Distal Embolization After Stenting of the Vertebral Artery: Diffusion-Weighted Magnetic Resonance Imaging Findings

Vertebral Artery Interventions: A Comprehensive Updated Review

Patients with posterior circulation ischemia due to vertebral artery stenosis account for 20 to 25% of ischemic strokes and have an increased risk of recurrent stroke. In patients treated with medical therapy alone, the risk of recurrence is particularly increased in the first few weeks after symptoms occur, with an annual stroke rate of 10 to 15%. Additionally, obstructive disease of the vertebrobasilar system carries a worse prognosis, with a 30% mortality at 2-years if managed medically without additional surgical or endovascular intervention. Percutaneous transluminal angioplasty and stenting of symptomatic vertebral artery stenosis are promising options widely used in clinical practice with good technical results; however, the improved clinical outcome has been examined in various clinical trials without a sufficient sample size to conclusively determine whether stenting is better than medical therapy. Surgical revascularization is an alternative approach for the treatment of symptomatic vertebral artery stenosis that carries a 10-20% mortality rate. Despite the advances in medical therapy and endovascular and surgical options, symptomatic vertebral artery stenosis continues to impose a high risk of stroke recurrence with associated high morbidity and mortality. This review aims to provide a focused update on the percutaneous treatment of vertebral artery stenosis, its appropriate diagnostic approach, and advances in medical therapies.

Percutaneous transluminal angioplasty and stenting of post-irradiation stenosis of the vertebral artery

BACKGROUND

The outcomes of percutaneous transluminal angioplasty and stenting (PTAS) in patients with medically refractory post-irradiation stenosis of the vertebral artery (PISVA) have not been clarified.

AIM

This retrospective study evaluated the safety and outcomes of PTAS in patients with severe PISVA compared with their radiation-naïve counterparts (non-RT group).

METHODS

Patients with medically refractory severe symptomatic vertebral artery stenosis and undergoing PTAS between 2000 and 2021 were classified as the PISVA group or the non-RT group. The periprocedural neurological complications, periprocedural brain magnetic resonance imaging, the extent of symptom relief, and long-term stent patency were compared.

RESULTS

As compared with the non-RT group (22 cases, 24 lesions), the PISVA group (10 cases, 10 lesions) was younger (62.0 ± 8.6 vs 72.4 ± 9.7 years, P = 0.006) and less frequently had hypertension (40.0% vs 86.4%, P = 0.013) and diabetes mellitus (10.0% vs 54.6%, P = 0.024). Periprocedural embolic infarction was not significantly different between the non-RT group and the PISVA group (37.5% vs 35.7%, P = 1.000). At a mean follow-up of 72.1 ± 58.7 (3-244) months, there was no significant between-group differences in the symptom recurrence rate (0.00% vs 4.55%, P = 1.000) and in-stent restenosis rate (10.0% vs 12.5%, P = 1.000).

CONCLUSION

PTAS of severe medically refractory PISVA is effective in the management of vertebrobasilar ischemic symptoms in head and neck cancer patients. Technical safety and outcome of the procedure were like those features in radiation-naïve patients.

The 2nd European Carotid Surgery Trial (ECST-2): rationale and protocol for a randomised clinical trial comparing immediate revascularisation versus optimised medical therapy alone in patients with symptomatic and asymptomatic carotid stenosis at low to intermediate risk of stroke

Background

Carotid endarterectomy is currently recommended for patients with recently symptomatic carotid stenosis ≥50%, based on randomised trials conducted 30 years ago. Several factors such as carotid plaque ulceration, age and associated comorbidities might influence the risk-benefit ratio of carotid revascularisation. A model developed in previous trials that calculates the future risk of stroke based on these features can be used to stratify patients into low, intermediate or high risk. Since the original trials, medical treatment has improved significantly. Our hypothesis is that patients with carotid stenosis ≥50% associated with a low to intermediate risk of stroke will not benefit from additional carotid revascularisation when treated with optimised medical therapy. We also hypothesise that prediction of future risk of stroke in individual patients with carotid stenosis can be improved using the results of magnetic resonance imaging (MRI) of the carotid plaque.

Methods

Patients are randomised between immediate revascularisation plus OMT versus OMT alone. Suitable patients are those with asymptomatic or symptomatic carotid stenosis ≥50% with an estimated 5-year risk of stroke of <20%, as calculated using the Carotid Artery Risk score. MRI of the brain at baseline and during follow-up will be used as a blinded measure to assess the incidence of silent infarction and haemorrhage, while carotid plaque MRI at baseline will be used to investigate the hypotheses that plaque characteristics determine future stroke risk and help identify a subgroup of patients that will benefit from revascularisation. An initial analysis will be conducted after recruitment of 320 patients with baseline MRI and a minimum of 2 years of follow-up, to provide data to inform the design and sample size for a continuation or re-launch of the study. The primary outcome measure of this initial analysis is the combined 2-year rate of any clinically manifest stroke, new cerebral infarct on MRI, myocardial infarction or periprocedural death.

Discussion

ECST-2 will provide new data on the efficacy of modern optimal medical therapy alone versus added carotid revascularisation in patients with carotid stenosis at low to intermediate risk of future stroke selected by individualised risk assessment. We anticipate that the results of baseline brain and carotid plaque MRI will provide data to improve the prediction of the risk of stroke and the effect of treatment in patients with carotid stenosis.

Trial registration

ISRCTN registry ISRCTN97744893. Registered on 05 July 2012

The Use of Aspiration Catheter Systems for Embolic Protection during Intracranial Vertebral Artery Angioplasty and Stenting

BACKGROUND

Posterior circulation strokes comprise approximately 20-25% of all strokes of ischemic origin. Strokes affecting this area carry a significantly higher risk for subsequent stroke or death as compared to anterior circulation strokes. Embolic protection device (EPD) use for carotid artery stenosis has translated into percutaneous interventions of proximal vertebral artery (VA) stenosis. However, the use of EPDs when treating intracranial lesions has yet to be studied and may not be feasible as the vessel caliber is frequently smaller than in existing devices.

OBJECTIVE

The aim of this study is to describe a proximal aspiration technique used during the treatment of intracranial VA and basilar artery (BA) atherosclerotic disease.

METHODS

Proximal embolic protection was utilized during the treatment of intracranial VA/BA stenosis with angioplasty and stenting in patients with medically refractory disease.

RESULTS

Three patients with severe symptomatic posterior circulation stenosis refractory to medical management were treated with angioplasty and stenting utilizing proximal aspiration. Pre- and post-treatment angiograms and MRIs were compared. Treated vascular stenoses were significantly improved, without new neurological deficits or ischemic injury identified on imaging.

CONCLUSIONS

The proposed technique of proximal embolic protection may help overcome the challenge of embolus propagation inherent to the treatment modality that was encountered during the treatment of intracranial VA/BA stenosis.

Comparison of self-expanding stents with distal embolic protection to balloon-expandable stents without a protection device in the treatment of symptomatic vertebral artery origin stenosis: a prospective randomized trial

PURPOSE

To compare the angiographic and clinical outcomes of self-expanding stents (SES) with distal embolic protection devices (EPD) vs balloon-expandable stents (BES) without EPD in the treatment of symptomatic atherosclerotic vertebral artery ostial stenosis (VAOS).

METHODS

Between July 2011 and March 2013, a prospective randomized trial was conducted involving 127 patients (mean age 67.3±10.2 years; 94 men) with symptomatic VAOS randomly assigned to treatment with SES + EPD (Precise RX or RX Acculink stent + Spider FX EPD; n=61) or BES (Palmaz Blue or Resolute RX; n=66) without EPD. In-stent restenosis (ISR) >50% detected by duplex ultrasound was the primary endpoint. Technical success, clinical success, complications within 30 days, and signal intensity abnormalities on diffusion weighted imaging (DWI) after stenting were compared.

RESULTS

The 30-day technical success rate was 95.5% (63/66) for SES+EPD vs 100% (70/70) for BES without EPD (p=0.072). DWI at 24 hours poststenting showed 2 hyperintense lesions in 2 (3.3%) SES + EPD cases and 15 hyperintense lesions in 13 (18.6%) BES patients (p<0.01). At a mean 18-month follow-up, the clinical success rate was 93.9% (62/66) for the SES + EPD group vs 85.7% (60/70) for the BES group (p=0.115). The ISR was seen in 16/70 (22.9%) arteries in the BES group and 2/66 (3.1%) arteries in SES + EPD group (p<0.01). Target vessel revascularization was performed in 7 (10.0%) BES arteries vs none in the SES + EPD group (p<0.01).

CONCLUSION

SES with EPD in the treatment of symptomatic VAOS is technically feasible and safe, with low rates of ISR and significantly reduced thromboembolic events on imaging when compared to BES without EPD.

Balloons in endovascular neurosurgery: history and current applications

The use of balloons in the field of neurosurgery is currently an essential part of our clinical practice. The field has evolved over the last 40 years since Serbinenko used balloons to test the feasibility of occluding cervical vessels for intracranial pathologies. Since that time, indications have expanded to include sacrificing cervical and intracranial vessels with detachable balloons, supporting the coil mass in wide-necked aneurysms (balloon remodeling technique), and performing intracranial and cervical angioplasty for atherosclerotic disease, as well as an adjunct to treat arteriovenous malformations. With the rapid expansion of endovascular technologies, it appears that the indications and uses for balloons will continue to expand. In this article, we review the history of balloons, the initial applications, the types of balloons available, and the current applications available for endovascular neurosurgeons.

Percutaneous transluminal angioplasty and stenting in patients with proximal vertebral artery stenosis

BACKGROUND

Atherosclerotic occlusive disease of the proximal vertebral artery is an important cause of cerebrovascular ischemic events with a significant associated morbidity and mortality. Endovascular treatment has emerged as a promising tool of the therapeutic armamentarium, along with medical therapy and surgical reconstruction. Our objective was to systemically review the pertinent evidence on the endovascular management of proximal vertebral artery disease and perform an analysis of the published outcomes.

METHODS

A systematic review of the literature identified all studies reporting percutaneous transluminal angioplasty or stenting, or both, for proximal vertebral artery stenosis. Web-based search engines were searched using the Medical Subject Headings terms "vertebral artery," "angioplasty," and "stents" in all possible combinations. Studies comprising a series of at least five patients were considered for analysis. Periprocedural transient ischemic attack and stroke and death from any cause ≤30 days of treatment were defined as the primary outcome end points.

RESULTS

One randomized controlled trial comparing angioplasty and stenting of the proximal vertebral artery and medical therapy was identified. No comparative studies of endovascular treatment and open surgical repair were found. Forty-two selected studies reported endovascular treatment (angioplasty or stenting, or both) of 1117 vertebral arteries in 1099 patients. The weighted mean technical success rate was 97% (range, 36%-100%). Periprocedural transient ischemic attack occurred in 17 patients (1.5%). The combined stroke and death rate was 1.1%. Recurrent symptoms of vertebrobasilar insufficiency developed in 65 of 967 patients (8%) within a reported follow-up of 6 to 54 months. Restenosis developed in 183 of 789 patients (23%) who underwent follow-up imaging (range, 0%-58%). Reintervention for recurrent disease during follow-up occurred in 86 patients (9%; range, 0%-35%).

CONCLUSIONS

There is limited comparative evidence on the efficacy of medical, surgical, and endovascular treatment of proximal vertebral artery disease. Percutaneous transluminal angioplasty and stenting has low periprocedural neurologic adverse events and mortality.

Stent placement for atherosclerotic stenosis of the vertebral artery ostium: angiographic and clinical outcomes in 117 consecutive patients

BACKGROUND

Although it is thought to be a safe treatment option, the main concerns related to treating vertebral artery ostium (VAO) stenosis with stents have been the rate of restenosis and the uncertain long-term results.

OBJECTIVE

To evaluate the angiographic and clinical results of stent placement for atherosclerotic stenosis of the VAO.

METHODS

One hundred seventeen consecutive patients with atherosclerotic VAO stenosis were treated with stent placement over a period of 12 years. All patients were retrospectively analyzed through the use of a prospectively collected database. The indication criteria for this treatment protocol were symptomatic severe VAO stenoses (> 60%) and asymptomatic severe VAO stenoses (> 60%) with incidentally detected infarction in the posterior circulation. The target diameter of stent dilatation from 1997 to 2000 was the normal vessel diameter just distal to the lesion. Moderate overdilation in the proximal portion of the stents has been performed since 2001.

RESULTS

Successful dilatation was obtained in 116 of 117 cases. Transient neurological complications developed in 2 patients; however, no patients experienced any permanent neurological complications. One hundred four patients underwent follow-up angiography at 6 months after stenting. The restenosis rate at the 6-month follow-up was 9.6% (10 of 104). Until 2000, the restenosis rate after stenting was 13.3%. Since 2001, the restenosis rate has decreased to 4.5%. The median clinical follow-up period was 48 months. The annual rate of strokes in the posterior circulation was 0.95%.

CONCLUSION

Stent placement for atherosclerotic VAO stenosis is considered to be a feasible and safe treatment and may be effective for stroke prevention. The moderate overdilation of stents may be an effective modality for the prevention of restenosis.

Experimental evaluation of a new antithrombogenic stent using ion beam surface modification

A new antithrombogenic stent using ion beam surface modification nanotechnology was evaluated. The ion stent is being developed to inhibit acute and chronic stent-related thrombosis. Thirty self-expanding mesh stents were fabricated from Ti-Ni metal wires with a dimension of 4 mm (diameter) x 25 mm (length) x 0.15 mm (thickness). Twenty stents were coated with type I collagen and irradiated with a He(+) ion beam at an energy of 150 keV with fluences of 1 x 10(14) ions/cm(2) (ion stent group). Ten stents had no treatment (non-ion stent group). The self-expanding stents were implanted into the right and left peripheral femoral arteries of 15 beagle dogs (vessel diameter approximately 3 mm) via a 6Fr catheter under fluoroscopic guidance. Heparin (100 units/kg) was administered intravenously before implantation. Following stent implantation, no antiplatelet or anticoagulant drugs were administered. The 1-month patency rate for the non-ion stent group was 10% (1/10), and for the ion stent group it was 80% (16/20) with no anticoagulant or antiplatelet drugs given after stent implantation (P = 0.0004 by Fisher's exact test). Ten stents remain patent after 2 years in vivo with no anticoagulant or antiplatelet drugs. These results indicate that He(+) ion-implanted collagen-coated Ti-Ni self-expanding stents have excellent antithrombogenicity and biocompatibility. This ion stent is promising for coronary and cerebral stent applications.

Microscopic and macroscopic evaluation of emboli captured during angioplasty and stent procedures in extracranial vertebral and internal carotid arteries

PURPOSE

To compare the quantities of emboli dislodged during percutaneous transluminal angioplasty/stenting in the vertebral artery (VA) with those released during stent placement in the internal carotid artery (ICA).

METHODS

Macroscopic images of distal protection devices (DPD) used during 30 stent procedures in 16 ICAs (11 men; mean age 64.6+/-10.6 years) and 14 VAs (9 men; mean age 67.1+/-9.8 years) were reviewed. The amount of captured embolic debris was calculated and expressed as a proportion to the size of the filter. Histological examinations were performed to characterize the material trapped in the filters.

RESULTS

Relative to the size of the filter, the proportion of captured debris ranged from 0.1% to approximately 22% in the ostial VA filters and from 0.1% to approximately 21% in the filters used in the ICA procedures (p = NS). Plaque fragments with or without thrombus were discovered in the histological examinations of captured material. There were no significant differences in the characteristics of the debris between the 2 vascular regions, nor did sex, race, or plaque morphology correlate significantly with the proportion of captured debris. However, the severity of stenosis was significantly (p<0.029) greater in the ICA (73%+/-0.11%) than the VA (63%+/-0.09%) territory.

CONCLUSION

The study suggests that the frequency and amount of captured emboli during stent procedures in ICA and ostial VAs are comparable. Therefore, the use of a DPD for stent placement in the vertebral artery may be advisable.

Manual therapy and cervical arterial dysfunction, directions for the future: a clinical perspective

This paper offers a contemporary, evidence-based perspective on the issue of adverse neurovascular events related to cervical spine manual therapy. The purpose of this perspective is to challenge traditional thought and practice and to recognize areas where practice and research should develop. By considering the themes presented in this paper, the clinician can broaden his or her approach to neurovascular assessment in line with contemporary evidence and thought. We present information based on clinically relevant questions. The nature of vertebrobasilar insufficiency and the utility of pre-treatment testing are examined in light of contemporary evidence. In addition, we report on internal carotid artery pathology, and the significance of appreciating atherosclerosis in clinical decision-making. These later two areas are not commonly recognized within manual therapy literature, and we suggest that their importance to differential diagnosis of head and neck pain, as well as estimating treatment related risk, is paramount. We propose that the term cervical arterial dysfunction is more appropriate than classically used nomenclature. This term refers more accurately and completely to the range of pathologies at different anatomical sites that manual therapists treating patients with head and neck pain are likely to encounter. Finally, we present a brief review of the medico-legal status pertaining to this area. Although this is English law-related, the themes derived from this section are of interest to all manual therapists.