Symptoms of Severe Carotid Stenosis
Severe carotid stenosis typically presents with focal neurologic deficits including motor weakness, sensory changes, speech disturbances, or transient monocular vision loss (amaurosis fugax), while isolated dizziness and headaches should NOT be attributed to carotid disease. 1
Classic Focal Neurologic Presentations
The hallmark symptoms of severe carotid stenosis are focal deficits referable to the affected carotid territory:
- Motor deficits manifest as isolated paresis of the hand, arm, arm and face together, or less commonly the leg, contralateral to the stenotic artery 1
- Sensory deficits include numbness or tingling affecting the same side of the body, contralateral to the culprit carotid artery 1
- Speech disturbances such as aphasia or dysarthria occur when the dominant hemisphere is affected 1
- Amaurosis fugax (transient monocular blindness) results from temporary reduction of blood flow to the ipsilateral eye and is a classic carotid stenosis symptom 1
These symptoms may present as either transient ischemic attack (TIA) with deficits lasting <24 hours, or as completed stroke with symptoms persisting >24 hours 1. The distinction is critical because TIA carries a stroke risk of up to 20% in the first 3 months in older studies, though more recent data shows approximately 6% risk in the first year 1.
Advanced and Hemodynamic Presentations
Beyond typical focal deficits, severe stenosis can produce unique hemodynamic symptoms:
- Limb-shaking TIA presents as positive motor phenomena (involuntary shaking movements) associated with hemodynamic impairment from severe stenosis 1
- Low-flow TIA involves transient cerebral hypoperfusion due to critically severe stenosis, often precipitated by postural changes or activities that reduce cerebral perfusion pressure 1
- Retinal emboli may be detected during eye examinations, even in otherwise asymptomatic patients 1
Critical Symptoms NOT Attributable to Carotid Stenosis
It is essential to recognize that nonfocal neurological symptoms should prompt evaluation for alternative diagnoses rather than being attributed to carotid disease:
- Isolated dizziness without focal deficits is not a symptom of carotid stenosis 1
- Isolated headaches should not be attributed to extracranial carotid artery disease 1
- Nonfocal events including transient global amnesia, acute confusion, syncope, isolated vertigo, nonrotational dizziness, bilateral weakness, and bilateral paresthesia are not clearly attributable to carotid disease 2, 1
Alternative causes such as vestibular disorders, medication effects, cardiac arrhythmias, orthostatic hypotension, migraine, and tension headaches should be evaluated when these symptoms occur 1.
Stroke Risk Stratification
The relationship between stenosis severity and stroke risk is well-established but complex:
- Symptomatic patients with 70-79% stenosis have 19% stroke rates at 18 months without revascularization, increasing to 28% with 80-89% stenosis and 33% with 90-99% stenosis 2
- Carotid stenosis >50% is the strongest predictor of new vascular events after TIA 1
- Symptomatic carotid stenosis (defined as acute neurologic deficit in the last 6 months ipsilateral to ≥50% stenosis) carries substantially higher stroke risk than asymptomatic disease 3
- Patients with symptomatic stenosis have mean annual stroke rates of 6% compared to 2% in asymptomatic patients with moderate stenosis 4
Clinical Pitfalls to Avoid
A common error is attributing nonspecific symptoms to carotid disease when imaging reveals stenosis. The stenosis must be ipsilateral to focal neurologic symptoms to be considered symptomatic 1. Additionally, in the Framingham Heart Study, fewer than half of stroke events in patients with carotid bruit affected the hemisphere ipsilateral to the stenosis, highlighting that carotid disease does not explain all neurologic events in these patients 2.