Carotid Artery Stenosis

Question 1

Carotid artery stenosis

Answer 1

A narrowing of the lumen of the carotid artery.

Atherosclerotic plaque in the cervical carotid artery is the most common cause. At risk of embolisation to cause TIA/stroke.

Question 2

What is the epidemiology of carotid artery stenosis?

Answer 2

Carotid artery stenosis is the most common preventable cause of stroke

Approximately 10% to 15% of all ischaemic strokes are associated with carotid artery stenosis.

Asymptomatic CAS affects ~7% of women and 12% of men aged >70 age.

Question 3

What is the aetiology of carotid artery stenosis?

Answer 3

• Atherosclerosis in the cervical carotid artery. The unique haemodynamics at the carotid bifurcation predispose this area to atherosclerosis. Some plaques rupture and embolise→ TIA or stroke or occlude retinal arteries (to cause transient monocular blindness or retinal strokes).
• Other less common causes: radiation arteritis, spontaneous or traumatic dissection, and fibromuscular dysplasia.

Question 4

How do you classify CAS based on degree of stenosis?

Answer 4

1. mild stenosis = <50% diameter reduction
2. moderate stenosis = 50-69% obstruction
3. haemodynamically significant or high-grade stenosis = 70-99%
4. near-occlusion = tight and long stenosis from bifurcation to base of skull ~>95% with collapse of the internal carotid artery sometimes called a string sign or pseudo-occlusion
5. occlusion

Question 5

What are the clinical features of carotid artery stenosis?

Answer 5

Asymptomatic

Cervical bruit - associated with presence of bruits with a carotid stenosis of any severity in 47% of patients

Stroke or TIA

Transient visual symptoms - amaurosis fugax, homonymous hemianopia, loss of vision on exposure to bright light, neovascularisation of iris, complete blindness

Question 6

What are the risk factors for carotid artery stenosis?

Answer 6

• old age - >65yrs
• smoking
• cardiovascular disease
• hypertension
• hypercholesterolaemia

Question 7

What investigations would you do for carotid artery stenosis?

Answer 7

Carotid duplex ultrasonography - no screening programme as it has low prevalence; shows elevated velocity and plaque

CTA - cheaper than MRA

MRA head/neck

CT brain - for complications

Question 8

What is the management of asymptomatic CAS?

Answer 8

Medical therapy - 1st line in <70% stenosis

• Antiplatelet (aspirin)
• Lifestyle measures - stop smoking
• Manage HTN, hypercholesterolaemia - high intensity statin

Question 9

What is the management of symptomatic carotid artery stenosis?

Answer 9

e.g. TIA, stroke, transient monocular blindness

• Refer to specialist urgently
• Antiplatelet (aspirin) - +/- clopidogrel/dipyrimadole
• Endarterectomy - if stenosis _>_50%, within 2 weeks
• Carotid stenting - this is more risky than the above especially in older patients; dual antiplatelet for 3 months then aspirin lifelong
• High intensity statin therapy - aim <1.8mmol/L

Manage other risk factors as for asymptomatic.

Question 10

In bilateral CAS, in a right handed person, which artery is treated first?

Answer 10

Left

Question 11

What is the prognosis with CAS?

Answer 11

<1% of patients per year have a stroke after carotid endarterectomy

6% restenosis rate after 2 yrs of procedure

Question 12

What are the complications of CAS?

Answer 12

• Stroke if untreated or after endarterectomy or stenting
• MI
• Haematomas and access site bleeding
• CN injuries - hypoglossal, vagus, and glossopharyngeal nerves occur in about 6% of patients after surgery
• Cerebral hypoperfusion syndrome
• Post-operative cerebral haemorrhage - due to anticoagulation/antiplatelets

Question 13

Which cranial nerves are at risk during carotid artery surgery?

Answer 13

Hypoglossal

Vagus

Glossopharyngeal