Cerebral microbleeds

Created 15/04/2021, last revision 10/05/2022


  • cerebral microbleeds (CMBs) – hemosiderin deposits inflicted by minor hemorrhages, may serve as a radiological biomarker of the small vessel diseases (SVD)
    • black, round or oval lesions on blood-sensitive MRI sequences – (T2*/GRE or SWI)
    • 2-5 mm in diameter (up to 10 mm is acceptable)
  • often incidentally detected on MRI scans, their incidence increases with age
    • incidence in the general population is around 11-15%   (Sveinbjornsdottir, 2008)
    • 6.5% in persons aged 45 to 50 years
    • in the population > 80 years up to 40%   [Poels, 2009]
    • incidence in AD 20-43%
    • in vascular dementia in up to 85%!  [Seo, 2007]
  • microhemorrhages are associated with:
    • older age
    • hypertension
    • smoking
    • white matter disease and lacunar infarcts
    • previous ischemic stroke or ICH
  • a high microbleed count is associated with an increased risk of:

  • higher risk of progression:
    • in severe SVD (Subcortical Vascular Disease or Small Vessel Disease)
    • in CAA with APOE ε2 and ε4  [McCarron, 2000]


  • subcortical (mainly caused by arteriolopathy)  → Binswanger´s disease
  • cortical (mostly caused by CAA – posing a higher risk of lobar hemorrhage)
  • combined (combination of CAA and arteriolosclerosis or rather arteriolosclerosis only) [Jung, 2020]

Cerebral amyloid angiopathy (CAA) on GRE

Cortical cerebral microbleeds and lobar hematomas in patient with cerebral amyloid angiopathy
Cortical cerebral microbleeds (CMBs)
Cortical cerebral microbleeds (CMBs) on SWI sequence

Differential diagnosis

Content available only for logged-in subscribers (registration will be available soon)


  • no specific therapy
  • rigorous treatment of hypertension
  • careful indication and monitoring of anticoagulant (prefer DOAC) and antiplatelet therapy (avoid DAPT if possible)

CMBs and the risk of a hemorrhage

  • the risk of ICH increases with the number of CMBs
    • ≥ 5 CMBs – OR for ICH is 2.8
    • ≥ 10 CMBs – OR for ICH 5.5!
  • according to the CROMIS-2 trial, the risk of bleeding in patients with CMBs is 9.8/1000 vs. 2.6/1000 patient-years (adjusted hazard ratio 3·67, 95% CI 1·27–10·60) [Wilson, 2018]
  • the incidence of ICH is up to 5%/year in multiple lobar CMBs [Van Etten, 2014]
CMBs and thrombolysis
  • the risk of symptomatic intracranial hemorrhage (sICH) may be increased after thrombolytic therapy in patients who have cerebral microbleeds (CMBs)
  • CMBs < 10  ⇒  IVT seems safe (ESO 2021) (AHA/ASA 2019 IIa/B-NR)
  • CMBs > 10 ⇒ IVT has a higher risk of ICH; the anticipated benefit of treatment must outweigh the risk – consider IVT in patients with a severe stroke (AHA/ASA 2019 IIb/B-NR)
    • the smaller study retrospectively found a slight increase in risk (3%) of bleeding in patients with microbleeds on GRE [Fiehler, 2007]
    • higher risk is connected with CAA as a cause of microbleeds
  • no MRI screening to assess CMBs burden before making a treatment decision regarding intravenous thrombolysis is recommended (ESO 2021)
CMBs and anticoagulation therapy
Content available only for logged-in subscribers (registration will be available soon)
CMBs and antiplatelet therapy
  • continuing antiplatelet therapy is a safe and beneficial approach, even in the presence of cerebral microbleeds (sub-analysis of the RESTART trial) [Salman, 2019]
icon-angle icon-bars icon-times