title: Cerebral microbleeds and the risk of intracerebral haemorrhage after thrombolysis for acute ischaemic stroke: systematic review and meta-analysis.
abstract: BACKGROUND
  Intracerebral haemorrhage (ICH) remains the most devastating yet unpredictable complication of intravenous thrombolysis for acute ischaemic stroke. We performed a systematic review and meta-analysis, to assess whether the presence of cerebral microbleeds (CMBs) on prethrombolysis MRI scans is associated with an increased risk of ICH.
  
  
  METHODS
  We searched PubMed for studies assessing ICH risk in patients with acute ischaemic stroke treated with thrombolysis, in relation to the presence of pre-treatment CMBs.
  
  
  RESULTS
  We identified five studies including 790 patients and pooled data in a meta-analysis. The CMB (+) versus CMB (-) groups were not significantly different in age, gender or stroke severity. The overall prevalence of CMBs was 135/790 (17.1%). Amongst patients with CMBs, 10/135 (7.4%) experienced a symptomatic ICH after thrombolysis, compared to 29/655 (4.4%) patients without CMBs. The pooled relative risk of ICH was 1.90 (95% CI 0.92 to 3.93; p=0.082).
  
  
  CONCLUSIONS
  The available evidence does not demonstrate a statistically significant increased risk of symptomatic ICH after thrombolysis for ischaemic stroke in patients with CMBs. However, in view of the methodological limitations of the studies included, the clinical relevance of any potential hazard associated with CMBs remains uncertain. Further studies are warranted to evaluate whether the risk of ICH might outweigh the benefit of thrombolysis, especially in patients with multiple lobar CMBs suggestive of cerebral amyloid angiopathy.
authors.affiliation: Stroke Research Group, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology and The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK.
authors.forename: Andreas
authors.initials: A
authors.lastname: Charidimou
authors.forename: Puneet
authors.initials: P
authors.lastname: Kakar
authors.forename: Zoe
authors.initials: Z
authors.lastname: Fox
authors.forename: David J
authors.initials: DJ
authors.lastname: Werring
mesh_terms: D002545:Brain Ischemia / Q000150:complications / Q000188:drug therapy; D002543:Cerebral Hemorrhage / Q000139:chemically induced*; D005343:Fibrinolytic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D012307:Risk Factors; D020521:Stroke / Q000150:complications / Q000188:drug therapy; D010959:Tissue Plasminogen Activator / Q000009:adverse effects* / Q000627:therapeutic use
chemical_list: D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator