Atherosclerotic narrowing of the cervical internal carotid artery; major modifiable cause of ischemic stroke and TIA.
Also known as: carotid stenosis, extracranial carotid disease, internal carotid artery stenosis, ICA stenosis
Overview
Narrowing of the extracranial internal carotid artery, most often at the carotid bifurcation, due to atherosclerotic plaque. Severity is graded by percent diameter reduction (NASCET method): <50% mild, 50-69% moderate, 70-99% severe, 100% occluded. Symptomatic stenosis = ipsilateral retinal or hemispheric ischemic event (TIA, stroke, amaurosis fugax) within 6 months.
Epidemiology
Moderate-to-severe (≥50%) stenosis in ~2% of adults under 70 and up to 8% over 70. Higher in men, smokers, diabetics, hypertensives. Accounts for ~10-15% of ischemic strokes.
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Atherosclerotic plaque develops preferentially at the carotid bifurcation due to disturbed flow patterns. Plaque progression narrows the lumen and may rupture, exposing thrombogenic material and producing embolization (artery-to-artery emboli to the ipsilateral hemisphere or retina). Hemodynamic compromise contributes when stenosis is critical (>70%) or collateral supply is poor.
Clinical presentation
Symptoms
Many cases asymptomatic — found on screening or workup of bruit/CAD
Transient ischemic attack — unilateral weakness, sensory loss, aphasia (dominant hemisphere), or visual field cut lasting <24 h
Amaurosis fugax — transient monocular vision loss ('curtain' descending), classic for carotid embolic disease
Ischemic stroke with persistent deficit in the ipsilateral hemisphere
Signs / physical exam
Carotid bruit on auscultation (insensitive and nonspecific — may be absent in severe stenosis or present in non-flow-limiting plaque)
Hollenhorst plaque on funduscopy (cholesterol embolus in retinal artery)
Focal neurologic deficit during or after ischemic event
Evidence of systemic atherosclerosis: diminished peripheral pulses, abdominal bruits, xanthomas
Classic findings
Older smoker with transient monocular vision loss or contralateral weakness — high suspicion for symptomatic carotid stenosis.
Carotid artery dissection — Young patient, neck pain, Horner syndrome, history of trauma or chiropractic manipulation; intimal flap or string sign on imaging
Fibromuscular dysplasia — Young to middle-aged women; 'string of beads' on imaging
flowchart TD
A[TIA, minor stroke,<br/>or amaurosis fugax] --> B[Carotid duplex<br/>ultrasound]
B --> C[CTA or MRA neck<br/>to confirm % stenosis]
C --> D{Symptomatic<br/>stenosis %}
D -->|70-99%| E[CEA within 2 weeks<br/>or CAS if high-risk anatomy]
D -->|50-69%| F[Individualized:<br/>consider CEA]
D -->|<50%| G[Medical therapy<br/>alone]
A2[Asymptomatic<br/>incidental finding] --> B
D2[Asymptomatic<br/>70-99%] --> H[Intensive medical<br/>therapy primary;<br/>CEA/CAS selected cases]
E --> I[Lifelong antiplatelet,<br/>statin, BP control,<br/>smoking cessation]
F --> I
G --> I
H --> I
Diagnostic and treatment algorithm for symptomatic and asymptomatic carotid artery stenosis.
Treatment
First-line
Aggressive medical therapy for ALL patients regardless of revascularization plan:
Antiplatelet — aspirin 81 mg daily; clopidogrel if ASA-intolerant; DAPT (aspirin + clopidogrel) for 21-90 days post stroke/TIA per CHANCE/POINT trial protocols
Smoking cessation — single most impactful modifiable factor
Lifestyle: Mediterranean diet, exercise, weight loss
Symptomatic stenosis 70-99%
Carotid endarterectomy (CEA) within 2 weeks of index event (greatest benefit) — strong indication (NASCET, ECST trials)
Surgeon-specific perioperative stroke/death rate must be <6%
Carotid artery stenting (CAS) — alternative when CEA high-risk anatomy (hostile neck, prior radiation, contralateral occlusion); younger age (<70) favors CAS while older age favors CEA (CREST: outcomes equivalent around age 70)
Hemodynamic instability with intervention (bradycardia, hypotension during CAS or CEA carotid sinus manipulation)
Death (most often from coexisting CAD)
PANCE pearls
Carotid bruit is neither sensitive nor specific — its absence does not exclude severe stenosis.
Amaurosis fugax is a TIA — workup urgently with carotid imaging; do not dismiss as 'just an eye problem.'
Symptomatic 70-99% stenosis: CEA within 2 weeks of the index event gives the maximal absolute risk reduction; do not delay for 'cooling off.'
Asymptomatic stenosis — modern medical therapy markedly reduced stroke risk; routine revascularization is no longer reflexive (await CREST-2).
Hyperperfusion syndrome after revascularization: severe ipsilateral headache, seizures, hemorrhage from sudden restoration of flow — control BP aggressively.
Patients with carotid disease die more often from MI than stroke — optimize cardiac risk.
References
NASCET — North American Symptomatic Carotid Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. NEJM 1991;325:445-453.
ACAS — Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA 1995;273:1421-1428.
CREST — Brott TG et al. Stenting versus endarterectomy for treatment of carotid-artery stenosis. NEJM 2010;363:11-23.
AHA/ASA 2021 — Kleindorfer DO et al. 2021 Guideline for the Prevention of Stroke in Patients With Stroke and Transient Ischemic Attack. Stroke 2021;52:e364-e467.
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