Stroke Types

The two primary stroke types are ischaemic and haemorrhagic; ischaemic stroke accounts for most stroke cases.11

Hemorrhagic and ischemic. Image courtesy of Adobe stock photos by pikovit.

Other stroke types include transient ischaemic attack (TIA), haemodynamic, cryptogenic, and brain stem strokes.

The risk factors include hypertension, diabetes, smoking, older age, gender, and history of TIA. The characteristics of these stroke types are summarized.

Stroke Types and Characteristics

Stroke TypeCharacteristics
  • Characterized by thromboembolism or clogged arteries
  • Account for 80 to 85% of strokes globally
  • Cause deficits within minutes to hours as stroke progresses (medical emergency)
  • Ages brain 3.6 years for every hour that passes after the onset of stroke
  • Recoverable penumbral tissue for up to three hours following the onset of symptoms
  • Categorized according to etiology (thrombotic or embolic) and classified into five subtypes (large-artery atherosclerosis (may be an embolus or thrombus); cardioembolism (may be high or medium risk based on evidence of embolism); small-vessel (lacuna) occlusion; other determined cause; and undetermined etiology)
    • Thrombotic stroke occurs when a thrombus impairs cerebral blood flow by narrowing or blocking an artery, typically around an atherosclerotic plaque. The blockage may be a large vessel (e.g., carotid artery systems, vertebral arteries, the Circle of Willis) or a small vessel (e.g., branches of the Circle of Willis, the posterior circulation).
    • Embolic stroke occurs when an artery that supplies oxygen to the brain is blocked. The blockage can be from blood clot, fatty deposits, atherosclerotic plaque fragments, and cancerous cells or infectious materials from conditions such as atrial myxoma or endocarditis.
  • Account for 15-20% of stroke cases globally and are associated with a higher risk of fatality than ischaemic stroke (~30% of patients die within 30 days after a stroke event)
  • Often caused by damage and rupture of cerebral blood vessel wall secondary to hypertension
  • Categorized by location of haemorrhage (intracerebral or subarachnoid)
    • Intracerebral haemorrhage (ICH) is the most common, accounts for 87% of haemorrhagic strokes, and is characterized by bleeding directly into the brain parenchyma.
    • Subarachnoid stroke is characterized by bleeding into the subarachnoid space between the arachnoid and pia mater layers of the meninges.
    • Other types of haemorrhagic stroke include:
      • Intraventricular haemorrhage (bleeding into the ventricles)
      • Nontraumatic categorized as primary (unrelated to congenital or acquired lesions), secondary (caused by a congenital or acquired condition), or spontaneous (unrelated to trauma or surgery)
Transient Ischaemic Attack (TIA)19-22
  • Sometimes referred to as "ministrokes"
  • Caused by inadequate cerebral blood flow
  • Often precede an ischaemic stroke
  • Uncommon causes include hypercoagulable states, arterial dissection, sympathomimetic drugs (e.g., cocaine), and arteritis (caused by noninfectious necrotizing vasculitis, drugs, irradiation, or local trauma)
  • Risk of ischaemic stroke is dangerously high in the period following a TIA (~5% of patients have a stroke within seven days of a TIA)
  • Risk of stroke is doubled for patients who do not seek treatment within 7 days of a TIA
    • Risk of stroke is 10% to 20% for patients who do not seek treatment within 3 months
    • Risk of stroke is 24% to 29% for patients who do not seek treatment within five years.
  • Characterized by hypoperfusion rather than embolism or vasculopathy
  • Caused by conditions that result in significant low blood pressure, reducing cerebral blood flow (e.g., heart failure, hypotension)
  • Suggested by infarcts that occur in multiple arterial territories
  • Most common cause is arterial fibrillation
  • Other potential causes include new ventricular thrombus after myocardial infarction or severe valvular heart disease (e.g., rheumatic disease, infective endocarditis, or bioprosthetic and mechanical heart valves)
  • Cerebral ischaemia of unknown origin
  • Possible causes may include paradoxical embolism through a patent foramen ovale, atrial fibrillation, large artery atherosclerosis or thrombophilia
  • Evidence suggests cryptogenic stroke incidence is higher in African-Americans (two times more likely)
Small Subcortical or Lacunar Infarct26
  • Commonly lead to isolated sensory or motor neurological deficits with little or no change in mental status
  • Often involve deep white matter, basal ganglia or brainstem
  • Often caused by occlusion of small penetrating arteries arising from the internal carotid arteries
  • Main risk factor is hypertension which leads to local damage at level of penetrating artery with subsequent occlusion
Brain Stem27
  • Often presents with vertigo, dizziness, imbalance, slurred speech, diplopia, or other symptoms related to the brainstem