Magnetic resonance imaging of white matter lesions in HIV infection.

Previous studies of the frequency of high-signal lesions in human immunodeficiency virus (HIV) infection have had methodological weaknesses regarding lack of control groups, differing machine strengths, and biased subject selection. To obtain a more accurate estimate of prevalence, MRI scans were performed on 243 HIV-positive and HIV-negative homosexual or bisexual men with no history of intravenous drug use. Axial T2-weighted (long TR/TE, spin-echo) MRI scans were rated blindly for presence of focal white matter high-signal lesions. Incidence of hyperintensities was low in all groups, although slightly higher in patients with AIDS, and was not associated with neuropsychological performance. The lower incidence of hyperintensities appears to relate to elimination of methodological problems in previous studies.     

Transient encephalopathy with reversible white matter lesions in children

We report on two children with acute encephalopathy showing mild clinical manifestations and reversible white matter lesions. In both patients, MRI revealed high intensities on T (2)-weighted imaging and marked reductions of water diffusion in the white matter of the bilateral centrum semiovale and the corpus callosum. These abnormalities disappeared along with the neurological symptoms within a week in both patients. These children represent a characteristic group of patients among childhood acute encephalopathy.     

Magnetic resonance imaging white matter lesions and cognitive impairment in hypertensive individuals

To search for a morphologic basis of cognitive impairment possibly associated with essential hypertension, we studied 35 otherwise asymptomatic hypertensive individuals (mean age, 38.7 years; range, 22 to 49 years) and 20 normotensive control subjects (mean age, 37.9 years; range, 26 to 49 years) using neuropsychologic tests and magnetic resonance imaging. Irrespective of drug treatment, hypertensive individuals performed significantly worse than did control subjects when assessed for verbal memory and total learning and memory capacity, while there were no differences in test results of visual memory, attention, vigilance, and reaction time. The hypertensive individuals also described themselves as less active but ranked similar on five other mood subscales. Punctate high-signal intensities of the white matter were found almost twice as often in the hypertensive group (38%) as in the control group (20%). There was no difference in test performance between hypertensive individuals with and those without white matter lesions, however. Our results confirm the presence of subtle neuropsychologic deficits and indicate a higher frequency of white matter signal abnormalities in essential hypertension, as shown on magnetic resonance imaging, but do not indicate a correlation of these findings with each other.     

Transient encephalopathy with reversible white matter lesions: a case report

We report on a boy with bilateral optic nerve hypoplasia and mild psychomotor retardation. At 1 year and 9 months of age, he was admitted to hospital with a cluster of febrile convulsions and unconsciousness. Magnetic resonance imaging (MRI) revealed widespread areas of high signal intensity on diffusion-weighted imaging of the deep cerebral white matter and corpus callosum. This imaging disappeared at five days of illness. No atrophy or abnormalities were noted on the 6-month follow-up MRI. Despite full recovery after the acute episode, the patient showed retarded developmental progress. We discuss the differential diagnosis for this case.     

Magnetic resonance imaging white matter hyperintensities and mechanism of ischemic stroke.

BACKGROUND AND PURPOSE: We sought to determine the relations between infarct subtype and white matter hyperintensities (WMHIs) on MRI. MATERIALS AND METHODS: We studied 395 ischemic stroke patients with 1. 0-T MRI. The number of lacunar, border-zone, and cortical infarcts was registered. WMHIs were analyzed in 6 areas. Univariate and multivariate statistical analyses were used to find the risk factors for different infarct subtypes and to study the connections between WMHIs and brain infarcts. RESULTS: Lacunar infarcts were associated with hypertension (odds ratio [OR], 1.79; 95% CI, 1.17 to 2.73), alcohol consumption (OR, 1.96; 95% CI, 1.17 to 3.28), and age (OR, 1. 03; 95% CI, 1.00 to 1.06). Border-zone infarcts were associated with carotid atherosclerosis (OR, 2.20; 95% CI, 1.15 to 4.19). Atrial fibrillation (OR, 3.02; 95% CI, 1.66 to 5.50) and carotid atherosclerosis (OR, 1.94; 95% CI, 1.12 to 3.36) were independent positive predictors, and history of hyperlipidemia (OR, 0.44; 95% CI, 0.26 to 0.75) and migraine (OR, 0.48; 95% CI, 0.25 to 0.93) were negative predictors for cortical infarcts. Patients with lacunar infarcts had more severe WMHIs than patients with nonlacunar infarcts in all WM areas (P相似文献   

Incidental multifocal white matter lesions in pediatric magnetic resonance imaging

This study sought to describe the occurrence and potential significance of white matter abnormalities of unknown cause on pediatric cranial magnetic resonance scans, and to review the literature. We included 16 children in whom white matter abnormalities were incidentally revealed on magnetic resonance scans performed during a 7-year period at a tertiary pediatric medical center. Background data were retrospectively collected from medical files. White matter lesions were classified by size, location, and extent. Indications for imaging included convulsive disorder (n = 5), headache (n = 5), endocrine disorder (n = 4), and others. Patients' abnormalities did not correlate with the locations and patterns of white matter lesions. No changes in lesions were evident over time. Given the absence of evident benefits from repeated imaging studies, we suggest they are not warranted in every patient, and should be tailored according to clinical course. Further investigations of incidental intracranial findings are required in this age group.     

Magnetic resonance imaging shows orientation and asymmetry of white matter fiber tracts

Apparent diffusion tensor maps of the human brain were acquired with a magnetic resonance imaging sequence (Gudbjartsson, H., Maier, S.E., Mulkern, R.V., Mórocz, I.A., Patz, S., Jolesz, F.A., Magn. Reson. Med. 36 (1996) 509–519). It was shown that the geometric nature of the apparent diffusion tensors can quantitatively characterize the tissue structure. Display of the orientation and directional uniformity of the water diffusion in the brain demonstrated most of the known major anatomical constituents of human white matter. A comparison of corresponding anatomic regions in the white matter of both hemispheres in 24 healthy volunteers revealed that fiber tracts within the anterior limb of the internal capsule have a significantly higher (P<0.01) measure of alignment in the right hemisphere. This method offers a unique tool for the in vivo demonstration of neural connectivity in healthy and diseased brain.     

Magnetic resonance imaging abnormalities in cat-scratch disease encephalopathy.

A 23-year-old woman who presented with a branch retinal artery occlusion followed by encephalopathy showed, by brain magnetic resonance imaging, a nonenhancing lesion in the right parietal gray matter with normal diffusion-weighted imaging. Of 64 reported cases of cat-scratch encephalopathy with documented neuroimaging findings, only 12 (18.8%) have had abnormal imaging findings. The abnormalities have included cerebral white matter lesions, basal ganglia and thalamic lesions, and multifocal lesions in immunocompromised patients, but no gray matter lesions similar to those in this patient. The variety of neuroimaging findings supports multiple pathophysiologic mechanisms of central nervous system involvement in this disorder.     

Magnetic resonance imaging abnormalities with septic encephalopathy

A 48 year old woman, status post renal transplantation six years earlier, died after a two week illness characterised by fever, recurrent seizures, and coma. Widespread abnormalities were seen on neuroimaging. A diagnosis of septic encephalopathy was established on postmortem. We describe the magnetic resonance imaging findings of bilateral basal ganglia, thalamic, cerebellar, brainstem, and cerebral abnormalities in this patient, which correlate with the pathophysiology of septic encephalopathy.     

Effects of white matter lesions and lacunes on cortical function

BACKGROUND: Subcortical ischemic vascular dementia has been ascribed to prominent frontal lobe dysfunction secondary to ischemic lesions in frontothalamic circuits.Whether small-vessel disease in fact predominantly affects the frontal lobes is not well documented. OBJECTIVE: To investigate the effects of subcortical lesions (lacunes and white matter lesions [WML]) on cortical function, as reflected in glucose metabolism and cognitive function, in elderly individuals. DESIGN: Cross-sectional analyses of case series. SETTING: Multicenter, university-based study of subcortical vascular dementia. PATIENTS: Persons with normal cognition, mild cognitive impairment, or dementia and with and without lacunes on magnetic resonance images. MAIN OUTCOME MEASURES: Regional cerebral glucose metabolism, normalized regional metabolic activity, and neuropsychological test scores. Major hypotheses were that volume of lacunes and WML correlate selectively with hypometabolism of prefrontal cortex and failure of executive cognitive ability. RESULTS: Lacunes correlated with metabolic rates in dorsolateral frontal cortex (DLF); WML substantially reduced metabolic rates throughout cortex, most strongly so in DLF. When regional metabolic activity was normalized to whole brain activity, lacunes remained correlated with DLF activity, whereas the WML effect was no longer found, probably because of its general distribution. Regional cerebral glucose metabolism and normalized activity in DLF also correlated with cortical atrophy. Metabolic activity in DLF correlated with executive function, memory, and global cognitive function, while activity in middle temporal gyrus correlated with memory and global function but not executive function. CONCLUSIONS: The metabolic effects of lacunes and WML are most apparent in DLF, but the effects of WML are generalized and frontal hypometabolism correlates with memory and global impairment, cognitive as well as executive function. The effects of subcortical cerebrovascular disease appear to converge on the frontal lobes but are diffuse, complex, and of modest magnitude.     

Magnetic resonance imaging of heterotopic gray matter

Heterotopic gray matter was detected by means of magnetic resonance imaging in a 3-year-old girl with left hemiparesis and atonic seizures. In the inversion recovery sequence, a large area of decreased signal intensity was noted in the right centrum semiovale and differentiation of the right basal ganglia was not clear. We speculated that the brain malformation in our patient occurred at ten weeks conceptional age.     

Hypoglycemic encephalopathy with extensive lesions in the cerebral white matter

Here we report an autopsy case of hypoglycemic encephalopathy with prolonged coma. Laboratory data obtained when the patient lapsed into a coma showed that she had a low level of serum glucose (27 mg/dL). Although the level of glucose returned to within the normal range rapidly after glucose infusion, the patient remained in a coma for 22 months. It was presumed that the state of hypoglycemia persisted for about 4 h. There was no evidence of hypotension or hypoxia. Magnetic resonance imaging was performed 3 h after glucose administration; diffusion‐weighted images revealed hyperintensity in the cerebral white matter and in the boundary zone between the middle and posterior cerebral arteries. Post‐mortem examination revealed superficial laminar necrosis throughout the cerebral cortex. Neuronal necrosis was also found in the hippocampus and dentate gyrus, although the CA3 region appeared normal. In addition to these lesions, which are consistent with hypoglycemia‐induced brain damage, the cerebral white matter exhibited severe loss of myelin and axons with reactive astrocytosis and macrophage infiltration. Old infarcts were also present in the bilateral occipital lobes. Since the cerebral blood flow is reported to be decreased during severe hypoglycemia, the present findings suggest that white matter lesions and boundary‐zone infarctions may develop primarily in uncomplicated hypoglycemia.     

Carotid atherosclerosis and cerebral white matter lesions in a population based magnetic resonance imaging study

Cerebral white matter lesions are frequently observed on magnetic resonance imaging of elderly, nondemented persons. There is evidence that white matter lesions are involved in the pathophysiology of cognitive decline and dementia. White matter lesions can be divided into those in the periventricular and those in the subcortical region. Pathological and epidemiological studies suggest that atherosclerosis is involved in the pathogenesis of these lesions. Our study reports on the association between atherosclerosis in the carotid arteries and white matter lesions in a population-based study among 1077 elderly subjects. We randomly sampled 1077 subjects aged between 60–90 years from two prospective population-based studies. All subjects underwent ultrasonography of the carotid artery. In addition, 1.5 T magnetic resonance imaging was performed; white matter lesions in the subcortical and periventricular regions were rated separately. With increasing number of plaques in the carotid artery the severity of periventricular white matter lesions increased (P _trend = 0.03), but not the severity of subcortical white matter lesions (P _trend = 0.19). In addition, an increase in intima media thickness was borderline significantly associated with an increased severity of periventricular white matter lesions (P _trend = 0.09), but not of subcortical white matter lesions (P _trend = 0.68). These findings suggest that partly dissimilar pathogenetic mechanisms are involved in the etiology of periventricular and subcortical white matter lesions. Received: 13 January 1999/Received in revised form: /15 November 1999/Accepted: 17 December 1999