TOAST Classification

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TOAST Classification

• 16/05/03
• Craig Douglas

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Need For Subclassification

• Prognosis, recurrence, aetiology and management
  differ between the subtypes
• The classification of ischaemic stroke according
  to the aetiological mechanism is considered
  logical, since it is only with understanding of
  the underlying mechanisms of stroke that rational
  acute and secondary therapies can be deployed
• (Bamford 2000)

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Classification Systems

• There are 2 systems which use aetiology as their
  basis
• -Stroke Data Bank (Gross, 1986)
• -TOAST (Adams, 1993)
• The main difficulty with this system is
  performing the necessary technical examinations
  on all patients

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Other Options?

• (Bamford et al)

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Oxfordshire Community Stroke Project

• Bamford et al. 1991
• Uses clinical localisation of the infarct
  topography
• Provides info. More relevant to the prognosis
  than to the underlying vascular pathology
• TACI, PACI, LACI, POCI

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TOAST Classification

• There are 5 diagnostic sub-types of ischaemic
  stroke
• 1.Large artery atherosclerosis
• 2.Cardioembolism
• 3.Small vessel occlusion (lacunar)
• 4.Other determined aetiology
• 5.Undetermined aetiology
• Multiple possible aetiologies (No.6)

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Determining TOAST Sub-type

• (VTACS)

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Section 1a History/Emboli

• High Risk Source
• -mechanical pros valve
• -AF
• -sick sinus syndrome
• -MI (prev 4 weeks)
• -dilated cardiomyopathy
• -atrial myxoema
• -IE
• -akinetic LV
• Scores 1

• Medium Risk Source
• -MI (gt4 weeks, lt6mon)
• -CCF
• -LV aneurysm
• -atrial flutter
• -bioprosthetic valve
• -mitral valve prolapse
• -mitral stenosis
• -ASD
• -patent foramen ovale
• Scores 2

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Section 1b History/Large Vessel Disease

• Known extracranial large vessel disease.
• Scores 1
• Negative prior carotid study
• Scores 2
• No previous carotid study
• Scores 3

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Section 1c History/Prior Specialised Tests

• Used for determining causes of stroke outwith
  LVA, cardioembolism or small vessel disease
• Positive past specialised tests (haematologic,
  CSF, histology)
• Scores 1
• Negative past specialised tests
• Scores 2
• None previously, scores 3

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Section 2 Physical Exam

• Findings obtained on the day of admission are
  used
• Atrial Fibrillation (1yes, 2no)
• Evidence of systemic emboli, such as clots on
  fundoscopy, splinter haemorrhages, RS, JL, ON
• Evidence of classical lacunar syndromes. Rule out
  LS if somnolence, aphasia, visual abnormalities,
  oculomotor abnormalities or disorders of higher
  motor function are new findings.

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Lacunar Syndromes

• Pure motor defecit
• Pure sensory defecit
• Mixed sensorimotor defecit
• Ataxic hemiparesis
• Dysarthria Clumsy hand!

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Section 3a Diagnostic Signs (CT Scan)

• Evidence of haemorrhage with no sign of recent
  infarction excludes the patient from typing
• Acute bland or haemorrhagic infarct involving
  cortical structures /- subcortical structures,
  scores 1
• Changes in the distribution of a circumferential
  artery in the brain stem or cerebellum, scores 2
• Multiple lesions of same age widely distributed
  large vessel disease, scores 3

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Section 3b Diagnostic Tests(MRI)

• Similar to section 3a, not many patients in
  Dundee will have had an MRI
• Also, look for absence of flow in major
  extracranial arteries, scored as 4 and indicative
  of large vessel atherosclerosis
• A scan not performed is scored as 7

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Section 3c Non Invasive Vascular Studies

• More than 50 stenosis of appropriate
  extracranial arteries
• Scores 1
• Less than 50 stenosis of same vessels described
  above
• Scores 2
• Investigations not done, scores 3

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Section 3d Cerebral Arteriogram

• Occlusion, gt50 stenosis or gt2mm ulceration of
  appropriate vessels, score 1
• Non-atherosclerotic pathology is scored 4 and may
  indicate stroke of other determined aetiology
• Normal is a score of 5

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Section 3e Cardiovascular Examination

• This section is scored by compiling data from
  echocardiography, an ECG and Holter monitoring
• High risk of emboli detected at any of the three
  subsections should be scored 1 (see section 1a
  for findings)
• Medium risk, scores 2
• Normal, scores 3

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Section 3f Specialised Tests

• Complete set of studies indicating the underlying
  cause, scores 1 and indicates stroke of other
  determined aetiology
• Incomplete set of studies suggestive of
  underlying cause, scores 2, think of other
  determined and multiple aetiologies
• Normal, score of 3

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Postmortem Examination

• This is a possible section for helping to subtype
  the stroke
• Use only in patients who had a primary infarct
  leading to fatality
• Look for large vessel narrowing
• Look for emboli and underlying heart disease
• Look for lacunar infarction

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Conclusions

• Using these criteria allows an experienced
  physician to sub-type ischaemic stroke
• By sub-typing according to aetiology, this allows
  better management of the patient and
  understanding of the condition
• It would take considerable time to use the
  described strategies for the sub-typing of
  stroke, and would demand huge resources