Extracranial cerebrovascular disease

Question 1

Describe the posterior circulation of the brain

Answer 1

Two vertebral arteries originate from the first part of the subclavian arteries. These join intra-cranially to form the basilar artery and supply the posterior cerebral circulation. This is the main blood supply to the brain stem, cerebellum and posterior cerebrum

Question 2

Describe the anterior circulation of the brain

Answer 2

Both internal carotid arteries arise from the carotid bifurcation in the neck. Intra-cranially the internal carotid arteries form the middle cerebral arteries

Question 3

Definition of a stroke

Answer 3

• Acute focal ischaemia or infarction of the brain secondary to vascular insufficiency
• Symptoms exceeding more than 24 hrs or lead to death

Question 4

Definition of transient ischaemic attack

Answer 4

• Temporary focal ischaemia of the brain secondary to vascular insufficiency with symptoms lasting less than 24 hours
• Majority of TIAs last less than 10 mintutes

Question 5

Definition of amaurosis fugax

Answer 5

• ‘Fleeting blindness’ Temporary retinal artery ischaemia

- Symptoms described as curtain coming down over the eye

Question 6

What are the two main types of strokes

Answer 6

• Ischaemic (80 percent)

- Hemorrhagic (15-20%)

Question 7

Causes of ischaemic strokes

Answer 7

• Embolisation or occlusion of an artery that supplies the brain - 25 %
• Atherosclerosis of large arteries (75% of ischaemic strokes)
• Small vessel occlusion (usually secondary to hypertension) - 10%

Question 8

Causes of haemorrhagic stroke

Answer 8

• Primary intracranial haemorrhage

- Subarachnoid haemorrhage

Question 9

List possible extracranial arterial pathology that may affect brain perfusion

Answer 9

• Atherosclerosis
• Fibromuscular dysplasia
• Aneurysms
• Dissection
• Arteritis (Giant cell and Takayasu’s)
• Carotid body tumours

Question 10

What are the two theories of how atherosclerosis at the carotid bifurcation may lead to strokes and TIAs

Answer 10

• Embolic theory: Embolisation of atherosclerotic or thrombotic material to the brain. Likelihood of embolisation or occlusion of the ICA increases with degree of stenosis
• Haemodynamic theory: Tight stenosis or occlusion of the ICA and incomplete collateral circulation leads to risk of cerebral hypoperfusion that can result in a TIA or stroke

Question 11

Bruits in the neck may indicate carotid artery disease; what are the differentials for bruit in the neck

Answer 11

Need to distinguish bruits that originate from the carotids and those radiating from the heart or great vessels

Question 12

Clinical presentation of symptomatic extracranial cerebrovascular disease (Excluding when the verterbrobasilar system is involved)

Answer 12

• Symptoms may be transient (TIA or amaurosis fugax) or more permanent (stroke)
• Focal or global
• Anterior or posterior circulation affected
• Motor and sensory symptoms are usually focal and involve the contralateral limbs
• Dysphasia and contralateral cranial nerve palsies

Question 13

What are the symptoms if the vertebrobasilar system is involved

Answer 13

-Symptoms may be less specific and may include limb weakness, bilateral visual disturbance (blurring, graying, double vision), ataxia, dizziness, vertigo or bradycardia, drop attacks, numbness or tingling and slurred or loss of speech

Question 14

What symptoms are more associated with intracranial haemorrhage or space-occupying lesion

Answer 14

Headache and loss of consciousness

Question 15

General medical evaluation of a patient presenting with neurological symptoms

Answer 15

• Blood pressure
• ECG
• Renal function, lipid and glucose levels
• Coagulopathy screening when appropriate

Question 16

First line diagnostic test to evaluate the carotid arteries?

Answer 16

Duplex doppler

Question 17

Imaging used to identify intracranial haemorrhage or space-occupying lesions

Answer 17

CT angiogram or MRI

Question 18

What are the parameters of the ABCD2 stroke risk score

Answer 18

• Age: greater than or equal to 60 = 1
• Blood pressure: SBP >=140 / DBP>=90 = 1
• Clinical features: focal weakness (=2) or speech impairment without local weakness (=1)
• Duration of symptoms: >= 60 mins (=2); <=59 mins (=1)
• Diabetes = 1

Question 19

What is the risk of another CVA at two days in a patient with an ABCD2 score of 6-7; and what should happen to these patients

Answer 19

• 8.7 % risk

- They should get urgent carotid duplex and possible intervention if warranted

Question 20

When should DSA be done?

Answer 20

• Ultrasound findings uncertain

- Aortic arch and other branch vessels need to be assessed for the planning of carotid artery stenting

Question 21

which risk factors should be controlled as part of the treatment of extracranial carotid artery disease

Answer 21

• Hypertension
• Diabetes
• Cholesterol
• Smoking cessation
• Aspirin is also administered to reduce the risk of future TIAs

Question 22

How should patients with a focal neurological event within the last 6 months with a residual ICA stenosis of more than 70 % be treated?

Answer 22

Carotid endarterectomy

Question 23

What should one consider before offering surgery to an asymptomatic patient with high grade ICA stenosis

Answer 23

-Patient’s fitness and life expectancy (>5years) and surgical complication risks (<3%)

Question 24

Steps in a carotid endarterectomy

Answer 24

• Carotid bifurcation exposed (longitudinal incision made along medial border of sternocleidomastoid)
• Internal jugular vein mobilized laterally to enter the carotid sheath
• Dissection continued proximally to expose the carotid bulb, internal and external carotid arteries
• Systemic heparin given
• Assess stump pressure
• Longitudinal ateriotomy is made from common carotid to internal carotid across the stenotic lesion
• Diseased intima and proximal media are then carefully removed from the remainder of the vessel wall
• Arteriotomy is then sutured closed using a prothetic Dacron or vein patch
• Platysma and skin are closed after haemostasis has been achieved

Question 25

What nerve runs over the internal and external carotid arteries

Answer 25

-Hypoglossal

Question 26

What are the requirements for stump pressures to perform a carotid endarterectomy without a shunt to maintain inline cerebral flow?

Answer 26

Stump pressure should be more than 50 mmHg with a pulsatile trace

Question 27

Which patients is carotid angioplasty limited to?

Answer 27

• Patients with symptomatic fibromuscular dysplasia of the carotid artery
• Symptomatic patients with high grade ICA stenosis who would not tolerate surgery
• Patients with previous neck surgery or radiation
• Patients with late restenosis of the ICA post carotid endarterectomy

Question 28

Procedure related complications of carotid angioplasty and stenting

Answer 28

• Ipsilateral ischaemic stroke from embolisation during the procedure
• Labile blood pressure and hypertension
• Acute coronary syndrome
• Death
• Local neck haemorrhage/ haematoma
• Nerve injuries: Vagus, recurrent laryngeal, hypoglossal, glossopharyngeal

Question 29

Pathology of vertebrobasilar insufficiency

Answer 29

• atherosclerosis commonest cause

- Rarely, arterial damage secondary to vertebral artery compression

Question 30

Uses and limitations of duplex doppler in vertebrobasilar insufficiency

Answer 30

• useful in assessing the first and second part of the vertebral artery but cannot visualize entire artery and is therefore not as sensitive as CTA/ MRA

Question 31

Limitations of CTA and MRA

Answer 31

• Subjects patients to radiation (CTA)
• Nephrotoxic contrast agent (CTA and MRA)
• Inaccurate for heavily calcified stenosis (MRA and CTA)

Question 32

When is enarterectomy performed in vetebrobasilar insufficiency

Answer 32

• Performed for focal, ostial or para-ostial vertebral lesion

Question 33

When is bypass grafting or direct arterial transpostion performed in vetebrobasilar insufficiency

Answer 33

-Performed for longer lesions, particularly diseased V2 segment of the vertebral artery

Question 34

When are endovascular procedures performed in vetebrobasilar insufficiency

Answer 34

• Shorter lesions
• Unfit patients
• Lesion is diffucult or not accessible to open surgery