What are the symptoms of carotid stenosis?

Symptoms of Carotid Stenosis

Carotid stenosis primarily manifests through focal neurological deficits caused by cerebral ischemia, including transient ischemic attacks (TIAs), amaurosis fugax, and ischemic stroke, with symptoms determined by the affected brain territory. 1

Primary Mechanisms of Symptom Development

Carotid stenosis symptoms develop through two main mechanisms:

1. Athero-thromboembolism (most common): Plaque inflammation and disruption with subsequent embolism of locally formed thrombus or plaque debris, leading to occlusion of retinal or cerebral arteries 1

2. Hemodynamic impairment: With high-grade stenosis or occlusion, cerebral ischemia may arise from flow reduction, especially in patients with inadequate collateral circulation 1

Specific Neurological Manifestations

Hemispheric (Cortical) Symptoms

• Motor deficits: Isolated paresis of the hand, arm, face, or less commonly, the leg (contralateral to the stenotic carotid artery) 1
• Sensory deficits: Numbness or tingling affecting the contralateral side of the body 1
• Language disturbances: Aphasia when the dominant hemisphere (usually left) is affected 1
• Cognitive symptoms: Hemineglect when the non-dominant hemisphere (usually right) is affected 1
• Visual field defects: Hemianopsia in cases of optic tract involvement 1

Ocular Symptoms

• Amaurosis fugax: Temporary monocular blindness in the ipsilateral eye 1
  • Particularly common in common carotid artery stenosis (50% of symptomatic patients) compared to internal carotid artery stenosis (6.6%) 2
• Permanent visual loss: Partial or total blindness in the ipsilateral eye due to retinal artery embolism 1

Special Clinical Presentations

• Stuttering stroke/aggravating stroke: Symptom progression over hours to days due to thrombus propagation from an occluded carotid artery 1
• Limb-shaking TIA: Positive motor phenomena associated with hemodynamic impairment leading to reduced cerebral perfusion 1

Duration of Symptoms

• TIA: Focal neurologic deficits lasting <24 hours (but more typically <60 minutes) 1
• Ischemic stroke: Symptoms lasting >24 hours 1

Risk Stratification

Patients with TIA caused by carotid stenosis are at significantly increased risk of stroke:

• Up to 20% in the first 3 months in older studies 1
• Approximately 6% in the first year in more recent registries 1
• Carotid stenosis >50% is the strongest predictor of a new vascular event after TIA 1

Important Clinical Considerations

1. Asymptomatic carotid stenosis: Many patients with carotid stenosis are asymptomatic despite significant narrowing 1

2. Symptom variability: The severity of symptoms can range from clinically silent to catastrophic, depending on the efficacy of compensatory collateral circulation 1

3. Plaque characteristics: Beyond degree of stenosis, plaque morphology (ulceration, echolucency, intraplaque hemorrhage, high lipid content) correlates with symptom risk 1

4. Rapid evaluation: All patients with neurological complaints potentially related to carotid stenosis should be evaluated promptly by a neurologist 1

5. Stroke risk: Annual stroke risk in moderate asymptomatic stenosis is approximately 2.1%, with higher risk associated with disease progression 3

Key Diagnostic Approach

Urgent imaging of the brain and supra-aortic vessels is mandatory in all patients presenting with TIA or stroke symptoms 1. Recommended imaging modalities include:

• Duplex ultrasonography (DUS): First-line assessment for detecting extracranial carotid stenosis and assessing plaque morphology 1
• CT/CTA: Differentiates between ischemic and hemorrhagic stroke; evaluates degree of stenosis 1
• MRI/MRA: More sensitive for detecting brain ischemia; assesses plaque characteristics 1

Remember that symptoms may be subtle or atypical, and careful neurological assessment is essential for proper diagnosis and management of carotid stenosis.