Carotid Arterial Disease

• atheroma affects the bifurcation of the carotid artery
• up to 30% of strokes result from emboli from or disease in major extracranial vessels.

Incidence

• annual event rate 258/100 000
• Causes 10% of deaths w/ 31% of pts dying and 35% remaining dependent
• M > F
• 50% > 75 y.o.

Risk Groups

• male
• increasing age
• degree of internal carotid a stenosis ( esp >70%)
• HT – systolic > 180mmHg, diastolic > 100mmHg
• Type II diabetes
• Hypercholesterolaemia, hyperlipidaemia
• Smoking

Pathogenesis

– May be:

1. emboli from an ulcerated plaque at the common carotid bifurcation (90%)
2. occlusion of the carotid bifurcation when circle of Willis perfusion is inadequete (10%)

Clinical Features

• Asymptomatic
  • neck bruit (1/3 indicate stenosis, 1/3 radiate from distant site, 1/3 insignificant)
• Symptomatic
  • may cause TIA’s
  • Clinical criteria: ischaemic neurological symptoms that resolve completely within 24 hours after onset
  • Radiological criteria: presence of ischaemic neurological symptoms without evidence of infarction on central nervous system (CNS) imaging
  • amaurosis fugax (sudden loss of vision)
  • fleeting paraesthesia in limbs
  • temporary paralysis
  • loss of cerebral functions such as speech
  • fundoscopy –may be platelet embolus w/in retinal vessels

• Complications 
  • Stroke
  • Clinical criteria: ischaemic neurological symptoms persisting for a period of >24 hours
  • Radiological criteria: presence of infarction on CNS imaging

Vascular territories involved in neurological ischaemia with some of the commonly observed clinical symptoms and signs
Vascular territory	Commonly involved vessels	Common clinical symptoms and signs
Anterior circulation	Internal carotid artery Anterior cerebral artery Middle cerebral artery Retinal artery	Contralateral hemiparesis – weakness involving the face, upper limb and/or lower limb on the opposite side as the cerebral hemisphere involved Contralateral hemiparesthesia – abnormal or impaired sensation involving the face, upper limb and/or lower limb on the opposite side as the cerebral hemisphere involved Dysphasia (if the dominant cerebral hemisphere is involved) – loss of the ability to speak Ipsilateral mono-ocular vision loss – complete loss of vision in a single eye. This may be transient (amaurosis fugax) or permanent.
Posterior circulation	Vertebral artery Basilar artery Cerebellar arteries Posterior cerebral artery	Homonymous hemianopsia – visual field loss in either the right or left half of both eyes Limb and gait ataxia – loss of coordination of the limbs and uncoordinated walking Vertigo – spinning sensation associated with nausea and vomiting Cranial nerve palsies – dysfunction of cranial nerves III–XII

Investigations

• FBC 
• Hemotology: anemia might precipitate SSx
• Biochem(UEC): renal function for undetected renal Dz
• Glucose: exclude DM
• Lipids
• ECG- AF? Cardiac Dz, previous infarcts, LV dysfunction

Special:

• Carotid Duplex Doppler ultrasound and angiography – to determine degree of stenosis
• CT/MRI – haemorrhage or infarction
• Carotid Angiogram -2% stroke risk

Management

• Treat risk factors
• HT
• DM
• Lipids
• Smoking
• Excessive weight

Antiplatelet therapy – 12% advantage in preventing CVA; Aspirin 150-300mg daily

Mx of 30 – 70% stenosis

• Carotid endarterectomy 
  • if
    • >70% stenosis OR
    • bilateral vessel disease (>50%)  and symptomatic OR
    • atheromatous ulceration with uncontrolled SSx
  • Here the atheromatous plaque of intima, media and fibrous tissue is dissected free from the adventitia to leave a thin walled vessel over the segment of the endarterectomy.
  • Usually distal point is smooth but may need to be sutured to prevent intimal flap to be raised with blood flow.
  •  HT is controlled prior to surgery and anticoagulants are ceased. 
  • Aspirin is continued after surgery
  • Complications
    • Emboli
    • Nerve palsies(hypoglossal nerve palsy)
    • Numbness of IL earlobe
    • Wound haematoma
    • Rarely wound infection and respiratory complications. 
    • Operative risk of stroke 2%
    • Operative mortality 2%
  • Prognosis – 95% at 5 years with surgery and 85% for medically treatment.