Definition
A.Carotid artery stenosis is the narrowing of one or both of the carotid arteries.
B.Classification of carotid artery stenosis:
1.Moderate:
a.Less than 69% narrowing.
2.Severe:
a.70% to 99% narrowing.
Incidence
A.Moderate carotid artery stenosis:
1.Prior to age 70: Male, 4.8%; female, 2.2%.
2.After age 70: Male, 12.5%; female, 6.9%.
B.Severe carotid artery stenosis:
1.All ages, both genders: 1.7%.
C.Severe asymptomatic carotid artery stenosis:
1.After age 80: Male, 3.1%; female, 0.9%.
Pathogenesis
A.As the human body ages the artery walls become thicker and less flexible (atherosclerosis). The plaques, also known as atheromas, can develop on the interior artery wall. Over time, the buildup of plaque reduces blood flow to the brain. The arterial narrowing also increases the risk of thrombus formation and subsequent stroke risk.
Predisposing Factors
A.Nonmodifiable factors:
1.Age:
a.Male: Increased risk prior to age 75.
b.Female: Increased risk after age 75.
2.Personal or family history of any of the following:
a.Stroke.
b.Angina.
c.Myocardial infarction (MI).
d.Peripheral arterial disease (PAD).
B.Modifiable factors:
1.Hypertension (HTN).
2.Hypercholesterolemia.
3.Diabetes mellitus.
4.Obesity.
5.Tobacco abuse.
6.Sedentary lifestyle.
Common Complaints
A.Asymptomatic carotid artery stenosis:
1.Often there are no symptoms.
B.Symptomatic carotid artery stenosis:
1.Focal neurologic symptoms, acute onset:
a.Monoparesis or hemiparesis.
b.Sensory alterations:
i.Paresthesias.
c.Speech disturbance:
i.Expressive aphasia.
ii.Receptive aphasia.
iii.Changes in speech pattern or vocal quality (dysprosody).
d.Visual changes:
i.Blurred vision.
ii.Blindness in one eye, partial or complete.
iii.Visual field loss: Specifically contralateral homonymous hemianopsia.
iv.Dimming of vision.
e.Constructional apraxia (i.e., inability to perform purposeful movements).
2.Vertigo and syncope are symptoms not generally caused by carotid artery stenosis.
Potential Complications
A.Cerebrovascular accident (CVA).
B.Transient ischemic attack (TIA).
C.Death.
D.Comorbidities that increase complication risk:
1.Age: Older than 80 years.
2.New York Heart Association (NYHA) III or IV heart failure (HF).
3.Left ventricular ejection fraction (LVEF): Less than 30%.
4.Class III or IV angina pectoris.
5.Coronary artery disease (CAD): Left main coronary artery.
6.CAD: Multivessel.
7.Planned cardiac surgery within 30 days.
8.History of MI within 4 weeks.
9.Severe chronic lung disease (i.e., chronic obstructive pulmonary disease [COPD], bronchitis, emphysema, asthma).
Subjective Data
A.Ask patient to describe any new neurologic symptoms:
1.Further determine the frequency, intensity, and duration of the symptoms.
B.Ask patient to list all medications currently being taken, including over-the-counter (OTC) substances.
Physical Examination
A.Patients presenting with acute neurologic symptoms indicative of a stroke (paresis, speech or swallowing difficulty, visual field loss, etc.) should be quickly assessed for the need to call emergency services/911 for immediate transport to the hospital.
B.Vital signs: Check blood pressure (BP), pulse, and respirations.
C.Inspect:
1.Inspect overall physical appearance, noting any distress.
2.Eyes: Assess papillary reflex bilaterally and perform a funduscopic exam noting arterial occlusions or ischemic retinal damage.
D.Auscultate:
1.Neck: Carotid bruits, bilaterally:
a.Studies have shown that carotid bruits have a poor predictive value in asymptomatic patients but are more indicative of CAD. However, the presence of a bruit should still be documented.
Diagnostic Tests
A.Noninvasive testing:
1.Carotid Doppler/duplex ultrasound.
2.Carotid magnetic resonance angiogram (MRA).
3.Computed tomographic angiography (CTA).
B.Invasive testing:
1.Cerebral angiography with contrast:
a.The gold standard for determination of carotid artery stenosis.
Differential Diagnosis
A.Monoparesis:
1.TIA.
2.CVA/stroke.
3.Multiple sclerosis.
4.Separated shoulder.
5.Fractured limb.
B.Hemiparesis:
1.TIA.
2.CVA/stroke.
3.Multiple sclerosis.
4.Spinal tumor.
C.Sensory alterations (paresthesias):
1.TIA.
2.CVA/stroke.
3.Peripheral neuropathy.
4.Cervical spinal stenosis.
5.Lead poisoning.
6.Lyme disease.
7.Wernicke syndrome.
8.Multiple sclerosis.
D.Speech disturbance (aphasia):
1.TIA.
2.CVA/stroke.
3.Myasthenia gravis.
4.Brain tumor.
E.Speech disturbance (speech pattern or vocal quality, i.e., dysprosody):
1.TIA.
2.CVA/stroke.
3.Brain tumor.
F.Visual changes:
1.TIA.
2.CVA/stroke.
3.Retinal detachment.
4.Ocular migraine.
5.Cataracts.
6.Giant cell arteritis.
7.HTN.
8.Macular degeneration.
9.Sarcoidosis.
10.Glaucoma.
11.Brain tumor.
G.Constructional apraxia:
1.TIA.
2.CVA/stroke.
3.Brain tumor.
Plan
A.General interventions:
1.The goal of therapy is to improve the patient’s quality of life by reducing morbidity and prolonging survival.
2.The estimated risk of stroke within 5 years when utilizing medical management is 11.8% versus the risk of perioperative death, which is 6.4%.
B.Patient teaching:
1.Educate patient about modifying controllable risk factors such as HTN, diabetes, hypercholesterolemia, obesity, tobacco abuse, and sedentary lifestyles.
2.If known carotid artery stenosis is present:
a.Make sure patient is aware of signs and symptoms of TIA and stroke.
b.Make sure patient knows to seek medical attention or dial 911 if signs and symptoms occur.
C.Dietary management:
1.Counsel patient regarding appropriate change to his or her diet (i.e., low-fat, low-cholesterol, and low-sodium diet if applicable).
2.Reinforce teaching with nutrition/diet handouts.
3.Consider referral to a registered dietitian.
D.Pharmaceutical therapy:
1.Antiplatelet therapy:
a.Aspirin:
i.Taken prior to carotid endarterectomy (CEA) surgery and for at least 3 months postoperatively.
ii.Dosage: 81 to 325 mg/d.
iii.Use caution when prescribing higher-dose aspirin therapy in older adults. See geriatrics discussion under Individual Considerations.
2.Additional pharmaceutical therapies:
a.Hypertensive therapy:
i.BP goal: Less than 140/90.
b.Hyperlipidemia therapy:
i.Low-density lipoprotein cholesterol (LDL-C) goal (primary): Less than 100 mg/dL.
ii.LDL-C goal (secondary): Less than 70 mg/dL.
c.Tobacco cessation therapy.
E.Surgical therapies:
1.CEA:
a.Goal of therapy: Stroke risk reduction.
b.Preferred clinical characteristics:
i.Recent TIA or CVA within 6 months and ipsilateral stenosis between 70% and 99% (severe):
•CEA is recommended.
•Morbidity/mortality: Less than 6%.
ii.Recent TIA or CVA within 6 months and ipsilateral stenosis between 50% and 69% (moderate):
•CEA is recommended after analysis of other factors that include age, gender, and comorbidities.
•Morbidity/mortality: Less than 6%.
iii.Ipislateral stenosis less than 50%:
•No indication for CEA surgery.
c.Pharmaceutical therapy and CEA:
i.Aspirin:
•Recommendations: Take prior to CEA surgery and for at least 3 months postoperatively unless contraindicated.
•Dosage: 81 to 325 mg/d.
ii.Other available antiplatelet agents do not have standardized dosage or frequency regimens established for postoperative CEA patients.