Carotid atherosclerosis is one of the main risk factors for ischaemic cerebrovascular events (CVEs). Carotid aherosclerosis causes about 90% of carotid artery stenosis but other much less common causes include aneurysms, arteritis, carotid dissection, coils and kinks, fibromuscular dysplasia and vasospasm.
The area of the carotid artery most commonly affected by atherosclerosis is the bifurcation of the common carotid artery.
Carotid endarterectomy is strongly recommended for severe symptomatic stenosis but not routinely recommended for asymptomatic patients or lesser degrees of stenosis. Trials define symptomatic patients as those having transient ischaemic attacks (TIAs) or minor strokes within three months of entry into the trial.
Moderate-to-severe asymptomatic carotid atherosclerotic stenosis occurs in 2-5% of European women and 2-8% of European men aged over 60 years. The prevalence is much higher in high-risk groups.
- Increasing age.
- High systolic blood pressure.
- Total cholesterol.
- Patients may present with TIAs or CVEs.
- Typical symptoms are contralateral weakness or sensory disturbance, ipsilateral loss of vision, and (if the dominant hemisphere is involved) dysphasia, aphasia or speech apraxia.
- Cognitive impairment and decline may be associated with asymptomatic stenosis of the left internal carotid artery.
- Asymptomatic patients may be identified when a carotid bruit is heard on physical examination or incidentally on imaging.
- Detection of a carotid bruit is a common physical examination finding that may lead to a referral for carotid duplex ultrasound.
- Carotid bruits are not sensitive or specific enough to confirm or exclude significant carotid stenoses.Absence of carotid bruit in patients with cardiovascular disease does not exclude a carotid stenosis.
- A carotid 'bruit' may also be caused by a cardiac murmur transmitted to the neck or may be due to stiff, calcified or tortuous vessels in the absence of stenosis.
- Colour duplex ultrasound is a safe and effective initial investigation to characterise the atheroma and quantify luminal stenosis. However, although colour duplex ultrasound has high sensitivity, it only has moderate specificity.
- Further assessment, such as using multidetector CT angiography or MR angiography, is recommended prior to endarterectomy.
- Other investigations include:
- FBC, electrolytes, renal function, lipid profile.
- Electrocardiogram: evidence of prior myocardial infarction and ischaemic changes (the most common cause of mortality following carotid endarterectomy is myocardial infarction).
- CT scan or MRI of the brain: for all symptomatic patients, in order to rule out other intracranial lesions and identify the presence of new and old cerebral infarcts.
- Guidance from the Royal College of Physicians (RCP) advises initial non-invasive carotid imaging with either duplex ultrasound or angiography (can be CT or MR). If significant stenosis is detected, a second imaging test should be performed. This should also be non-invasive - eg, MR angiography or a second ultrasound.
Carotid arterial stenosis is associated with all presentations of cardiovascular disease (including CVEs, angina, acute coronary syndrome and peripheral arterial disease) as well as conditions predisposing to cardiovascular disease (including diabetes mellitus, hypertension and hyperlipidaemia).
Best medical management of carotid stenosis includes lowering of blood pressure, treatment with statins and antiplatelet therapy in symptomatic patients.See also the separate Stroke Prevention and Prevention of Cardiovascular Disease articles.
- Carotid endarterectomy (surgical removal of the fatty deposits and blood clots from inside the carotid artery wall):
- A Cochrane review found:
- Endarterectomy is of some benefit for 50-69% symptomatic stenosis and highly beneficial for 70-99% stenosis without near-occlusion.
- Benefit in patients with carotid near occlusion is marginal in the short term and uncertain in the long term.
- The results only included surgically fit patients operated on by surgeons with low complication rates.
- The benefit from endarterectomy depended not only on the degree of carotid stenosis but also on several other factors, including the delay to surgery after the presenting event.
- Despite a 3% perioperative stroke or death rate, carotid endarterectomy for asymptomatic carotid stenosis reduces the risk of any stroke by approximately 30% over three years. However, the absolute risk reduction is small (1% per annum over the first few years of follow-up in trials).
- Indications include:
- Carotid endarterectomy should be considered if the symptomatic internal carotid artery is greater than or equal to 50% stenosed.
- Symptomatic patients with 50-99% stenosis on duplex ultrasound should be referred urgently for consideration of confirmatory imaging and endarterectomy. It is recommended that surgery is performed within one week and ideally within 48 hours, when stroke is most common and the benefit from endarterectomy is greatest.
- The RCP recommends that surgery or angioplasty/stenting should not be routinely performed for patients with asymptomatic carotid artery stenosis unless as part of a randomised trial.
- Carotid angioplasty and stenting:
- Stenting with the use of an emboli protection device is a less invasive revascularisation strategy than endarterectomy in carotid artery disease. For patients with severe carotid artery stenosis and co-existing conditions, carotid stenting with the use of an emboli protection device appears to be as safe and as effective as carotid endarterectomy.[4, 8]
- One meta-analysis has reported that carotid endarterectomy is superior to endovascular treatment for short-term outcomes. However, stenting was associated with significantly fewer cranial nerve and myocardial complications.
- One study, however, has shown that angioplasty can be as effective as carotid endarterectomy over three years at preventing stroke, with similar major risks.
Studies have found that ipsilateral stroke rates associated with asymptomatic carotid stenosis are less than 1% a year. However, there is a greater risk of death from coronary heart disease.
For primary prevention of cardiovascular disease, see the separate article Cardiovascular Risk Assessment.
Further reading and references
; Diagnosis and management of carotid atherosclerosis. BMJ. 2013 Mar 18346:f1485. doi: 10.1136/bmj.f1485.
; Carotid stenosis and the cognitive function. J Neurol Sci. 2009 Aug 15283(1-2):36-40. doi: 10.1016/j.jns.2009.02.307. Epub 2009 Mar 9.
; Carotid bruits as predictor for carotid stenoses detected by ultrasonography: an observational study. BMC Neurol. 2008 Jun 248:23.
; Royal College of Physicians (2012)
; The evidence for medicine versus surgery for carotid stenosis. Eur J Radiol. 2006 Oct60(1):3-7. Epub 2006 Aug 21.
; Carotid endarterectomy for symptomatic carotid stenosis. Cochrane Database Syst Rev. 2011 Apr 13(4):CD001081.
; Carotid endarterectomy for asymptomatic carotid stenosis. Cochrane Database Syst Rev. 2005 Oct 19(4):CD001923.
; Protected carotid-artery stenting versus endarterectomy in high-risk patients. N Engl J Med. 2004 Oct 7351(15):1493-501.
; Short term and intermediate term comparison of endarterectomy versus stenting for BMJ. 2010 Feb 12340:c467. doi: 10.1136/bmj.c467.
; Restenosis after carotid angioplasty, stenting, or endarterectomy in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS). Stroke. 2005 Feb36(2):281-6. Epub 2005 Jan 13.