Symptoms of Carotid Stenosis
Carotid stenosis primarily manifests through focal neurological deficits caused by athero-thromboembolism or, less commonly, by hemodynamic mechanisms in cases of high-grade stenosis or occlusion. 1
Primary Manifestations
Transient Ischemic Attack (TIA) and Stroke
- TIA presents as focal neurologic deficits lasting <24 hours (typically <60 minutes), while ischemic stroke involves symptoms lasting >24 hours 1
- Patients with TIA caused by carotid stenosis have significantly elevated stroke risk—up to 20% in the first 3 months in older studies, and approximately 6% in the first year according to more recent data 1
- Carotid stenosis >50% is the strongest predictor of new vascular events after TIA 1
Specific Focal Neurological Symptoms
- Motor deficits: Isolated paresis of the hand, arm, arm and face, or more rarely, the leg 1
- Sensory deficits: Numbness or tingling affecting the same side of the body, contralateral to the culprit carotid artery 1
- Language deficits: Aphasia when the dominant hemisphere (usually left) is affected 1
- Cognitive deficits: Hemineglect predominantly in the right hemisphere 1
- Visual deficits: Hemianopsia in cases of optic tract involvement or if the posterior cerebral artery originates from the carotid artery 1
Ocular Symptoms
- Amaurosis fugax (transient monocular blindness): Temporary reduction of blood flow to the eye, causing partial or total blindness in the ipsilateral eye 1
- Retinal emboli: May be detected during eye examinations, even in otherwise asymptomatic patients 1
Advanced Manifestations and Special Presentations
Hemodynamic Symptoms
- Limb-shaking TIA: Positive motor phenomena associated with hemodynamic impairment leading to reduced cerebral perfusion 1
- Low-flow TIA: Transient cerebral hypoperfusion due to severe stenosis 1
- Stuttering stroke/aggravating stroke: Symptom progression over hours to days due to thrombus propagation from an occluded carotid artery 1
Severity Spectrum
- Internal carotid artery occlusion may present with varying symptom severity, from clinically silent to catastrophic, depending on the efficacy of compensatory collateral circulation via the circle of Willis and/or external carotid artery 1
Risk Factors and Clinical Correlations
- Men tend to have larger plaques with more calcifications, lipid-rich necrotic cores, and intra-plaque hemorrhage compared to women 1
- Risk of subsequent stroke after TIA or amaurosis fugax is related to the presence of other risk factors such as hypertension, hypercholesterolemia, diabetes, and cigarette smoking 1
- Carotid stenosis >50% represents the inflection point at which blood flow velocity accelerates above normal due to atherosclerotic plaque 1
Important Clinical Considerations
- Asymptomatic carotid stenosis is defined as stenosis without associated recent (typically <6 months) ipsilateral stroke, TIA, or amaurosis fugax 1
- Patients with evidence of silent brain infarction or retinal emboli with ipsilateral carotid stenosis are conventionally considered "asymptomatic" despite evidence of prior brain infarction 1
- Not all neurological events are attributable to carotid stenosis—nonfocal events such as transient global amnesia, acute confusion, syncope, isolated vertigo, nonrotational dizziness, bilateral weakness, and paresthesia should prompt consideration of alternative diagnoses 1
Diagnostic Approach
- Duplex ultrasound is commonly used as the first-line imaging modality to detect extracranial carotid stenosis and assess its severity 1
- Peak systolic velocity in the internal carotid artery and the ratio to that in the ipsilateral common carotid artery correlate with angiographically determined stenosis 1
- Urgent imaging of the brain and supra-aortic vessels is mandatory in all patients presenting with TIA or stroke 1
- Vulnerable plaque features that increase stroke risk include increased plaque volume, ultrasound echolucency, inflammation, neovascularization, intra-plaque hemorrhage, ulcerations, lipid-rich necrotic cores, and ruptured fibrous caps 1