Are multiple cerebral infarcts synergistic?

Systematic Review and Meta-Analyses of Word Production Abilities in Dysfunction of the Basal Ganglia: Stroke, Small Vessel Disease, Parkinson's Disease, and Huntington's Disease

Clinical populations with basal ganglia pathologies may present with language production impairments, which are often described in combination with comprehension measures or attributed to motor, memory, or processing-speed problems. In this systematic review and meta-analysis, we studied word production in four (vascular and non-vascular) pathologies of the basal ganglia: stroke affecting the basal ganglia, small vessel disease, Parkinson's disease, and Huntington's disease. We compared scores of these clinical populations with those of matched cognitively unimpaired adults on four well-established production tasks, namely picture naming, category fluency, letter fluency, and past-tense verb inflection. We conducted a systematic search in PubMed and PsycINFO with terms for basal ganglia structures, basal ganglia disorders and language production tasks. A total of 114 studies were included, containing results for one or more of the tasks of interest. For each pathology and task combination, effect sizes (Hedges' g) were extracted comparing patient versus control groups. For all four populations, performance was consistently worse than that of cognitively unimpaired adults across the four language production tasks (p-values < 0.010). Given that performance in picture naming and verb inflection across all pathologies was quantified in terms of accuracy, our results suggest that production impairments cannot be fully explained by motor or processing-speed deficits. Our review shows that while language production difficulties in these clinical populations are not negligible, more evidence is necessary to determine the exact mechanism that leads to these deficits and whether this mechanism is the same across different pathologies.

Revisiting 'brain modes' in a new computational era: approaches for the characterization of brain-behavioural associations

The study of brain-function relationships is undergoing a conceptual and methodological transformation due to the emergence of network neuroscience and the development of multivariate methods for lesion-deficit inferences. Anticipating this process, in 1998 Godefroy and co-workers conceptualized the potential of four elementary typologies of brain-behaviour relationships named 'brain modes' (unicity, equivalence, association, summation) as building blocks able to describe the association between intact or lesioned brain regions and cognitive processes or neurological deficits. In the light of new multivariate lesion inference and network approaches, we critically revisit and update the original theoretical notion of brain modes, and provide real-life clinical examples that support their existence. To improve the characterization of elementary units of brain-behavioural relationships further, we extend such conceptualization with a fifth brain mode (mutual inhibition/masking summation). We critically assess the ability of these five brain modes to account for any type of brain-function relationship, and discuss past versus future contributions in redefining the anatomical basis of human cognition. We also address the potential of brain modes for predicting the behavioural consequences of lesions and their future role in the design of cognitive neurorehabilitation therapies.

Closing-in behavior in mild cognitive impairment: an executive deficit

This study explored Closing-in behavior (CIB), the tendency in figure copying to draw very close to or on top of the model, in mild cognitive impairment (MCI). The files of 154 people diagnosed with MCI were reviewed and CIB was identified in 21% of cases. Two approaches were used to explore CIB. First, we capitalized on the diverse cognitive profiles within MCI, subdividing the overall sample into people with and without memory deficits. The frequency of CIB was significantly higher in multidomain non-amnestic MCI than in multidomain amnestic MCI, suggesting that CIB is not associated with specific memory impairment. Second, we assessed the cognitive correlates of CIB, by selecting patients with MCI who completed a battery of executive, visuo-constructional and memory tasks. Sub-groups of patients with and without CIB showed a similar overall severity of cognitive decline and comparable performance in visuo-constructional and memory tasks, but those with CIB were slightly but significantly more impaired on executive function tasks. The study provides evidence against memory-based accounts of CIB, and supports recent suggestions that executive impairments are the dominant cognitive correlate of this clinical sign.

Mild cognitive impairment in stroke patients with ischemic cerebral small-vessel disease: a forerunner of vascular dementia?

Ischemic cerebral small-vessel disease accounts for a third of acute cerebral ischemic events and contributes to the development of cognitive decline and dementia. Cerebral small-vessel disease can be visualized on MRI studies as lacunar infarcts, white matter lesions and cerebral microbleeds. In general, the short-term prognosis of ischemic cerebral small-vessel disease compared with other stroke subtypes is more favorable, with almost negligible early mortality, absence of neuropsychological impairment and excellent neurological recovery. However, it has been shown recently that the proportion of dementia caused by small-vessel disease ranges from 36 to 67%. On the other hand, patients with a first-ever lacunar infarction present with cognitive impairment (mainly executive dysfunction) in more than half of cases and more than 55% of patients fulfil the criteria of mild cognitive impairment of the vascular type. Moreover, patients with small-vessel disease have an increase in the mid- and long-term risk of death, stroke recurrence and dementia. Neuropsychological abnormalities in small-vessel disease occurred more frequently than previously recognized. Ischemic cerebral small-vessel disease should be regarded as a potentially severe condition prodrome of subcortical vascular dementia rather than a relatively benign disorder.

Supratentorial Age-Related White Matter Changes Predict Outcome in Cerebellar Stroke

Background and Purpose— Little is known about the relevance of age related white matter lesions (WMLs) concerning outcome after first-ever territorial stroke. Based on an index patient, we hypothesized that age and pre-existent WMLs rather than infarct volume and topography determine outcome.

Patients and Methods— Thirty-four consecutive patients with magnetic resonance diffusion-weighted imaging–proven isolated acute cerebellar infarction were prospectively entered on our stroke data registry. Patients with pre-existent neurological deficits, hemorrhagic, or malignant cerebellar infarction were excluded. Patients were stratified using Rankin and Barthel disability scales into groups: I complete recovery, II moderate, and III significant disability 14 days after stroke onset.

Results— Initial neurological and functional scores were similar among all the groups with vertigo, nausea, unsteadiness, and limb ataxia being the most common. Infarct volume, vascular territories, and comorbidity did not predict clinical outcome. In contrast, presence and severity of supratentorial WMLs and age significantly determined outcome by functional tests.

Conclusions— In patients with isolated cerebellar infarction functional outcome correlated with the coexistence of age-related WMLs rather than stroke volume and topography. This reflects the loss of compensatory network integrity as the equivalent of functional incapacity beyond local lesion disturbances.

Frontal lobe dysfunction caused by multiple lacunar infarction in community-dwelling elderly subjects

We examined the factors that influence frontal lobe function among 119 community-dwelling elderly subjects, based on magnetic resonance imaging (MRI) and clinical findings. We interviewed the subjects, and conducted a neurological examination, electrocardiogram, blood test, brain MRI examination, and cognitive function tests. The modified Stroop test and a personal computer version of the Wisconsin Card Sorting Test (WCST) were used to evaluate frontal lobe function. The subjects with impaired frontal lobe function defined by the modified Stroop test were significantly older, had more lacunar infarcts, and had lower HDL cholesterol values based on a logistic regression model. Among the aged who appear apparently normal, multiple lacunar infarcts are the cause of latent frontal lobe dysfunction.

Cognitive impairment after stroke

The concept of vascular dementia is undergoing revision. The multi-infarct model and the Alzheimer's model of dementia, usually referred to as 'multi-infarct dementia', are gradually being replaced by a much broader concept of vascular cognitive impairment. This conceptual evolution reflects a more profound understanding of the pathogenic mechanisms that underlie this complex syndrome. As a consequence of this revision new diagnostic criteria have been established during the past 25 years, resulting in new problems with regard to precise disease definition and limited inter-rater reliability. The particular criteria chosen by a clinician or investigator to diagnose vascular dementia have a major impact on epidemiology, disease management and health economic estimates.

An overview of common non-alzheimer dementias

Approximately 20% to 40% of dementia is caused by diseases other than Alzheimer's disease. This article reviews the major categories of non-Alzheimer dementia, including dementia associated with cerebrovascular disease, dementia associated with extrapyramidal features, and the frontotemporal dementias. Dementia associated with cerebrovascular disease is a heterogeneous condition the importance of which is often misunderstood. Dementia with Lewy bodies, the most common of the dementias associated with extrapyramidal disease, is becoming better recognized for its unique management issues. At least some of the frontotemporal dementias, which in this article encompass the progressive aphasias, have mutations in the tau gene that account for some of the phenotypic variations.

Blood pressure lowering for the prevention of cognitive decline in patients with cerebrovascular disease. PROGRESS Management Committee. Perindopril Protection Against Recurrent Stroke Study

Cerebrovascular disease and high blood pressure both appear to increase the risk of vascular dementia. PROGRESS aims to investigate whether blood pressure lowering with an angiotensin coverting enzyme inhibitor-based regimen will reduce the risk of cognitive impairment in patients with a history of stroke or transient ischaemic attack. A total of at least 6000 patients will be randomised to receive perindopril (+/- indapamide) or matching placebo(s), with treatment and follow-up scheduled to continue for at least 4 years. Substudies will investigate the effects of treatment on cognitive decline in subgroups defined by apo-E genotype and on white matter lesions assessed by magnetic resonance imaging. Final results from the study should be available in 2001.

Do silent brain infarctions predict the development of dementia after first ischemic stroke?

BACKGROUND AND PURPOSE

Silent brain infarctions (SBI) are common findings in advanced age, but their relationship to dementia is still uncertain. The present study was designed to evaluate whether SBI predict the development of dementia after first clinical ischemic stroke.

METHODS

We blindly studied admission CT scans of 175 consecutive nondemented patients presenting with ischemic stroke that clinically was their first stroke episode. SBI were defined as CT evidence of infarcts not compatible with the acute event. The patients were subsequently followed for their mental state for 5 years. Survival analysis, wherein onset of dementia was the end point, was performed on the total sample population and conducted separately on those with and without SBI at admission.

RESULTS

Dementia developed in 56 patients (32%), including 22 of the 63 (35%) with SBI and 34 of the 112 (30%) without SBI. Thus, dementia was not related to SBI.

CONCLUSIONS

Our data indicate that SBI do not predict the development of dementia after stroke.

Vascular dementia

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Prospective CT confirms differences between vascular and Alzheimer's dementia

BACKGROUND AND PURPOSE

Cognitive test performances were correlated prospectively with changes in cerebral CT measurements of atrophy, infarct volume, ventricular enlargement, local tissue density, and local perfusion to contrast annual rates of changes among patients with ischemic vascular dementia (IVD) or dementia of the Alzheimer type (DAT).

METHODS

The cerebral atrophic index (ATI; ratio of cerebrospinal fluid or infarcted brain to intracranial volume), infarct volume ratio, ventricular volume ratio (VVR; ventricular volume/intracranial volume), cortical and subcortical gray and white matter local perfusion (local cerebral blood flow [LCBF]), and local Hounsfield unit (HU) density were measured concurrently and compared longitudinally with Cognitive Capacity Screening Examinations (CCSE) scores among 24 treated IVD (age, 68.2 +/- 9.7 years; follow-up, 42 +/- 27 months) and 24 DAT patients (age, 74.2 +/- 6.2 years; follow-up, 30 +/- 19 months).

RESULTS

IVD annual changes were as follows: CCSE, +1.2 +/- 5.9; ATI, +2.1%/y; VVR, +3.2%/y; and LCBF in the subcortical basal ganglia, -0.74 mL.100 g-1.min-1.y-1 (-1.8%/y). DAT annual changes were as follows: CCSE, -1.8/y; ATI, +8.1%/y; VVR, +9.6%/y; cortical LCBF, -2.0 mL.100 g-1.min-1.y-1 (-5.2%/y); LCBF in the basal ganglia, -3.0 mL.100 g-1.min-1.y-1 (-6.7%/y); white matter LCBF, -0.75 mL.100 g-1.min-1.y-1 (-4.1%/y); and all cortical tissue densities, -0.83 HU/y (-2.1%/y). In IVD, multiple regression analyses correlated cognitive changes directly with (1) recurrent silent infarctions and (2) bidirectional changes of perfusions within frontal white matter, thalamus, and internal capsules. In DAT, cognitive declines correlated with cerebral atrophy and cortical hypoperfusion related to frontotemporal and parietal cortical polioaraiosis (decreased gray matter tissue densities).

CONCLUSIONS

In IVD, recurrent strokes were not observed clinically during risk factor control, and antiplatelet therapy and cognitive impairments improved or stabilized. In DAT, cognitive performance relentlessly declined. Ischemic pathogenesis for vascular dementia is supported by the following: (1) cognitive declines correlate directly with recurrent "silent" strokes, and (2) bidirectional cognitive changes correlate directly with frontal white matter, thalamic, and internal capsular perfusional changes.