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ischaemic stroke Flashcards

1
Q

define ischaemic stroke

A

a clot blocks blood flow to an area of the brain

neurological dysfunction due to ischaemia and death of brain, spinal cord, or retinal tissue following vascular occlusion or stenosis.

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2
Q

define haemorrhagic stroke

A

bleeding occurs inside or around brain tissue

neurological dysfunction caused by a focal collection of blood from rupture of a blood vessel within the brain (intracerebral haemorrhagic stroke) or between the surface of the brain and the arachnoid tissues covering the brain (subarachnoid haemorrhagic stroke).

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3
Q

define ischaemia

A
  • insufficient blood flow to the brain to meet metabolic demand
  • This leads to poor oxygen supply or cerebral hypoxia, and may in turn lead to the death of brain tissue or cerebral infarction
  • Ischaemia may be reversible
  • Infarction is irreversible
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4
Q

pathway from ischaemia to infarction

A

Tissue hypoperfusion
- Dysfunction

Early & reversible failure of the Na+ K+ pump
- Some cellular oedema

Progressive failure Na+ K+ pump until an irreversible ‘tipping point’ is reached
- Sudden influx Na+ ions
Cytotoxic oedema

BBB opens for macromolecules
- Vasogenic oedema

BBB opens for RBC’s
- Haemorrhage into the infarct

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5
Q

define TIA

A

A brief episode of neurological dysfunction caused by focal brain and/or retinal ischaemia, with clinical symptoms typically lasting < 1 hour, and without evidence of acute infarction

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6
Q

what are the ages of a infarct

A 
Hyperacute (1st 6 hours)
late hyperacute (6 to 24 hours)
Acute (up to 7 days)
Subacute (up to 4 months)
Chronic (after 4 months)
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7
Q

treatment for hyperacute infarct

A

The only approved therapy is intravenous thrombolysis with Alteplase within 4.5 hours of onset of stroke symptoms

Thrombolysis may not be given until haemorrhage has been excluded

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8
Q

Ix for stroke

A

unenhanced CT - highly sensitive for the detection of acute haemorrhage

FBC, U&Es, glucose, ESR, lipid profile
ECG
CXR
CT head scan
consider doppler USS of carotids
CT is sensitive to the detection of stroke mimics e.g. tumour, arterial venous malformation (AVM) that could be the cause of the neurological defect
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9
Q

signs of cerebral infarct on CT

A
  • Hypoattenuating
  • Cortical-sub cortical
  • Within a vascular territory
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10
Q

role of unenhanced CT

A
  • Eliminate haemorrhage as a cause as itll preclude thrombolysis
  • look for any early features of ischaemia
  • exclude other intracranila pathologies that may mimc a stroke and determine further investigations
  • May show a target - thrombosed vessel
  • Identify infarctions that are too big, too old for thrombolysis (increased risk of haemorrhage) - based on hyppattenuation
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11
Q

role of MRI

A 
Detection and diagnosis of acute infarction
- Diffusion weighted imaging
- Positive from 2 hours to 3 weeks
- Useful
----- Previous CVD makes CT difficult
----- Difficult location for CT - posterior fossa
------ Equivocal case - query tumour?
------ Sensitivity - TIA clinic
MRA and MRV
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12
Q

Immediate recognition of stroke done by which tools

A

outside of hospital - FAST

Exclude hypoglycaemia in people with sudden onset of neurological symptoms as the cause of these symptoms.

at ED use ROSIER

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13
Q

criteria to do CT

A

immediately at least within one hour

indications for thrombolysis or thrombectomy
on anticoagulant treatment
a known bleeding tendency
a depressed level of consciousness (GCS below 13)
unexplained progressive or fluctuating symptoms
papilloedema, neck stiffness or fever
severe headache at onset of stroke symptoms

thrombectomy might be indicated, perform imaging with CT contrast angiography following initial non-enhanced CT. Add CT perfusion imaging (or MR equivalent) if thrombectomy might be indicated beyond 6 hours of symptom onset.

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14
Q

oxygen therapy and sugar control

A

give oxygen only if their sats drop below 95%

maintain blood glucose between 4 and 11 mmol.l

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15
Q

who to offer thrombectomy

A

within 6 hours of symptom onset plus IV thrombolysis

  • acute ischaemia stroke
  • confirmed occlusion of the proximal anterior circulation demonstrated by CTA or MRA

last known to be well between 6 hours and 24 hours previously (including wake-up strokes):

  • who have acute ischaemic stroke and confirmed occlusion of the proximal anterior circulation demonstrated by CTA or MRA and
  • if there is the potential to salvage brain tissue, as shown by imaging such as CT perfusion or diffusion-weighted MRI sequences showing limited infarct core volume
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16
Q

Tx foe cerebral venous sinus thrombosis

A

full-dose anticoagulation treatment (initially full-dose heparin and then warfarin [INR 2 to 3]

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17
Q

when do you give BP medications

A
  • hypertensive encephalopathy
  • hypertensive nephropathy
  • hypertensive cardiac failure/myocardial infarction
  • aortic dissection
  • pre-eclampsia/eclampsia.

Blood pressure reduction to 185/110 mmHg or lower should be considered in people who are candidates for intravenous thrombolysis.

attempt to reduce it after 2 weeks

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18
Q

earliest CT sign

A

hyperdense segment of a vessel which needs to be differentiated from a calcified cerebral embolus

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19
Q

most commonly affected vessel in stroke

A

middle cerebral artery

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20
Q

early hyperacute signs on CT

A

loss of grey-white matter differentiation, and hypoattenuation of deep nuclei

cortical hypodensity with associated parenchymal swelling with resultant gyral effacement

21
Q

acute signs on CT

A

With time the hypoattenuation and swelling become more marked resulting in a significant mass effect. This is a major cause of secondary damage in large infarcts.

22
Q

subacute signs on CT

A

As time goes on the swelling starts to subside and small amounts of cortical petechial haemorrhages result in elevation of the attenuation of the cortex. This is known as the CT fogging phenomenon 5.

Imaging a stroke at this time can be misleading as the affected cortex will appear near normal.

contrast CT or MRI will show you wrong

23
Q

old infarct how does it look

A

well demarcated

very low density similar looking to CSF

negative mass effect

24
Q

old infarct how does it look

A

well demarcated

very low density similar looking to CSF

negative mass effect

25
Q

role of CT angiography

A

may identify thrombus within an intracranial vessel, and may guide intra-arterial thrombolysis or clot retrieval

26
Q

what is a time attenuation curve

A

As contrast passes through the brain it causes a transient hyperattenuation directly proportional to the amount of contrast in the vessels of that region

27
Q

how do you calculate cerebral blood flow

A

cerebral blood volume divide mean transit time

28
Q

reduction in the CBV represents what

A

irreversible infarction

29
Q

what can u use to distinguish ischaemia from infarction

A

CBF and CBV maps

30
Q

if you have a large core infarct and do thrombolysis what risk does it increase

A

secondary haemorrhage

31
Q

causes of ischaemic stroke

A

occluded by thrombus ((often as a complication of atherosclerosis)

Embolus of fatty material from an atherosclerotic plaque or a clot in a larger artery or the heart (often as a complication of atrial fibrillation or atherosclerosis of the carotid arteries).

32
Q

causes of haemorrhagic stroke

A

Intracerebral haemorrhage – bleeding within the brain parenchyma or ventricular system. The main cause of intracerebral haemorrhage is high blood pressure.

Subarachnoid haemorrhage – bleeding into the subarachnoid space from a cerebral blood vessel, aneurysm or vascular malformation.

33
Q

rarer causes of stroke

A

Cerebral venous thrombosis — more likely in patients with a prothrombotic tendency, for example, related to pregnancy, infection, dehydration or malignancy.

Carotid artery dissection — tends to occur in younger people and may be preceded by neck trauma.

34
Q

risk factors of stroke

A 
age
men
COCP
Cardiovascular disease such as angina, myocardial infarction and peripheral vascular disease
Previous stroke or TIA
Atrial fibrillation
Carotid artery disease
Hypertension
Diabetes
Smoking
Vasculitis
Thrombophilia
35
Q

early complications of stroke

A

Haemorrhagic transformation of ischaemic stroke.

Cerebral oedema.

Seizures.

Venous thromboembolism — pulmonary embolism

hydration and nutritional difficulties

pressure sores

spasticity with pain and/or contractures

Cardiac complications — cardiac complications (myocardial ischemia, congestive heart failure, atrial fibrillation, and arrhythmias) are common due to shared aetiology.

Infection — people with stroke are at increased risk of infection including aspiration pneumonia, urinary tract infection, and cellulitis from infected pressure sores.

36
Q

long term complications

A 
mobility 
sensory problems
continence problems
pain
fatigue
problems with swallowing, hydration adn nutrition
sexual dysfunction
skin problems
visual problems
cognitive problems
difficulties with activities of daily living
emotional and psychological problems
communication problems
financial problems
37
Q

mobility complications from stroke

A

hemiparesis or hemiplegia
ataxia
falls
spasticity and contractures

38
Q

when do you suspect a TIA

A

sudden onset, focal neurological deficit which has completely resolved within 24 hours of onset and cannot be explained by another condition such as hypoglycaemia

  • Unilateral weakness or sensory loss.
  • Dysphasia.
  • Ataxia, vertigo, or incoordination.
  • Syncope.
  • Sudden transient loss of vision in one eye (amaurosis fugax).
  • Homonymous hemianopia.
  • Cranial nerve defects.
39
Q

when do u suspect stroke

A

longer than 24 hours onset

  • Confusion, altered level of consciousness and coma.
  • Headache – sudden, severe and unusual headache which may be associated with neck stiffness. Sentinel headache(s) may occur in the preceding weeks.

Weakness − sudden loss of strength in the face or limbs.

Sensory loss – paraesthesia or numbness.

Speech problems such as dysarthria.

Visual problems – visual loss or diplopia.

Dizziness, vertigo or loss of balance — isolated dizziness is not usually a symptom of TIA.

Nausea and/or vomiting.
Specific cranial nerve deficits such as unilateral tongue weakness or Horner’s syndrome (miosis, ptosis, and facial anhidrosis).

Difficulty with fine motor co-ordination and gait.

Neck or facial pain (associated with arterial dissection

40
Q

when to suspect a posterior circulation strok

A 
Symptoms of acute vestibular syndrome — acute
persistent
continuous vertigo
dizziness with nystagmus
nausea or vomiting
head motion intolerance
new gait unsteadiness.
41
Q

what do you ask in the histroy

A

clinical features mentioned such as
headache
vomiting
decreased level of consciousness

time of onset, activity at onset

risk factors mentioned CVS disease smoking alcohol

PMH - miscarriage
thromboembolic events 
 past myocardial infarct (MI)
• recent chest pain suggesting recent MI (or thoracic root aortic
dissection)
• atrial fibrillation
• rheumatic fever as a child
• valvular heart disease or valve replacement
• symptoms of heart failure
• palpitations
• pacemaker
PVD

FH of stroke or hyperlipidaemia or hypercoagulability

current medications such as anticoagulants, HRT or illicit

always take a collateral history ie witness ambulance personnel family members

42
Q

What has MRI showed in terms of TIA lasting longer than an hour

A

associated with a new infarction

43
Q

what conditions have a sudden onset

A

stroke
epilepsy
trauma

44
Q

what conditions have subacute onset that build up over hours or days

A

infectious
inflammatory
metabolic
malignant

45
Q

main differentials for stroke/TIA

A

blackouts/syncope
epilepsy
migraine with aura
metabolic, particularly hypoglycaemia

46
Q

Mx of stroke acutely

MDT involved who

A
  1. aspirin 300 mg AFTER CT SCAN daily for 2 weeks then clopidogrel 75 mg daily long-term.
  2. Thrombolysis w altpeplase - tissue plasminogen activator
    - refere to stroke unit
    - monitor BP

secondary prevention
A statin should also be offered if the patient is not already on statin therapy.
aspirin
stop smoking

LONG TERM
Nurses
Speech and language (SALT)
Dieticians
Physiotherapy
Occupational therapy
Social services
Optometry and ophthalmology
Psychology
Orthotics
speech therapy
liaison between district services and social workers
47
Q

Diagnostic of which area is affected

A

diffusion weighted MRI

48
Q

how do u initially manage a stroke pt

A 
reassure pt 
monitor GCS
CT/MRI to distinguish
bloods - glucose, U&Es, FBC - polycythaemia, ESR
ECG- AF,MI
NBM

ICB (30 decks)

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