Cerebral microbleeds (CMBs) are small focal intracerebral hemorrhages visible only on susceptibility-sensitive MRI. STRIVE-2 recommends the term microbleed rather than microhemorrhage.
Prevalence increases with age and is higher in cerebral small-vessel disease, mild cognitive impairment, Alzheimer disease, vascular dementia, and patients with prior stroke. In small-vessel disease, microbleeds are associated with increased cognitive-decline and stroke risk.
Imaging Definition
STRIVE-2 definition: A conspicuous 2–10 mm circular or elliptical punctate region of intraparenchymal signal loss with blooming artifact.
- Detected only on susceptibility-sensitive T2* sequences: GRE and SWI.
- Blooming markedly overestimates true lesion size.
- Usually inapparent on conventional MRI sequences and CT.
- Distribution is a major etiologic discriminator.
Small-Vessel Patterns
Cerebral amyloid angiopathy
- Lobar and cortical-subcortical junction distribution.
- Typically spares basal ganglia.
Hypertensive arteriopathy
- Basal ganglia
- Thalami
- Brainstem and cerebellum
- Corona radiata
Mixed lobar and deep distributions may reflect overlapping arteriopathies or another cause.
Trauma and Cavernomas
- Diffuse axonal or vascular injury: gray-white junction, corpus callosum splenium, and dorsolateral brainstem.
- Cerebral cavernous malformations, especially Zabramski type IV.
- Familial multiple cavernous-malformation syndrome.
- Post-radiotherapy cavernous malformations.
- Microbleeds may also occur after cardiac bypass surgery.
Other Vascular Causes
- Amyloid-related imaging abnormalities (ARIA-H)
- CADASIL, CARASIL, CARASAL, PADMAL, and NIT1 disease
- COL4A1- and HTRA1-related small-vessel disease
- Fabry disease and ataxia-telangiectasia
- Moyamoya disease or syndrome
- PRES and cerebral hyperperfusion syndrome
- Radiation-induced vasculopathy
- RVCL-S and Sneddon syndrome
- Thrombotic microangiopathy (HUS/TTP), sometimes producing a susceptibility-etching pattern
Inflammatory and Infectious
- Acute hemorrhagic leukoencephalitis
- Primary or secondary cerebral vasculitis
- ICANS
- Cerebral malaria, mycotic aneurysm, dengue, or HSV encephalitis
- Neuro-Behçet disease and neurosarcoidosis
- Tumefactive demyelination
Embolic Causes
- Fat embolism: usually after long-bone fracture; may produce a walnut-kernel pattern.
- Air embolism: including catheter placement, decompression illness, ECMO, or hydrogen-peroxide exposure.
- Septic embolism: commonly from infective endocarditis.
Malignancy and Systemic Causes
- Hemorrhagic micrometastases, especially melanoma or renal-cell carcinoma
- Intravascular lymphoma
- Acute hepatic encephalopathy
- Hemophagocytic lymphohistiocytosis
- Hypoxia or critical illness, including ARDS, high-altitude cerebral edema, and COVID-19
- MTHFR deficiency, incontinentia pigmenti, linear scleroderma, late-onset Pompe disease, and progressive facial hemiatrophy
Mimics
- Venous flow voids
- Intracranial calcification
- Intracranial iron deposition
- Punctate susceptibility loss in CLIPPERS
- Pneumocephalus
- Metal emboli, including from artificial heart valves
- Residual iofendylate contrast (Myodil/Pantopaque)
Phase information, CT correlation, lesion location, morphology, and clinical history help separate these entities from true blood products.
Management and Prognosis
Management depends on the underlying cause and the clinical context, particularly when considering antithrombotic therapy or amyloid-lowering treatment.
Cerebral microbleeds are associated with future ischemic and hemorrhagic stroke and with overall mortality.
Source text last revised by Rohit Sharma on 10 August 2026.