Cerebral microbleeds: a new dilemma in stroke medicine

Abstract

Cerebral microbleeds (CMBs) are an increasingly common neuroimaging finding in the context of ageing, cerebrovascular disease and dementia, with potentially important clinical relevance. Perhaps the most pressing clinical question is whether CMBs are associated with a clinically important increase in the risk of intracerebral haemorrhage (ICH), the most feared complication in patients treated with thrombolytic or antithrombotic (antiplatelet and anticoagulant) drugs. This review will summarize the evidence available regarding CMBs as an indicator of future ICH risk in stroke medicine clinical practice.

Figure 1

(a) A T2*-weighted gradient-echo (T2*-GRE) magnetic resonance imaging (MRI) scan of a patient with cognitive decline, showing multiple strictly lobar cerebral microbleeds (CMBs) meeting the Boston criteria for probable cerebral amyloid angiopathy. Note the posterior/occipital distribution of CMBs, characteristic of amyloid angiopathy. (b) T2*-GRE MRI of a patient with a history of longstanding hypertension: CMBs are predominantly located in deep brain structures including the basal ganglia and thalami, consistent with hypertensive angiopathy (including arteriolosclerosis and fibrohyalinosis). CMBs are also visible in lobar brain regions

Figure 2

(a) Susceptibility-weighted imaging (SWI) is currently the most sensitive means for the detection of cerebral microbleeds (CMBs). Although SWI can detect significantly more CMBs compared with conventional T2*-weighted gradient-recalled echo (T2*-GRE) magnetic resonance imaging, whether it has ‘added value’ in clinical practice is still under investigation

Figure 3

The Microbleed Anatomical Rating Scale, showing lobar, deep and infratentorial regions

Figure 4

Risk of cerebral haemorrhage (ICH) and cerebral infarction (CI) and myocardial infarction (MI) in an Asian cohort of 908 patients with ischaemic stroke treated with an antithrombotic agent (93% of patients received aspirin). The mean follow-up period was 26 months (from Soo et al., 2008, with permission)

Figure 5

(a) Two simultaneous warfarin-related intracerebral haemorrhages in an elderly patient with atrial fibrillation. (b, c) T2*-weighted gradient-recalled echo reveals the presence of multiple strictly lobar cerebral microbleeds (some shown with arrowheads), consistent with underlying cerebral amyloid angiopathy. Note that the symptomatic haematomas are also lobar