title: Towards understanding the cause of stroke in young adults utilising a new stroke classification system (A-S-C-O).
abstract: BACKGROUND
  Stroke in younger people is relatively common and frequently unexplained. While understanding of the causes of young stroke has improved, there remains uncertainty over the role of low-risk lesions such as a patent foramen ovale (PFO). The TOAST criteria are often used to describe stroke aetiology, but in younger people in whom PFOs are frequent, there is a very high proportion of cases attributed to cardiac embolism. The impact of using the newer A-S-C-O criteria on stroke aetiology was investigated.
  
  
  METHODS
  Consecutive patients with ischaemic stroke were investigated and categorised by the TOAST and ASCO1 criteria. Stroke aetiology was presented and compared by the different classification systems.
  
  
  RESULTS
  Of the 106 ischaemic stroke cases, by TOAST 6% were 'large artery atheroma', 11% 'small vessel occlusion', 28% 'cardioembolic', 22% 'other determined cause' and 33% 'undetermined cause'. The vascular territory and associated causes are presented. With the ASCO1 criteria, there were more cases of unclassified stroke (51.9 vs. 34.0%; p < 0.001) and fewer cases of cardiac embolism. Kappa ranged from 0.5 for 'undetermined aetiology' to 1.0 for both 'large artery atheroma' and 'other determined aetiology'. Younger cases (<45 years) were less likely to be either 'large artery atheroma' or 'small vessel occlusion'.
  
  
  CONCLUSIONS
  Using the ASCO criteria, more patients fall into the undetermined group which more accurately reflects our current uncertainty regarding the pathogenic relevance of PFOs in this age group.
authors.affiliation: Department of Medicine, University of Cambridge, Cambridge, UK.
authors.forename: P E
authors.initials: PE
authors.lastname: Cotter
authors.forename: M
authors.initials: M
authors.lastname: Belham
authors.forename: P J
authors.initials: PJ
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002545:Brain Ischemia / Q000145:classification / Q000150:complications* / Q000175:diagnosis; D016009:Chi-Square Distribution; D032882:Comprehension; D004739:England; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000145:classification / Q000175:diagnosis / Q000209:etiology*; D055815:Young Adult