapy. With respect to recurrence after treatment, the two patients who underwent endovascular embolisation had no recurrence after treatment; in contrast, three of the six patients who received pharmacological therapy had recurrence of infarction ranging from post-admission days 4 to 9.

Table 1.

Characteristics of Patients with Vertebral Artery Stump Syndrome as Reported in the Literature.

Reference	Age	Sex	Neurological findings	Prior stroke history	Risk factor	Infarction site	Arterial region	Distal antegrade collateral flow via the deep cervical artery	Treatment	Secondary Prevention	Recurrence after treatment	Follow up period
Nguyen, 2008	66	Male	Rt superior homonymous quadrantanopia, Lt heel-to-shin ataxia	None	None	Lt calcarine cortex, Lt cerebellar  hemisphere	Occlusion at Lt VA origin	C5	Coiling	Warfarin	None	1 year
	54	Male	Lt superior quadrantanopsia, Gait instability, Aphagia,	None	None	Lt thalamocapsularregion, Lt infero-occipital  and temporal  lobe	Occlusion at Lt VA origin	C1	Coiling	Clopidogrel and aspirin	None	3 years
Kawano, 2010	56	Male	Dysmetria on the Lt side, Vertigo,	None	None	Rt occipital lobe, Lt cerebellar  hemisphere, Cerebellar vermis	Occlusion at Rt VA origin	C3 and C6	Heparin and aspirinfollowed by cilostazol	Warfarin	Day9	1 year
	64	Male	Consciousness disturbance, Anisocoria, Quadriplegia	None	Hypertension	Lt cerebellar hemisphere	Occlusion at Lt VA origin	C6	tPA followed by warfarin, aspirin and argatroban	Warfarin	Day4	3 years
	66	Female	Lt inferiorquadrantic hemianopsia	None	Hypertension	Lt cerebellar hemisphere, Rt occipital lobe	Occlusion at Lt VA origin	C5	Heparin and Warfarin	Warfarin	None	6 months
Tempaku, 2017	75	Male	Not examined	None	None	Rt PICA area, Rt PCA area, Rt lateral medullary  area	Occlusion at Rt VA origin	Not examined	Warfarin	Warfarin	None	N/A
Suzuki, 2018	66	Male	Dysarthria	16 year before	Hypertension, Diabetes, Dyslipidemia,	Rt SCA area, Lt PICA area	Occlusion at Lt VA origin	C4/5	Clopidogrel and ozagrel	Clopidogrel	Day6	11 months

VA: vertebral artery, PICA: posterior inferior cerebellar artery, PCA: posterior cerebral artery, SCA: superior cerebellar artery, tPA: tissue-plasminogen activator

Our patient

Our patient showed acute onset of posterior circulation stroke as determined by diffusion-weighted imaging. MRA showed occlusion at the origin of the left VA. Angiography revealed distal antegrade flow via the deep cervical artery at the C6 level. These findings satisfied the diagnostic criteria for VASS. We ruled out a cardiogenic embolism in our patient based on the absence of any abnormalities on transthoracic echocardiography and 24-hour electrocardiography monitoring. We performed PTA towards the occluded site at the left VA, which effectively prevented stroke recurrence. Our treatment was performed 4 hours after symptom onset, which is typical for intravascular treatment. To our knowledge, this is the first report of PTA performed for VASS. However, such cases are rare, and more discussion is needed.

Possible effective intervention

Considering that three of six patients who underwent pharmacological therapy developed recurrence whereas two patients who underwent endovascular treatment had no recurrence, endovascular intervention might be the preferred choice for the initial treatment of VASS. Kawano et al.⁶ reported the pathogenesis of ischaemic stroke in patients with VASS. Ipsilateral VA origin occlusion can be caused by the distal limit of the propagated thrombus. Consequently, the occurrence of ischaemic events after VA occlusion might be associated with emboli of the stagnating clot fragment and a low-flow state caused by the collateral circulation via the deep cervical arteries. Based on this unique mechanism of thrombus formation, embolisation of the VA to eliminate the low-flow state from the collateral circulation or transluminal angioplasty of the VA to eliminate the origin of occlusion might be more effective than pharmacological treatment. We performed PTA to eliminate the low-flow state, which has the same purpose as embolisation. Stent placement to the VA might also be an effective treatment to maintain the original VA flow. However, the real effect of PTA should be considered with caution.

Five of seven patients were treated with anticoagulants for secondary prevention. In previous reports, anticoagulant therapy was useful in preventing recurrence from VA origin embolism.^9,10 Intravascular stasis at the proximal end of the VA through the collateral flow detected on conventional angiography reportedly suggests a low-flow state or turbulent flow in the culprit lesion. Because a low-flow state or turbulent flow might cause thrombus formation that can lead to distal embolism,¹¹ anticoagulant therapy such as warfarin or direct oral anticoagulants might be the preferred treatment to prevent stroke recurrence in patients with VASS.

Conclusion

We have herein presented a case of VASS that was effectively treated with PTA. Although the most effective treatment cannot be determined because of the insufficient number of published cases, endovascular intervention might reduce the recurrence rate based on past reports.