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17 results

Cerebral Microbleeds
  • Pathophysiology to Clinical Practice
  • Edited by David J. Werring
  • Published online:
    05 July 2011
    Print publication:
    26 May 2011
  • Stroke is a leading cause of death and disability throughout the world. About one in three symptomatic strokes are due to disease of small perforating arteries; however, most effective interventions are targeted at disease of large arteries. The underlying mechanisms and treatment of small vessel disease remain poorly understood. Microbleeds have emerged as a critical imaging marker of small vessel disease, being found in all types of stroke. With increasing evidence that microbleeds are caused by hypertensive arteriopathy and cerebral amyloid angiopathy, they are likely to play a strong future role in increasing our understanding of the causes of small vessel disease and the potential link between cerebrovascular disease and neurodegeneration. Cerebral Microbleeds summarizes our current knowledge, bringing together expert research from global authorities in the field. This authoritative and systematic text will be of interest to all clinical researchers and physicians in the fields of stroke and cognitive impairment.

  • Chapter 16 - Miscellaneous conditions associated with cerebralmicrobleeds

  • from Section 3 - Microbleeds in relation to specific populations, diseases and neurological symptoms
  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 142-151

  • Summary

    This chapter summarizes the current knowledge on prevalence and characteristics of cerebral microbleeds (CMBs) in normal individuals. The most solid knowledge on CMBs comes from the population-based studies, in particular those that have included higher age groups and have used a sensitive technique to detect CMBs. The four population-based studies with reported findings on CMBs in normal individuals are the Austrian Stroke Prevention Study, the Framingham Study, the Age Gene/Environment Susceptibility (AGES)-Reykjavik study (AGES-R) and the Rotterdam Scan Study. A pioneering study from Japan studied the prevalence of CMBs in 450 neurologically healthy Japanese adults with a mean age of 52.9 years. The overall incidence was 3.1% (14/450), and lesions detected were closely related to hypertension and heavy cigarette smoking. Patterns of risk factors and comorbidities are different between regions, and one can assume that such factors should also affect prevalence rates of CMBs.

  • Chapter 17 - Cerebral microbleeds and cognitiveimpairment

  • from Section 3 - Microbleeds in relation to specific populations, diseases and neurological symptoms
  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 152-158

  • Summary

    This chapter describes how cerebral microbleeds (CMBs) fit broadly within the spectrum of vascular cognitive impairment, and more specifically with interactions between vascular and degenerative mechanisms. It reviews the evidence of associations between CMBs and cognitive function across different clinical groups. Cerebral microbleeds are commonly found in patients with cerebrovascular diseases, including populations with first-ever or recurrent ischemic or hemorrhagic stroke. It has also become clear in recent years that the distinction between vascular cognitive impairment and Alzheimer's disease may be an oversimplification since both are diseases of older people and must commonly co-exist. Furthermore, it is recognized that vascular and degenerative processes will have complex interactions and sometimes synergistic or additive effects on brain function. CMBs are found in 20-30% of patients with a clinical diagnosis of Alzheimer's disease and are common in sporadic cerebral amyloid angiopathy (CAA).

  • Chapter 4 - Definingand mapping cerebral microbleeds

  • from Section 1 - Historical aspects, detection and interpretation
  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 34-43

  • Summary

    Cerebral microbleeds (CMBs) are an increasingly common radiological finding in stroke, neurological and general medical practice. There are two published CMB rating scales that have been validated in hospital cohorts of stroke patients. The rating scales are the microbleed anatomical rating scale (MARS) and the brain observer micro bleed scale (BOMBS). This chapter considers the radiological criteria for defining CMBs and then discusses these standardized rating scales. The potential for automatically detecting and mapping CMBs in future is discussed briefly in the chapter. Mapping CMBs gives information on the burden of CMBs in different anatomical regions in the brain. Quantifying the number of CMBs may be relevant in exploring their relationship with other quantitative imaging or clinical data and for prognostic purposes. Although visual rating scales can improve the reliability of identifying and mapping CMBs, more sophisticated automated methods are under investigation.

  • Section 2 - Mechanisms underlying microbleeds

  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 49-78

  • Summary

    This chapter describes the vascular pathologies that underlie cerebral microbleeds (CMBs), concentrating on the two commonest disorders: hypertensive small vessel disease (SVD) and cerebral amyloid angiopathy (CAA). It also describes the process of blood degradation, and the correlation of imaging with histological findings. The chapter concentrates on hypertensive arteriopathy and CAA, which is usually diagnosed following symptomatic lobar intracerebral hemorrhage (ICH). Hypertensive arteriopathy is thought to be caused by a forced dilation of resistance vessels: that is, those vessels that regulate the blood supply volume to the distal capillary bed. The first event in a hemorrhage is the extravasation of all constituents of blood along with plasma. Extravasation may occur by rhexis (rupture of a vessel wall) or by diapedesis affecting arterioles, veins or capillaries. From the perspective of neuroimaging, CMBs are focal deposits of hemosiderin and can be visualized with MRI.

  • Section 3 - Microbleeds in relation to specific populations, diseases and neurological symptoms

  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 79-177

  • Summary

    This chapter summarizes the current knowledge on prevalence and characteristics of cerebral microbleeds (CMBs) in normal individuals. The most solid knowledge on CMBs comes from the population-based studies, in particular those that have included higher age groups and have used a sensitive technique to detect CMBs. The four population-based studies with reported findings on CMBs in normal individuals are the Austrian Stroke Prevention Study, the Framingham Study, the Age Gene/Environment Susceptibility (AGES)-Reykjavik study (AGES-R) and the Rotterdam Scan Study. A pioneering study from Japan studied the prevalence of CMBs in 450 neurologically healthy Japanese adults with a mean age of 52.9 years. The overall incidence was 3.1% (14/450), and lesions detected were closely related to hypertension and heavy cigarette smoking. Patterns of risk factors and comorbidities are different between regions, and one can assume that such factors should also affect prevalence rates of CMBs.

  • Chapter 1 - Historicaloverview

  • from Section 1 - Historical aspects, detection and interpretation
  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 1-12

  • Summary

    This chapter describes the development of knowledge concerning microaneurysmal and small hemorrhagic lesions in relation to intracerebral hemorrhage (ICH) and small vessel diseases, which may be relevant in understanding the origin of radiologically defined cerebral microbleeds (CMBs). The hypothesis that has arisen from the work of Jean-Martin Charcot and Charles-Joseph Bouchard is that pathological changes (degenerative or inflammatory, and often associated with arterial hypertension) in small caliber arterioles (up to approximately 300 µm) cause weakening of the wall and microaneurysm formation, which subsequently may rupture to cause ICH. Cerebral microbleeds are particularly common in ICH suggesting that they may provide clues to the underlying cause and could potentially shed light on the role of microaneurysms. Cerebral amyloid angiopathy is now recognized as a common disorder of elderly populations and is characterized by the deposition of amyloid in cerebral cortical and leptomeningeal small vessels.

  • Chapter 8 - Relationship of cerebral microbleeds to other imaging findings

  • from Section 2 - Mechanisms underlying microbleeds
  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 71-78

  • Summary

    Of the metals that are commonly present in the human brain, it is considered that only iron in the form of ferritin and hemosiderin is present in sufficient quantities and appropriate oxidation state to be visualized by magnetic resonance imaging (MRI). Histology has shown that cerebral microbleeds (CMBs) contain hemosiderin deposits, a paramagnetic substance. In attempts to quantify the actual susceptibility distribution, many different models have been proposed, which relate measurable MRI effects to the underlying susceptibility distribution. However, for the detection of CMBs it is probably sufficient to use qualitative techniques with a high sensitivity to magnetic field inhomogeneities to provide information on the location and approximate size of the CMB. This chapter describes some possible technical developments to discriminate between some of the different origins of signal loss. The introduction of higher-field scanners and the development of new sequences can provide increased sensitivity for the detection of CMBs.

  • Section 1 - Historical aspects, detection and interpretation

  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 1-48

  • Summary

    This chapter describes the development of knowledge concerning microaneurysmal and small hemorrhagic lesions in relation to intracerebral hemorrhage (ICH) and small vessel diseases, which may be relevant in understanding the origin of radiologically defined cerebral microbleeds (CMBs). The hypothesis that has arisen from the work of Jean-Martin Charcot and Charles-Joseph Bouchard is that pathological changes (degenerative or inflammatory, and often associated with arterial hypertension) in small caliber arterioles (up to approximately 300 µm) cause weakening of the wall and microaneurysm formation, which subsequently may rupture to cause ICH. Cerebral microbleeds are particularly common in ICH suggesting that they may provide clues to the underlying cause and could potentially shed light on the role of microaneurysms. Cerebral amyloid angiopathy is now recognized as a common disorder of elderly populations and is characterized by the deposition of amyloid in cerebral cortical and leptomeningeal small vessels.

  • Chapter 18 - Other clinical manifestations of cerebralmicrobleeds

  • from Section 3 - Microbleeds in relation to specific populations, diseases and neurological symptoms
  • Edited by David J. Werring, Institute of Neurology, London
  • Book:
    Cerebral Microbleeds
    Published online:
    05 July 2011
    Print publication:
    26 May 2011, pp 159-164

  • Summary

    This chapter provides an overview of the prevalence and associations, temporal evolution and prognostic significance of cerebral microbleeds (CMBs) in patients with cerebrovascular diseases. The spatial distribution of microbleeds, as markers of small vessel microhemorrhagic or microaneurysmal lesions, may be of particular interest in attempts to understand the causes of macroscopic intracerebral hemorrhage (ICH) in life. Cerebral amyloid angiopathy is an important cause of primary ICH, particularly of lobar location. Chronic hypertension has been repeatedly identified as a strong influence on the frequency and extent of CMBs, in patients with established stroke as well as in healthy subjects without stroke. Hypertension is an important risk factor for CMBs. As CMBs reflect the bleeding tendency of the brain through fragile microvascular walls, interest has increased in utilizing CMBs in risk stratification of hemorrhagic complications for patients with antithrombotic treatment.