Stroke Flashcards

1
Q

What is a stroke?

A

A neurological deficit, of sudden onset, lasting more than 24 hours of vascular origin

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2
Q

What is a Transient ischaemic attack?

A

Same stroke symptoms but only lasts less than 24 hours

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3
Q

What are the causes of stroke

A
  • Blockage with thrombus or clot
  • Disease of vessel wall
  • Disturbance of normal properties of blood
  • Rupture of vessel wall (haemorrhage)
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4
Q

How many strokes are due to infarction and how many are due to haemorrhage?

A

85-90% due to infarction
10-15% due to haemorrhage

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5
Q

Describe the difference between a hemorrhagic stroke and an ischaemic stroke

A

Haemorrhage - blood leaks into brain tissue
Ischaemic - Clot stops blood supply to an area of the brain

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6
Q

What is the most common cause of large artery disease?

A

Carotid stenosis

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7
Q

What is the most common cause of cardioembolic stroke?

A

Atrial fibrilation commonest cause

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8
Q

Describe the aetiology of haemorrhagic strokes

A

60-70% due to hypertension
15-20% due to amyloid
Excess alcohol
Hypocholesterolaemia
Haemorrhagic transformation

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9
Q

Describe the ischaemic cascade in a stroke

A
  • Without adequate blood supply and thus lack of oxygen and glucose, brain cells lose their ability to produce energy (ATP)
  • Cells in the affected area switch to anaerobic metabolism which leads to a lesser production of ATP but releases lactic acid
  • Lactic acid is an irritant which has the potential to destroy cells by disruption of the normal acid-base balance in the brain
  • ATP reliant ion transport pumps fail
  • Membrane becomes depolarised
  • Influx of calcium and efflux of potassium
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10
Q

What is the effect in the ischaemic cascade in a stroke of the influx of calcium and the efflux of pottasium

A
  • Intracellular calcium levels become too high and trigger the release of glutamate (excitory amino acid neurotransmitter)
  • Glutamate stimulates AMPA receptor and calcium permeable NMDA receptors which leads to even more calciumm influx into cells
  • Excess calcium entry overexcites cells and activates proteases (enzymes which digest cell proteins), lipases (enzymes which digest cell membranes) and free radicals formed as a result of the ischaemic cascade in a process called excitotoxicity
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11
Q

What is the effect of cell membranes being broken down by phospholipases within a stroke?

A
  • It becomes more permeable and more ions and harmful chemicals enter the cell
  • Mitochondria break down, releasing toxins and apoptotic factors into the cell
  • Cell undergoes apoptosis
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12
Q

What is the effect of a cell dying via necrosis?

A
  • It releases glutamate and toxic chemicals into the environment around it
  • Toxins poison nearby neurons and glutamate can overexcite them
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13
Q

What is the effect of the loss of vascular structural integrity caused by a stroke?

A
  • Breakdown in the protective blood brain barrier
  • Contributes to cerebral oedema which can cause secondary prevention of the brain injury
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14
Q

Define ‘ penumbra’

A

Penumbra” is the term used for the reversibly injured brain tissue around ischemic core

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15
Q

What can prolonged hypoxia cause?

A

Hypoxia can turn to anoxia (no oxygen)

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16
Q

What are the symptoms of occlusion of the anterior cerebral artery

A
  • Paralysis of contra-lateral foot and leg
  • Sensory loss over contra-lateral toes, foot and leg
  • Impairment of gait and stance
17
Q

What are the symptoms of occlusion of the middle coronary artery?

A
  • Contralateral paralysis of face/arm/leg
  • Contralateral sensory impairment
  • Contralateral homonymous hemianopnia (where there is a loss of one half of your visual field)
  • Gaze paralysis to the opposite side
  • Aphasia if stroke on the dominant (left) side
  • Unilateral neglect for half of external space if non-dominant stroke (usually right side)
18
Q

What are the symptoms of lucuar stroke?

A
  • Devoid of ‘cortical signs’ (no dysphasia, neglect, hemianopia
  • Pure motor stroke
  • Pure sensory stroke
  • Dysarthria - clumsy hand syndrome
  • Ataxic hemiparesis
19
Q

What is the sensory cortex responsible for?

A

Pain, heat and other sensations

20
Q

What is the parietal lobe responsible for

A

Comprehension of language

21
Q

What is the temporal lobe responsible for?

22
Q

What is the occipital lobe responsible for?

A

Primary visual area

23
Q

What is the wernicke’s area responsible for?

A

Speech comprehension

24
Q

What is the cerebrellum responsible for?

A

Coordination

25
What is the brainstem responsible for?
Swallowing, breathing, heartbeat, wakefulness centre and other involuntary functions
26
What is the temporal lobe responsible for?
Intellectual and emotional functions?
27
What is the frontal lobe responsible for?
Smell, judgement, foresight and voluntary movement
28
What is broca's area responsible for?
Speech
29
What is the motor cortex responsible for?
Movement
30
What parts of the anatomy are involved in a posterior circulated stroke?
Brain stem/Cerebellum/Thalamus Parts of occipital lobe and temporal lobes
31
What are the 4 stroke substypes?
TACS - Total anterior circulation stroke PACS - Partial anterior circulation stroke LACS - Lacunar stroke POCS - Posterior circulation stroke
32
What is the timeframe for administering Thrombolysis/Alteplase?
4 and a half hours of stroke
33
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