Introduction to Stroke

Question 1

define ischaemia

Answer 1

deficient supply of blood to an organ or tissue due to obstruction of inflow of arterial blood

Question 2

define occlusion

Answer 2

shutting off or obstruction

Question 3

define thrombus

Answer 3

a blood clot formed within a vessel and remaining attached to its place of origin

Question 4

define embolus

Answer 4

a mass, such as an air bubble, detached blood clot, or foreign body, that travels in the blood stream and lodges in a blood vessel thus serving to obstruct or occlude such a vessel

Question 5

define hypoxia

Answer 5

a deficiency of oxygen reaching the tissues of the body

Question 6

describe the brain

Answer 6

only 2% of body’s mass
most metabolically active part of the body
requires constant delivery of O2 and glucose to maintain brain cell function
if arterial supply to an area of brain is disrupted brain cells will start to die within minutes of oxygen deprivation

Question 7

what is a stroke

Answer 7

occurs when the blood supply to the brain is disrupted - either due to occlusion or rupture of bloody vessel supplying or within the brain - brain cells therefore starve of oxygen and die or are damaged

Question 8

what does TIA stand for

Answer 8

transicent ischaemic attack

Question 9

what is a TIA

Answer 9

short-lived episode (less than 24hrs) of temporary impairment in brain function caused by insufficient volume of blood supply to the brain due to a temporary or partial blockage of a blood vessel
usually no permanent damage occurs as a result of a TIA

Question 10

how many of those who have a TIA eventually will have an acute stroke

Answer 10

1/3

Question 11

what is ischaemic stroke

Answer 11

most common type (80% of all strokes)
occurs when a clot or blockage prevents the flow of blood in the brain
Hyproxia (deprived of O2 and other nutrients), the brain suffers damage and eventually will die as a result of stroke

Question 12

what may vascular occlusion be caused by - 3 points

Answer 12

thrombus
embolism
general decrease in blood supply - e.g. shock

Question 13

what is an intracerebral haemorrhage

Answer 13

when blood vessels within the brain become damaged (poss trauma) or weakened due to hypertension, cerebral aneurysm, vascular malformation (inc AVM) - more likely to rupture and cause haemorrhage in the brain

higher fatality rate/ poorer prognosis than ischaemic infarcts
location > size - tends to be greater factor in influencing severity of stroke

Question 14

what 3 ways can damage be caused in haemorrhagic stroke

Answer 14

blood is prevented from reaching the brain cells beyond the point of rupture leading to hyproxia

leaked blood can irritate and harm the brain cells in the areas where it accumulates

mass effect can damage brain tissue and raise ICP

Question 15

what is a subarachnoid haemorrhage

Answer 15

a type of intracerebral haemorrhage
bleeding from a damaged vessel causes blood to accumulate in the subarachnoid space - commonly due to rupture of cerebral aneurysm
can also be due to trauma and AVM
often in the circle of willis
commonly present with ‘thunderclap’ headache and photophobia

Question 16

what are the signs and symptoms of a stroke

Answer 16

vary from person to person
depend on part of the brain affected and extent of damage
main stroke symptoms - FAST
face arms speech time

Question 17

common clinical indications - 7 points

Answer 17

hemipariesis - muscle weakness on one side of the body
visual field defect
ataxic gait - unsteady walk
dysphagia
dysarthria - difficulty with articulation
aphasia - inability to speak
dysphagia - difficulty speaking, reading, writing due to brain damage

Question 18

what are the recommended guidelines for stroke - 4 points

Answer 18

rapid diagnosis
admission to specialist stroke unit
immediate brain imaging
thrombolysis where indicated

Question 19

what are implications from these stroke guidelines - 4 points

Answer 19

services need to be reorganised to allow scanning to be performed urgently when indicated
all hospitals admitting stroke patients have 24 hour access to scanning
scans should scheduled appropriately and running an out of hours service
US and angiography require the same consideration

Question 20

which is the modality of choice and why

Answer 20

CT
relatively inexpensive 
widely available 
immediate access
speed in scanning patients and results

Question 21

which modality is less suitable and why

why can this be used

Answer 21

MRI
speed - long acquisition times, sensitive to patient movement artefact
inability to screen acute patient
magnetic field excludes A/E equipment and staff

difficult cases
follow up
functional studies - where thrombolysis is an option

Question 22

how does an acute ischaemic infarct radiologically present - 2 points

Answer 22

ill-defined/wedge-shaped area of hypo density
affects both grey and white matter
mass effect - effacement of adjacent sulci/ventricle, possible midline shift

Question 23

how does a chronic ischaemic infarct radiologically present - 4 points

Answer 23

well defined wedge shaped area of low attenuation
CSF fills space where the tissue has died
associated expansion of the ipsi-lateral ventricle and sulcal widening
affects both grey and white matter

Question 24

how does an acute intracerebral haemorrhage radiologically present - 5 points

Answer 24

hyper density surrounded by brain
possibly rim of hypo density indicating oedema
mass effect - effacement of adjacent sulci/ventricles, possible midline shift
may have intraventricular extension
overtime acute blood = reabsorbed, the tissue has died due to lack of oxygen, and an area of encephalomalacia (dead tissue) remains - appears as a hypodense area

Question 25

how does a subarachnoid haemorrhage radiologically present

Answer 25

hyperdensity (blood) seen within the subarachnoid spaces
C.O.W in subarachnoid space
typical ‘star of david’ appearance
blood also seen following pattern of ‘sulci/gyri’

Question 26

why is treatment for each type significantly different

Answer 26

incorrect treatment could have significant life-threatening consequences
imaging critical in order to give quick, reliable diagnosis
allowing the correct treatment ASAP

Question 27

treatment for acute ischaemic infarct - 4 points

Answer 27

aspirin/anticoagulants - prevent clots/reduce further blood clots occurring
statins - block the liver enzyme that produces cholesterol
diuretics and ACE inhibitors - reduce blood pressure
carotid endarterectomy - incision in neck to open up carotid artery and remove fatty deposits

Question 28

treatment for intracerebral haemorrhage - 3 points

Answer 28

ACE inhibitors - to lower blood pressure
emergency craniotomy - to evacuate clot and relieve pressure
endovascular emobilsation or surgical clipping - of any aneurysm related to haemorrhage within 48 hrs

Question 29

describe thrombylisis

Answer 29

brain tissue at periphery of area of infarction remains viable for a short time (ischaemic penumbra) and may recover function if blood is restored
pharmaceutical method used to breakdown clots - only effective if started in first 4 hours after onset - speed of receiving delivery = better chance of recovery
no benefits if after 4 hours of onset
BUT can cause potentially fatal bleeding in brain

Question 30

what does it require in order to receive thrombylisis - 5 points

Answer 30

accurate knowledge of onset of symptoms
immediate access to specialist stroke centre
no contraindications
expertise in producing and analysing images
specialist trained to administer drug

Question 31

role of imaging in thrombylisis

Answer 31

function CT and MR perfusion studies demonstrate and evaluate the size of penumbra - potentially viable tissue
images taken during IV admin of contrast media
provide quantitative measurements of CSF flow - critical because it indicates brain tissue viability and haemorrhagic risk