Stroke (summary)

Dr Derek Smith et al.

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.

  • 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
  • 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
  • initial diagnosis
  • assessment of the likely benefit of thrombolysis/thrombectomy
  • follow up

Imaging is critical in diagnosis and management of stroke. Treatment guidelines rely on imaging findings and the clear communication between clinical and radiology teams.


Non-contrast CT is the first line imaging investigation for stroke.

In the emergency setting, CT is used to exclude haemorrhage (case 2) which appears as hyperdense regions, usually in vessel rich areas such as the basal ganglia. Haemorrhage excludes thrombolysis as a treatment option.

An important early sign of ischaemic stroke is the hyperdense vessel sign (case 4). This is the result of thrombus/embolus in the vessel and is associated with increased complications when thrombolysis is used.

Other early signs include loss of grey-white differentiation with "blurring" at the edges of ischaemic areas (case 1, first CT). As infarction develops, the affected territories appear hypodense with swelling and oedema of surrounding tissues (case 1, second CT).

Later appearances liquifying necrosis occurs following cell death to leave large areas of low-density corresponding to encephalomalacia, with surrounding scarring corresponding to gliosis (case 1, fourth CT).


Angiography has a growing role in CT imaging and has a number of roles. It can identify thrombi in vessels guiding thrombolysis clot retrieval. It can also reveal other causative factors for stroke (dissection, atherosclerosis, aneurysms).


MRI is a fantastic tool for investigating stroke but is time-consuming and not widely available in the acute setting.

It can contrast between haemorrhagic and ischaemic infarcts, assess parenchymal damage, determine the age of stroke (diffusion imaging) and assess perfusion of the affected region.


Carotid doppler ultrasound is used to assess the carotid arteries in patients who have had a stroke. After acute investigations and management have been started, patients may be for consideration of carotid endarterectomy if there is stenosis in relevant arteries.

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Article Information

rID: 34332
Synonyms or Alternate Spellings:
  • Ischaemic stroke (summary)
  • Haemorrhagic stroke (summary)
  • Ischemic stroke (summary)

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Cases and Figures

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    Figure 1: diagram of cerebral vascular territories
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    Case 1: loss of grey/white differentiation (left MCA)
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    Case 1: some hours later - hypodensity (left MCA)
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    Case 1: after one day - high signal DWI (left MCA)
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    Case 1: follow-up, gliosis (left MCA)
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    Case 2: Hyperdense collection in left basal ganglia with extension into ventricular system
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    Case 3: Hypodensity in left PCA territory (ischaemic stroke)
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    Case 4: Hyperdense right MCA
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    Case 4: Hypodensity in right MCA territory
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