Carotid artery disease

Pathological features:

• ~80% of all strokes are ischaemic rather than haemorrhagic
• Of these, as many as 50% are caused by atherosclerosis at the carotid artery bifurcation
• This leads to either distal or thrombotic occlusion

Symptoms:

Amaurosis fugax:

Microembolism to the eye leads to ipsilateral transient loss of vision

Described as a black curtain coming across the eye

Usually lasts from a few seconds to a few minutes

A larger embolus may cause permanent blindness due to a retinal infarct

Embolisation to the middle cerebral artery leads to hemispheric symptoms:

Usually a contralateral hemiparesis

Loss of speech (if the dominant hemisphere is affected)

Transient ischaemic attack (TIA): A focal neurological deficit lasting less than 24 hours. The major complication of carotid artery disease is a stroke

Signs:

• The neurological findings and their duration are consistent with the size of the area of brain affected

Diagnosis and intervention:

• Carotid artery stenosis may be visualised by angiography, but this technique may be associated with a 1-2% stroke rate and is not suitable as a first-line investigation
• Colour-flow duplex scanning can give accurate information on the presence and degree of stenosis
• A CT brain scan before operation is commonly done to define the presence of pre-existing cerebral damage or to exclude other pathology

Management:

Indications for carotid endarterectomy (CEA):

• In cases of amaurosis fugax, TIA or stroke with good recovery plus an internal carotid artery stenosis of >70%, the risk of future stroke is significantly reduced by CEA carried out as a supplement to best medical therapy alone
• Most stenoses <70% should be treated medically.

Technique for CEA:

• The major complication of CEA is a stroke
• The benefits of the operation depend crucially upon a low perioperative stroke rate, which should be less than:
• 7.5% after a previous stroke
• 5% in amaurosis fugax or TIA
• 3% in those who are asymptomatic

Balloon angioplasty:

• Early data suggests that the immediate complication rate from endovascular treatment is higher than that associated with CEA