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Brain microbleeds: Epidemiology and clinical implications
I Boyano1, N Bravo2, J Miranda2
1Servicio de Geriatría, Hospital Universitario de Móstoles, Madrid, España.
Introduction:
Brain microbleeds (BMB) are haemosiderin deposits contained within macrophages, which are displayed as hypointense images in some T2-weighted magnetic resonance imaging sequences. There are still many questions to be answered about the pathophysiology and clinical relevance of BMB.
Development:
We conducted a literature review of the main epidemiological, clinical, and anatomical pathology studies of BMB performed in the general population, in patients at risk of or already suffering from a vascular disease, and in patients with cognitive impairment. We analysed the prevalence of BMB, risk factors, and potential pathophysiological mechanisms and clinical implications.
Conclusions:
The prevalence of BMB is highly variable (3%-27% in the general population, 6%-80% in patients with vascular risk factors or vascular disease, and 16%-45% in patients with cognitive impairment). BMB are associated with ageing, Alzheimer disease (AD), and in particular haemorrhagic or ischaemic cerebrovascular disease. The pathological substrate of BMB is either lipohyalinosis (subcortical BMB) or cerebral amyloid angiopathy (lobar BMB). BMB exacerbate cognitive impairment, possibly through cortical-subcortical and intracortical disconnection, and increase the risk of death, mostly due to vascular causes. BMB also increase the risk of cerebral haemorrhage, particularly in patients with multiple lobar BMB (probable erebral amyloid angiopathy). Therefore, anticoagulant treatment may be contraindicated in these patients. In patients with lower risk of bleeding, the new oral anticoagulants and the combination of clinical and magnetic resonance imaging follow-up could be helpful in the decision-making process.
Insights
Brain microbleeds (BMB) are linked to aging and vascular issues, worsening cognitive decline and increasing mortality risk. Their presence may contraindicate anticoagulant therapy due to heightened hemorrhage risks.
Area of Science:
- Neurology
- Radiology
- Pathology
Background:
- Brain microbleeds (BMB) are haemosiderin deposits within macrophages, visualized as hypointense signals on specific MRI sequences.
- The pathophysiology and clinical significance of BMB remain incompletely understood.
Purpose of the Study:
- To review the epidemiology, clinical relevance, and pathology of BMB.
- To analyze BMB prevalence, risk factors, and clinical implications across different populations.
Main Methods:
- A comprehensive literature review of epidemiological, clinical, and anatomical pathology studies on BMB.
- Analysis of studies in the general population, patients with vascular disease, and those with cognitive impairment.
Main Results:
- BMB prevalence varies significantly: 3-27% (general population), 6-80% (vascular disease patients), and 16-45% (cognitive impairment patients).
- BMB are associated with aging, Alzheimer disease, and cerebrovascular diseases (hemorrhagic/ischemic).
- Pathological substrates include lipohyalinosis (subcortical) and cerebral amyloid angiopathy (lobar).
Conclusions:
- BMB worsen cognitive impairment and increase mortality, primarily from vascular causes.
- Multiple lobar BMB suggest cerebral amyloid angiopathy, increasing cerebral hemorrhage risk and potentially contraindicating anticoagulants.
- Careful consideration of anticoagulant therapy is needed, with MRI and clinical follow-up aiding decision-making in lower-risk patients.
