Carotid Artery Stenosis

Why Does an AVM Matter?

Carotid artery stenosis is a condition in which one or both carotid arteries narrows due to plaque build-up. The carotid arteries are the large arteries on either side of the neck that supply oxygenated blood to the brain. Plaque build-up tends to occur with a condition called atherosclerosis, in which cholesterol, fatty substances and inflammatory cells accumulate along the walls of arteries over time. Eventually, medium to severe stenosis will either drastically reduce blood flow to the brain or it may lead to clot formation at the plaque location. Both of these resulting conditions are highly susceptible to stroke for the patient.

Stenosis severity is classified based on the percentage amount of narrowing in either artery, usually using ultrasound, CT-angiography, MR-angiography, or catheter-based cerebral angiography. Stenosis is classified as MILD (0-49%), Moderate (50-69%), or Severe (70-99%) according to the North American Symptomatic Carotid Endarterectomy Trial criteria. A separate category is 100%, or complete occlusion. For patients who have already been presented with a stroke or TIA, procedural intervention is almost ALWAYS indicated if the stenosis shown is greater than or equal to 50%. Asymptomatic patients usually only qualify for treatment if the stenosis is greater than or equal to 70% and they have at least 5 years of life expectancy.

There have been several large-scale clinical trials that have supported the benefit of carotid intervention in selected patients. In the NASCET trial, endarterectomy, which is a surgery to remove plaque build-up, was shown to reduce the risk of recurrent stroke by 17% after two years, specifically in patients who had symptomatic carotid stenosis of 70-99%. The Asymptomatic Carotid Atherosclerosis Study demonstrated that in patients with asymptomatic stenosis of greater than 60%, surgery was associated with a reduction in the five-year risk of stroke, from 11% to 5.1%. Most recently, the Carotid Revascularization Endarterectomy vs Stenting Trial illustrated that both approaches, surgical and endovascular, had similar long-term results over the five-year follow-up.

Studies that have attempted revascularization in cases with complete (100%) carotid artery occlusion are implicated with higher risk of complications, and have not been shown to provide stroke prevention benefit. The EC/IC Bypass Trial and further analysis, including data from the CAVATAS trial, showed that neither surgical nor endovascular intervention have advantage over no procedure at all in cases of complete occlusion, or in some instances, that procedural risk outweighed potential benefit. Current guidelines recommend against revascularization in the case of complete carotid artery occlusions, with management reserved for intensive medical therapy, lifestyle changes, and control of vascular risk factors.

Certain risk factors have been implicated in carotid stenosis, including high blood pressure, high cholesterol, diabetes, smoking, advancing age, and history of coronary artery disease or peripheral vascular disease. Because carotid stenosis is often asymptomatic until a stroke occurs, immediate recognition of the condition and tailored assessment is essential to prevent serious neurological damage.

References:

  1. The EC/IC Bypass Study Group. Failure of extracranial–intracranial arterial bypass to reduce the risk of ischemic stroke. N Engl J Med. 1985;313(19):1191–1200. doi:10.1056/NEJM198511073131904
  2. CAVATAS investigators. Endovascular versus surgical treatment in patients with carotid stenosis in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS). Lancet. 2001;357(9270):1729–1737. doi:10.1016/S0140-6736(00)04826-3

Symptoms

Carotid artery stenosis may be symptomatic or asymptomatic; this is important because symptomatic and asymptomatic stenosis will be managed differently and involve different risks of stroke. Symptomatic carotid stenosis entails a transient ischemic attack or stroke that is attributed to diminished blood flow or embolization from the stenosed artery. Symptoms may include sudden weakness or numbness on one side of the body, difficulty with speaking or understanding speech, sudden vision loss in the one eye, dizziness, or poor coordination. These symptoms may be temporary or permanent. Any one of these signs warrants immediate medical follow-up.

The majority of people with asymptomatic carotid stenosis have no warning signs, and are usually unaware of their condition until diagnosed incidentally after assessment of some other issue, like a vascular screening. It’s still important to realize that asymptomatic carotid disease is clinically relevant even when it doesn’t present with symptoms. For instance, patients with high-grade asymptomatic stenosis have a risk of stroke that remains elevated even when they are asymptomatic, especially if they have unstable plaque or irregular plaque morphology. With time, the clot could travel to the brain from unstable plaque, producing a sudden ischemic event, even in the absence of prior neurologic symptoms.

Caring for symptoms is important because stroke may be the first and only manifestation of the disease. In well-selected patients with significant narrowing, patients may have lower stroke risk with intervention rather than medical therapy only. The Asymptomatic Carotid Atherosclerosis Study and the trial design support this concept, which has been further refined into individualized treatment that combines medical therapy optimized, and carotid intervention as indicated, to prevent first-time catastrophic strokes. Thus carotid artery stenosis is a serious condition irrespective of symptoms, and ongoing assessment and tailored clinical decisions are required to reduce long-term stroke risk irrespective of symptoms or asymptomatic event occurrence.

Diagnosis

Carotid artery stenosis is often diagnosed with a combination of noninvasive and invasive imaging studies. A patient’s initial evaluation begins with a carotid ultrasound, which is a painless noninvasive study that uses sound waves to assess blood flow and provide some estimate of stenosis severity. While useful for screening, ultrasound can underestimate or overestimate stenosis severity in some patients. CT angiography and MR angiography produce more detailed anatomical images of the carotid arteries and surrounding structures using contrast dye and advanced imaging methods.

If a more accurate evaluation is required, catheter-based digital subtraction angiography is viewed as the gold standard to diagnose carotid artery stenosis. DSA provides dynamic, high-resolution, real-time imagery with a direct measurement of stenosis severity associated with views of arterial anatomy and visual evaluation of blood flow.

At Golden State Neurosurgery, Dr. Yim uses a snuffbox radial access approach, which accesses the artery at the wrist rather than at the groin. Compared to traditional femoral access to conceal a snuffbox, the radial access was associated with less bleeding, faster mobilization, and more comfort for the patient. (Kiemeneij & Laarman, 1997; Dahm at al., 2023).

Although catheter angiography shows great diagnostic accuracy, it does carry minimal procedural risk. Specific risks include the risk of stroke, which is approximately 0.5-1%, access site complications such as a hematoma or bleeding, contrast-induced nephropathy, and the rare potential for arterial dissection or vasospasm (Higashida et al., 2013; Cloft et al., 2002). When performed with experienced neurosurgeons, these risks are mitigated and are often offset by detailed preprocedural planning.

References

  1. Higashida RT, Meyers PM, Connors JJ, et al. The safety of neuroangiography and neurointerventional procedures in the United States: review of 100,000 cases from the Nationwide Inpatient Sample database. J Vasc Interv Neurol. 2013;6(3):47–52.
  2. Cloft HJ, Kallmes DF. Complication rates for diagnostic cerebral angiography: a meta-analysis. AJNR Am J Neuroradiol. 2002;23(9):1706–1708.
  3. Kiemeneij F, Laarman GJ. Snuffbox approach for transradial coronary angiography and interventions. Cathet Cardiovasc Diagn. 1997;42(4):467–470./li>
  4. Dahm J, Htun WW, Koshy A, et al. Snuffbox radial access for neurointervention: feasibility, safety, and early experience. J Neurointerv Surg. 2023;15(2):142–147. doi:10.1136/neurintsurg-2021-018639

Treatment Options and Ideal Candidates

Management of carotid artery stenosis and associated carotid pathology is individualized, including consideration of the degree of stenosis, the presence or absence of symptoms, patient-related factors including age and overall health, the anatomy of the lesions, and the underlying cause.

  1. Medical therapy is typically recommended for asymptomatic patients with mild-to-moderate atherosclerotic stenosis. Medical therapy generally includes antiplatelet agents, such as aspirin or also statins to control blood pressure and lifestyle modifications. Medical therapy may also be appropriate for selective patients with asymptomatic high-grade stenosis, specifically when procedural risk is high or imaging indicates no concerning plaque characteristics.
  2. Carotid endarterectomy remains the gold standard for patients with symptomatic atherosclerotic stenosis greater than 70%. This treatment option is best for patients younger than 75, in overall good health, at low risk of having surgery, and have a surgical anatomy that can easily be assessed. It remains a preferred option in asymptomatic patients with greater than 70% stenosis with an expected life of 5 years or more. Good candidates for CEA are patients without prior neck surgery or neck radiation and patients with plaque that is lower in the neck and not near the skull base.
  3. Carotid artery stenting is a minimally invasive alternative and is best reserved for patients with a high risk of complications during open surgery due to their age, prior neck surgery, neck radiation, higher bifurcation of the carotid artery, or significant cardiac or pulmonary complications. CAS can also be considered in younger patients who would prefer a less invasive procedure than open surgery.
    • At Golden State Neurosurgery, stenting is primarily done through snuffbox/radial artery access. It is excellent access, quicker recovery, less risk of bleeding, and more comfortable for the patient. The CREST trial and new studies in the past few years have shown the possibility of equivalent stenting results to surgery in selected patients, in the hands of experienced operators.

In all cases, treatment decisions are individualized. Careful evaluation of the patient’s clinical history, imaging findings, procedural risk, and stroke recurrence risk is essential to determine the best approach. At Golden State Neurosurgery, Dr. Yim offers comprehensive evaluation and both surgical and endovascular solutions tailored to the underlying pathology and the patient’s unique needs.

Who Should Consider Treatment?

You may be a candidate for surgery or stenting if:

  • You’ve had a stroke and have greater than 50% carotid narrowing
  • You have greater than 70% narrowing without symptoms and are in overall good health
  • If you have high surgical risk factors, then stenting via snuffbox access is the safer option

Risks of Treatment

Treatment of carotid artery disease is aimed at reducing the risk of future stroke. All of the treatment options have unique risks that must be evaluated against the potential benefits. Different risk profiles exist depending on the patient’s anatomy, clinic and surgical comorbidities, age, and the vascular pathology.

Medical Management


Medical management is generally well tolerated because it requires serious commitment to medications and lifestyle changes. The primary risks include:

  • Side effects of medications such as gastrointestinal bleeding with aspirin or dual antiplatelet therapy.
  • Statin intolerance such as muscle aches or elevated liver enzymes.
  • Remaining stroke risk associated with high-grade stenosis even with best medical therapy.
  • The annual stroke risk on medical therapy alone is estimated to be ~1-2% for asymptomatic patients with greater than 70% stenosis, depending on plaque morphology. (Spence et al., 2014; Howard et al., 2021)



Carotid Endarterectomy (CEA)


CEA is an established intervention with decades of data, and is effective for symptomatic patients with 70–99% stenosis. However, this treatment option is invasive and has the risks associated with any open neck surgery:

  • Perioperative stroke risk: 2–3% when performed by experienced surgeon
  • Myocardial infarction (MI): to about ~1–2%; higher risk in older or patients with coronary disease
  • Cranial nerve injury: transient cranial nerve injury in up to 10% and permanent injury in 1-3% of patients
  • Wound complications including hematoma, infection, and/or revisit for reoperation
  • Restenosis: typically rates < 5% over 5 years in modern series

Carotid Artery Stenting (CAS)

CAS is a less invasive option in comparison to CEA, and particularly it is useful in patients needing intervention at high surgical risk. Using CAS, the surgery is performed without a neck incision and could be done with transradial and/or snuffbox access. However, the risks are somewhat different from the surgical options:

  • Periprocedural stroke risk: ~4–5% in symptomatic patients; stroke risk after CAS is higher than CEA particularly in older adults
  • Embolic complications: even with the use of distal embolic protection devices, breakdown of plaque will still emboli the cerebral vascular.
  • Restenosis or in-stent re-narrowing: occurs in roughly 6–10% at 1–2 years, typically asymptomatic but may require surveillance and re-intervention
  • Contrast-induced nephropathy: rare, but possible in cases of chronic kidney disease

Special Considerations

  • For the carotid web, both CEA and CAS have similar risk profiles. Some case series suggest that CAS may have slightly higher rates of embolic events when compared to CEA unless specified technique with embolic protection is utilized.
  • In carotid dissection, an intervention is reserved for the patients failing to improve with medical therapy or for the patients who have flow limiting lesions. Stenting may be performed safely but there is a risk of dissection progression, in-stent thrombosis, or stroke if the procedure is undertaken.

Key References

  1. Brott TG, Hobson RW 2nd, Howard G, et al. Stenting versus endarterectomy for treatment of carotid-artery stenosis. N Engl J Med. 2010;363(1):11–23. doi:10.1056/NEJMoa0912321
  2. Rothwell PM, Eliasziw M, Gutnikov SA, et al. Endarterectomy for symptomatic carotid stenosis in relation to clinical subgroups and timing of surgery. Lancet. 2004;363(9413):915–924. doi:10.1016/S0140-6736(04)15785-1
  3. Yadav JS, Wholey MH, Kuntz RE, et al. Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med. 2004;351(15):1493–1501. doi:10.1056/NEJMoa040127
  4. Howard VJ, Howard G. Asymptomatic carotid stenosis: risk of stroke and effectiveness of intervention. Stroke. 2021;52(5):2031–2038. doi:10.1161/STROKEAHA.121.033170
  5. Spence JD, Coates V, Li H, et al. Effects of intensive medical therapy on microemboli and cardiovascular risk in asymptomatic carotid stenosis. Arch Neurol. 2010;67(2):180–186. doi:10.1001/archneurol.2009.272
  6. Dahm J, Htun WW, Koshy A, et al. Snuffbox radial access for neurointervention: feasibility, safety, and early experience. J Neurointerv Surg. 2023;15(2):142–147. doi:10.1136/neurintsurg-2021-018639
  7. Haussen DC, Grossberg JA, Bouslama M, et al. Carotid web associated with recurrent ischemic strokes. J Neurointerv Surg. 2017;9(10):E39. doi:10.1136/neurintsurg-2016-012827
  8. Kadkhodayan Y, Jeck DT, Moran CJ, et al. Endovascular treatment of extracranial carotid artery dissection. AJNR Am J Neuroradiol. 2005;26(2):341–348.

Scientific Background

The management of carotid artery stenosis has been transformed by a series of important trials over the past 30 years, which have delineated the best candidates for medical treatment, surgery, or stenting. The North American Symptomatic Carotid Endarterectomy Trial established the guidelines for the management of symptomatic carotid stenosis in 1991. It showed that patients with 70 – 99% narrowing of the internal carotid artery who underwent carotid endarterectomy had 17% absolute risk reduction of stroke over two years compared to patients receiving medical therapy only. Patients with 50 – 69% stenosis had less benefit from CEA, and those with less than 50% narrowing did not show any benefit. In 1995, the Asymptomatic Carotid Atherosclerosis Study expanded these findings to asymptomatic patients. ACAS showed that CEA reduces the five-year risk of ipsilateral stroke from 11% to 5.1% for patients with greater than 60% stenosis provided they are at low surgical risk.

In 2010, the Carotid Revascularization Endarterectomy vs. Stenting Trial compared CEA to carotid artery stenting in symptomatic and asymptomatic patients with stenosis is greater than 50%. CREST found that long-term outcomes were similar for both procedures with respect to stroke, myocardial infarction, and mortality. CAS had a slightly greater risk of periprocedural stroke and CEA had a slightly greater risk of perioperative myocardial infarction. Subgroup analysis found that patients younger than 70 years of age had significantly better outcomes with CAS compared to CEA and patients aged 70 years and older had a trend towards improved outcomes with CEA compared to CAS. A major advancement of CREST was identifying both CEA and CAS as acceptable procedures when performed by an experienced surgeon or operator, taking into account the patient’s age and risk characteristics for each procedure.

The current CREST-2 trial builds on these findings by determining if either procedure of revascularization provides any additive benefit compared to modern intensive medical therapy alone in asymptomatic patients with greater than 70% stenosis. This study illustrates changing patterns of practice, as medical therapy for patients with carotid disease has rapidly improved since the ACAS trial.

Other notable trials included in the overview also remain informative to our understanding of the indications for carotid artery stenting are the International Carotid Stenting Study which reported higher 30-day stroke rates for patients undergoing CAS than endarterectomy in symptomatic disease. However both groups displayed comparable long-term outcomes, the Asymptomatic Carotid Trial demonstrated that low-risk asymptomatic patients treated with CAS were non-inferior to CEA for the prevention of stroke, death, and MI for a five-year period.

Overall, these studies support an individualized approach to carotid artery disease. For symptomatic patients with 70-99% stenosis, CEA definitely remains the most evidence-based treatment approach. CAS is used to care for patients that are at high surgical risk or have vascular anatomy that is unfavorable. Under these indications, revascularization for asymptomatic patients with high-grade stenosis may be discussed if low procedural risk, and good life expectancy.

Our Approach at Golden State Neurosurgery

As a dual-trained cerebrovascular and endovascular neurosurgeon, Dr. Benjamin Yim provides:

  • Comprehensive evaluation with advanced imaging
  • Minimally invasive snuffbox radial access for angiograms and stenting
  • Surgical and endovascular options
  • Shared care with your referring physician and stroke team
  • Long-term follow-up to monitor artery health and prevent next event

Interested in learning more about our practice?

Request Consultation
Scroll to Top