Progressive cognitive deficits in a mouse model of recurrent photothrombotic stroke.

BACKGROUND AND PURPOSE: In spite of its high disease burden, there is no specific treatment for multi-infarct dementia. The preclinical evaluation of candidate drugs is limited because an appropriate animal model is lacking. Therefore, we aimed to evaluate whether a mouse model of recurrent photothrombotic stroke is suitable for the preclinical investigation of multi-infarct dementia. METHODS: Recurrent photothrombotic cortical infarcts were induced in 25 adult C57BL/6 mice. Twenty-five sham-operated animals served as controls. The object recognition test and the Morris water maze test were performed >6 weeks to assess cognitive deficits. Afterward, histological analyses were performed to characterize histopathologic changes associated with recurrent photothrombotic infarcts. RESULTS: After the first infarct, the object recognition test showed a trend toward an impaired formation of recognition memories (P=0.08), and the Morris Water Maze test revealed significantly impaired spatial learning and memory functions (P<0.05). After recurrent infarcts, the object recognition test showed significant recognition memory deficits (P<0.001) and the Morris water maze test demonstrated persisting spatial learning and memory deficits (P<0.05). Histological analyses revealed remote astrogliosis in the hippocampus. CONCLUSIONS: Our results show progressive cognitive deficits in a mouse model of recurrent photothrombotic stroke. The presented model resembles the clinical features of human multi-infarct dementia and enables the investigation of its pathophysiological mechanisms and the evaluation of treatment strategies.

[Current concepts in vascular dementia]. / Démences vasculaires : concepts actuels.

Vascular dementias, VD, are dementias due to cerebrovascular lesions. Subgroups of VD include multi-infarct dementia, single infarct (or strategic infarct) dementia, subcortical ischemic vascular dementia, hemorrhagic dementia, hypoperfusion dementia. VD are also related to post-stroke dementia, mixed Alzheimer's disease and vascular dementia and vascular cognitive impairment. These various entities allow to characterize more homogenous subgroups within the heterogeneous group of vascular dementias. However, ambiguities in their definitions, associated with frequent overlaps as well as lack of consensual definition for mixed dementia limit both their theoretical value and use in clinical practice. The diagnosis of cerebrovascular diseases should be dissociated from that of dementia, which could be associated with other pathologies.

Varicella zoster virus vasculopathy: a treatable form of rapidly progressive multi-infarct dementia after 2 years' duration.

We describe an extraordinarily protracted case of varicella zoster virus (VZV) multifocal vasculopathy in a man who presented initially with ischemic optic neuropathy and then suffered 4 episodes of stroke manifesting as multi-infarct dementia over a 2-year period. Brain magnetic resonance imaging (MRI) and angiography (MRA) revealed cortical and subcortical infarctions as well as vasculitic occlusion and stenosis. The patient was treated with corticosteroids and later with cyclophosphamide. More than 2 years after the onset of neurological disease, two cerebrospinal fluid (CSF) examinations revealed the presence of anti-VZV IgG antibody with reduced serum-to-CSF ratios of anti-VZV IgG compared with ratios for total IgG and albumin, indicative of intrathecal synthesis of anti-VZV IgG. After definitive diagnosis, immunosuppressive drugs were discontinued and he was treated with intravenous acyclovir; both mental status and gait improved and no further episodes of neurological dysfunction ensued. The favorable outcome in this patient indicates that VZV vasculopathy can be treated successfully even after 26 months. VZV must be considered as a possible cause of neurological disease in any patient with idiopathic multifocal vasculopathy.

Vascular cognitive impairment in small vessel disease: clinical and neuropsychological features of lacunar state and Binswanger's disease.

BACKGROUND: ischaemic cerebrovascular small vessel disease (SVD) is a prevalent and under-diagnosed condition that triggers vascular cognitive impairment (VCI). OBJECTIVE: to describe the neuropsychological and clinical profiles in SVD (Binswanger's disease, BD; lacunar state, LS) from the clinician's perspective at the VCI stage. METHODS: a total of 1257 patients admitted to a tertiary center with a diagnosis of stroke, neuroradiological vascular disease, cognitive impairment/dementia, during a 13-year period were investigated. We prospectively assessed cognition in a subset of 141 patients with VCI (LS n = 28, BD n = 69, large vessel disease-LVD-n = 44) with MMSE, CAMDEX-H, WAIS-R, EXIT-25 and Trail making test. RESULTS: executive dysfunction (ECD) (n = 89, 91.7% versus n = 10, 22.7%; P < 0.001) and gait disturbances (n = 74, 76.3% versus n = 15, 34.1%; P < 0.001) characterized SVD. Prior strokes (n = 9, 9.3% versus n = 23, 52.3%; P < 0.001) and embologenous cardiopathy (n = 39, 40.2% versus n = 28, 63.6%; P < 0.04) featured LVD cases. BD was defined by hypertension (n = 52, 75.4% versus n = 30, 44.1%; P < 0.001), ECD (n = 65, 94.2% versus n = 34, 47.2%; P < 0.001) and VCI onset with cognitive impairment but not strokes (n = 44, 63.8% versus n = 34, 50%; P < 0.01). CONCLUSIONS: ECD and a frontal gait are SVD's clinical landmarks in our sample. LS and BD cases share a similar cognitive profile.

[Vascular dementia]. / Vaskuläre Demenz.

Vascular dementia (VaD) constitutes the second most frequent cause of dementia following Alzheimer's disease (AD). In contrast to AD, VaD encompasses a variety of conditions and dementia mechanisms including multiple and strategic infarcts, widespread white matter lesions and hemorrhages. The diagnosis of VaD is based on the patient history, the clinical evaluation and neuroimaging. Treatment of VaD should account for the underlying vascular condition and is directed towards the control of vascular risk factors and stroke prevention. The need for early diagnosis and preventive treatment has promoted the concept of vascular cognitive impairment (VCI). Harmonization standards for the description and study of VCI have recently been published. A common and distinct subtype of VaD is subcortical ischemic vascular dementia (SIVD) which is related to cerebral small vessel disease. SIVD is clinically characterized by impairment of executive functions and processing speed with relatively preserved memory. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a genetic variant of SIVD, represents an important differential diagnosis and may serve as a model of SIVD.

Vascular and biochemical risk factors of vascular dementia after lacunar strokes (S-VaD) and after multiinfarcts in strategic areas (M-VaD).

Vascular cognitive impairment is an important cause of cognitive decline in the elderly. Ischemic lesions in the brain have an influence on the natural history of dementia. Vascular dementia can be caused by small-vessels disease (S-VaD) or by large-artery atherosclerosis with vascular lesions in strategic areas of the brain (M-VaD). In both cases changes in white matter are observed. In 60 patients with S-VaD and in 34 with M-VaD the presence of vascular and biochemical risk factors was evaluated and compared to age and sex matched 126 controls without dementia. Coronary artery disease, atrial fibrillation, hypertension and strokes were observed more frequently in both investigated groups. Of biochemical risk factors, hyperhomocysteinemia (associated with low levels of folic acid and vitamin B 12) and low HDL cholesterol levels were found in both forms of VaD.

Stroke and multi-infarct dementia as presenting symptoms of giant cell arteritis: report of 7 cases and review of the literature.

Cerebrovascular accidents (CVAs) and multi-infarct dementia have rarely been reported as presenting symptoms of giant cell arteritis (GCA), although 3%-4% of patients with GCA may present with CVAs during the course of the disease. We describe 7 patients with biopsy-proven GCA who presented with stroke or multi-infarct dementia. Most of them had other symptoms of GCA when the disease began that were misdiagnosed or not noticed. The internal carotid arteries were involved in 4 patients and the vertebrobasilar arteries in 3, with bilateral vertebral artery occlusion in 1. Small cerebral infarction foci on cranial computed tomography (CT) scan and magnetic resonance imaging (MRI) were found in 5 cases, and cerebellar infarction, in 2. MR angiography showed intracranial arteritis in 4 cases. Treatment with glucocorticoids and adjunctive antiplatelet or anticoagulant therapy was given in all cases, with neurologic improvement in 5. Two patients died. Necropsy demonstrated generalized GCA involving the medium and small cerebral vessels in 1 case. Central nervous system involvement is a rare complication in GCA but is important to recognize, as it can be reversible if diagnosed and treated promptly. Suspicion should arise in elderly patients suffering from strokes with a quickly progressing stepwise course and associated headache, fever, or inflammatory syndrome. In these cases, temporal artery biopsy should be performed without delay. Early diagnosis of GCA and immediate initiation of corticosteroid treatment may prevent progressive deterioration and death. Additional antiplatelet or anticoagulant therapy should be evaluated according to the individual risk and benefit to the patient under care.

Autosomal dominant leukoencephalopathy with mild clinical symptoms due to cerebrovascular dysfunctions: a new disease entity?

A family with cerebrovascular dysfunctions and extensive white matter lesions was presented. The proband had suffered migraine. His brother showed syncopal episodes and migraine. His mother also suffered severe migraine with aura, and had transient hemiparesis during pregnancy. Their brain MRIs, being quite similar to each other, revealed diffuse bilateral deep white matter lesions, with no changes in serial follow-up. His grandmother showed similar white matter changes on CT, consistent with autosomal dominant inheritance. Lesions were considered to be due to chronic vasogenic edema based upon increased apparent diffusion coefficient (ADC) values on diffusion-weighted imaging, normal spectrum ratio of metabolites on (1)H MR spectroscopy, and decreased regional cerebral blood flows on single-photon emission CT (SPECT). A deficiency of genetically determined factors contributing to the autoregulation of small blood vessels might possibly lead to both clinical symptoms and white matter lesions through the breakdown of the blood-brain barrier and resultant vasogenic edema. Although cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) was suspected, neither NOTCH3 mutation nor granular osmiphilic material (GOM) in the arteriole walls were detected. Further accumulation of similar cases is necessary to establish the possibility of a new familial leukoencephalopathy.

Pathophysiology and classification of stroke.

There are a wide variety of causes of stroke and as many different forms of presentation, depending on the area of the brain affected. This article describes how different types of stroke present and outlines the likely outcome for patients for each type.

Vascular dementia: potential of antiplatelet agents in prevention.

The term 'vascular dementia' (VaD) corresponds to a clinicoradiological syndrome that can be defined with more or less restriction. VaD can result from: (1) cortical or subcortical ischemic lesions related to the occlusion of large vessels, (2) lacunar infarcts with or without white-matter lesions at the subcortical level related to small-vessel diseases, (3) ischemic lesions related to hypoperfusion or anoxic-ischemic encephalopathy or (4) hemorrhagic lesions. The prevention of VaD is based on stroke prevention which implies risk factor manipulation and use of antithrombotic drugs among which the most widely used are antiplatelet drugs. The efficiency of these drugs to prevent cognitive impairment and dementia is not proven. Prospective studies are needed to investigate their potential in patients at risk of VaD: after ischemic stroke, in the presence of cognitive impairment of vascular origin or when MRI shows 'silent' ischemic white-matter lesions and/or infarcts.

White matter lesion progression: a surrogate endpoint for trials in cerebral small-vessel disease.

There is neuropathologic evidence that confluent MRI white matter lesions in the elderly reflect ischemic brain damage due to microangiopathy. The authors hypothesize that measuring changes in the progression of white matter lesions as shown by MRI may provide a surrogate marker in clinical trials on cerebral small-vessel disease in which the currently used primary outcomes are cognitive impairment and dementia. This hypothesis is based on evidence that confluent white matter lesions progress rapidly as shown in a recent follow-up study in community-dwelling subjects. The mean increase in lesion volume was 5.2 cm(3) after 3 years. Based on these data in a clinical trial, 195 subjects with confluent lesions would be required per treatment arm to demonstrate a 20% reduction in the rate of disease progression over a 3-year period. Like any other MRI metric, the change in white matter lesion volume cannot be considered preferable to clinical outcomes unless it has been demonstrated that it matters to the patient in terms of function.

Notch signaling in development and disease.

Notch receptors and ligands were first identified in flies and worms, where they were shown to regulate cell proliferation, cell differentiation, and, in particular, binary cell fate decisions in a variety of developmental contexts. The first mammalian Notch homolog was discovered to be a partner in a chromosomal translocation in a subset of human T-cell leukemias. Subsequent studies in mice and humans have shown that Notch signaling plays essential roles at multiple stages of hematopoiesis, and also regulates the development or homeostasis of cells in many tissues and organs. Thus, it is not surprising that mutations which disrupt Notch signaling cause a wide range of cancers and developmental disorders. Perhaps because it is so widely used, Notch signaling is subject to many unusual forms of regulation. In this review, we will first outline key aspects of Notch signaling and its regulation by endocytosis, glycosylation, and ubiquitination. We will then overview recent literature elucidating how Notch regulates cell-lineage decisions in a variety of developmental contexts. Finally, we will describe the roles of dysregulated Notch signaling in causing several types of cancer and other pathologies.