7th June 2023

Classification

Stroke is defined by the World Health Organisation as a ‘clinical syndrome of vascular origin, with rapidly developing signs of focal or global cerebral dysfunction, lasting for over 24 hours or leading to death’.

85% of strokes are ischaemic. These are due to an interruption in the blood supply to a particular area of the brain. Ischaemic strokes can be caused by the following:

• Cardioembolism – most commonly due to atrial fibrillation
• Large vessel thrombosis
• Small vessel disease
• Hypoperfusion – for example, due to systemic hypotension during a period of critical illness
• Venous sinus thrombosis

The remaining 15% are haemorrhagic due to the rupture of a blood vessel or vascular structure in the brain. This can be due to the following:

• Intracerebral haemorrhage – bleeding within the brain, which can be further divided into:
  • Intraparenchymal – within the brain tissue
  • Intraventricular – within the ventricles of the brain
• Subarachnoid haemorrhage