Stroke

Question 1

what is the definition of stroke

Answer 1

• The consequence of an interruption to blood flow to part of the brain, cuasing ischemia (inadequate blood flow) and hypoxia

Question 2

why might interruption of flow happen to the brain

Answer 2

• infarction (blockage of an artery)

- haemorrhage (e.g. rupture fo an aneurysm)

Question 3

what are the 2 types of haemorrhage stroke

Answer 3

• Parenchymal – into brain tissue

- Subarachnoid- into the subarachnoid space

Question 4

what is the 3rd most common cause of death after cancer and heart disease

Answer 4

• Stroke is the third most common cause of death in the UK after heart disease and cancer

Question 5

what are the symptoms of stroke

Answer 5

• Numbness or weakness of face, arm or leg, especially on one side of the body
• Confusion, trouble understanding or speaking
• Trouble seeing in one or both eyes
• Dizziness, loss of balance or coordination
• Severe headache with no known cause

Question 6

all symptoms happen….

Answer 6

suddenly

Question 7

describe the parts of FAST

Answer 7

• Face – is their loss of tone or weakness in any facial muscles
• Arms – can they raise both arms equally
• Speech – is there any changes e.g. slurring and slowness
• Time – the quicker the person receives help, the more brain function can be preserved

Question 8

name the types of stroke

Answer 8

1. (TIA)
2. Thrombotic
3. Embolic
4. Haemorrhagic

Question 9

what are the types of ischeamic stroke

Answer 9

Thrombotic and Embolic strokes are forms of ischaemic stroke

Question 10

what percentage of strokes are ischaemic strokes

Answer 10

75% of all strokes

Question 11

what is a distinguiable trait between a TIA and stroke

Answer 11

• If the symptoms go away within the day then it is a TIA and not a stroke, usually confined to one functional part of the brain
• typically last 1 hour but always last less than 24 hours

Question 12

what is a TIA caused by

Answer 12

• The cause is assumed to be an embolise, that is small enough to be dissolved by the tissue lysing agents
• Most TIAs dissolve quickly, therefore the symptoms are only shorter

Question 13

what is the TIA a sign of

Answer 13

it is a sign that a thrombotic stroke is about to happen

Question 14

name the tests you would use to diagnose stroke

Answer 14

• physical examination
• blood tests
• CT scan
• MRI

Question 15

describe the tests you would use to diagnose stroke

Answer 15

Physical examination.

• Neurological signs/ symptoms
• Blood pressure, ophthalmoscope exam

Blood tests.
- Cholesterol, C-reactive protein

CT scan. Really important part of the diagnosis
- A CT scan can show a hemorrhage, tumor, stroke and other conditions. (computerized tomography angiography). CT most important imaging.

MRI
- MRI can detect brain tissue damaged by an ischemic stroke and brain hemorrhages.

Question 16

what is the most important test for the diagnosis of stroke

Answer 16

CT scan
- this Is because it can tell the difference between an haemorrigic stroke and an infract which is important for treatment

Question 17

what other tests can you perform on someone who you suspect to have a stroke

Answer 17

• Carotid ultrasound. This test shows presence of plaques and blood flow in your carotid arteries.
• Cerebral angiogram.
• Echocardiogram

Question 18

what is the percentage of thrombotic strokes that develop during sleep

Answer 18

• About 60% of thrombotic strokes develop during sleep

Question 19

why do thrombotic strokes tend to develop during sleep

Answer 19

• unsure
• but one theory is that obstructive sleep apnea where the airway gets blocked during sleep can cause the blood pressure to shoot up and this can cause the rupture of the surface off a plaque

Question 20

what is cerebral thrombosis

Answer 20

• Cerebral thrombosis is the formation of a blood clot in a cerebral artery, normally at the site of an atherosclerotic plaque

Question 21

how can a thrombus cause a stroke

Answer 21

. If the surface of the plaque breaks open collagen and tissue factor are exposed which produce a thrombus that blocks blood supply to the local tissue (much like an AMI blocks blood supply to part of the heart).

Question 22

describe how slow onset strokes develop

Answer 22

• About 20% of thrombotic strokes develop stepwise over a several hours to a few days.
• In these situations initial neurological deficits appear, followed by a period without further deterioration.
• Another period of deterioration is heralded by expansion of the neurological signs

Question 23

why do slow onset strokes develop

Answer 23

This may be due to several plaques in different vessels forming thrombi.

Question 24

what is arteriosclerosis

Answer 24

• This is the thickening hardening and loss of elasticity of the walls of the arteries due to fibrotic deposition, the elastin is converted to collagen and they lose their elasticity, this happens naturally in ageing but can be accelerated by smoking and other chemicals in the blood

Question 25

what is atherosclerosis

Answer 25

- this is when there is a plaque that comes on after there has been some arteriosclerosis, this causes the artery to narrow

Question 26

is atherosclerosis or aterioscloersis associated with nearly half of all strokes

Answer 26

atherosclerosis is associated with nearly half of all strokes

Question 27

what are the blood vessels like in the brain

Answer 27

- They are much more tortuous than in other structures, they twist and turn in a convoluted way - This is different to the normal arteries in the body - This twist and turn can make it much more vulnerable to thrombi formation because thrombi form where there is reduced or stagnant blood or due to a vortex effect - therefore the intrinsic pathway is triggered and it is strongly correlated with clots forming

Question 28

why is AF a risk factor for stroke

Answer 28

AF is a major risk factor for stroke, because if the atria is in fibrillation and not contracting properly the blood can be stagnant in the auricles which triggers the intrinsic pathway and this causes clot formation - When the sympathetic nervous system starts making the heart beat faster the clots can get dislodged and they pass up the vertebral arteries and you can get an embolic stroke

Question 29

how is damage to the heart valves a risk factor that can cause an embolic stroke

Answer 29

- Damage to the heart valves can induce turbulence, this is a risk factor in increasing spontaneous thrombi form

Question 30

what is an embolism

Answer 30

- An embolism is a foreign substance that occludes a blood vessel .

Question 31

what are most embolism made out of and what can some embolisms be made out

Answer 31

- Many embolisms are blood clots that broke free from a thrombus and lodged in a remote part of the circulation. - Embolism can also be a mass of bacteria.

Question 32

neurological signs develop rapidly with ...

Answer 32

Neurological signs develop rapidly with cerebral embolisms and usually do not progress

Question 33

what stroke is rarely preceded by a TIAs

Answer 33

embolic stroke

Question 34

where is the source of the embolism from embolic strokes usually for

Answer 34

- The source of the embolism is almost always the left side of the heart. Heart diseases that lead to the production of emboli include atrial fbrillation, myocardial infarct, and defective or artificial heart valves, particularly the mitral valve

Question 35

what percentage of strokes do thrombotic and embolic strokes make up

Answer 35

- Thrombotic & embolic strokes make up ~ 85% of all strokes

Question 36

what is haemorrhage stroke associated with

Answer 36

- Intracerebral haemorrhage is associated with the sudden onset (minutes to hours) of neurological symptoms. - It is frequently associated with severe headache. (Possible due to stretch of the vessel before rupture). - Nausea and vomiting, intolerance of noise or light - can be associated with hypertension but sometimes bleeds happen under normal pressure

Question 37

what is haemorrgic stroke often caused by

Answer 37

Often caused by a ruptured aneurysm.

Question 38

is consuiness preserved in haemorrhage stroke

Answer 38

- Unlike the occlusive strokes, in which consciousness is preserved, intracerebral haemorrhage may cause stupor or coma that may progress with time.

Question 39

what is a lacunar stroke

Answer 39

- Lacunar stroke is a type of stroke where there is occlusion of one of the arteries that provides blood to the brain's deep structures as opposed to the cerebral cortex

Question 40

what are the deep structures of the brain

Answer 40

``` basal ganglia, cerebral white matter, thalamus pons cerebellum. ```

Question 41

what are the signs of lacunar strokes

Answer 41

- Well defined deficits are present but cortical infarct signs (such as aphasia, neglect, and visual field defects) are always absent

Question 42

what percentage of lacunar strokes count for ischemci strokes

Answer 42

. Lacunar stroke accounts for 15 – 20% of ischemic strokes

Question 43

what are the common forms of lacunar stroke

Answer 43

- Motor hemiparesis with dysarthria(difficult articulation of speech): the most common lacunar syndrome: (33-50%): infarct in posterior limb of internal capsule - Ataxia(lack of muscle coordination) & hemiparesis(weakness of one half of the body) : the second most common form of lacunar stroke ; infarct also in posterior limb of internal capsule - Dysarthria & clumsy hand : infarct in anterior limb of internal capsule

Question 44

what are the 5 main risk factors for stroke

Answer 44

1. Hypertension 2. Atrial fibrillation 3. Smoking 4. Diabetes 5. Hyperlipidaemia

Question 45

what percentage of risk does hypertension cause for stroke

Answer 45

Hypertension accounts for 35-50% of stroke risk

Question 46

what can lowering blood pressure prevent

Answer 46

Lowering blood pressure has been conclusively shown to prevent both ischemic and hemorrhagic strokes

Question 47

what is the risk of stroke caused by AF

Answer 47

Those with atrial fibrillation have a 5% a year risk of stroke, and this risk is higher in those with valvular atrial fibrillation.

Question 48

what is a useful prevention for reducing risk of stroke caused by atrial fibrillation

Answer 48

anticoagulation with medications such as warfarin or aspirin or other anticoagulants is useful for prevention

Question 49

how much does diabetes increase your risk of stroke

Answer 49

- Diabetes mellitus increases the risk of stroke by 2 to 3 times

Question 50

how can diabetes cause stroke

Answer 50

- Dameges the endothelium, reduces NO therefore increases vasoconstriction and causes hypertension

Question 51

how much does statins reduce the risk of stroke by

Answer 51

- Statins reduce the risk of stroke by about 15-20% in those with high LDL cholesterol

Question 52

how does smoking increase the risk of stroke

Answer 52

- Causes general inflammation in blood vessels, increases formation of atheromas, causes hypertension

Question 53

how much does obstructive sleep apnea increase stroke risk in

Answer 53

- Increases stroke risk by up to 3x especially in men

Question 54

what are the other factors that can cause stroke

Answer 54

- diet low in potassium and low blood potassium (hypokalaemia) - sickle cell disease

Question 55

how does a die low in potassium and low blood potassium cause stroke

Answer 55

- they may cause hypokalaemia | - and can therefore increase the risk of stroke and hypertension

Question 56

how does sickle cell disease cause stroke

Answer 56

- Increased risk of clotting due to increased fragility of red cells, don’t bend so easily so when they go through capillaries they tend to break open and this releases haemoglobin and once the haemoglobin is out of the red cell it can act to produce clotting

Question 57

why is ATP so important in the sodium pump

Answer 57

- most of ATP is used to fuel the sodium pump in the brain cells - in nerve cells the sodium pump does not just keep the membrane potential intact but has a role in maintaining nerve cell size and shape - when sodium enters water follows

Question 58

what happens if the sodium pumps stop working in cells

Answer 58

- if the sodium pump stops working or works at a reduced rate this means that too much water can enter and this can cause the nerve cells to swell as the sodium is not being pumped out

Question 59

how long does it take for a brain cell to die

Answer 59

- After 2-3 minutes of hypoxia nerve cell starts to die

Question 60

why is swelling so bad in the brain

Answer 60

- In most cells of the body swelling doesn’t matter but in the brain it is serious because if the neurones swell there is no where for them to swell to except against each other as the brain is a bony box and the amount of extracellular space decreases - The intracranial pressure arises as cant remove fluid

Question 61

how much extracellular space is there in a normal brain

Answer 61

- In a normal brain there is 20% extracellular space, this is where the CSF seeps through the space and drains

Question 62

what is a raised ICP a major sign of

Answer 62

- A raised icp is a major sign of cerebral hypoxia

Question 63

what is the cerebral perfusion pressure

Answer 63

- The cerebral perfusion pressure (CPP) is the difference between mean arterial pressure and ICP

Question 64

what is cerebral blood flow determined by

Answer 64

cerebral perfusion pressure

Question 65

what is the extracellular space in a hypoxic brain

Answer 65

In a hypoxic brain the extracellular space is 5%

Question 66

what happens in tonsillar herniation

Answer 66

- Rise in ICP can cause the cerebellum to extrude through the foramen magnum - This is called coning or tonsillar herniation - The cerebellar tonsils move downward through the foramen magnum causing compression of the lower brainstem and upper cervical spinal cord

Question 67

what are the most common signs of tonsillar herniation

Answer 67

- intractable headache - head tilt - neck stiffness - The level of consciousness may decrease and also give rise to flaccid paralysis

Question 68

what do glial cells do

Answer 68

In a healthy brain the potassium released in to the ECS space in the brain by action potentials is removed by glial cells. - The glial cells maintain the homoeostasis of the brain environment

Question 69

what happens in an seizure

Answer 69

- Neurones in a particular part release potassium ions, the diffusion of the potassium may be comprised - The membrane potential is caused by the ratio of potassium inside and outside, if the outside potassium goes up the ratio gets smaller and the membrane potential is less - This is what happens during seizure – lot of neurones simultaneously release potassium, which makes them more active so release more potassium, this only stops when they cant release anymore potassium as they are so depolarised

Question 70

what do glial cells need to work

Answer 70

- Potassium rise is normally controlled by glial cells but the glial cells need ATP to do this but if hypoxic cant do this

Question 71

what does a build up of potassium cause to be released

Answer 71

- A build up of potassium in the extraceullar space, which causes glutmate to be released

Question 72

what happens in a hypoxic brain when the potassium is not removed

Answer 72

- In a hypoxic brain the potassium is not removed; the increased extracellular potassium depolarizes adjacent cells and leads to excess (excitatory) neurotransmitter release. - After release from synaptic endings, neurotransmitters are normally taken back up into nerve cells by uptake pumps or ‘transporters’. These transporters use ATP. When ATP levels are low, the neurotransmitters are not taken up, but remain in the synaptic cleft or extracellular space. - Glutmate diffuses around, high levels of glutmate cause excitotoxicity

Question 73

what does high amounts of glutamate cause

Answer 73

- excitotoxicity

Question 74

what receptors does glutamate act on

Answer 74

NMDA | AMPA

Question 75

what does excess stimulation of the NMDA receptor do

Answer 75

Excess stimulation of the NMDA receptor after 3-5 minutes anoxia leads to excess influx of calcium ions into nerve cells and this is cause of fast (early) excitotoxicity.

Question 76

what does excess stimulation of AMPA do

Answer 76

Excess stimulation of AMPA receptors over several hours leads to slow (delayed) excitotoxicity

Question 77

what is the difference between slow and fast excitotoxcity

Answer 77

slow is due to excess stimulation of AMPA receptors | fast is due to excess stimulation of NMDA receptors

Question 78

what is the basic excitotoxic loop

Answer 78

- The increased influx of calcium increases the metabolic demand on the cell and uses more oxygen. - The high metabolic demand in the absence of oxygen leads to the formation of free radicals which trigger cell death or apoptosis - this is the main reason why cells die

Question 79

what are the 3 regions of the brain that focus around a stroke and what happens to the cells there

Answer 79

- The centre – cells here face inventible death - The penumbra region – neurones are hypoxic and/or damaged but survival is possible - At a distance there are cells supplied by other arterial arteries or there is enough oxygen that pass through which keeps them alive

Question 80

what are the three main treatment strategies for stroke

Answer 80

1. Restore blood flow 2. Combat excitotoxicity 3. Combat free radical damage

Question 81

how do you restore blood flow

Answer 81

- Use of i.v. tissue plasminogen activators (thrombolysis) improves outcome after stroke (thrombotic stroke). However, fibrinolytic agents should be withheld until CT has ruled out a brain hemorrhage. = ONLY FOR ISCHEMIC STROKE

Question 82

when is the best time frame to use tissue plasminogen activators as a treatment of stroke

Answer 82

- Efficacy of treatment depends critically on how soon it is administered: within 3-4 hours at most for significant benefit

Question 83

Describe how quickly IV fibrinolytic therapy can be given and how effective they are

Answer 83

- within the first 3 hours of ischemic stroke onset offers substantial net benefits . - within 3-4.5 hours offers moderate net benefits . - in the 3-6 hour window offers moderate net benefits - After 3 hours it is progressive decline, after 6 hours not so good

Question 84

how to we treat excitotoxicty

Answer 84

NMDA antagonists AMP antagonist Newer drugs to prevent delayed triggering of apoptotic pathways- ‘programmed cell death’. (e.g. Lithium,)

Question 85

How do NMDA antagonists work

Answer 85

block NMDA receptors & fast excitotoxicity

Question 86

how do AMP antagonists work

Answer 86

to reduce slow excitotoxicity. - (Appear to hold out more hope as AMPA effects are delayed and drug treatment after one hour may be beneficial)

Question 87

How can we reduce free radical damage

Answer 87

1. Antioxidants such as vitamin C and E have been administered i.v. to boost brain’s antioxidant defenses. 2. Free radical scavenging enzymes such as superoxide dismutase have been found to be low in stroke patients. Clinical trials with SOD are showing hopeful results. 3. Cool Down the Brain. Reducing body temperature reduces oxygen demand, and may allow neurones in the penumbra to survive if there is a small oxygen supply from collateral blood vessels

Question 88

how to you treat hypertension thus lowering the risk of stroke

Answer 88

Diuretics, ACE inhibitors, AR antagonists. Change diet

Question 89

how do you treat atrial fibrillation thus lowering the risk of stroke

Answer 89

Give Aspirin for healthy patients < 65 years Give Warfarin for patients > 65 years or having other stroke risk factors