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Physiology and Neuroscience > Stroke > Flashcards

Flashcards in Stroke Deck (56):
1

What is a stroke?

Sudden death of brain tissue due to lack of oxygen and glucose delivery arising from an interrupted blood supply (ischaemia)

2

How many deaths per year are caused by strokes in the UK?

152,000
1 every 3.5 minutes

3

How many first time strokes were there worldwide in 2010/

17 million
1 every 2 seconds

4

Whats the difference in men and women and the likelihood of getting a stroke?

Men are 25% higher risk of having stroke compared to women
However, incidence of stroke in women is higher due to longer lifespan

5

How many stroke survivors are there in the UK?

Around 1.2 million

6

How many strokes are fatal within the first 30 days?

1 in 8

7

How many strokes are fatal within the first year?

1 in 4

8

What are modifiable risk factors towards a stroke?

Hypertension- single most important modifiable risk factor
Smoking
Waist to hip ratio
Diet (i.e. obesity)
Physical inactivity
Diabetes
Alcohol intake (>30 drinks per month)
Psychological factors (stress, depression)
Cardiac causes (Atrial fibrillation, Previous transient ischaemic attack)
Apoliopoproteins
o All 10 combined about for 90% of risk of stroke

9

What are non-modifiable risk factors towards a stroke?

Age- most important risk factor
Gender
Ethnicity- Black and south Asian origin

10

What is stroke the leading cause of?

Disability

11

How many stroke survivors are dependent on others?

More than half
42% will be independent
22% have mild disability
14% have moderate disability
10% have severe disability
12% have very severe disability

12

What are the stroke warning signs?

Face
Arms
Speech
Time

13

What are the stroke subtypes?

15% primary intracerebral haemorrhage
5% subarchanoid haemorrhage
80% ischaemic

14

What are the subtypes of ischaemic stroke?

Thrombotic stroke
Embolic stroke

15

What is a thrombotic stroke caused by?

A blood clot in an artery supplying the brain

16

What is the most common cause of thrombotic stroke?

Atherosclerosis- results in narrowing of arteries
Accounts for half of all strokes

17

How is an embolic stroke caused?

Blood clot forms elsewhere in the body and travels to the brain

18

What is the most common cause of embolic stroke?

Atrial fibriliation- increased risk of clots
Air bubbles, plaque form in an artery wall

19

When does a haemorrhagic stroke occur?

Occurs when a blood vessel within the brain ruptures

20

What can cause a haemorrhagic stroke?

Aneurysm
Arteriovenous malformation

21

What is an aneurysm?

Ballooning of weakened region of blood vessel

22

What is arteriovenous malformation?

Abnormal connection between arteries and veins. Increased risk of bleeding due to increased pressure

23

What happen in a haemorrhagic stroke?

The blood accumulates and causes compression of brain tissue and increased pressure within brain (intracranial pressure)

24

What is there an increased mortality for?

Haemorrhagic stroke than ischaemic stroke

25

What is a Transient Ischaemic Attack (TIA)?

Sometimes referred to as mini-stroke
Brief period of symptoms similar to stroke
At greater risk of subsequent stroke

26

What is TIA caused by?

Caused by a temporary decrease in blood supply to a particular brain region
Caused by a clot or other debris blocks blood flow temporarily

27

What happens to ischaemic core in ischaemic stroke?

Irreversibly damaged and cells are destined to die within 2 mins

28

What happens to ischaemic penumbra in ischaemic stroke?

Tissue does not function normally but is still viable and may recover if blood flow is restored or drugs given to support survival

29

Who introduced the ischaemic penumbra?

Originally by Astrup and Symon 1981

30

What is the the ischaemic penumbra?

A region of reduced CBF with impaired electrical activity but still maintained ionic homeostasis and transmembrane electrical potentials. This definition further evolved to include preserved energy metabolism and increased oxygen extraction faction (OEF)

31

Where do most ischaemic strokes occur?

Forebrain

32

What is the composition of the forebrain?

22 billion neurones
84,500 miles of myelinated fibres
157 trillion synapses

33

What is the timeframe of brain damage associated with occlusive stroke/

Occurs roughly a 10 hour time frame

34

What happens if the patient is left untreated?

Patient will lose
1.9 million neurones (every minute)
13.8 billion synapses (every minute)
7 miles of axonal fibres (every minute)

35

What is infarction dependent on?

Severity and duration of ischaemia

36

What is acute ischaemic stroke treatment?

Thrombolysis (clot buster) (recombination tissue plasminogen activator; Alteplase)
Can only be used in specialist stroke units

37

What is a CT scan essential to exclude?

Haemorrhagic stroke

38

In thrombolysis how long before treatment?

Treatment within 4.5 hours of stroke onset

39

What are the side effects of thrombolysis?

Bleeding- must not be used in haemorrhagic stroke

40

How many patients are eligible for thrombolysis?

5-10%

41

What happens in Thrombolysis?

Tissue plasminogen activator (t-PA) binds to fibrin on clot surface
t-PA (Alteplase) activates Plasminogen → Plasmin
Plasmin is a proteolytic enzyme
Plasmin breaks down fibrin molecules and results in clot dissolving
t-PA preferentially binds fibrin bound plasminogen

42

What is a thrombectomy?

Used for acute stroke treatment?
Stent retriever into cerebral vessel
Five different clinical trials have shown efficacy of mechanical thrombectomy in acute stroke (MRCLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, REVASCAT)

43

What is the efficacy of thrombectomy?

Up to 6 hours post stroke

44

What is thrombectomy often used in combination with?

rt-PA

45

What does Ischaemic penumbra contain?

Salvageable tissue

46

What is acute treatment of ischaemic penumbra?

Selection of patients for acute treatment
Acute treatment futile in patients without salvageable tissue
Patients with penumbra most likely to benefit from “clotbuster” therapy

47

What is penumbra the main target tissue for?

Acute neuroprotection

48

What does Computerised Tomography (CT) scans use?

X-rays

49

What does Magnetic Resonance Imaging (MRI) scans use?

Signals are generated by nuclei with a positive charge (i.e. H, P)
MRI most commonly uses the signal from hydrogen atoms
Hydrogen most abundant atom in body (approx. 70-90% of body)
Non-invasive

50

What are the purposes of imagining a stroke?

Exclude haemorrhage
To discriminate between irreversibly damaged brain tissue and tissue at risk of infarction
To identify location of stroke
To identify patients that will benefit from thrombolysis

51

What are the benefits of CT scans?

Very good at detecting haemorrhage
Quicker than MRI
Cheaper and more widely available

52

What are the disadvantages of CT scans?

CT scanning not very sensitive for detecting early ischaemic damage following stroke

53

What are the advantages of MRI?

More detail than CT
MRI sequences can be used to detect very early brain damage due to stroke
Diffusion weighted imaging (DWI) an MR sequence which is sensitive to motion of water molecules can detect ischaemic damage within minutes of stroke
Perfusion weighted MRI can be used to assess the tissue at risk

54

What is perfusion?

Delivery of blood to capillary bed for supply of nutrients and oxygen

55

What information can be obtained by MRI?

Information about the perfusion status of the brain can be obtained (blood flow)

56

What can Perfusion Weighted Imaging (PWI) combined with diffusion weighted imaging (DWI) be used to clinically determine?

Which patient will benefit from thrombolysis