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This article provides an overview of the classification of stroke based on underlying pathophysiology and clinical presentation.


Major categories of stroke

Strokes can be classified into two major categories: ¹

  • Ischaemic stroke (87%)
  • Haemorrhagic stroke (13%)

 

Ischaemic stroke

Ischaemic strokes occur when the blood supply to an area of the brain is reduced, resulting in tissue hypoperfusion.

There are several mechanisms which can result in an ischaemic stroke including:

  • Embolism: An embolus from somewhere else in the body (e.g. the heart) causes obstruction of a cerebral vessel, resulting in hypoperfusion to the area of brain the vessel supplies.
  • Thrombosis: A blood clot forms locally within a cerebral vessel (e.g. due to atherosclerotic plaque rupture).
  • Systemic hypoperfusion: Reduced blood supply to the entire brain secondary to systemic hypotension (e.g. cardiac arrest).
  • Cerebral venous sinus thrombosis: Blood clots form in the veins that drain the brain, resulting in venous congestion and hypoxia which damages brain tissue.

 

Haemorrhagic stroke

Haemorrhagic strokes occur when there is a rupture of a blood vessel or abnormal vascular structure within the brain.

There are two sub-types of haemorrhagic stroke:

  • Intracerebral haemorrhage: Bleeding within the brain itself secondary to a ruptured blood vessel.
    • Intraparenchymal (bleeding within the brain tissue)
    • Intraventricular (bleeding within the ventricles)
  • Subarachnoid haemorrhage: Bleeding that occurs outside of the brain tissue, between the pia mater and arachnoid mater.

Bamford classification of ischaemic stroke

The most commonly used classification system for ischaemic strokes is the Bamford classification (or Oxford classification) system. This categorises stroke based on the initial presenting symptoms and clinical signs. This system does not require imaging to classify the stroke, instead, it is a purely clinical diagnosis.

Total anterior circulation stroke (TACS)

A total anterior circulation stroke (TACS) involves a large cortical stroke affecting the areas of the brain supplied by both the middle and anterior cerebral arteries.

All three of the following need to be present for a diagnosis of TACS:

  • Unilateral weakness (and/or sensory deficit) of the face, arm and leg
  • Homonymous hemianopia
  • Higher cerebral dysfunction (dysphasia, visuospatial disorder)

 

Partial anterior circulation stroke (PACS)

A partial anterior circulation stroke (PACS) is a less severe form of TACS, in which only part of the anterior circulation has been compromised.

Two of the following need to be present for a diagnosis of PACS:

  • Unilateral weakness (and/or sensory deficit) of the face, arm and leg
  • Homonymous hemianopia
  • Higher cerebral dysfunction (dysphasia, visuospatial disorder)

 

Posterior circulation syndrome (POCS)

A posterior circulation syndrome (POCS) involves damage to the area of the brain supplied by the posterior circulation (e.g. cerebellum and brainstem).

One of the following need to be present for a diagnosis of POCS:

  • Cerebellar or brainstem syndromes (e.g. ataxia, nystagmus, vertigo)
  • Loss of consciousness
  • Isolated homonymous hemianopia

Lacunar syndrome (LACS)

A lacunar syndrome (LACS) involves a subcortical stroke that occurs secondary to small vessel disease. There is no loss of higher cerebral functions (e.g. dysphasia).

One of the following needs to be present for a diagnosis of LACS:

  • Unilateral weakness (and/or sensory deficit) of the face, arm and leg (or all 3)
  • Pure sensory stroke
  • Ataxic hemiparesis
Bamford stroke classification (Oxford Stroke Classification)

Bamford Stroke Classification


References

1.  Donnan GA, Fisher M, Macleod M, Davis SM (May 2008). “Stroke”. Lancet. 371 (9624): 1612–23. doi:10.1016/S0140-6736(08)60694-7. PMID 18468545.

2. By CFCF [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons

3. By James Heilman, MD [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons

4. By Lipothymia (Anonymised CT scan from my own practice) CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) via Wikimedia Commons

5. By James Heilman, MD [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], from Wikimedia Commons