Blood supply and stroke Flashcards

1
Q

What percentage of the cardiac output is used by the brain?

A

15%

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2
Q

What do the right and left vertebral arteries join to form?

A

Basilar artery

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3
Q

What arteries make up the anterior circulation of the brain?

A

Branches of the internal carotid arteries:

  • Middle Cerebral Artery
  • Anterior cerebral artery
  • Perforating branches (striate, leticulochoroidal arteries, etc.)
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4
Q

What does the anterior circulation of the brain supply?

A
  • Anterior 3/5s of the cerebrum

- Diencephalon

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5
Q

What arteries make up the posterior circulation of the brain?

A
Vertebrobasilar arteries 
Main branches:
- Cerebellar (PICA, AICA, SCA)
- Pontine 
- Posterior cerebral arteries 
- Striate and thalmic branches
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6
Q

How does the brain regulate cerebral blood flow despite variations in blood pressure?

A

Autoregulation - blood vessels respond to changes in BP to maintain a safe and steady flow rate

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7
Q

What happens when blood pressure is extremely low (below 50mmHg)?

A

Arteries collapse and ischaemia occurs

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8
Q

What happens if blood pressure is too high in the cerebrum (above 150mmHg)?

A

Force-mediated dilation increased flow, vasogenic oedema

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9
Q

If blood flow into brain is compromised how should you check BP?

A

Bilaterally

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10
Q

What are the common symptoms of stroke?

A
  • Sudden onset
  • Facial asymmetry
  • Speech disturbance (dysphasia)
  • Asymmetrical weakness in muscles
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11
Q

What is the definition of a stroke?

A
  • 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
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12
Q

What is a Transient ischaemic attack (TIA)?

A
  • The same as a stroke although the symptoms last less than 24 hours
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13
Q

How are strokes classified?

A
  • Ischaemic: 80-85%
  • Haemorrhagic: 15%
  • Subarachnoid haemorrhage 5%
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14
Q

What are the causes of haemorrhagic stroke?

A
  • Hypertension
  • Tumour
  • Bleeding disorders
  • Vascular malformation (AVM)
  • Amyloid angiopathy
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15
Q

What is the primary brain damage of a haemorrhagic stroke?

A
  • Mechanical damage associated with the mass effect

- Within minutes to hours from the onset of bleeding

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16
Q

What is the secondary brain damage of a haemorrhagic stroke?

A
  • Surrounding oedema

- Oxidative stress and inflammation

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17
Q

What is an ischaemic stroke caused by?

A

A blood clot obstructing an artery

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18
Q

What is the most common origin of an embolism that causes ischaemic stroke?

A

Heart (cardio-embolism)

- Asssociated with Atrial fibrilation

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19
Q

What are the different causes of ischaemic stroke (origins where clots can arise)?

A
  • Large vessel atheroma / thrombosis
  • Cardio-embolism
  • Hypoperfusion
  • Small vessel disease
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20
Q

What is a lacunar stroke?

A

Type of ischaemic stroke (most common) that occurs in deep areas of the brain where small perforating branches are obstructed by microatheroma

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21
Q

What is the “core” in an ischaemic stroke?

A

Where the permanent damge of a stroke is - everything is dead here

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22
Q

What is the ischaemic penumbra?

A

Surrounds core - neurons which can be saved (aka area of salvagable damage)

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23
Q

What are watershed area (border zones) most vulnerable to?

A

Hypoperfusion (furthest away from source) - areas which will dies first

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24
Q

What are the different watershed areas (border zones)?

A
  • Cortical border zone (between ACA and MCA)
  • Internal Border Zone (between LCA and MCA)
  • Cortical Border Zone
    (between MCA and PCA)
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25
Q

What can reducing the blood pressure to greatly after an ischaemic stroke result in?

A

Watershed infarcts (malpractice issue)

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26
Q

What are the most common arteries affected by stroke?

A
  • 51% Middle Cerebral artery
  • 13% Small Vessels
  • 7% Anterior cerebral artery
  • 5% Posterior cerebral artery
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27
Q

What is an Endarterectomy?

A

Surgical procedure to remove the atheromatous plaque material, or blockage, in the lining of an artery constricted by the buildup of deposits

28
Q

What does FAST stand for and what else should be included?

A
  • Face
  • Arms
  • Speech
  • Time
    Check the glucose
29
Q

If you suspect stroke what questions must you ask yourself?

A
  • Is it a stroke?
  • What type of stroke is it?
  • Which part of the brain is affected?
  • What caused the stroke?
  • What is the prognosis?
  • What are the risk factors?
  • What are the functional + emotional consequences?
30
Q

What should your asssesment include in a stroke?

A
  • Airway
  • Breathing
  • Circulation
  • Clarify the history
  • Past medical history: conditions, medications
  • Check the signs
  • Level 1 investigations
31
Q

What should be examined in a vascular neurology examination?

A
  • BP and pulse measurement in 2 arms
  • Level of consciousness (GCS)
  • Cardiac and carotid bruits
  • Blood glucose level
  • Neck stiffness/meningism (kering’sBrudzinski signs)
  • Abnormal or involuntary movements
  • ANy seizure-like activity
  • Skin rash/infarcts e.g. vasculitic, papular rash
  • Specific neurological (eye movements speech, visual fields, inattention, motor and sensory, gait assessment)
32
Q

What are the different ways strokes can be classified?

A
  • Oxford Community Stroke Project (OCSP) - clinical
  • TOAST classification - mecahnism (e.g large vessel, small vessel, cardioembolic)
  • Carotid or vertebrobasilar territory
33
Q

What is the purpose of OCSP Classification?

A

To determine what type of stroke it is

34
Q

What is checked in the OCSP classification?

A
  • Motor/sensory pathways (muscle power, sensation)
  • Visual pathways (field of vision)
  • Higher cortical functions (speech, spatial awareness)
  • Brainstem functions (swallowing, eye movements)
35
Q

What are the different types of stroke classifications (OCSP)?

A
  • Total Anterior Circulation Syndrome (TACS)
  • Partial Anterior Circulation Syndrome (PACS)
  • Lacunar Syndrome (LACS)
  • Posterior Circulation Syndrome (POCS)
36
Q

What are the clinical signs of a Lacunar Syndrome (LACS) (OCSP)?

A
  • Pure motor
  • Pure sensory
  • Sensorimotor
  • Ataxic hemiparesis
37
Q

What are the clinical signs of Posterior Circulation Syndrome (POCS) (OCSP)?

A
  • Brainstem

- Cerebellar and/or isolated homonymous hemianopia

38
Q

What are the clinical signs of Total Anterior Circulation Syndrome (TACS) (OCSP)?

A
  • Triad of hemiparesis (or hemisensory loss)
  • Dysphasia (or other higher cortical function)
  • Homonymous hemianopia
39
Q

What are the clinical signs of Partial anterior Circulation Syndrome (PACS) (OCSP)?

A

2 of the features of TACS or isolated dysphasia or parietal lobe signs (e.g inattention, agnosia, apraxia, agraphaesthesia, alexia)

40
Q

What is the 7 points score to predict erly stroke risk post TIA?

A
  • Age (>=60) = 1
  • BP (syst>140 diast>90) = 1
  • Clinical features (unilateral weakness = 2 speech disturbacne w/o weakness = 1)
  • Duration of symptoms in mins (>=60 = 2) (10-59 =1) (<10=0)
  • Diabetes = 1
41
Q

What is the 2 day stroke risk for each stroke score?

A
  • 0-3 (1%)
  • 4-5 (4%)
  • 6-7 (8%)
42
Q

What are the 5 S’s?

A

Things that can mimic strokes

  • Seizures
  • Sepsis
  • Syncope
  • SOL (tumour, subdural)
  • Somatisation
43
Q

What drugs can cause strokes?

A
  • Newly prescribed
  • Oral-contraceptiv, ACEi
  • Recreational (cocaine)
44
Q

What is visuo-spatial neglect?

A

After damage to one hemisphere of the brain is sustained, a deficit in attention to and awareness of one side of the field of vision

45
Q

What is truncal ataxia

A
  • Gait characteried by uncertain starts and stops and unequal steps
  • Affects muscles closer to the body
  • Caused by midline damage to the cerebellar vermis
46
Q

What investigations should take place in order to diagnose stroke?

A
  • Good history and examination
  • ECG / Holter (24 hr ECG), ECHO
  • Cholesterol/autoimmune and thrombophilia screen
  • Carotid doppler
  • CT brain/MRI brain
  • Cerebral angiography
47
Q

When is an urgent head image indicated?

A
  • Depressed level of consciousness
  • Unexplained progressive or fluctuating symptoms
  • Papilloedema, neck stiffness or fever
  • Severe headache at onset
  • History of trauma prior to onset
  • Indication for thrombolysis or anticoagulation
  • History of anticoagulant treatment or known bleeding tendancy
48
Q

What can CTs show?

A
  • Cerebellar haemorrhage
  • Another cause (tumour; SDH)
  • Early ischemia
  • Less sensitive
49
Q

What is the mass effect?

A

When a focal lesion or contusion causes surrounding areas of the brain to be compressed or injured due to the degree of space that leaking blood, CSF or oedema takes up within the restricted skull space

50
Q

What are the different variants of MRI?

A
  • T1-weighted MRI
  • T2-weighted MRI (more sensitive to pathologies)
  • PErfusion MRI
  • Diffusion Weighted Imaging
  • Apparent Diffusion Coef. Imaging
  • Flair
51
Q

How long can it take for a small infarct to be seen on a CT?

A

days

52
Q

What types of MRIs are useful for seeing the imapct of an infarct within a couple of minutes?

A
  • ADC - Apparent Diffusion Coefficient Imaging

- Diffusion Weighted Imaging

53
Q

What MRI is more specific for diffusion ADC or DWI?

A

ADC - Apparent Diffusion Coefficient imagining ADC and DWI complement each other

54
Q

What should be done immediately after a person is suspected or clinically confirmed of having a stroke?

A

Non-enhanced CT immediatey to rule out intracranial haemorrhage especially if the patient:

  • Is on an anticoagulant
  • Has papilloedema, neck stiffness or fever
  • Has depressed level of cansciousness (GCS<13)
55
Q

What else should be carried out (apart from imaging) if patient is suspected of stroke?

A
  • Oxygen saturation if below <95%
  • Maintain a blood glucose level between 4-11 mmol/litre
  • Blood test, including coagulation screen, FBC and UandEs
56
Q

When can thrombolysis be initiated in an ischemic stroke?

A

Within the first 4-4.5 hours (Mortality can be high, done by expert, only if patient has significant disability)

57
Q

When should aspirin be given to an ischaemic stroke victim?

A

300mg as soon as possible but certainly within 24 hrs

58
Q

How is blood pressure controlled in an ischaemic stroke?

A

Antihypertensive medications are to be avoided unless mean arterial pressure > 130 mmHg or hypertensive encephalopathy/nephropathy

59
Q

In a haemorrhagic stroke is surgical intervention usually required?

A

No

60
Q

What should the blood pressure be controlled at in a haemorrhagic stroke?

A

If within 6h and SBP between 150-220 mmHg -> Start antihypertensive treatment in 1 hr and aim for SBP <140 mmHg

61
Q

If patient is receiving warfarin and has a haemorrhagic stroke what should be done to reverse this?

A
  • Combination of prothrombin complex concentrate and intravenous vitamin K
62
Q

What would the drug treatment be for secondary prevention of a haemorhagic stroke?

A
  • Anti-thrombotics: Clopidogrel or Aspirin + Dipyridamole. In aFib: Warfarin or NOAC (dabigatan, riveroxaban, apixaban)
  • Target BP to < 130/80 with calcium channel blocker, thiazide diuretic, ACEi
  • Anti-lipids If total cholesterol > 4.0 mmol/l (or LDL-C . 2.5mmol/l [100mg/dl], treat with statin
63
Q

How is a subarachnoid haemorrhage managed?

A
  • CT brain/ lumbar puncture if CT normal. Look for bilirubin and xanthochromia. Cerebral angiogram
  • Management:
  • Airway: intubate if severe hypoxia
  • Fluid: 3L of 0.9% NaCl per 24hrs
  • BP: keep MAP < 130mmHg. If higher: IV labetolol or esmolol or enlapril
  • Nimodipine 60 mg 6x/day (for 3 wks)
  • Codeine or tramadol for pain (avoid NSAID)
  • Phenytoin if seizures have occured
  • Antiemetics
64
Q

What is hemianopia?

A

Loss of vision (anopsia) in half the visual field, usually on one side of the vertical midline

65
Q

What is diplopia?

A

Double vision