Cerebral microbleeds: overview and implications in cognitive impairment.

Sergi Martinez-Ramirez,Steven M Greenberg,Anand Viswanathan

doi:10.1186/alzrt263

Sergi Martinez-Ramirez, Steven M Greenberg + Show 1 more

Open Access

https://doi.org/10.1186/alzrt263

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Abstract

Cerebral microbleeds (MBs) are small chronic brain hemorrhages which are likely caused by structural abnormalities of the small vessels of the brain. Owing to the paramagnetic properties of blood degradation products, MBs can be detected in vivo by using specific magnetic resonance imaging (MRI) sequences. Over the last decades, the implementation of these MRI sequences in both epidemiological and clinical studies has revealed MBs as a common finding in many different populations, including healthy individuals. Also, the topographic distribution of these MBs has been shown to be potentially associated with specific underlying vasculopathies. However, the clinical and prognostic significance of these small hemorrhages is still a matter of debate as well as a focus of extensive research. In this article, we aim to review the current knowledge on the pathophysiology and clinical implications of MBs, with special emphasis on the links between lobar MBs, cerebral amyloid angiopathy, and Alzheimer’s disease.

Highlights

Cerebral microbleeds (MBs) are small chronic brain hemorrhages, likely caused by structural abnormalities of the small vessels
We aim to summarize the current knowledge on the pathophysiology and clinical implications of MBs, with special emphasis on the links between lobar MBs, cerebral amyloid angiopathy and Alzheimer’s disease
Criteria were established by the Boston Cerebral Amyloid Angiopathy Group: Steven M Greenberg, Daniel S Kanter, Carlos S Kase and Michael S Pessin. aAs defined in [26]. bOther causes of intracerebral hemorrhage were excessive warfarin (international normalized ratio (INR).3.0); antecedent head trauma or ischemic stroke; central nervous system tumor, vascular malformation, or vasculitis; and blood dyscrasia or coagulopathy. (INR.3.0 or other non-specific laboratory abnormalities are permitted for diagnosis of possible cerebral amyloid angiopathy)

Summary

Introduction

Cerebral microbleeds (MBs) are small chronic brain hemorrhages, likely caused by structural abnormalities of the small vessels. Concerning MB size, a study on hemorrhage volumes in patients with cerebral amyloid angiopathy (CAA) found a bimodal distribution, instead of a continuum, with a large gap between the two peaks representing MBs and macrobleeds. Several populationbased studies have reported on MB prevalence in healthy older individuals, which can be as high as 23.5% [16] This observation raises questions about the pathological significance of MBs and the importance of MB detection in asymptomatic individuals. Direct extrapolations from the Boston Criteria for the diagnosis of CAA-related hemorrhage [22] (Table 1) seem inadequate, as they have been validated only in subjects with lobar ICH At present, it is indirect evidence from population-based studies that mostly supports the associations between lobar/deep MBs and CAA/HV.

Possible CAA

Conclusions

Findings

52. Attems J