Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MATTER”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2004

Relationship between information processing speed in temporal lobe epilepsy and white matter volume.

Abnormalities in white matter have been linked to processing speed impairment in clinical populations (e.g., multiple sclerosis, closed head injury). Recent studies indicate the presence of significant reduction in cerebral white matter volume in some patients with chronic temporal lobe epilepsy (TLE). The objective of this study was to examine the relationship between white matter volume and processing speed and performance efficiency on the Sternberg Memory Scanning Test (SMST). The study groups included TLE subjects with white matter volume reduction (n=13), TLE subjects with normal white matter volume (n=14), and healthy controls (n=18). The groups did not differ in total cerebral gray matter volume. Compared with the controls, the reduced white matter volume TLE group exhibited a significantly steeper slope on the SMST. This was characterized by a disproportionate increase in reaction time with increased processing demands (set size), particularly for negative probe trials. In contrast, no significant differences on the SMST were evident between controls and the normal white matter volume TLE group. These findings suggest the presence of information processing speed and efficiency impairment in TLE and its relationship with white matter volume integrity.

Adolescent↗
PubMed1999

A new model of white matter injury in neonatal rats with bilateral carotid artery occlusion.

Periventricular leukomalacia is an important cause of cerebral palsy and characterized by cysts and coagulation necrosis in the periventricular white matter. Since no model of periventricular leukomalacia has been established in small animals, it is expected to establish a new model of white matter injury in immature rodents. Bilateral carotid arteries were occluded in neonatal rats at 5 days of age, and the brain neuropathologically examined at 7 days of age. Among 22 brains histologically examined, 20 (90.9%) had white matter changes including coagulation necrosis and cystic lesions in and around the internal capsule, while only two had small cerebral infarction and five showed some ischemic neurons in the cerebral cortex. Cerebral blood flow (CBF) decreased to about 25% of controls in the subcortical white matter in the animals with bilateral carotid artery occlusion (BCAO). Amyloid precursor protein (APP) immunohistochemistry demonstrated various APP-immunoreactive axonal profiles in the internal capsule and the subcortical white matter, and stronger expression of APP in pyramidal neurons in the cerebral cortex of BCAO brains. These results indicated that the white matter is more vulnerable than the cerebral cortex in 5-day-old rats when CBF decreases to about 25% and suggested that this model is useful for investigating the white matter changes induced by cerebral hypoperfusion in the neonatal brain, since previous models of hypoxic-ischemic brain injury in neonatal mice and rats revealed preferential susceptibility of the gray matter. It was also indicated that APP is a sensitive marker for mild axonal disruption in the white matter of the immature brain.

Amyloid beta-Protein Precursor↗
PubMed1999

Quantitative ultrasonography of the periventricular white and grey matter of the developing brain.

This study addresses the value of operator-independent computer processing of ultrasonograms of the developing brain. With this aim, routine cranial ultrasonograms obtained from 39 term and preterm infants without clinical or sonographic evidence of brain damage were analyzed by five observers. The procedure, respectively, included: 1. the definition of four regions of interest (ROI), one white matter and one grey matter area on each side of the brain; 2. digitization of the sonogram data within these ROIs; 3. correction for the equipment settings, using data from a tissue-mimicking phantom as a reference; and 4. calculation of four sonogram characteristics (i.e., mean echo level, MEAN, signal-to-noise ratio, SNR, and axial and lateral correlation, CORAX and CORLAT, of the echo level co-occurrence matrix). Significant differences between both sides of the brain or a significant influence of ROI size were not found. The interobserver spread was considerable, but less than the intersubject spread. Two sonogram characteristics seemed strongly correlated in white and grey matter (CORAX and CORLAT) and another only in white matter (SNR with CORAX and CORLAT). MEAN seemed not to be correlated with any other characteristic. Furthermore, it was found that maturation equally decreases white and grey matter MEAN and, thus, hardly affects the ratio between the two. An effect on the other sonogram characteristics was only found in the white matter (i.e., an increase of SNR and a decrease of CORAX and CORLAT). Except for MEAN, the grey matter sonogram characteristics seem hardly affected by maturation. In view of these findings, we conclude that quantitative ultrasonography reveals white and grey matter maturation and, furthermore, provides a conceptional-age-independent reference (MEAN white:grey matter ratio) that might be found to facilitate the detection of pathologic brain alterations.

Age Factors↗
PubMed1998

Effects of two new lubricants on the mutagenicity of scooter exhaust particulate matter.

Scooter exhaust particulate matter, which is known to be mutagenic, has caused heavy air pollution in Shanghai. There are about 400,000 scooters in the city, and the number will not significantly decrease for several years. In order to manage the pollution caused by scooter emissions, many new catalytic instruments and additives were developed. In this paper, the effect of two new lubricants on the emission of scooter exhaust particulate matter was evaluated using gas chromatography/mass spectrometer (GC/MS), in vitro Salmonella/microsomal assay and the in vivo mouse micronucleus assay. The purpose was to learn if these new lubricants could have the ability to reduce the exhausts of particulate matter, and decrease the mutagenicity of exhaust particles. The domestic Jinniao (TN36L) vehicle was chosen as the test vehicle. The results showed that the two new lubricants reduced the emission of scooter exhaust particulate matter, including the quantity of particulate matter and the organic substances adsorbed onto the particles. Compared with the control oil, the two new lubricants reduced the emission of particulate matter by 33% and 36%. When using the two new lubricants, only 20 and 23 kinds of compounds were identified separately in the organic extracts of the exhaust particulate matter by GC/MS, while 45 kinds of compounds were detected in the organic extracts of the exhaust particulate matter when the control oil was used. Mutagenicities of the extracts of scooter exhaust particulate matter were significantly reduced when the two new lubricants were used, including the number of histidine-independent colonies over the background in TA98 with and without S9 mix in the Salmonella test (F2 sample); and the frequencies of bone marrow micronucleated polychromatic erythrocytes in the mouse micronucleus assay (both F1 and F2 samples). These results seem to indicate that these new lubricants can effectively reduce the pollution of scooter exhaust particulate.

Animals↗
PubMedDate not supplied

Selective aging of the human cerebral cortex observed in vivo: differential vulnerability of the prefrontal gray matter.

In a prospective cross-sectional study, we used computerized volumetry of magnetic resonance images to examine the patterns of brain aging in 148 healthy volunteers. The most substantial age-related decline was found in the volume of the prefrontal gray matter. Smaller age-related differences were observed in the volume of the fusiform, inferior temporal and superior parietal cortices. The effects of age on the hippocampal formation, the postcentral gyrus, prefrontal white matter and superior parietal white matter were even weaker. No significant age-related differences were observed in the parahippocampal and anterior cingulate gyri, inferior parietal lobule, pericalcarine gray matter, the precentral gray and white matter, postcentral white matter and inferior parietal white matter. The volume of the total brain volume and the hippocampal formation was larger in men than in women even after adjustment for height. Inferior temporal cortex showed steeper aging trend in men. Small but consistent rightward asymmetry was found in the whole cerebral hemispheres, superior parietal, fusiform and orbito-frontal cortices, postcentral and prefrontal white matter. The left side was larger than the right in the dorsolateral prefrontal, parahippocampal, inferior parietal and pericalcarine cortices, and in the parietal white matter. However, there were no significant differences in age trends between the hemispheres.

Aged↗
PubMed2004

White matter asymmetry in the human brain: a diffusion tensor MRI study.

Language ability and handedness are likely to be associated with asymmetry of the cerebral cortex (grey matter) and connectivity (white matter). Grey matter asymmetry, most likely linked to language has been identified with voxel-based morphometry (VBM) using T(1)-weighted images. Differences in white matter obtained with this technique are less consistent, probably due to the relative insensitivity of the T(1) contrast to the ultrastructure of white matter. Furthermore, previous VBM studies failed to find differences related to handedness in either grey or white matter. We revisited these issues and investigated two independent groups of subjects with diffusion-tensor imaging (DTI) for asymmetries in white matter composition. Using voxel-based statistical analyses an asymmetry of the arcuate fascicle was observed, with higher fractional anisotropy in the left hemisphere. In addition, we show differences related to handedness in the white matter underneath the precentral gyrus contralateral to the dominant hand. Remarkably, these findings were very robust, even when investigating small groups of subjects. This highlights the sensitivity of DTI for white matter tissue differences, making it an ideal tool to study small patient populations.

Adult↗
PubMed2006

Reevaluation of gray and white matter injury after spinal cord ischemia in rabbits.

BACKGROUND: Although gray matter injury has been well characterized, the available data on white matter injury after spinal cord ischemia (SCI) in rabbits are limited. The current study was conducted to investigate the evolution of ischemia induced injury to gray and white matter and to correlate this damage to hind-limb motor function in rabbits subjected to SCI. METHODS: Thirty-eight rabbits were randomly assigned to 24-h, 4-day, or 14-day reperfusion groups or a sham group (n = 9 or 10 per group). SCI was induced by occlusion of the infrarenal aorta for 16 min. Hind-limb motor function was assessed using the Tarlov scale (0 = paraplegia, 4 = normal). The gray matter damage was assessed on the basis of the number of normal neurons in the anterior spinal cord. White matter damage was assessed on the basis of the extent of vacuolation and accumulation of amyloid precursor protein immunoreactivity. RESULTS: Tarlov scores gradually decreased and reached a nadir 14 days after reperfusion. There were no significant differences in the number of normal neurons among the 24-h, 4-day, and 14-day groups. The extent of vacuolation, expressed as a percent of total white matter area, was significantly greater in the 4-day and 14-day groups in comparison with the sham group. By contrast, there was no difference in vacuolation between the sham and 24-h groups. Amyloid precursor protein immunoreactivity was greater in the 4-day and 14-day groups. CONCLUSION: The results in the current study show that SCI induced white matter injury as well as gray matter injury in a rabbit model of SCI. The time course for 14 days after reperfusion may differ among the gray and white matter damages and hind-limb motor function in rabbits subjected to SCI.

Amyloid beta-Protein Precursor↗
PubMed2005

Migraine and cerebral white matter lesions: when to suspect cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

BACKGROUND: Patients with migraine are at an increased risk for white matter lesions, typically multiple, small, punctate hyperintensities in the deep or periventricular white matter, best observed on magnetic resonance imaging utilizing T2-weighted or FLAIR sequences. The underlying pathogenesis of white matter lesions in migraineurs is unknown, and the lesions are usually nonspecific and of unclear clinical significance. REVIEW SUMMARY: Often the presence of white matter lesions causes uncertainty for physicians and anxiety for patients and may lead to a variety of diagnostic tests and treatments. Occasionally, white matter lesions may represent a secondary cause for headaches such as CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). CADASIL is underrecognized and underdiagnosed; it should be suggested by (i) 1 or more of recurrent subcortical ischemic strokes (especially before age 60 and in the absence of vascular risk factors), migraine (especially with aura, including atypical or prolonged auras) and/or early cognitive decline or subcortical dementia; (ii) bilateral, multifocal, T2/FLAIR hyperintensities in the deep white matter and periventricular white matter with lesions involving the anterior temporal pole, external capsule, basal ganglia, and/or pons; and (iii) an autosomal-dominant family history of migraine, early-onset stroke, or dementia. The clinical spectrum of CADASIL is broad, and there is a poor genotype-phenotype correlation. In certain individuals or families, migraine may be the only clinical manifestation. CONCLUSIONS: While the prevalence of nonspecific white matter lesions in migraineurs is increased, the white matter lesions may occasionally represent a secondary cause for headache such as CADASIL. Greater awareness of the unique clinical, neuroimaging, and pathologic features, as well as the availability of diagnostic genetic testing, should enhance the recognition and diagnosis of this fascinating condition.

Brain↗
PubMed1992

Identification of plasmolipin as a major constituent of white matter clathrin-coated vesicles.

We have isolated and characterized coated vesicles from bovine white matter and compared them to those isolated from gray matter. The virtual absence of synaptic vesicle antigens in the white matter coated vesicles indicates they are distinct from those found in gray matter and from vesicles derived from synaptic membranes. The white matter coated vesicles also lack compact myelin components, e.g., the myelin proteolipid, galactocerebroside, and sulfatides, as well as the periaxolemmal myelin marker myelin-associated glycoprotein. On the other hand, these vesicles contain 2',3'-cyclic nucleotide phosphohydrolase. The vesicles also contain high levels of plasmolipin, a protein present in myelin and oligodendrocytes. Plasmolipin was found to be four to five times higher in white matter coated vesicles than in gray matter coated vesicles. Based on western blot quantitation, the concentration of plasmolipin in white matter coated vesicles is 3-4% of the vesicle bilayer protein. These studies indicate that a significant proportion of coated vesicles from white matter may be derived from unique membrane domains of the myelin complex or oligodendroglial membrane, which are enriched in plasmolipin.

Animals↗
PubMed1997

Cognitive impairment and cellular/vascular changes in the cerebral white matter.

A possible relation between cerebral white-matter injury and dementia was intuitively attributed by Alzheimer to changes affecting the small penetrating vessels that supply the cerebral white matter. Several observations support the view that white-matter changes detectable by neuroimaging may contribute to cognitive deficits in the elderly. But many questions concerning this matter remain partially answered. In this communication we review: (1) Selected anatomic features of the blood vessels supplying the white matter; (2) possible pathogenetic mechanisms responsible for the white-matter changes; (3) observations on humans and animals suggesting a causal relationship between ischemia/hypoxemia and white-matter injury; (4) epidemiologic studies linking white-matter abnormalities with cognitive disorders. We conclude that abnormalities in the small vessels caused by aging and arterial hypertension, or other processes (cerebral amyloid angiopathy, CADASIL) together with systemic circulatory disturbances, such as abrupt variations in blood pressure values or cardiac diseases, may be the substrate of selective white-matter injury. The damage is structurally characterized by incomplete infarction or selective cellular injury.

Alzheimer Disease↗
PubMed2004

Fibrosis and stenosis of the long penetrating cerebral arteries: the cause of the white matter pathology in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

In cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) the vascular smooth muscle cells are destroyed and granular osmiophilic material is deposited followed by fibrosis of the arterial wall. To verify whether true stenosis of the fibrotic white matter arteries is a key pathogenic event in CADASIL, we analyzed the thickness of walls (expressed as sclerotic index) and luminal diameters of penetrating arterioles in both grey matter and white matter of four CADASIL patients due to the C475T (R133C) mutation in the Notch3 gene and in 9 age-matched controls. We also reconstructed 9 arterioles from 1000 serial sections in two CADASIL patients. The thickness of the arteriolar walls in both grey matter and white matter was significantly increased in the CADASIL patients compared with controls. Furthermore, in CADASIL patients the arteriolar walls were significantly thicker in the white matter than in the grey matter. The distribution curve of arteriolar internal diameters in CADASIL patients shifted towards smaller sizes. In serial sections, the marked increase in the thickness of the white matter penetrating arterioles or their branches did not occur until the internal diameters had decreased to about 20 to 30 pm and external diameters to about 100 to 130 microm. In conclusion, long penetrating arterioles and their branches supplying subcortical structures in CADASIL are stenosed and their walls are thickened. This conforms to the abundance of infarcts and primary ischemic damage in CADASIL patients' white matter.

Actins↗
PubMed2000

Cerebral white matter lesions are not associated with apoE genotype but with age and female sex in Alzheimer's disease.

Cerebral white matter lesions, such as leukoaraiosis, may be a result of damage from cerebral ischaemia, and may also be associated with the degenerative process in Alzheimer's disease. The apolipoprotein epsilon4 (apoepsilon4) genotype is a genetic risk factor for both Alzheimer's disease and ischaemic brain damage through acceleration of atherosclerosis. The aim was to determine whether apoepsilon4 may be related to the formation of cerebral white matter lesions in Alzheimer's disease. The association of apoE genotype, sex, age, and the presence of several vascular risk factors, with the presence of white matter lesions in 55 patients clinically diagnosed with Alzheimer's disease was investigated. The cerebral white matter lesions were identified by T2 weighted MRI and classified on a 4 grade scale from no lesion to diffuse lesion. The odds ratio (OR) of the factors mentioned above to the presence of white matter lesions was determined and tested by Fisher's exact test. The association of the lesion grades with these factors was analysed by non-parametric tests. The apoE 4 genotype was strongly associated with Alzheimer's disease (p=0.0001), but not associated with the presence or the degree of cerebral white matter lesions in Alzheimer's disease (OR=1.09, p>0.99). Aging (>70 years old) was a significant risk factor for white matter lesions (OR=7.2, p=0.0006) and age was significantly correlated with the lesion (p=0.0075). The OR of female sex to the lesion grades was 2.89 (p=0.084) and the lesion grade of female sex was significantly higher than that of the male sex (p=0.047). Other vascular risk factors were not significantly associated with the presence of white matter lesions. These findings suggest that there is a sex difference in white matter pathology in Alzheimer's disease.

Age Factors↗
PubMed2001

Magnetisation transfer ratio and mean diffusivity of normal appearing white and grey matter from patients with multiple sclerosis.

OBJECTIVE: To assess the feasibility of a new technique based on diffusion anisotropy to segment white and grey matter of the brain. To use this technique to measure the mean diffusivity () and magnetisation transfer ratio (MTR) of normal appearing white matter (NAWM) and grey matter (NAGM) from patients with multiple sclerosis. METHODS: Dual echo turbo spin echo, MT, and diffusion weighted scans of the brain were obtained from 30 patients with multiple sclerosis and 18 sex and age matched healthy controls. After image coregistration and removal of T2 visible lesions, white and grey matter were segmented from 10 supratentorial slices using diffusion anisotropy thresholds. Histograms of the average MTR and were created for normal white and grey matter of controls and NAWM and NAGM of patients with multiple sclerosis. RESULTS: All the MTR histogram derived metrics of the NAWM from patients with multiple sclerosis were significantly lower than those of white matter from controls. The peak height of the histogram of NAWM from patients with multiple sclerosis was also significantly different from that of normal white matter. The average MTR, the peak location of the MTR histogram, and peak height of the histogram of the NAGM of patients with multiple sclerosis were significantly lower than the corresponding quantities of grey matter from controls. CONCLUSIONS: A technique was developed for segmenting white and grey matter with the potential for improving the understanding of the pathophysiology of many neurological conditions. Its application to the study of multiple sclerosis confirms the presence of a diffuse tissue damage in the NAWM of these patients and suggests that subtle changes also occur in the NAGM.

Adult↗
PubMed2002

White matter damage in Alzheimer's disease assessed in vivo using diffusion tensor magnetic resonance imaging.

OBJECTIVE: To investigate the extent and the nature of white matter tissue damage of patients with Alzheimer's disease using diffusion tensor magnetic resonance imaging (DT-MRI). BACKGROUND: Although Alzheimer's disease pathology mainly affects cortical grey matter, previous pathological and MRI studies showed that also the brain white matter of patients is damaged. However, the nature of Alzheimer's disease associated white matter damage is still unclear. METHODS: Conventional and DT-MRI scans were obtained from 16 patients with Alzheimer's disease and 10 sex and age matched healthy volunteers. The mean diffusivity (D), fractional anisotropy (FA), and inter-voxel coherence (C) of several white matter regions were measured. RESULTS: D was higher and FA lower in the corpus callosum, as well as in the white matter of the frontal, temporal, and parietal lobes from patients with Alzheimer's disease than in the corresponding regions from healthy controls. D and FA of the white matter of the occipital lobe and internal capsule were not different between patients and controls. C values were also not different between patients and controls for any of the regions studied. Strong correlations were found between the mini mental state examination score and the average overall white matter D (r=0.92, p<0.001) and FA (r=0.78; p<0.001). CONCLUSIONS: White matter changes in patients with Alzheimer's disease are likely to be secondary to wallerian degeneration of fibre tracts due to neuronal loss in cortical associative areas.

Aged↗
PubMed2001

Neuropsychologic correlates of brain white matter lesions depicted on MR images: 1921 Aberdeen Birth Cohort.

PURPOSE: To examine relationships between brain white matter hyperintensities depicted at magnetic resonance (MR) imaging and performance on neuropsychologic tests in community-dwelling elderly adults. MATERIALS AND METHODS: The 1921 Aberdeen Birth Cohort is a subsample of survivors of the Scottish Mental Survey of 1932 whose mental ability was tested at 11 years of age. Ninety-five of these subjects agreed to undergo brain MR imaging, an examination of general health, and a neuropsychologic evaluation. White matter hyperintensities detected at T2-weighted MR imaging were rated by using a semiquantitative method yielding two continuous variables: white matter lesions and periventricular lesions. Cognitive ability, including crystallized and fluid intelligence domains, was assessed with standard neuropsychologic tests. RESULTS: Rating scores of white matter lesions were normally distributed (on a devised scale) with means of 1.14 for white matter lesions and 1.28 for periventricular lesions. Intra- and interobserver reliability coefficients for scores were high, generally above 0.7. There were significant correlations of medium effect size between the T2-weighted MR imaging-depicted white matter lesions and performance on tests of fluid-type intelligence. No significant correlation was demonstrated between white matter lesion ratings and tests of crystallized intelligence. CONCLUSION: Lower fluid-type ("prevailing") intelligence test scores were associated with increased severity of white matter lesion ratings but not crystallized-type ("premorbid") intelligence test scores. This indicates that MR imaging-depicted white matter lesions are of clinical importance.

Aged↗
PubMed2005

Diffusion-weighted MR imaging in patients with phenylketonuria: relationship between serum phenylalanine levels and ADC values in cerebral white matter.

PURPOSE: To prospectively determine the relationship between serum phenylalanine levels and apparent diffusion coefficient (ADC) values in the cerebral white matter of patients with phenylketonuria (PKU). MATERIALS AND METHODS: Institutional review board approval was obtained, and participants provided informed consent. Magnetic resonance (MR) imaging, which included T1- and T2-weighted, fluid-attenuated inversion-recovery (FLAIR), and diffusion-weighted examinations, was performed in 21 patients with PKU (nine male and 12 female patients; age range, 3-44 years; mean age, 19.4 years). ADC values in deep cerebral white matter were calculated for each patient. Serum phenylalanine levels were obtained in all patients within 12 days after MR imaging. Serum phenylalanine levels were measured in 16 patients 1 year before MR imaging. ADC values in cerebral white matter and serum phenylalanine levels were compared. A total of 21 control subjects (12 male and nine female patients; age range, 3-33 years; mean age, 20.6 years) underwent MR imaging. ADC values in cerebral white matter were compared with serum phenylalanine levels by using the Pearson correlation. RESULTS: Abnormal high signal intensity in white matter on T2-weighted and FLAIR MR images was noted in patients with PKU who had serum phenylalanine levels of more than 8.5 mg/dL (514.2 micromol/L). Diffusion in posterior deep cerebral white matter tended to be restricted in patients when increased serum phenylalanine levels were measured after MR imaging (r = -0.62). There was a correlation between ADC values in posterior cerebral white matter and serum phenylalanine levels measured 1 year before MR imaging (r = -0.77). ADCs of control subjects were significantly higher than ADCs of patients with PKU (P < .005). CONCLUSION: Posterior deep white matter in patients with PKU and a serum phenylalanine level of more than 8.5 mg/dL showed high signal intensity in white matter on T2-weighted and FLAIR MR images and revealed decreased ADC. We suggest that to avoid brain-restricted diffusion due to hyperphenylalanemia, patients with PKU should maintain serum phenylalanine levels of less than 8.5 mg/dL (514.2 micromol/L).

Adolescent↗
PubMed2004

The association between blood pressure, hypertension, and cerebral white matter lesions: cardiovascular determinants of dementia study.

Cerebral white matter lesions are frequently observed on magnetic resonance imaging (MRI) scans in elderly people and are associated with stroke and dementia. Elevated blood pressure is presumed one of the main risk factors, although data are almost exclusively derived from cross-sectional studies. We assessed in 10 European cohorts the relation between concurrently and previously measured blood pressure levels, hypertension, its treatment, and severe cerebral white matter lesions. In total, 1805 nondemented subjects aged 65 to 75 years were sampled from ongoing community-based studies that were initiated 5 to 20 years before the MRI. White matter lesions in the periventricular and subcortical region were rated separately using semiquantitative measures. We performed logistic regression analyses adjusted for potential confounders in 1625 people with complete data. Concurrently and formerly assessed diastolic and systolic blood pressure levels were positively associated with severe white matter lesions. Both increases and decreases in diastolic blood pressure were associated with more severe periventricular white matter lesions. Increase in systolic blood pressure levels was associated with more severe periventricular and subcortical white matter lesions. People with poorly controlled hypertension had a higher risk of severe white matter lesions than those without hypertension, or those with controlled or untreated hypertension. Higher blood pressure was associated with an increased risk of severe white matter lesions. Successful treatment of hypertension may reduce this risk; however, a potential negative effect of decreasing diastolic blood pressure level on the occurrence of severe periventricular white matter lesions should be taken into account.

Aged↗
PubMed2005

The existence and evolution of diffusion-perfusion mismatched tissue in white and gray matter after acute stroke.

BACKGROUND AND PURPOSE: Although white matter is a potential target of acute stroke therapy, there is uncertainty about its relative resistance to ischemia and whether it is capable of mounting a penumbral response. To explore these issues further, we examined the differential effects of ischemia on gray and white matter using magnetic resonance (MR) perfusion-diffusion mismatch after acute stroke. METHODS: MR imaging studies were performed within 12 hours in patients with initial hemispheric ischemic stroke. "At-risk" tissue was defined as tissue with abnormal diffusion-weighted imaging/perfusion-weight imaging or infarction on follow-up image. Tissue was segmented using a probabilistic atlas generated from age-matched controls. The proportions of "at-risk" tissue, which was penumbral at the time of imaging, were compared between gray and white matter. RESULTS: Thirty-two patients had diffusion-perfusion mismatched penumbral tissue present in both gray and white matter compartments. Although the absolute mismatch volumes were greater in gray (median 42 cm3, interquartile range 18 to 70 cm3) than in white matter (39 cm3, 17 to 49 cm3; P<0.001), the proportion of "at-risk" tissue, which was penumbral at the time of imaging (median 3.7 hours, range 1.5 to 9.9 hours) was greater in white (69%, 49% to 86%) than gray matter (62%, 52% to 75%; P=0.026). However, the proportions spontaneously salvaged by 3 months were similar in both compartments. CONCLUSIONS: These findings are consistent with white matter being able to mount an ischemic penumbral response in humans and being more resistant to cerebral ischemia than gray matter. They also raise the possibility that the therapeutic window is longer for white matter and may require alternative therapeutic strategies.

Aged↗