title: Multiple cerebral microbleeds in hyperacute ischemic stroke: impact on prevalence and severity of early hemorrhagic transformation after thrombolytic treatment.
abstract: OBJECTIVE
  The purpose of our study was to assess whether cerebral microbleeds are related to early hemorrhagic transformation after thrombolytic therapy for hyperacute ischemic stroke.
  
  
  METHODS
  The cases of 279 patients with suspected ischemic stroke who underwent MRI including T2*-weighted images were retrospectively evaluated. The inclusion criteria were as follows: imaging performed within 6 hr after symptom onset, presence of territorial infarct of anterior circulation, no history of intracerebral hemorrhage, thrombolytic treatment, and available follow-up MR images. Microbleeds were classified according to number as follows: absent (grade 1, 0 bleeds), mild (grade 2, 1-2 bleeds), moderate (grade 3, 3-10 bleeds), and severe (grade 4, > 10 bleeds). The prevalence and severity of early hemorrhagic transformation after thrombolysis were assessed on follow-up images.
  
  
  RESULTS
  Among 279 patients, 65 patients (37 men, 28 women; mean age, 67 years) met the inclusion criteria. Microbleeds were found in 25 patients. Early hemorrhagic transformation occurred in nine of 40 patients without microbleeds (grade 1) and in eight of 25 patients with microbleeds: two of 12 patients with grade 2, three of eight patients with grade 3, and three of five patients with grade 4 microbleeds. The presence of symptomatic hemorrhage did not correlate with the number of microbleeds. Results of multivariate logistic regression analysis showed that the presence of microbleeds was not associated with hemorrhagic transformation after thrombolytic treatment.
  
  
  CONCLUSIONS
  Small and large numbers of microbleeds are not independent risk factors for early hemorrhagic transformation and symptomatic hemorrhage after thrombolytic therapy for hyperacute ischemic stroke. Additional studies with large groups of subjects are needed to confirm our conclusion.
authors.affiliation: Department of Radiology, Neuroradiology, and Research Institute of Radiology, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul, South Korea.
authors.forename: Ho Sung
authors.initials: HS
authors.lastname: Kim
authors.forename: Deok Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Chang Woo
authors.initials: CW
authors.lastname: Ryu
authors.forename: Jeong Hyun
authors.initials: JH
authors.lastname: Lee
authors.forename: Choong Gon
authors.initials: CG
authors.lastname: Choi
authors.forename: Sang Joon
authors.initials: SJ
authors.lastname: Kim
authors.forename: Dae Chul
authors.initials: DC
authors.lastname: Suh
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000150:complications* / Q000188:drug therapy; D002543:Cerebral Hemorrhage / Q000209:etiology* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies; D012720:Severity of Illness Index; D020521:Stroke / Q000150:complications* / Q000188:drug therapy; D015912:Thrombolytic Therapy / Q000009:adverse effects*