title: Cerebral microbleeds are common in ischemic stroke but rare in TIA.
abstract: BACKGROUND
  In patients with stroke, gradient-echo MRI commonly detects microbleeds, indicating small artery disease with increased risk of macroscopic intracranial bleeding. Antithrombotic treatments are frequently prescribed after TIA and stroke, but there have been no previous studies of microbleeds in TIA. Because microbleeds may predict the hemorrhagic risk of antithrombotic treatments, we studied the prevalence of microbleeds, risk factors, and pathophysiologic mechanisms in patients with ischemic stroke and TIA.
  
  
  METHODS
  One hundred twenty-nine consecutive patients with ischemic stroke or TIA were studied with MRI including T2, fluid-attenuated inversion recovery, and gradient-echo MRI sequences. Blinded observers counted microbleeds and graded white matter T2 hyperintensities throughout the brain. TIA patients with previous ischemic stroke were excluded.
  
  
  RESULTS
  Sixty-seven percent of patients had ischemic stroke; 33% had TIA. Microbleeds were found in 23% of ischemic stroke patients but only 2% of TIA patients (p < 0.001). There were no significant differences in conventional risk factors or the severity of white matter disease on T2 MRI between stroke and TIA patients. Patients with microbleeds were more often hypertensive (81 vs 59%; p = 0.04) and had more severe MRI white matter disease on T2 MRI (p = 0.003).
  
  
  CONCLUSIONS
  Microbleeds are common in ischemic stroke but rare in TIA, an observation not explained by differences in vascular risk factors or severity of white matter disease seen on T2 MRI. This finding has implications for the safety of antithrombotic therapy and clinical trial design in the two groups. Microbleeds may also be a new marker for severe microvascular pathology with increased risk of permanent cerebral infarction.
authors.affiliation: Stroke Research Group, Institute of Neurology, University College London, National Hospital for Neurology and Neurosurgery, London, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Werring
authors.forename: L J
authors.initials: LJ
authors.lastname: Coward
authors.forename: N A
authors.initials: NA
authors.lastname: Losseff
authors.forename: H R
authors.initials: HR
authors.lastname: Jäger
authors.forename: M M
authors.initials: MM
authors.lastname: Brown
mesh_terms: D000368:Aged; D015415:Biomarkers; D001921:Brain / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology; D002545:Brain Ischemia / Q000453:epidemiology*; D015984:Causality; D002536:Cerebral Arteries / Q000473:pathology / Q000503:physiopathology; D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D015897:Comorbidity; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000453:epidemiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation / Q000473:pathology / Q000503:physiopathology; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology
chemical_list: D015415:Biomarkers