Pathologic correlates of increased signals of the centrum ovale on magnetic resonance imaging

The role of routine laboratory studies and neuroimaging in the diagnosis of dementia: a clinicopathological study

OBJECTIVE

To determine the neuropathological diagnoses of longitudinally followed patients with potentially reversible causes of dementia and to examine the results of the "dementia work-up," especially neuroimaging, by comparison with the pathological diagnosis.

DESIGN

A neuropathologic series of 61 consecutive patients, with review of clinical, laboratory, neuroimaging, and pathological results.

RESULTS

Of the 61 patients, forty-eight (79%) had a clinical diagnosis of probable or possible Alzheimer's disease (AD). Compared with the pathological diagnosis, the sensitivity and specificity of the clinical diagnosis of AD were 96% and 79%, respectively. Of the 61 patients, 9 had abnormal laboratory tests, the correction of which did not improve the subsequent course. These patients were found to have AD8 and frontotemporal dementia on pathology. In two patients, neuroimaging was helpful in the clinical diagnoses of frontotemporal dementia and progressive supranuclear palsy (PSP). Neuroimaging revealed cerebrovascular disease in 18 patients, only two of whom were suspected clinically. Pathology confirmed AD in 17 and PSP in 1 of these patients. Sensitivity and specificity for the clinical diagnosis of cerebrovascular disease in comparison with pathology were 6% and 98%, respectively. With the added information from neuroimaging, that sensitivity increased to 59% and specificity decreased to 81%.

CONCLUSIONS

All cases with abnormal laboratory or neuroimaging results had AD or some other neurodegenerative disease on pathology. The "dementia work-up" did not reveal any reversible causes for dementia in this group of patients. Neuroimaging may have a role, especially in the diagnosis of possible AD with concomitant cerebrovascular disease.

Cerebrovascular pathology in Alzheimer's disease and leukoaraiosis

A high percentage of patients with Alzheimer's disease (AD) show evidence of white matter degeneration known as leukoaraiosis (LA), which is due to chronic ischemia. We found that the periventricular veins tend to become occluded by multiple layers of collagen in the vessel walls in the elderly. This collagen deposition is particularly excessive in LA lesions. Therefore, it is present in the brains of many AD patients, along with other ischemia-causing cerebrovascular pathology. We found evidence that there is severe loss of oligodendrocytes in LA, due to extensive apoptosis. No evidence of inflammation was found in the LA lesions. In thick celloidin sections of AD brain, we have obtained detailed 3D views of small (early) deposits of amyloid (stained with beta-amyloid antibody) around capillaries (stained with collagen IV antibody).

The contribution of spinal cord MRI to the diagnosis and differential diagnosis of multiple sclerosis

Imaging considerations for the diagnosis and differential diagnosis of MS are based primarily on results of MR studies of the brain. Recent studies suggest that with current technology, MR imaging of the spinal cord can make important contributions, particularly in cases with equivocal or negative brain MRI studies. Spinal cord MRI may also assume an important role in early diagnosis.

Periventricular white matter hyperintensities on MRI: correlation with neuropathologic findings

Periventricular white matter hyperintensities on postmortem magnetic resonance imaging (MRI) and myelin-stained frontal and parietal histologic sections were evaluated independently in 12 cases. There was a strong relationship between the extent of white matter hyperintensities on MRI and the extent of gross and microscopic changes seen in the white matter of myelin-stained sections, particularly in the frontal lobe. In this material, the extent of myelin rarefaction correlated with a 0- to 8-point white matter hyperintensity scale rating on MRI in the same brains.

Visual hallucinations, white matter lesions and disease severity in Parkinson's disease

OBJECTIVES

To determine if visual hallucinations in patients with Parkinson's disease are associated with an increased prevalence of white matter lesions.

PATIENTS AND METHODS

Fifteen patients with (group 1) and 15 patients without (group 2) a history of visual hallucinations were studied. Both groups were matched for age. Magnetic resonance imaging was performed in all patients using standard T2 weighted Fast-Spin-Echo sequences. Assessment of cerebral white matter changes was performed using a modification of established criteria, with semiquantitative evaluation of periventricular and deep white matter changes.

RESULTS

There was no significant group difference with regard to the total amount of white matter changes, nor was a group difference found between the amount or extent of periventricular hyperintensities or deep white matter lesions. Group 1 was significantly (P = 0.001) more disabled as evaluated by Hoehn/Yahr stage controlling for age and duration of disease. Mean increases in Hoehn/Yahr stage were not significantly greater in group 1 compared with group 2 at a 2-year follow-up examination (0.6 vs. 0.3, P = 0.166).

CONCLUSION

Our data suggest that visual hallucinations are an indicator of a more aggressive course of the disease, but are not associated with a higher prevalence of global or occipital white matter lesions.

Volumetric magnetic resonance imaging study of the brain in subjects with sex chromosome aneuploidies

OBJECTIVES

Cognitive impairment has been reported in people with sex chromosome aneuploides (SCAs) and it has been proposed that the presence of an extra sex chromosome may have an adverse effect on neurodevelopment. This study examines the hypothesis with structural MRI of the brain.

METHODS

Thirty two subjects with SCA (XXX (n=12), XYY (n=10), and XXY (n=10)) from a birth cohort study were matched groupwise for age, parental social class, and height with normal controls (13 female, 26 male). Brain MRI, measurements of IQ, and a structured psychiatric interview were performed.

RESULTS

The XXX females and XXY males had significantly smaller whole brain volumes than controls of the same phenotypic sex (p=0.003 and p</=0.05 respectively). The XXY group also had bilaterally enlarged lateral ventricles (p</=0.05). No significant differences were found between the XYY group and controls. IQ scores in all SCA groups were lower than in the control groups.

CONCLUSIONS

The main result of reduced brain volumes in XXX and XXY subjects, but not in XYY subjects, indicates that the presence of a supernumerary X chromosome has a demonstrable effect on brain development.

Age-related brain changes associated with motor function in healthy older people

OBJECTIVE

To identify the MRI imaging findings associated with motor changes in healthy older people.

DESIGN

A cross-sectional study.

SETTING

A study of neurologic function in very healthy older people, the Oregon Brain Aging Study.

PARTICIPANTS

Clinical and MRI data were examined in 50 very healthy older subjects (mean age = 85.1, SD = 7.2 years).

MEASUREMENTS

Clinical measures (finger tapping, hand opening and closing, steps and time to walk 30 feet and timed standing on one foot) were dependent variables in multiple regression analyses using age and the following MRI measures as independent variables: total brain volume (TBV)/intracranial volume; ventricular volume/TBV; periventricular high signal/TBV; deep high signal/TBV.

RESULTS

The number of steps and the time to walk 30 feet were each associated with periventricular high signal (steps: r = .58, P < .001; time: r = .60, P < .001) and ventricular volume (steps: r = .54, P < .001; time: r = .58, P < .001). These associations remained significant after adjusting for age. None of the other clinical variables was associated with the MRI volumes.

CONCLUSIONS

Gait measures were associated significantly with periventricular high signal and ventricular volume. These CNS changes contribute to the cause of these important markers of aging.

The spectrum of age-associated brain abnormalities: their measurement and histopathological correlates

Magnetic resonance imaging (MRI) has dramatically increased our ability to detect morphological abnormalities in relation to aging of the brain. Among those changes are alterations of the white matter which display high signal intensity on both proton density and T2-weighted images. They may be seen in the deep and subcortical white matter or in a periventricular location. In clinically asymptomatic individuals the reported prevalence ranges from 20% to 60% for deep and subcortical white matter hyperintensities and from 15% to 94% for periventricular changes. Besides different characteristics of the populations examined these wide ranges are a consequence of quite diverse rating schemes and measurement approaches. Inadequate grading of MRI hyperintensities may also explain some of the inconsistencies in the reported associations of white matter damage with cerebrovascular risk factors or cognitive functions. Therefore development of a commonly accepted rating scheme would be desirable. Histopathologic observations could lay the basis. Hyperintense periventricular capping of the frontal horns and a smooth halo of periventricular hyperintensity have been linked to disruption of the ependymal lining, subependymal gliosis and concomitant loss of myelin. Punctate lesions in the deep and subcortical white matter corresponded to minor perivascular reduction in myelin content possibly because of a lower permeability of thickened arteriolar walls. Larger patchy and confluent hyperintensities, however, appear to indicate more extensive ischemic damage consistent with advanced microangiopathy. In parallel, newer MRI techniques may also contribute to the delineation and separation of these various types of tissue alteration.

Neuroimaging of the aging brain

Age-related white matter injury has been recognized increasingly with the improvement of brain imaging technology. Arteriosclerosis and venous collagenosis, which occur with aging, result in a spectrum of white matter changes that range from periventricular to subcortical and deep white matter hyperintensities best seen on T2 weighted magnetic resonance imaging. These white matter changes are associated not only with aging, but with hypertension and silent infarctions. Loss of brain volume and accumulation of iron in putamen occur with normal, healthy aging. This article discusses the imaging appearance of healthy aging and pathological correlates of similar appearing alterations. The imaging findings of the most common neurodegenerative disorders, Alzheimer's and Parkinson's disease, are highlighted.

Posteroventral medial pallidotomy for treatment of Parkinson's disease: preoperative magnetic resonance imaging features and clinical outcome

OBJECT

The goal of this study was to investigate the impact of mild or moderate degrees of degenerative or ischemic encephalopathy on predicting clinical outcome following unilateral posteroventral medial pallidotomy for treatment of advanced Parkinson's disease (PD).

METHODS

Thirty-five patients with PD were studied prospectively. The presence and degree of cortical atrophy, ventriculomegaly, deep white matter lesions (DWML), periventricular lucencies (PVL), and the presence of lacunes and status cribriformis (multiple and bilateral enlarged Virchow-Robin spaces) were determined by magnetic resonance (MR) imaging before the patients underwent stereotactic pallidotomy performed according to a standard protocol. Clinical outcome was measured using a standard battery of tests including application of the Unified Parkinson's Disease Rating Scale (UPDRS). The preoperative MR imaging features were correlated with UPDRS subscores such as motor "off' score, the activities of daily living (ADL) off score, the off subscore for bradykinesia, the percentage of "on" time dyskinesias, and a global outcome rating. The MR findings were also correlated with the occurrence of side effects. Global outcome was rated as markedly improved in 22 patients (63%) and as moderately improved in 12 patients (34%) 6 months postoperatively. At the 1-year follow-up examination, global outcome in 31 patients was rated as markedly improved in 14 patients (45%), as moderately improved in another 14 (45%), as slightly improved in two (6%), and as worse in one patient (3%). The mean UPDRS motor off score changed from 58.7 preoperatively to 33.2 at 6 months and 33.4 at 1 year (p < 0.0001), the ADL off score from 31.8 to 18.2 at 6 months and 18.6 at 1 year (p < 0.0001), the off score from contralateral bradykinesia from 11.6 to 5.6 at 6 months and 4.1 at 1 year (p < 0.0001), and the percentage of awake time with dyskinesias from 37.4 to 17.4% at 6 months and 21.1% at 1 year (p < 0.0001). The presence of mild or moderate degrees of cortical atrophy, PVL, and DWML had no effect on clinical outcome. Patients with status cribriformis and those with lacunes tended to show comparatively less improvement in the UPDRS ADL off score (p = 0.014 and p = 0.016, respectively) at 6 months. This tendency was also present in patients with status cribriformis 1 year postoperatively (p = 0.046). Patients with both status cribriformis and lacunes had a higher incidence of transient altered mental status immediately postoperatively (p = 0.05).

CONCLUSIONS

Mild-to-moderate degrees of cortical atrophy, ventriculomegaly, and ischemic encephalopathy do not predispose patients to less favorable outcomes following unilateral pallidotomy. Patients with both status cribriformis and lacunes have a higher risk of transient side effects; however, with regard to clinical outcome, these patients should not be denied surgical treatment.

Vascular dementia: dead or alive?

The term 'Vascular Dementia' remains popular as a diagnostic entity, since it encompasses a variety of vascular pathologies. This is in stark contrast to many clinical classificatory systems that weight their definitions strongly towards stroke alone. A diagnosis of vascular dementia is complicated by compounding factors that reduce both the validity and specificity of diagnostic systems. This review highlights some of the problems faced in epidemiological, clinical, neuropathological and radiological studies attempting to define a clear-cut syndrome of dementia associated with cerebrovascular disease. The role of non-stroke ischaemia is also discussed. It is concluded that the term vascular dementia may have outlived its usefulness as a valid concept; alternative approaches are suggested.

Serum protein leakage in Alzheimer's disease revisited

Leakage of serum proteins into the brain parenchyma has been repeatedly used as evidence of blood-brain barrier (BBB) damage in experimental and human studies. However, there is no consensus in the literature concerning this phenomenon in Alzheimer's disease (AD). We have examined this question by comparing frontal lobe sections in seven groups of patients: Multi-infarct dementia (n = 6), AD with (n = 10) and without (n = 10) infarcts, age-matched controls with (n = 10) and without (n = 10) infarcts, controls with neurodegenerative diseases other than AD, and young controls (n = 10). An additional series compared prospectively followed patients with a diagnosis of either multi-infarct dementia (n = 5) or AD (n = 4). Albumin was detected in white-matter astrocytes in all cases, without significant variation in intensity. In addition, diverse combinations of neurons, astrocytes, and (in AD patients) senile plaques were present in the cerebral cortex in an inconsistent manner. Semiquantitative analysis showed no statistically significant differences among groups. Anti-IgG labeled astrocytes in infarcts only. Complement C3c component was detected in rare amyloid plaques in a minority (15%) of AD cases. Selective labeling of AD-specific lesions in a patchy manner was observed for serum amyloid P. We conclude that there is no immunohistochemical evidence of alteration of the BBB in Alzheimer's disease with or without vascular factors or in old age. Serum amyloid P binds avidly to AD lesions, but our findings are consistent with leakage through the BBB during the agonal or immediate postmortem period. Finally, no specific pattern of abnormality in the BBB was detected in multi-infarct dementia.

Cerebral microvascular alterations in aging, leukoaraiosis, and Alzheimer's disease

We have been using alkaline phosphatase (AP) histochemical staining, formerly a research tool for the study of cerebral cortical vascular morphology, to examine pathological changes in the cortex and deep cerebral structures. Deep structures stain similarly to the cortex. The AP stain is found in the afferent vessels (small arteries, arterioles, and capillaries), but not in venules and veins. The stain is also present in leaky vessels, such as those in the area postrema. The vascular supply to the cerebrum is not homogeneous. Supply to the deep white matter, for instance, derives from the leptomeningeal border zone, and then medullary arterioles must wind their way for up to 4 cm before arriving at their ultimate destination. Adding to the difficulties, tortuosities develop in some of these vessels with aging. According to some calculations, hypertensive levels of blood pressure would be required to maintain irrigation through some of these vessels. We have identified a venous alteration that attends aging: periventricular venous collagenosis (PVC) is a previously unrecognized, noninflammatory, mural disease of the periventricular veins. In severe cases, examples can be found of veins that are completely occluded by this process. PVC is found in 65% of subjects over 60 years old, and it strongly correlates with leukoaraiosis. In addition to previously mentioned aging-related changes, we have found extreme tortuosity, multiplications, and aneurysms of the smallest arterioles and lumpy-bumpy capillaries in the deep structures of patients with Alzheimer's disease.

Qualitative cerebral morphology in schizophrenia: a magnetic resonance imaging study and systematic literature review

Patients with schizophrenia have larger lateral ventricles, less cerebral substance and smaller mesial temporal lobe structures than groups of normal controls, but it has proved difficult to link these volumetric abnormalities with clinical features of the illness. Such quantitative techniques may overlook qualitative abnormalities of importance. We therefore compared a neuroradiologists' clinical assessment of gross structural abnormalities, generalised 'atrophy' and high intensity signal (HIS) foci, as detected on the first and second echo of a long TR sequence, in 42 patients with schizophrenia (22 treatment responsive, 20 treatment resistant) and 50 normal controls. The schizophrenic group included two (5%) subjects with gross lesions, two (5%) with cerebellar atrophy, 21 (52%) with at least a mild degree of cerebral atrophy, and 15 (38%) with one or more HIS foci; the comparable figures in the controls being 2, 0, 2 and 14%, respectively. Controlling for age, patients with schizophrenia had a substantially elevated rate of cerebral atrophy (odds ratio (OR) = 11.7, p < 0.0001). Treatment-resistant schizophrenics showed a tendency (OR = 2.8, p = 0.06) to greater atrophy than those who were treatment responsive, whereas our previous volumetric study showed no such difference. In contrast, the presence of HIS foci was only related to age. The degree of atrophy was correlated with the number of HIS foci (r = 0.31, p = 0.014). Taken together with previous studies, these findings demonstrate the value of qualitative examination of MRI images in patients with schizophrenia.

Xenon contrast CT-CBF measurements in high-intensity foci on T2-weighted MR images in centrum semiovale of asymptomatic individuals

BACKGROUND AND PURPOSE

White matter lesions (WMLs) on T2-weighted MR images occurring in the centrum semiovale of normal individuals are a subject of great clinical interest. We therefore investigated regional cerebral blood flow (rCBF) of the centrum semiovale among neurologically normal individuals.

METHODS

One hundred thirty-five neurologically normal subjects were divided into four grades of WML on the basis of their MR images. rCBF values in the centrum semiovale were measured by xenon contrast CT methods.

RESULTS

Advanced age and associated hypertension were significant risk factors for higher grade WMLs. Centrum semiovale rCBF values on the left side were 24.27 +/- 2.60 mL.100 g-1.min-1 in grade 0, 23.52 +/- 2.78 in grade I, 19.35 +/- 2.81 in grade II, 15.82 +/- 2.05 in grade III, and 11.31 +/- 2.56 in grade IV. Differences were significant between grades (P < .005 between grade 0 and grades II, III, and IV; between grade II and grades III and IV; and between grades III and IV). Patients with hypertension had lower rCBF values than those without in grades 0, I, II, and III, with significant difference in grade I (P < .005). Age-matched studies between patients 61 to 70 years old confirmed a significant difference between WML grades.

CONCLUSIONS

WMLs in centrum semiovale are associated with greater age, hypertension, and reduced rCBF values.

Magnetic resonance imaging in the congenital adrenal hyperplasia population: increased frequency of white-matter abnormalities and temporal lobe atrophy

Congenital adrenal hyperplasia results from an adrenal enzyme deficiency, that causes an underproduction of glucocorticoids and sometimes mineralocorticoids and a resultant overproduction of androgens, until treatment with replacement glucocorticoids is instituted. The goal of this study was to determine the frequency and etiology of white-matter changes and temporal lobe atrophy demonstrable on magnetic resonance imaging (MRI) in a group of children and young adults with congenital adrenal hyperplasia. About one third of the patients evidenced white-matter abnormalities or temporal lobe atrophy. All patients, except one with a known stroke, had normal neurologic examinations. Exposure to excess exogenous glucocorticoids in the process of being treated for congenital adrenal hyperplasia is the most theoretically appealing explanation for these MRI findings. However, the relationship of MRI findings to treatment status (over-versus under-suppressed) does not run in clear parallel.

White matter lesions in patients with idiopathic normal pressure hydrocephalus and in an age-matched control group: a comparative study

OBJECTIVE

To compare the occurrence of periventricular lesions (PVLs) and deep white matter lesions (DWMLs) in elderly patients with idiopathic normal pressure hydrocephalus (NPH) and in an age-matched control group.

METHODS

PVLs and DWMLs were evaluated using T2-weighted magnetic resonance scans of 37 patients with idiopathic NPH and 35 participants from an age-matched control group. All patients with idiopathic NPH included in this study improved after shunting. The control group consisted of 16 healthy elderly persons and 19 patients with depression. To allow quantitative assessment and comparison, scores for PVLs and DWMLs were calculated. Furthermore, possible correlations between white matter lesion scores, ventricular width, and age were investigated.

RESULTS

There was a significantly higher incidence of PVLs and DWMLs in patients with idiopathic NPH. The mean total PVL was 12.1 (range, 2-24) in the NPH group and 3.9 (range, 0-10) in the control group (P < 0.001). The mean total DWML score was 12.9 (range, 3-24) in the NPH group and 4.5 (range, 0-16) in the control group (P < 0.001). There were significant correlations between the severity of PVL and DWML scores in both groups. Only a weak positive correlation between the severity of DWMLs and age was found in the NPH group, whereas this correlation was significant in the control group. There was a significant negative correlation between the width of the anterior horns and the severity of both PVLs and DWMLs in patients with NPH; however, positive correlations were found in the control group.

CONCLUSION

Elderly patients with idiopathic NPH have more frequent and more severe PVLs and DWMLs than people in age-matched control groups. Our data suggest a frequent co-occurrence of idiopathic NPH and vascular subcortical encephalopathy; however, they do not support a direct causal relationship.

Pathogenesis of leukoaraiosis: a review

BACKGROUND

Changes in the cerebral hemispheric white matter, detectable with increasing frequency by modern neuroimaging methods, are associated with aging and conceivably may contribute to the development of specific cognitive deficits. The pathogenesis of these cerebral white matter abnormalities (sometimes described as leukoaraiosis) is unknown. This review evaluates the available evidence in support of the hypothesis that the etiology of leukoaraiosis is related to a specific type of cerebral ischemia and highlights mechanisms by which ischemic injury to the brain may induce selected structural alterations limited to the cerebral white matter.

SUMMARY OF REVIEW

The review is based on the critical analysis of over 100 publications (most appearing in the last decade) dealing with the anatomy and physiology of the arterial circulation to the cerebral white matter and with the pathogenesis of leukoaraiosis.

CONCLUSIONS

A significant number of clues support the hypothesis that some types of leukoaraiosis may be the result of ischemic injury to the brain. Structural changes affecting the small intraparenchymal cerebral arteries and arterioles that are associated with aging and with stroke risk factors, altered cerebral blood flow autoregulation, and the conditions created by the unique arterial blood supply of the hemispheric white matter each seem to contribute to the development of leukoaraiosis. To the best of our ability to interpret current information, the type of ischemic injury that is most likely responsible for these white matter changes involves transient repeated events characterized by moderate drops in regional cerebral blood flow that induce an incomplete form of infarction. This hypothesis could be tested in appropriate experimental models.

Movement disorders in adult hydrocephalus

In a prospective series of symptomatic adult hydrocephalus characterized by gait disturbance, cognitive impairment, and/or urinary incontinence, 88 of 118 patients (75%) had additional akinetic, tremulous, hypertonic, or hyperkinetic movement disorders. Their prevalence was highest in patients with idiopathic normal pressure hydrocephalus (NPH) of the elderly (56/65 patients, 86%), and they were less frequent in patients with secondary NPH (10/15, 66%), with nonhydrodynamic atrophic/other hydrocephalus (20/33, 61%), and with obstructive hydrocephalus/aqueductal stenosis (2/5, 40%). Akinetic symptoms were found in 73 of 118 patients (62%), and the most frequent movement disorder was upper extremity bradykinesia (55%). Akinetic, tremulous, hypertonic, and hyperkinetic movement disorders were exclusively secondary to causes not related to hydrocephalus in 24 of 118 patients (20%). The proportion of patients with movement disorders not attributable to only such causes was highest in the idiopathic NPH group (44/65, 68%). Thirteen of 118 patients (11%) presented with a parkinsonian syndrome. There was evidence for coexistent Parkinson's disease in four of these patients. Parkinsonism was found to be secondary to NPH in five patients and was found improved after shunting. Akinetic symptoms in patients with NPH generally responded favorably to CSF diversion, which was evident in 80% of a subset of this group. Various other movement disorders did not show definite improvement. The high prevalence of bradykinesia and other akinetic symptoms in NPH and the beneficial effect of shunting on such symptoms suggest that NPH may cause a more generalized disorder of motor function.

Cerebrospinal fluid shunting in idiopathic normal-pressure hydrocephalus of the elderly: effect of periventricular and deep white matter lesions

OBJECTIVE

We investigated the effect of periventricular and deep white matter lesions (DWMLs) on outcome after cerebrospinal fluid shunting in a prospective series of elderly patients with idiopathic normal-pressure hydrocephalus.

METHODS

White matter lesions were assessed with T2-weighted magnetic resonance scans according to a standard protocol in 41 patients with idiopathic normal-pressure hydrocephalus of the elderly who underwent subsequent shunting. In all patients, the diagnosis of idiopathic normal-pressure hydrocephalus had been established preoperatively by clinical and diagnostic investigations.

RESULTS

At a mean follow-up of 16 months, clinical improvement was observed in 37 of 41 patients (90%). There was no persistent morbidity related to surgery. The degree of overall clinical improvement was negatively correlated with the extension of periventricular lesions (correlation coefficient r = -0.324 [P = 0.04]) and DWMLs (correlation coefficient r = -0.373 [P = 0.02]). This negative correlation was also noted when the analysis was conducted separately for each of the cardinal symptoms (gait disturbance, cognitive impairment, and urinary incontinence). There was no consistent pattern of periventricular and DWMLs in the four patients who failed to respond to shunting.

CONCLUSION

Periventricular and DWMLs of varying degrees are common findings on magnetic resonance scans of patients with idiopathic normal-pressure hydrocephalus of the elderly. After careful preoperative selection of patients with idiopathic normal-pressure hydrocephalus, individuals with DWMLs suggestive of concomitant vascular encephalopathy may also benefit from cerebrospinal fluid diversion. Although, in general, the degree of improvement depends on the severity of periventricular and DWMLs, patients with more extensive WMLs still may derive clinical benefit from the operation.

Multifocal white matter lesions

There is a long differential diagnosis for multifocal white matter lesions on MR. The most common causes are prominent Virchow-Robin spaces, white matter ischemic change, and multiple sclerosis, but many other causes have been reported. Most of these are related to vascular or other demyelinating etiologies, but infectious/inflammatory disease, trauma, and neoplastic and other unusual causes may also be responsible. Typical imaging features of the more common multifocal white matter disorders are outlined, and the rarer causes are discussed briefly. An approach to imaging differential diagnosis is given, with emphasis on the differences between white matter ischemic lesions and multiple sclerosis.

H-1 MR spectroscopic imaging of white matter signal hyperintensities: Alzheimer disease and ischemic vascular dementia

PURPOSE

To investigate the association of white matter signal hyperintensities (WMSHs) with changes in hydrogen-1 metabolites.

MATERIALS AND METHODS

T2-weighted magnetic resonance (MR) imaging and H-1 MR spectroscopic imaging were performed in 21 elderly control subjects without or with minimal WMSHs, eight elderly subjects with substantial WMSHs, 11 probable Alzheimer disease patients with WMSHs, and eight ischemic vascular dementia (IVD) patients with WMSHs. N-acetylaspartate (NAA), choline-containing metabolites (Cho), and creatine-containing metabolites (Cr) were analyzed.

RESULTS

Differences in regional metabolite levels were found within the supraventricular brain of elderly control subjects. In Alzheimer disease patients, extensive WMSHs showed a lower percentage of NAA and a higher percentage of Cho compared with contralateral normal-appearing white matter (NAWM); in IVD patients, extensive and large WMSHs were associated with a higher percentage of Cho and a lower percentage of Cr compared with contralateral NAWM.

CONCLUSION

Regional metabolite variation and the presence of WMSHs are important covariants that must be accounted for in analysis of MR spectroscopic data.

White matter hyperintensity in neurologically asymptomatic subjects

Recent advances in magnetic resonance imaging (MRI) technology have had a great impact on the delectability of minute, asymptomatic lesions of the central nervous system. The clinical significance and treatment modes of these lesions, such as white matter hyperintensity (WMH) lesions detected by T2 MRI, remain controversial. To address these problems, we retrospectively evaluated WMH lesions in relation to clinical parameters for 240 neurologically asymptomatic persons who had visited a hospital for a medical check-up of the brain. Proton and T2-weighted MRI were obtained using a 0.5 T superconducting MR imager using the spin echo technique with a repetition time (TR) of 2800 msec. An echo delay times (TE) of 40 msec was used for the proton MRI, and a TE of 100 msec was used for the T2-weighted MRI. The images were visually analyzed according to a four-point grading system. The MRI findings were correlated with clinical parameters including age, gender, presenting symptoms, and hypertension. The overall frequency of WMH increased with age. Grades 2 and 3 of WMH were more frequent in aged persons, whereas the occurrence of grade 1 WMH remained relatively constant across age groups. Based on multiple regression analysis, age was the most significant variable influencing the frequency of WMH, followed by hypertension. These results imply that WMH lesions may simply be a phenomenon of aging, or may be an indicator of prepathologic state in an ischemic brain.

The significance of cerebral white matter abnormalities 100 years after Binswanger's report. A review

BACKGROUND

Changes in the cerebral hemispheric white matter are detected with increasing frequency by CT and MRI among persons older than 60 years. The pathogenesis, clinical significance, and morphological substrate of these changes are incompletely understood. Patients who have such neuroimaging abnormalities are sometimes diagnosed with "Binswanger's disease," an eponym that has generated much confusion because of its imprecise meaning. The objectives of this study were to determine whether the term Binswanger's disease merits acceptance as a distinct clinicopathologic entity, to deduce the clinical significance of these white matter abnormalities from the analysis of appropriate publications, and to evaluate studies that correlate in vivo changes in the cerebral white matter with pathological features.

SUMMARY OF REVIEW

We evaluated Binswanger's original case description and, after conducting a Medline search, reviewed more than 160 publications, mostly in the English language, on the subject of white matter abnormalities detectable by currently used neuroimaging methods (ie, leukoaraiosis).

CONCLUSIONS

Binswanger's original description appears to be insufficient for the purpose of defining a new nosological entity. After evaluating the vaguely outlined pathological correlates described in a few of these subcortical cerebral leukoencephalopathies, we conclude that the clinical significance of leukoaraiosis remains incompletely defined. However, its frequency increases with age independent of other risk factors, and in nondemented subjects leukoaraiosis is associated with deficits in selected cognitive functions. Moreover, leukoaraiosis correlates with an increased risk for the subsequent development of strokes. We make specific suggestions for future studies that may help to clarify this topic.

Leukoaraiosis in stroke patients. The Copenhagen Stroke Study

BACKGROUND AND PURPOSE

This study was undertaken to determine factors of importance for the development of leukoaraiosis and to evaluate whether leukoaraiosis influences stroke outcome.

METHODS

The study was prospective and consecutive and included 1084 unselected patients with acute stroke and transient ischemic attack admitted from the community of Bispebjerg (Copenhagen, Denmark) during a 25-month period from September 1, 1991, to September 30, 1993. All patients were treated in a stroke unit from the time of acute admission to completion of rehabilitation. Daily alcohol consumption and other putative risk factors were registered on admission, and patients were evaluated weekly to death or time of completed rehabilitation by means of neurological (Scandinavian Stroke Scale) and functional (Barthel Index) scores. Leukoaraiosis was diagnosed on computed tomographic scan. Multivariate analyses were applied to test relations independent of other influencing factors.

RESULTS

Leukoaraiosis was present in 15% of the patients. Age was the only factor that significantly increased the risk of leukoaraiosis (odds ratio [OR] per 10-year increase, 2.4; 95% confidence interval [CI], 1.8 to 3.1), whereas the presence of atrial fibrillation was adversely related to leukoaraiosis (OR, 0.26; 95% CI, 0.13 to 0.52). Moderate daily alcohol consumption (1 to 5 drinks) reduced the risk of leukoaraiosis (OR, 0.50; 95% CI, 0.28 to 0.87), whereas heavy daily alcohol consumption (> 5 drinks) tended to increase the risk (OR, 1.3; 95% CI, 0.5 to 3.3). Leukoaraiosis was not related to the presence of hypertension, diabetes, ischemic heart disease, atrial fibrillation, intermittent claudication, smoking, or sex. The presence of leukoaraiosis had no influence on neurological outcome (P = .20), functional outcome (P = .47), length of hospital stay (P = .75), or mortality (P = .31).

CONCLUSIONS

Moderate daily alcohol intake seems associated with a decreased risk of leukoaraiosis in stroke patients. The relation between alcohol intake and leukoaraiosis may even be U-shaped, like the relation between alcohol intake and coronary heart disease, alcohol intake and mortality, and alcohol intake and stroke. The presence of leukoaraiosis does not seem to influence the rehabilitation process or outcome of stroke.

Correlation of magnetization transfer ratio with clinical disability in multiple sclerosis

We performed spin echo magnetic resonance imaging with and without application of an off-resonance saturation pulse in 43 patients with multiple sclerosis (MS), 10 age-matched controls, and 4 elderly asymptomatic patients with the radiological diagnosis of small-vessel disease. Magnetization transfer (MT) ratio images were obtained from these. All MS subgroups (primary progressive, secondary progressive, benign, early relapsing-remitting) showed significantly lower average lesion MT ratios than small-vessel disease patients. Secondary progressive MS patients showed significantly lower lesion MT ratios than those with benign disease, and there was an inverse correlation of disability with average lesion MT ratio. The degree of reduction of MT ratios is an indicator of the extent of tissue destruction. Thus, reduced MT ratios in MS may provide an indication of the degree of demyelination and axonal loss, both of which are likely to cause functional deficits in MS. We conclude that MT measurement is (1) a robust quantitative method that may increase the pathological specificity of magnetic resonance imaging, (2) has the potential to differentiate demyelination in MS from less destructive pathological changes, and (3) may be useful in monitoring modifications in tissue structure brought about by treatment.

Cerebral lesions on magnetic resonance imaging, heart disease, and vascular risk factors in subjects without stroke. A population-based study

BACKGROUND AND PURPOSE

To assess the prevalence of asymptomatic abnormalities on magnetic resonance imaging of the brain and their possible relation to hypertension, heart disease, and carotid artery disease, we studied 77 randomly selected subjects (mean age, 65.1 years; range, 36 to 95 years) with no history of focal brain lesions.

METHODS

The study protocol included magnetic resonance imaging of the brain, transthoracic and transesophageal echocardiography, ultrasonography of the carotid arteries, and electrocardiographic recording. Deep and periventricular white matter hyperintensities on magnetic resonance imaging were assessed both separately and together.

RESULTS

On magnetic resonance imaging of the brain 62.3% (95% confidence interval [CI], 51.5% to 73.2%) of the subjects had white matter hyperintensities. These abnormalities increased significantly with age (chi 2 test; P = .0001), from 13.6% (95% CI, 0% to 28.0%) of subjects aged younger than 55 years to 85.2% (95% CI, 71.8% to 98.6%) of subjects aged 75 years or older. Six subjects had deep gray matter hyperintensities localized in the basal ganglia, and one had a cerebellar infarction. Stepwise logistic regression analysis identified age and a history of heart disease (but not echocardiographic findings) to be independently associated with deep and periventricular white matter hyperintensities. Hypertension was only independently associated with periventricular white matter hyperintensities. Of the 68 subjects examined with both transthoracic and transesophageal echocardiography, potential cardioembolic sources were detected in 38.2% (95% CI, 26.7% to 49.8%) of the subjects with transthoracic echocardiography and in 47.1% (95% CI, 35.2% to 58.9%) of those with transthoracic and transesophageal echocardiography combined. In subjects aged 75 years or older, a possible cardiac embolic source was detected in 64.0% on transthoracic echocardiography and in 72.0% on transthoracic and transesophageal echocardiography combined, compared with 5.3% and 15.8%, respectively, in subjects aged younger than 55 years.

CONCLUSIONS

White matter hyperintensities and potential cardioembolic sources are frequently present in asymptomatic individuals, stressing the need for age-matched control subjects in studies of patients with stroke or dementia.