18-09-23 – Blood supply and stroke

Question 1

Learning outcomes

Answer 1

• Describe the anterior and posterior circulations and explain their clinical significance
• List the branches of vertebral and carotid arteries, describe their courses and the regions of the brain supplied by them.
• Describe the blood supply of the brain stem.
• List the deficits caused by stroke in the territories of major vessels
• Recognise stroke syndromes and their mimics
• Be aware of the primary and secondary prevention factors for stroke
• Differentiate acute, subacute and chronic stroke on medical images
• Explain the medical treatment of stroke

Question 2

What is the weight of the brain vs its received cardiac output?

What are the sources of arterial blood to the brain?

Answer 2

• The brain accounts for 2% of the body’s weight, yet gets 15% of cardiac output
• The brain has 2 sources of arterial blood that are connected (anterior and posterior)

Question 3

Arterial supply to the brain

Answer 3

Question 4

What supplies the anterior circulation of the brain?

What 2 structures are supplied by the anterior circulation?

What are the 3 main branches of the internal carotids that supply the brain?

Where is it easier to remove plaques?

Answer 4

• The internal carotid arteries supply the anterior circulation of the brain
• 2 structures are supplied by the anterior circulation:
  1) Anterior 3/5 of the cerebrum
  2) Diencephalon
• 3 main branches of the internal carotids that supply the brain:
  1) Middle cerebral artery (MCA)
  2) Anterior cerebral artery (ACA)
  3) Perforating branches (choroidal, lenticulostriate arteries (LSAs), etc)
• It is easier to remove plaques (Endarterectomy) from the anterior circulation

Question 5

What supplies the posterior circulation of the brain?

What 4 structures does the posterior circulation of the brain supply?

What are the 4 main branches of Vertebrobasilar arteries?

Answer 5

• The Vertebrobasilar arteries supply the posterior circulation of the brain
• 4 structures the posterior circulation of the brain supplies:
  1) Brainstem
  2) Cerebellum
  3) Posterior 2/5 of cerebrum
  4) Diencephalon
• 4 main branches of Vertebrobasilar arteries:

1) Cerebellar (PICA, AICA, SCA)
* CA – cerebellar artery

2) Pontine

3) Posterior cerebral arteries

4) Striate & thalamic branches

Question 6

What are the main arterial supplies to the midbrain, pons, and medulla?

Where are sensory and motor fibres located in the brainstem?

What does this mean in terms of artery damage/ischaemia?

Answer 6

• Main arterial supplies:
• Midbrain
• Basilar; posterior cerebral; posterior communicating; superior cerebellar
• Pons
• Basilar; anterior inferior cerebellar
• Medulla
• Vertebral; anterior & posterior inferior cerebellar; anterior spinal & posterior spinal
• Sensory fibres/nuclei are located in the lateral brainstem, while motor fibres are located in the medial/middle of the brainstem
• This means artery damage/ischaemia will affect different functions depending on where it is

Question 7

Blood supply to the brain summary. What does the LSA supply?

Answer 7

• Lenticulostriate arteries (LSAs) supply deep structures – thalamus, basal nuclei, internal capsule etc

Question 8

How is the brain well-adapted to keep cerebral blood flow in an optimal range?

What happens if there is decreased/increased blood flow to the brain?

Answer 8

• Blood vessels in the brain respond locally to changes in blood pressure to maintain steady and safe flow rate – Autoregulation
• If there is decreased blood flow to the brain there will be:
  1) Impaired dilation
  2) Artery collapse
  3) Ischaemia
• These will lead to stroke
• If there is increased blood flow to the brain there will be:
  1) Force-mediated dilation
  2) Increased flow
  3) Vasogenic oedema
• These will lead to stroke

Question 9

What causes steal syndrome?

Answer 9

• Steal syndrome is caused by subclavian stenosis proximal to the origin of the vertebral artery
• In this case, the subclavian artery steals reverse-flow blood from the vertebrobasilar artery circulation to supply the arm during exertion, resulting in vertebrobasilar insufficiency.

Question 10

What are 5 signs of a stroke?

Answer 10

• 5 signs of a stroke:
  1) Sudden onset
  2) Facial asymmetry
  3) Speech disturbance (Dysphasia)
  4) Asymmetrical weakness in muscles
  5) Onset may be subtle, may be in coma

Question 11

What is the cause of a stroke?

How long do symptoms of a stroke last?

What is the cause of a Transient ischaemic attack (TIA)?

How long do TIA symptoms last?

Can TIAs be prevented?

Answer 11

• A stroke is caused by Interruption of the blood supply to a focal part of the brain causing loss of neurological function
• Symptoms last >24 hours or lead to death with no apparent cause other than that of vascular origin
• A transient ischaemic attack (TIA) has the same cause as a stroke
• Symptoms of TIA last <24 hours
• With TIA, there is an element of prevention, which is far more cost-effective than a stroke

Question 12

What are the 3 classifications of stroke?

What % of strokes are made up of each class?

Answer 12

• 3 classifications of stroke:
• Ischaemic: 80-85% of strokes
• Haemorrhagic: 15%
• Subarachnoid haemorrhage: 5%

Question 13

What are 5 causes of Haemorrhagic stroke?

Answer 13

• 5 causes of Haemorrhagic stroke:
  1) Hypertension
  2) Tumour
  3) Bleeding disorders
  4) Vascular malform (AVM – Arteriovenous malformation)
  5) Amyloid angiopathy

Question 14

What is primary damage?

What is the primary brain damage from haemorrhagic stroke?

How soon does it occur?

What 5 factors contribute to secondary brain damage from haemorrhagic stroke?

Answer 14

• Primary damage is damage that affects the anatomy
• The primary brain damage from haemorrhagic stroke is mechanical damage associated with the mass effect
• Primary brain damage occurs within minutes to hours from the onset of bleeding
• The secondary brain damage from haemorrhagic stroke is contributed to by:
  1) Oedema
  2) Oxidative stress and
  3) Inflammation
  4) Comorbidities (other simultaneous conditions)
  5) Age

Question 15

What is ischaemic stroke caused by?

What are 4 sources of interruption of blood flow in ischaemic stroke?

Answer 15

• Ischaemic stroke is caused by interruption of blood flow to the brain
• 4 sources of interruption of blood flow in ischaemic stroke:

1) Large vessel atheroma/thrombosis

2) Small vessel disease
* Can be from diabetes, smoking, high BP

3) Hypoperfusion

4) Cardio-embolism
* E.g patient with atrial fibrillation, valve disease, endocarditis, causes a clot to appear in the chambers
* With asystole, this clot can go anywhere in the body, including a brain, causing an ischaemic stroke

Question 16

What type of stroke is lacunar stroke?

Answer 16

• Lacunar stroke is a type of ischaemic stroke
• In lacunar stroke, the lenticulostriate arteries (LSA) become blocked, causing necrosis
• This results in the necrosed tissues being resorbed, leaving behind cavities

Question 17

Ischaemic stroke progression.

What exists around in the ischaemic core in an ischaemic stroke?

Answer 17

• Ischaemic stroke progression.
• Around the ischaemic core of an ischaemic stroke, there are penumbra, which are areas of salvageable damage
• It is the doctor’s job to try and keep these areas alive

Question 18

What are watershed areas (border zones)?

What are these most vulnerable to?

When can watershed infarcts especially occur?

What are the 3 border zones?

Answer 18

• Watershed areas (border zones) are neighbouring areas supplied by different cerebral arteries
• The watershed areas are most vulnerable to hypoperfusion
• Watershed infarcts can occur especially if the blood pressure drops very rapidly (Malpractice?)
• 3 border zones:

1) Cortical border zone
* Between ACA and MCA

2) Internal border zone
* Between LCA and MCA

3) Cortical border zone
* Between MCA and PCA

Question 19

Describe the neural circuitry loss due to ischaemic stroke (in picture).

What 4 vessels are most often responsible for ischaemic stroke?

Which ischaemic stroke are preventable?

Answer 19

• Neural circuitry loss due to ischaemic stroke (in picture)
• 4 vessels most often responsible for ischaemic stroke:
  1) 51% MCA
  2) 13% small vessels
  3) 7% ACA
  4) 5% PCA
• Ischaemic strokes from small vessels are often preventable, provided we treat the diabetes, hypertension, smoking etc. that causes this small vessel damage

Question 20

MCA (middle cerebral artery) occlusion - the most common artery involved in acute stroke.

Answer 20

Question 21

What is the FAST tests?

Answer 21

• The FAST tests help us recognise the most common signs of stroke:
• Facial weakness: Can the person smile? Has their mouth or eye drooped?
• Arm weakness: Can the person raise both arms?
• Speech problems: Can the person speak clearly and understand what you say?
• Time to call 999: if you see any of these signs.
• Also need to check the blood glucose

Question 22

What are 7 things we want to know about a stroke?

Answer 22

• 7 things we want to know about a stroke:
  1) Is it a stroke?
  2) What type of stroke is it?
  3) Which part of the brain is affected?
  4) What caused the stroke?
  5) What is the prognosis?
  6) What are the risk factors?
  7) What are the functional + emotional consequences?

Question 23

What are 6 potential presenting symptoms and signs of stroke from least to most common?

Answer 23

• 6 potential presenting symptoms and signs of stroke from least to most common:

1) Diplopia – double vision

2) Ataxia - a term for a group of disorders that affect co-ordination, balance and speech

3) Hemianopia – loss of one half of vision field

4) Speech

5) Sensory

6) Motor

Question 24

Describe the assessment for stroke.

Answer 24

• Assessment for stroke
• Airway
• Breathing
• Circulation
• Clarify the history!!
• Past medical history: Conditions, Medications
• Check the signs
• Level 1 investigations

Question 25

What are 9 parts of the examination in vascular neurology?

Answer 25

• 9 parts of the examination in vascular neurology:

1) BP and pulse measurement in 2 arms

2) Level of consciousness (Glasgow Coma Score; document progress)

3) Cardiac and carotid bruits

4) Blood glucose level

5) Neck stiffness/meningism (Kernig’s/Brudzinski signs)

6) Abnormal or involuntary movements

7) Any seizure-like activity

8) Skin rash/infarcts e.g. vasculitic, papular rash.

9) Specific neurological exam
* Eye movements (gaze preference, fixed deviation)
* Speech, visual fields, inattention, motor & sensory
* Gait assessment

Question 26

What are 3 ways strokes are classified?

Answer 26

• 3 ways strokes are classified:

1) Oxford Community Stroke Project (OCSP)
* Based on clinical signs:
* Total anterior circulation syndrome
* Partial anterior circulation syndrome
* Lacunar syndrome
* Posterior circulation syndrome

2) TOAST classification
* Mechanism (e.g. large vessel, small vessel, cardioembolic)

3) Carotid or vertebrobasilar territory

Question 27

Describe the OCSP classification for strokes

Answer 27

• Oxford Community Stroke Project (OCSP) classification for strokes:
• Based on clinical signs:

1) Total anterior circulation syndrome (TACS)
* Motor / Sensory pathways (muscle power, sensation)
* triad of hemiparesis (or hemisensory loss), dysphasia (or other higher cortical function) and homonymous hemianopia

2) Partial anterior circulation syndrome (PACS)
* Visual pathways (field of vision)
* 2 of the features of TACS or isolated dysphasia or parietal lobe signs (e.g. inattention, agnosia, apraxia, agraphaesthesia, alexia)

2) Lacunar syndrome (LACS)
* Higher cortical functions (Speech, spatial awareness)
* pure motor, pure sensory, sensorimotor, ataxic hemiparesis

4) Posterior circulation syndrome (POCS)
* Brainstem functions (swallowing, eye movements)
* brainstem, cerebellar and/or isolated homonymous hemianopia

Question 28

OCSP definitions (in picture)

Answer 28

Question 29

Describe the ABCD2 Assessment for stroke risk post TIA

Answer 29

• ABCD2 Assessment for stroke risk post TIA:
• 7 points score to predict early stroke risk post TIA:

1) Age [60 or above;=1]

2) Blood pressure [systolic > 140 and/or diastolic =/> 90; =1]

3) Clinical features [unilateral weakness = 2; speech disturbance w/o weakness = 1; other = 0] 

4) Duration of Symptoms in mins [=/> 60 =2; 10-59 =1; < 10 = 0) Diabetes = 1

• 2-day strokes scores/risk: 0-3 (1%), 4-5 (4%), 6-7 (8%)

Question 30

What are the 5 Ss for stroke mimics?

Answer 30

• 5 Ss for stroke mimics:

1) Seizures

2) Sepsis

3) Syncope - a loss of consciousness for a short period of time

4) SOL (tumour, subdural) - space-occupying lesion of the brain

5) Somatisation
* The tendency to experience psychological distress in the form of somatic symptoms and to seek medical help for these symptoms
* Somatic symptom disorder is diagnosed when a person has a significant focus on physical symptoms, such as pain, weakness or shortness of breath, to a level that results in major distress and/or problems functioning.
* The individual has excessive thoughts, feelings and behaviors relating to the physical symptoms

Question 31

What are 4 red flags for a stroke?

What symptoms may be present if there are no red flags present?

Answer 31

• 4 red flags for a stroke:
  1) History
  2) Risk factors
  3) Imaging abnormality
  4) Old age
• If these red flags are not present, symptoms may include seizures, or very unusual headaches

Question 32

What are 4 factors that are frequently overlooked with strokes?

What are 3 conditions that are frequently overlooked with strokes?

Answer 32

• 4 factors that are frequently overlooked with strokes:

1) History

2) Evolution of symptoms: Getting better or worse

3) Maximum deficit: How long did it take?

4) Drugs
* Newly prescribed
* OCP - oral contraceptives pills
* Recreational

• 3 conditions that are frequently overlooked with strokes:

1) Visuo-spatial or perceptual disorder

2) Truncal ataxia
* Truncal ataxia is a wide-based “drunken sailor” gait characterised by uncertain starts and stops, lateral deviations and unequal steps.
* It is an instability of the trunk and often seen during sitting.
* It is most visible when shifting position or walking heel-to-toe

3) Apraxias
* Apraxia is the loss of ability to execute or carry out skilled movement and gestures, despite having the physical ability and desire to perform them

Question 33

What are 6 common risk factors for strokes?

Answer 33

• 6 common risk factors for strokes:
  1) HT
  2) IHD
  3) Smoker
  4) PVD (peripheral vascular disease)
  5) TIA
  6) DM (diabetes mellitus)

Question 34

What 6 investigations should be conducted for stroke?

Answer 34

• 6 investigations should be conducted for stroke:
  1) Good history and examination
  2) ECG/ Holter (24 hr ECG), ECHO
  3) Cholesterol/autoimmune & thrombophilia screen
  4) Carotid doppler
  5) CT brain/MRI brain
  6) Cerebral angiography

Question 35

What are 7 indications for urgent head imaging?

Answer 35

• 7 indications for urgent head imaging:

1) Depressed level of consciousness

2) Unexplained progressive or fluctuating symptoms

3) Papilloedema, neck stiffness or fever

4) Severe headache at onset

5) History of trauma prior to onset

6) Indication for thrombolysis or anticoagulation

7) History of anticoagulant treatment or known bleeding tendency

Question 36

What are 3 advantages of CT head imaging?

What 3 pathologies in the brain can CT imaging show?

What is a disadvantage of CT imaging?

Answer 36

• 3 advantages of CT head imaging:
  1) Fast image acquisition
  2) Widely available
  3) Good at showing blood and bone
• 3 pathologies in the brain can CT imaging show:
  1) Cerebellar haemorrhage
  2) Another cause (tumour; SDH gene)
  3) Early ischemia
• A disadvantage of CT imaging is it is less sensitive

Question 37

CT image of stroke

Answer 37

Question 38

CT image of stroke

Answer 38

Question 39

What is an advantage of MRI imaging?

What are the 6 variants of MRI imaging?

What are 3 disadvantages of MRI imaging?

Answer 39

• An advantage of MRI imaging is Excellent soft tissue contrast
• 6 variants of MRI imaging:
  1) T1-weighted MRI
  2) T2-weighted MRI
  3) Perfusion MRI
  4) Diffusion Weighted Imaging
  5) Apparent Diffusion Coef. Imaging
  6) Flair
• 3 disadvantages of MRI imaging:
  1) Limited availability
  2) Longer to obtain images
  3) Contraindications

Question 40

Which MRIs are useless in the first 6 hours of a stoke?

What MRI imaging is used for a stroke?

Describe acute, subacute, and chronic strokes on an ADC and DWI MRI (in picture)

Answer 40

• T1 and T2 weighted MRIs are useless in the first 6 hours of a stroke, as they don’t show the pathology
• We can use ADC-MRI and DWI MRI and compare them in order to determine if a stroke is acute (0-7 days), subacute (8-21 days), or chronic (more than 21 days
• Acute, subacute, and chronic strokes on an ADC and DWI MRI (in picture)

Question 41

Stroke Summary

Answer 41

Question 42

Describe the 5 stages in the Immediate treatment of an ischaemic stroke

Answer 42

• 5 stages in the Immediate treatment of an ischaemic stroke:

1) Consider for thrombolysis

2) Supplemental oxygen only if sats below 95% and no contraindication

3) Aim blood glucose 5-15 mmol/litre

4) Swallow screen before any oral medication

5) Antihypertensives only if emergency (including if required for thrombolysis)

Question 43

Immediate treatment of an ischaemic stroke- thrombolysis.

Who is this conducted by? When will this occur?

What medications are used?

What should be done prior to thrombolysis?

Answer 43

• Immediate treatment of an ischaemic stroke- thrombolysis
• Only where staff are trained and experienced
• Within 4.5 hours of known onset- alteplase or tenecteplase
• At 4.5-9 hours of known onset AND evidence of the potential to salvage brain tissue - alteplase
• Prior to thrombolysis, blood pressure should be reduced to below 185/110 mmHg

Question 44

Immediate treatment of an ischaemic stroke-antiplatelets.

When this this be started?

What should be given for disabling acute ischaemic stroke?

Answer 44

• Immediate treatment of an ischaemic stroke-antiplatelets
• If thrombolysed, start anti-platelets after 24 hours unless contraindicated
• Disabling acute ischaemic stroke- aspirin 300 mg as soon as possible within 24 hours continued for 2 weeks
• Then switched to long-term antithrombotic

Question 45

TIA and minor stroke – antiplatelets.

When should secondary prevention of stroke begin?

How much aspirin should be given?

What should be given if there is a low bleeding risk?

What should be given if DAPT is not appropriate?

Answer 45

• TIA and minor stroke – antiplatelets
• If there is a high risk of further vascular events-start secondary prevention as soon as possible
• Aspirin 300mg immediately and assessed within 24 hours by a specialist
• Low bleeding risk: DAPT with clopidogrel plus aspirin for
  21 days OR ticagrelor plus aspirin for 30 days then
  switched to long-term antithrombotic
• If DAPT not appropriate, clopidogrel 300 mg loading dose
  followed by 75 mg daily

Question 46

What are 4 stages in the secondary prevention of ischaemic stroke?

Answer 46

• 4 stages in the secondary prevention of ischaemic stroke:
  1) Antiplatelet/anticoagulant
  2) Lifestyle factors (smoking, alcohol, diet, exercise)
  3) High intensity statin
  4) Blood pressure-lowering therapy

Question 47

Secondary prevention – Antiplatelets.

What antiplatelet medication should be given for secondary prevention?

What should be considered if there is a recurrent event on clopidogrel?

What is not recommended for long-term prevention?

When should the risk vs benefits for antiplatelet use be considered?

Answer 47

• Secondary prevention – Antiplatelets
• Clopidogrel antiplatelet 75 mg daily (aspirin 75 mg daily if cannot tolerate) for secondary prevention
• DAPT (dual antiplatelet therapy) is not recommended for long-term prevention
• For antiplatelet use in Ischaemic stroke with acute haemorrhagic transformation consider the risks vs. benefits
• Spontaneous intracerebral haemorrhage (ICH) already taking an antithrombotic may be restarted on antiplatelets beyond 24 hours depending on risks vs benefits

Question 48

Secondary prevention – Anticoagulants. When should anticoagulants be used instead of antiplatelets?

What should happen first before using anticoagulants in the case of hypertension of Minor stroke or TIA?

How long should anticoagulants be used for in mile to moderate to severe stroke?

What condition is DOAC first line treatment in?

When should Warfarin be used?

When should an antiplatelet be considered instead of an anticoagulant?

Answer 48

• Secondary prevention – Anticoagulants
• Ischaemic stroke or TIA AND atrial fibrillation or atrial flutter- oral anticoagulation instead of antiplatelet
• Severe hypertension should be treated first before starting anticoagulants
• Minor stroke or TIA - as soon as intracranial bleeding excluded, we can start anticoagulants
• Mild stroke - <5 days of anticoagulants if benefits outweigh the risks
• Moderate to severe stroke – anticoagulants for 5-14 days after onset
• DOAC (direct oral anticoagulants) is first line treatment in non-valvular AF
• In valvular/rheumatic AF or with mechanical heart valve replacement, and those with contraindications or intolerance to DOAC - warfarin (target INR 2.5, range 2.0 to 3.0)
• Agent with rapid onset recommended, so LMWH (Low molecular weight heparin) until target INR (international normalised ratio blood test) achieved if using warfarin
• If anticoagulation is inappropriate for reasons other than high risk of bleeding − antiplatelet may be considered

Question 49

Secondary prevention- lipids.

When should statins be used?

What should we begin with?

When should we use a lower dose?

When should we use an alternative statin?

What should we aim to reduce the fasting/non-fasting LDL-cholesterol to?

When should further investigations be conducted?

What should be done if there is no evidence of atherosclerosis?

Answer 49

• Secondary prevention- lipids
• Statin unless contraindicated or no evidence of atherosclerosis
• Begin with a high-intensity statin (e.g. atorvastatin 80 mg)
• Lower dose if medication interactions or high risk of adverse effects
• Alternative statin at the maximum tolerated dose if high-intensity statin unsuitable
• Aim to reduce fasting LDL-cholesterol to <1.8 mmol/L (non-HDL-cholesterol <2.5 mmol/L in a non-fasting sample)
• If not achieved after 4-6 weeks, further investigation and specialist advice on addition of other agents may be required
• If no evidence of atherosclerosis, lipid-lowering therapy on the basis of overall cardiovascular risk

Question 50

Secondary prevention – BP.

What clinical systolic BP should we consistently aim to achieve?

What anti-hypertensives should be used for Aged 55 or over, or of African or Caribbean origin?

What should be given if target blood pressure is not achieved?

What anti-hypertensives should be given to patients Not of African or Caribbean origin and younger than 55 years?

When should antihypertensives be initiated?

Answer 50

• Secondary prevention – BP
• Aim to consistently achieve a clinic systolic blood pressure below 130 mmHg (home systolic blood pressure below 125 mmHg).
• Aged 55 or over, or of African or Caribbean origin: long-acting dihydropyridine calcium channel blocker or a thiazide-like diuretic.
• If target blood pressure is not achieved, an angiotensin converting enzyme inhibitor (ACE inhibitor) or angiotensin II receptor blocker (ARB) should be added
• Not of African or Caribbean origin and younger than 55 years: ACE inhibitor or ARB
• Should be initiated within 2 weeks of presentation

Question 51

Intracerebral haemorrhage.

What medications potential could be worsening this condition?

When does intracerebral haemorrhage require urgent treatment?

What BP should we aim for?

When should statins be used?

Answer 51

• Intracerebral haemorrhage
• Review anticoagulation and antiplatelet therapy (are these medications making the condition worse) - Warfarin reversal, local guidance for DOAC reversal
• Acute spontaneous intracerebral haemorrhage with a systolic BP of 150-220 mmHg -urgent treatment within 6 hours of symptom onset (aim systolic BP 130-139 mmHg within one hour and sustained for at least 7 days unless contraindicated)
• Statin use only if there is a cardiovascular disease risk, not for secondary prevention of intracerebral haemorrhage