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Back| Classification | Description | |
|---|---|---|
| I | Large Artery Atherosclerosis (LAA) | Carotid ultrasound shows carotid artery occlusion or stenosis (stenosis ≥ 50% of the arterial cross-section); angiography or MRA shows stenosis ≥ 50% in the carotid, anterior cerebral, middle cerebral, posterior cerebral, vertebrobasilar arteries.
The following findings are important for diagnosing LAA: (1) History of multiple transient ischemic attacks (TIA), often in the same arterial territory; (2) Symptoms of aphasia, neglect, motor dysfunction, or cerebellar/brainstem involvement; (3) Carotid bruit, weakened pulse, asymmetric blood pressure; (4) CT or MRI shows cortical or cerebellar damage, or subcortical/brainstem lesions > 1.5 cm; (5) Color Doppler, transcranial Doppler (TCD), MRA, or digital subtraction angiography (DSA) shows stenosis > 50% or occlusion in relevant intracranial or extracranial arteries; (6) Exclude cardioembolic stroke. |
| II | Cardioembolic Stroke (CE) | (1) Clinical and imaging findings similar to LAA; (2) History of multiple TIAs or strokes in different vascular territories and other embolic events; (3) Presence of at least one cardiac condition causing embolism. |
| III | Small Artery Occlusion or Lacunar Stroke (SAA) | Diagnosis can be confirmed if any of the following three criteria are met: (1) Typical clinical presentation of lacunar infarction, with imaging showing a corresponding stroke lesion < 1.5 cm; (2) Atypical clinical symptoms of lacunar infarction, but no corresponding lesion on imaging; (3) Atypical clinical presentation of lacunar infarction, with imaging showing a lesion < 1.5 cm corresponding to clinical symptoms. |
| IV | Stroke of Other Determined Etiology (SOE) | SOE is relatively rare and includes strokes caused by infections, immune or non-immune vasculopathies, hypercoagulable states, hematologic disorders, genetic vasculopathies, and drug abuse. These patients should have clinical, CT, or MRI evidence of acute ischemic stroke, with lesion size and location. Hematologic disorders should be confirmed by blood tests, and large/small artery disease and cardioembolic stroke should be excluded. |
| V | Stroke of Undetermined Etiology (SUE) | Cause remains unidentified after extensive testing. |
Explanation
The TOAST subtype classification standard is used for early etiological classification of ischemic stroke and has certain clinical value. However, clinical studies have shown that some patients still cannot obtain a clear TOAST diagnosis three months after onset. This may be because TOAST classification focuses on etiological diagnosis, which requires time for examination, observation, and follow-up. In clinical practice, laboratory and imaging tests, as well as observation and follow-up, take time. Only when these data are complete can a correct etiological diagnosis be made.
The TOAST subtype classification standard for acute ischemic stroke is currently the internationally recognized etiological classification standard for ischemic stroke. This standard is derived from a multicenter, randomized, double-blind, controlled clinical study. The TOAST subtype classification standard focuses on the etiological classification of ischemic stroke. The theory of large and small vessel disease proposed by this classification method plays an important role in the study of the pathogenesis of cerebral infarction. According to clinical characteristics and imaging/laboratory tests, TOAST classifies ischemic stroke into five types.
