Ischemic stroke (summary)

Changed by Jeremy Jones, 9 Jan 2018
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Stroke is a clinical diagnosis where an acute neurological deficit follows a cerebrovascular insult. There are two main groups of stroke: ischaemic (>80%) or haemorrhagic (<20%) 1.

Reference article

This is a summary article; read more in our article on stroke.

Summary

  • anatomy
  • epidemiology
    • common
    • leading cause of disability
    • third highest cause of mortality in the UK 2,3
  • presentation
    • sudden neurological deficit
    • manifest symptoms depend on the vascular territories involved
    • time of onset is important when considering treatment
  • pathophysiology
    • brain parenchyma is deprived of blood flow and therefore oxygen
    • ischaemic
      • arteries occluded by thrombus or embolus
      • temporary loss of blood flow may occur (TIA)
    • cell death results in oedema and swelling
  • investigation
    • non-contrast CT head in the first instance
      • exclude haemorrhage or other cause
      • may show hyperdense vessel or evidence of infarction
    • CT angiography
      • some centres use this to identify blockages and assess collaterals when planning clot retrieval
    • MRI
      • less commonly used for acute events, but good for identifying infarcts (especially using DWI sequences)
    • ultrasound
      • carotid Doppler ultrasound in the peri-stroke period to select patients who may benefit from endarterectomy
  • treatment
    • thrombolysis or thrombectomy
      • ischaemic strokes less than 4.5 hours old
      • depends on the local protocol
      • should be discussed with an acute stroke service
    • stroke patients should be managed in a stroke centre
    • medical management of hypertension and risk factor reduction

Imaging

  • role of imaging
    • is there evidence of stroke?
    • what is the distribution and severity of the stroke?
    • is there haemorrhagic transformation?
    • is a cause visible, e.g. in situ thrombus?
    • are there contraindications to IV thrombolysis?
    • are there indications for clot-retrieval?
    • is there significant carotid stenosis?
  • radiographic features
    • CT
      • parenchymal infarction may not be visible in the acute setting
      • with time, cytotoxic oedema causes reduced density on CT
      • clot within a vessel may be seen as hyperdensity
      • acute haemorrhage will appear dense
    • MRI
      • the most important sequence is the DWI (diffusion sequence)
      • diffusion restriction in this context is highly sensitive for ischaemia
    • angiography (CTA/MRA/DSA)
      • assessment of arterial supply to confirm whether a clot is present
    • perfusion (CT/MRI)
      • assessment of ischaemic/infarcted areas
      • ischaemic may be reversible
    • carotid doppler
      • not used in the acute setting
      • assessment of the neck vessels looking for carotid stenosis
  • +</ul><h4>Imaging</h4><ul>
  • +<li>
  • +<strong>role of imaging</strong><ul>
  • +<li>is there evidence of stroke?</li>
  • +<li>what is the distribution and severity of the stroke?</li>
  • +<li>is there haemorrhagic transformation?</li>
  • +<li>is a cause visible, e.g. in situ thrombus?</li>
  • +<li>are there contraindications to IV thrombolysis?</li>
  • +<li>are there indications for clot-retrieval?</li>
  • +<li>is there significant carotid stenosis?</li>
  • +</ul>
  • +</li>
  • +<li>
  • +<strong>radiographic features</strong><ul>
  • +<li>CT<ul>
  • +<li>parenchymal infarction may not be visible in the acute setting</li>
  • +<li>with time, cytotoxic oedema causes reduced density on CT</li>
  • +<li>clot within a vessel may be seen as hyperdensity</li>
  • +<li>acute haemorrhage will appear dense</li>
  • +</ul>
  • +</li>
  • +<li>MRI<ul>
  • +<li>the most important sequence is the DWI (diffusion sequence)</li>
  • +<li>diffusion restriction in this context is highly sensitive for ischaemia</li>
  • +</ul>
  • +</li>
  • +<li>angiography (CTA/MRA/DSA)<ul><li>assessment of arterial supply to confirm whether a clot is present</li></ul>
  • +</li>
  • +<li>perfusion (CT/MRI)<ul>
  • +<li>assessment of ischaemic/infarcted areas</li>
  • +<li>ischaemic may be reversible</li>
  • +</ul>
  • +</li>
  • +<li>carotid doppler<ul>
  • +<li>not used in the acute setting</li>
  • +<li>assessment of the neck vessels looking for carotid stenosis</li>
  • +</ul>
  • +</li>
  • +</ul>
  • +</li>

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