31 - Stroke

Question 1

What is a stroke

Answer 1

Ischaemia and hypoxia due to cerebrovascular disease

Question 2

What are causes of a stroke

Answer 2

Infarction

Haemorrhage

Question 3

Parenchymal stroke

Answer 3

Stroke in brain tissue

Question 4

Subarachnoid stroke

Answer 4

Into subarachnoid space

Question 5

Where do most strokes occur and why

Answer 5

Branches of middle cerebral artery as highly tortuous

The branches from MCA form lenticulo-striate arteries which leave the MCA at 90 degree angle

Question 6

What do the lenticulo-striate arteries supply blood to

Answer 6

Basal ganglia adn internal capsule

Question 7

Symptoms of a stroke

Answer 7

ALL SUDDEN 
Numbness, weakness of arm/face on one side of the body
Confusion
trouble seeing
trouble walking
severe headache

Question 8

What does FAST stand for

Answer 8

F - Face
A - Arms
S - Speech
T - Time (quicker help means more brain function can be preserved)

Question 9

What are the types of stroke

Answer 9

TIA
Thrombotic
Ischaemic
Hemorrhagic
Lacunar

Question 10

Which are the most common strokes

Answer 10

Thrombotic and embolic strokes make up 85% of all strokes

Question 11

Transient Ischaemic Attack

Answer 11

Lasts less than 24 hours
Result of a small emboli
Mini-stroke

Question 12

Thrombotic Stroke

Answer 12

Ischaemic stroke
The blood clot in cerebral artery, plaque opens and collagen and TF are exposed that produce a thrombus that blocks blood supply

Question 13

What percentage of thrombotic strokes develop during sleep and what is the reason

Answer 13

60%

Due to obstructive sleep apnea that increases BP and ruptures the plaque

Question 14

Embolic Stroke

Answer 14

Ischaemic
Can be blood broken from a thrombus or bacteria
Neurological signs develop rapidly
Usually occur during activity

Question 15

What is the usual source for an embolic stroke

Answer 15

Left side of the heart - A Fib, MI, defective valves

Question 16

Hemorrhagic stroke

Answer 16

Sudden neurological symptoms
Severe headache
Causes stupor or coma
Usually hypertensive

Question 17

Lacunar stroke

Answer 17

Occlusion in one of the arteries that provides blood to the brain’s deep structures

Question 18

What are example of the brain’s deep structures

Answer 18

Basal ganglia, cerebral white matter, thalamus, pons,cerebellum

Question 19

What percentage of ischaemic strokes are lacunar strokes

Answer 19

15-25%

Question 20

Motor hemiparesis with dysarthria

Answer 20

33-55%(most common) infarct in posterior limb of internal capsule

Question 21

Ataxia & hemiparesis

Answer 21

infarct also in posterior limb of internal capsule

Question 22

Dysarthria & clumsy hand

Answer 22

infarct in anterior limb of internal capsule

Question 23

Risk factors

Answer 23

Hypertension 
Heart disease (AFIB)
Hyperlipidaemia (use statins)
Diabetes
Smoking
Obstructive Sleep Apnea
Low potassium diet

Question 24

How do you diagnose a stroke

Answer 24

Physical examination (BP)
Blood tests (Cholesterol, C-reactive protein)
CT Scan (Show haemorrhage, tumor, stroke)
MRI - Detect damaged brain tissue

Question 25

Why do nerve cells have a high ATP usage

Answer 25

To fuel a sodium pump

Question 26

What happens when a Na pump stops working bc of hypoxia

Answer 26

Na leaks into cells Cell swelling Swelling exerts pressure on the cells and EC space decreased Cells contact each other - Raise in intercranial pressure

Question 27

By how much does the EC space decrease in a normal brain to hypoxic brain

Answer 27

20% to 5%

Question 28

What can a severe raise in ICP cause

Answer 28

Cerebellum extrudes through the foramen magnum | Compression on lower brainstem

Question 29

What removes the potassium that is released into ECS and what happens in a hypoxic brain

Answer 29

Glial cells | In a hypoxic brain - K+ not removed so excess NT release

Question 30

What is excitotoxicity

Answer 30

Follows a stroke Hypoxic brain cells subjected to excessive NTS due to a smaller ECS and reduced reuptake Lead to cell damage

Question 31

What is the main excitatory brain transmitter and what does it act on

Answer 31

Glutamate anion Main excitatory brain transmitter Acts on NMDA and AMPA receptors

Question 32

What does excess NMDA receptor stimulation and excess AMPA receptor stimulation cause

Answer 32

Excess NMDA receptor stimulation - Excess influx of Ca ions into nerve cells Excess AMPA receptor stimulation - Slow excitotoxicity

Question 33

What happens to ATP-ase uptake sites for glutamate in hypoxia and what is the result of this

Answer 33

The ATP drops reuptake fails post synaptic glutamate receptors overstimulated Leads to an influx of calcium and the excitotoxic loop

Question 34

What does an influx of calcium lead to

Answer 34

increased metabolic demand on the cell Uses more oxygen when no oxygen there is free radical formation which triggers apoptosis

Question 35

What is the penumbra region

Answer 35

neurons are hypoxic and /or damaged but survival is possible

Question 36

What happens to cells in the middle and outside in a stroke

Answer 36

Cells in the middle face inevitable death | Cells on the outside will survive

Question 37

What are the 3 main treatment strategies for a stroke

Answer 37

Restore blood flow Combat excitotoxicity Combat free radical damage

Question 38

How can you restore blood flow

Answer 38

Tissue plasminogen activators – thrombolysis

Question 39

How can you combat excitotoxicity?

Answer 39

- NMDA antagonists e.g Cerestat – block NMDA receptors and fast excitotoxicity but has serious side effects - AMP antagonists e.g NBQX – reduce slow excitotoxicity

Question 40

How can you combat free radical damage?

Answer 40

- Antioxidants e.g Vitamin C and E to boost brain’s antioxidant defences - Dietary vitamin C and E reduce risk in vulnerable populations - Free radical scavenging enzymes e.g superoxide dismutase low in in patients - Cool down the brain – reduces oxygen demand

Question 41

How do you reduce the primary risk of stroke

Answer 41

Treat hypertension - Diuretics, ACE inhibitors, AR antagonist, change diet Treat A Fib - Give Aspirin Statins - reduce LDL cholesterol