The Clinical Importance of White Matter Hyperintensities on Brain MRI
The Clinical Importance of White Matter Hyperintensities on Brain MRI
Objectives To review the evidence for an association of white matter hyperintensities with risk of stroke, cognitive decline, dementia, and death.
Design Systematic review and meta-analysis.
Data sources PubMed from 1966 to 23 November 2009.
Study selection Prospective longitudinal studies that used magnetic resonance imaging and assessed the impact of white matter hyperintensities on risk of incident stroke, cognitive decline, dementia, and death, and, for the meta-analysis, studies that provided risk estimates for a categorical measure of white matter hyperintensities, assessing the impact of these lesions on risk of stroke, dementia, and death.
Data extraction Population studied, duration of follow-up, method used to measure white matter hyperintensities, definition of the outcome, and measure of the association of white matter hyperintensities with the outcome.
Data synthesis 46 longitudinal studies evaluated the association of white matter hyperintensities with risk of stroke (n=12),cognitive decline (n=19), dementia (n=17), and death (n=10).22 studies could be included in a meta-analysis (nine of stroke, nine of dementia, eight of death). White matter hyperintensities were associated with an increased risk of stroke (hazard ratio 3.3, 95% confidence interval 2.6 to 4.4), dementia (1.9, 1.3 to 2.8), and death (2.0, 1.6 to 2.7). An association of white matter hyperintensities with a faster decline in global cognitive performance, executive function, and processing speed was also suggested.
Conclusion White matter hyperintensities predict an increased risk of stroke, dementia, and death. Therefore white matter hyperintensities indicate an increased risk of cerebrovascular events when identified as part of diagnostic investigations, and support their use as an intermediate marker in a research setting. Their discovery should prompt detailed screening for risk factors of stroke and dementia.
As magnetic resonance imaging has become widely available and brain magnetic resonance imaging is increasingly being carried out in various clinical settings, clinicians often have to deal with the incidental discovery of white matter lesions, appearing as hyperintensities on T2 weighted images (fig 1). In the general population the prevalence of white matter hyperintensities ranges from 11-21% in adults aged around 64 to 94% at age 82. Pathological findings in regions of white matter hyperintensity include myelin pallor, tissue rarefaction associated with loss of myelin and axons, and mild gliosis. These lesions are located in the deep white matter, typically sparing subcortical U-fibres, an dare often seen together with vessels affected by small vessel disease. The affected vessels are presumed to induce the lesions in deep white matter through chronic hypoperfusion of the white matter and disruption of the blood-brain barrier, leading to chronic leakage of plasma into the white matter. white matter hyperintensities are more common and extensive in patients with cardiovascular risk factors and symptomatic cerebrovascular disease. White matter hyperintensities can be measured quantitatively and non-invasively on large population samples and have been proposed as an intermediate marker, which could be used for the identification of new risk factors and potentially as a surrogate end point in clinical trials.
(Enlarge Image)
Figure 1.
White matter hyperintensities on magnetic resonance imaging (axial fluid attenuated inversion recovery sequence) in two 80 year old patients: (left) minor white matter hyperintensities; (right) extensive white matter hyperintensities predominating in periventricular region. White matter lesions are considered present if hyperintense on T2 weighted, fluid attenuated inversion recovery, and proton density images, without prominent hypointensity on T1 weighted images
Several studies have assessed the relation between white matter hyperintensities and risk of stroke, dementia, and death, with partly conflicting results. We systematically reviewed and meta- analysed all published longitudinal studies that tested the association of white matter hyperintensities with risk of stroke, dementia,and death, both in the general population and in a hospital based setting.
Abstract
Objectives To review the evidence for an association of white matter hyperintensities with risk of stroke, cognitive decline, dementia, and death.
Design Systematic review and meta-analysis.
Data sources PubMed from 1966 to 23 November 2009.
Study selection Prospective longitudinal studies that used magnetic resonance imaging and assessed the impact of white matter hyperintensities on risk of incident stroke, cognitive decline, dementia, and death, and, for the meta-analysis, studies that provided risk estimates for a categorical measure of white matter hyperintensities, assessing the impact of these lesions on risk of stroke, dementia, and death.
Data extraction Population studied, duration of follow-up, method used to measure white matter hyperintensities, definition of the outcome, and measure of the association of white matter hyperintensities with the outcome.
Data synthesis 46 longitudinal studies evaluated the association of white matter hyperintensities with risk of stroke (n=12),cognitive decline (n=19), dementia (n=17), and death (n=10).22 studies could be included in a meta-analysis (nine of stroke, nine of dementia, eight of death). White matter hyperintensities were associated with an increased risk of stroke (hazard ratio 3.3, 95% confidence interval 2.6 to 4.4), dementia (1.9, 1.3 to 2.8), and death (2.0, 1.6 to 2.7). An association of white matter hyperintensities with a faster decline in global cognitive performance, executive function, and processing speed was also suggested.
Conclusion White matter hyperintensities predict an increased risk of stroke, dementia, and death. Therefore white matter hyperintensities indicate an increased risk of cerebrovascular events when identified as part of diagnostic investigations, and support their use as an intermediate marker in a research setting. Their discovery should prompt detailed screening for risk factors of stroke and dementia.
Introduction
As magnetic resonance imaging has become widely available and brain magnetic resonance imaging is increasingly being carried out in various clinical settings, clinicians often have to deal with the incidental discovery of white matter lesions, appearing as hyperintensities on T2 weighted images (fig 1). In the general population the prevalence of white matter hyperintensities ranges from 11-21% in adults aged around 64 to 94% at age 82. Pathological findings in regions of white matter hyperintensity include myelin pallor, tissue rarefaction associated with loss of myelin and axons, and mild gliosis. These lesions are located in the deep white matter, typically sparing subcortical U-fibres, an dare often seen together with vessels affected by small vessel disease. The affected vessels are presumed to induce the lesions in deep white matter through chronic hypoperfusion of the white matter and disruption of the blood-brain barrier, leading to chronic leakage of plasma into the white matter. white matter hyperintensities are more common and extensive in patients with cardiovascular risk factors and symptomatic cerebrovascular disease. White matter hyperintensities can be measured quantitatively and non-invasively on large population samples and have been proposed as an intermediate marker, which could be used for the identification of new risk factors and potentially as a surrogate end point in clinical trials.
(Enlarge Image)
Figure 1.
White matter hyperintensities on magnetic resonance imaging (axial fluid attenuated inversion recovery sequence) in two 80 year old patients: (left) minor white matter hyperintensities; (right) extensive white matter hyperintensities predominating in periventricular region. White matter lesions are considered present if hyperintense on T2 weighted, fluid attenuated inversion recovery, and proton density images, without prominent hypointensity on T1 weighted images
Several studies have assessed the relation between white matter hyperintensities and risk of stroke, dementia, and death, with partly conflicting results. We systematically reviewed and meta- analysed all published longitudinal studies that tested the association of white matter hyperintensities with risk of stroke, dementia,and death, both in the general population and in a hospital based setting.
Source...