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Biomedical subjects

H Chabriat

Publications and source records attributed to H Chabriat.

At least 19 recordsLinked to original sources
PubMed2006

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.

Aged↗
PubMed2006

Clinical correlates of cerebral water diffusion in Wilson disease.

OBJECTIVE: To investigate the course of diffusion changes in Wilson disease (WD) and to evaluate their clinical and radiologic correlates. METHODS: MRI with fluid-attenuated inversion recovery (FLAIR) and diffusion weighted images (DWI) were performed in 13 symptomatic patients with WD who had typical neurologic manifestations of the disease (sWD patients) and in 5 presymptomatic patients (psWD patients). Follow-up clinical and MRI data were obtained in 12/13 patients with sWD. Ten subjects without neurologic disease and with normal cerebral MRI were used as controls. Apparent diffusion coefficient (ADC) was measured in areas where hyperintense lesions were detected on FLAIR images and in the normal-appearing white matter. RESULTS: Hyperintense lesions were detected in all symptomatic patients on FLAIR MR images but only in 11 of 13 patients with sWD on DWI. These lesions were absent in patients with psWD. The mean ADC was found increased in the putamen, pallidum, internal capsule, mesencephalon, and within the white matter in the symptomatic group in comparison to controls. This was not observed in patients with psWD, who even had a decreased ADC in the putamen. A significant correlation was found between the increase in diffusion and the modified Rankin Scale in presence of symptoms. Moreover, the variation of the clinical scale was significantly correlated with the variation of diffusion in the putamen of symptomatic patients. CONCLUSION: A decrease in diffusion in the putamen can be detected before the occurrence of neurologic manifestations in WD. In contrast, a large increase in diffusion is detected after the occurrence of symptoms within the putamen, pallidum, internal capsule, and subcortical white matter parallel to the signal changes as seen on fluid-attenuated inversion recovery and diffusion weighted images.

Adolescent↗
PubMed2006

[CADASIL with minimal symptoms after 60 years].

INTRODUCTION: CADASIL is a hereditary cerebral arteriopathy leading to progressive disability and dementia usually observed at 60 years. OBSERVATION: We report four patients aged>60 years with typical Notch3 mutations leading to CADASIL who did not have dementia or disability. Three of them presented with only transient neurological manifestations. MRI results showed extensive hyperintense signals in the white-matter on T2-weighted images contrasting with very few lacunar infarcts. CONCLUSION: These observations suggest that silent or symptomatic infarcts, which were rare in the present cases may be responsible for the clinical severity in this disorder.

Aged↗
PubMed2006

Kearns Sayre syndrome: an unusual form of mitochondrial diabetes.

Kearns Sayre syndrome (KSS) is a mitochondrial disorder characterized by the emergence before age 20 of progressive external ophthalmoplegia, pigmentary retinopathy, together with other heterogeneous clinical manifestations, including cardiac conduction defects, muscle abnormalities and endocrinopathies. KSS is associated with large heteroplasmic deletions in mitochondrial DNA. We report the case of a 43-year-old woman, with diabetes mellitus as a first manifestation at age 19. Later, she exhibited bilateral ptosis and external ophthalmoplegia with progressive worsening. DNA analysis identified a large mitochondrial DNA (mtDNA) deletion, which confirmed the diagnosis of KSS. By reporting this case with diabetes mellitus as first manifestation, we aim at emphasizing problems of diagnosis in these subtypes of mitochondrial diabetes.

Biopsy↗
PubMed2006

Dilation of Virchow-Robin spaces in CADASIL.

To precise the severity of dilated Virchow-Robin spaces (VRS) in CADASIL patients and to determine their correlation with clinical presentation and other abnormalities on cerebral Magnetic Resonance Imaging (MRI). Dilated VRS were previously associated with aging, hypertension, dementia, epilepsy or migraine. We already reported increased frequency of enlarged VRS in CADASIL patients when compared with family members without the affected haplotype. We analysed clinical and MRI data from 50 CADASIL patients collected prospectively in our center. The presence of dilated VRS was assessed in the subcortical white matter of temporal lobes, the centrum semi-ovale and the basal ganglia. Their severity in each region was evaluated according to the scale proposed by Heier. We compared the clinical data, the severity of white matter abnormalities and the presence of microbleeds in patients with and without dilated VRS. Seventy-eight percent of patients in our series had dilated VRS, mostly located in the lentiform nuclei (94%) and subcortical white matter of the temporal lobes (66%). The severity of these lesions was variable but not correlated neither to the extent of white matter abnormalities nor to the clinical presentation in our patients. Only the age was found to be related to the extent of dilated VRS. Dilated VRS are frequent in CADASIL and mostly located in the temporal white matter and basal ganglia. The dilation of perivascular spaces does not seem to be directly related to the occurrence of ischemic or hemorrhagic lesions in CADASIL. In contrast, the relation with age suggests that either aging, progression of vascular wall alterations during the course of the disease, or both of these processes can favour the extension of VRS in CADASIL.

Adult↗
PubMed2006

EFNS guideline on neuroimaging in acute stroke. Report of an EFNS task force.

Neuroimaging techniques are necessary for the evaluation of stroke, one of the leading causes of death and neurological impairment in developed countries. The multiplicity of techniques available has increased the complexity of decision making for physicians. We performed a comprehensive review of the literature in English for the period 1965-2005 and critically assessed the relevant publications. The members of the panel reviewed and corrected an initial draft, until a consensus was reached on recommendations stratified according to the European Federation of Neurological Societies (EFNS) criteria. Non-contrast computed tomography (CT) scan is the established imaging procedure for the initial evaluation of stroke patients. However, magnetic resonance imaging (MRI) has a higher sensitivity than CT for the demonstration of infarcted or ischemic areas and depicts well acute and chronic intracerebral hemorrhage. Perfusion and diffusion MRI together with MR angiography (MRA) are very helpful for the acute evaluation of patients with ischemic stroke. MRI and MRA are the recommended techniques for screening cerebral aneurysms and for the diagnosis of cerebral venous thrombosis and arterial dissection. For the non-invasive study of extracranial vessels, MRA is less portable and more expensive than ultrasonography but it has higher sensitivity and specificity for carotid stenosis. Transcranial Doppler is very useful for monitoring arterial reperfusion after thrombolysis, for the diagnosis of intracranial stenosis and of right-to-left shunts, and for monitoring vasospasm after subarachnoid hemorrhage. Currently, single photon emission computed tomography and positron emission tomography have a more limited role in the evaluation of the acute stroke patient.

Humans↗
PubMed2006

Cognitive profile in CADASIL.

BACKGROUND: The spectrum of cognitive alterations associated with CADASIL, a model of pure vascular dementia, has not been thoroughly evaluated. OBJECTIVES: The aims of this study were: (i) to describe the cognitive profile in CADASIL patients according to age; (ii) to compare the profile of patients with dementia with that of patients without dementia; and (iii) to determine the association between alterations in performance in different cognitive domains. METHODS: Forty two consecutive individuals with CADASIL (35-73 years old) were investigated. Cognitive skills were analysed in five domains (executive functions, reasoning, attention, memory, visuospatial abilities) according to age and compared between patients with and without dementia. Associations between cognitive performance and stroke were tested. RESULTS: The youngest patients presented with attention (69%), memory (70%), and executive disturbances (100%). Visuospatial abilities and reasoning deteriorated with age, mainly after the age of 60. About one quarter of patients had dementia, and 75% of these were >60 years of age. Age >60 years was associated with a Rankin score >3 and a significant deficit in all cognitive domains. No association was found between dementia and the number of ischaemic attacks. Episodic memory disorder was characterised by difficulties in retrieval rather than impairment of the encoding process. CONCLUSION: Cognitive decline in CADASIL is dominated by early impairment of executive functions. Skills in other cognitive domains deteriorate with age and are found to be diffusely impaired in patients with dementia. The relative preservation of the encoding process in episodic memory impairment, even in individuals with dementia, is noteworthy.

Adult↗
PubMed2005

Intra-arterial thrombus visualized on T2* gradient echo imaging in acute ischemic stroke.

BACKGROUND: MR signal loss related to arterial thrombosis leading to vascular susceptibility artifacts (VSA) has recently been reported on gradient echo images. The time course and sensitivity of VSA in acute stroke patients has been scarcely investigated. The aim of this study was to assess the frequency and course of VSA in acute stroke patients, to compare its sensitivity to distinct features of arterial occlusion as detected on FLAIR images or on CT scan. METHODS: Twenty-nine patients were scanned from 45 min to 6 h after stroke onset using identical MR parameters. All had an acute ischemic lesion identified on diffusion-weighted images, 25 had an occlusion of MCA or PCA confirmed by magnetic resonance angiography. RESULTS: VSA was detected in 22/25 patients having an occluded artery at the time of MRI examination. Flair disclosed a hyperintense vessel in all of these 25 cases, but CT scan revealed a hyperdense artery in only 15 cases. Follow-up studies showed that VSA can vanish or disappear after partial recanalization. When the artery remains occluded, VSA can decrease, disappear or increase in the next hours, possibly related to structural modifications of the thrombus with time. Most occlusions were due to cardiac and arterial emboli or to intracranial extension of carotid occlusion. CONCLUSIONS: VSA are frequent in the first hours of MCA or PCA occlusion in acute stroke patients. The sensitivity of VSA appears lower than the arterial hyperintensity on FLAIR images but higher than the hyperdense artery sign on CT scan. The extent and intensity of VSA can change with recanalization or structural modifications of the thrombus.

Adolescent↗
PubMed2005

Longitudinal thalamic diffusion changes after middle cerebral artery infarcts.

BACKGROUND: Cerebral infarcts are responsible for functional alterations and microscopic tissue damage at distance from the ischaemic area. Such remote effects have been involved in stroke recovery. Thalamic hypometabolism is related to motor recovery in middle cerebral artery (MCA) infarcts but little is known concerning the tissue changes underlying these metabolic changes. Diffusion tensor imaging (DTI) is highly sensitive to microstructural tissue alterations and can be used to quantify in vivo the longitudinal microscopic tissue changes occurring in the thalamus after MCA infarcts in humans. METHODS: Nine patients underwent DTI after an isolated MCA infarct. Mean diffusivity (MD), fractional anisotropy (FA), and thalamic region volume were measured from the first week to the sixth month after stroke onset in these patients and in 10 age matched controls. RESULTS: MD significantly increased in the ipsilateral thalamus between the first and the sixth month (0.766 x 10(-3) mm(2)/s first month; 0.792 x 10(-3) mm(2)/s third month; 0.806 x 10(-3) mm(2)/s sixth month). No significant modification of FA was detected. In six patients, the ipsilateral/contralateral index of MD was higher than the upper limit of the 95% CI calculated in 10 age matched controls. An early decrease of MD preceded the increase of ipsilateral thalamic diffusion in one patient at the first week and in two other patients at the first month. CONCLUSION: After MCA infarcts, an increase in diffusion is observed with DTI in the ipsilateral thalamus later than 1 month after the stroke onset. This is presumably because of the progressive loss of neurons and/or glial cells. In some patients, this increase is preceded by a transient decrease in diffusion possibly related to an early swelling of these cells or to microglial activation. Further studies in larger series are needed to assess the clinical correlates of these findings.

Adult↗
PubMed2004

Vertebrobasilar occlusive disorders presenting as sudden sensorineural hearing loss.

BACKGROUND: Isolated sudden sensorineural hearing loss (SSHL) has been rarely related to vertebrobasilar occlusive disorders (VBOD). This is an important issue for both neurologists and otolaryngologists, since the management and prognosis of this type of hearing loss widely differs from that of hearing loss from other causes. OBJECTIVES: To describe the clinical characteristics and report the incidence of SSHL related to VBOD. METHODS: Retrospective analysis of clinical charts from 333 patients admitted for SSHL in a large ear, nose, and throat emergency tertiary care center from 1999 to 2002. RESULTS: Four cases (1.2%) of VBOD as the unique cause of SSHL were diagnosed among 333 patients. The most typical features of these cases were the presence of one of the following characteristics: (1) bilateral SSHL, (2) associated occipital or posterior nuchal pain, and (3) the occurrence of delayed neurologic deficits. The underlying vascular disease affected the vertebral arteries: dissection in two cases and atherosclerosis in two other cases. The audiometric features of hearing loss were endocochlear in one case, of both types in one case, and unknown in two cases. Hearing recovered partially or completely. CONCLUSIONS: Our results confirm the low incidence of SSHL related to VBOD and show that the observation of endocochlear audiometric features cannot preclude a central cause in SSHL. The clinical presentation of our cases related to VBOD emphasize that a careful follow-up of any patient with SSHL is warranted and that the presence of nuchal pain suggestive of arterial dissection in younger subjects, a past history of atherosclerosis or embolism in older patients, or the occurrence of delayed associated neurologic symptoms should be considered with particular caution in this situation.

Adult↗
PubMed2004

Retinal abnormalities in CADASIL: a retrospective study of 18 patients.

BACKGROUND: CADASIL is an inherited small vessel disease related to Notch3 gene mutations. AIM: To report retinal findings in symptomatic CADASIL patients. METHODS: Assessment of visual acuity (VA), testing of visual fields (VF), funduscopic examination (FE), and fluorescein angiography (FA) were carried out in 18 symptomatic patients. RESULTS: No visual symptoms were presented by our patients. VA was normal in all. Ophthalmologic abnormalities were found in 8 patients. VF were normal except for a right hemianopia in one subject due to ischemic stroke. FE and FA revealed significant abnormalities in seven other subjects (mean age: 55 years; range: 39-74): nerve fibre loss (n = 4), cotton wool spots (n = 3), sheathed arteries (n = 1), and tortuous arteries (n = 1). Only one patient with both tortuous arteries and nerve fibre loss had multiple vascular risk factors, and another patient with cotton wool spots was a current smoker. DISCUSSION: FE and FA revealed silent retinal abnormalities in CADASIL patients with nerve fibre loss in 22% and cotton wool spots in 17%. The presence of these abnormal retinal findings does not seem related to the severity of the disorder but may be considered as peripheral markers of this genetic disease.

Adult↗
PubMed2002

Transient decrease of water diffusion in Wernicke's encephalopathy.

We report water diffusion abnormalities in periventricular areas in a patient with Wernicke's encephalopathy. The reduction in diffusion disappeared after 2 weeks of treatment with intravenous thiamine. We suggest that the restricted mobility of cerebral water is related to inflammatory lesions.

Adult↗
PubMed2001

Skin biopsy immunostaining with a Notch3 monoclonal antibody for CADASIL diagnosis.

CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy) is a small-artery disease of the brain caused by NOTCH3 mutations that lead to an abnormal accumulation of NOTCH3 within the vasculature. We aimed to establish whether immunostaining skin biopsy samples with a monoclonal antibody specific for NOTCH3 could form the basis of a reliable and easy diagnostic test. We compared the sensitivity and specificity of this method in two groups of patients suspected of having CADASIL with complete scanning of mutation-causing exons of NOTCH3 (in a retrospective series of 39 patients) and with limited scanning of four exons that are mutation hotspots (prospective series of 42 patients). In the retrospective series skin biopsy was positive in 21 (96%) of the 22 CADASIL patients examined and negative in all others; in the prospective series, seven of the 42 patients had a positive skin biopsy whereas only four had a mutation detected by limited NOTCH3 scanning. Our immunostaining technique is highly sensitive (96%) and specific (100%) for diagnosis of CADASIL.

Adult↗
PubMed2001

Diffusion tensor imaging: concepts and applications.

The success of diffusion magnetic resonance imaging (MRI) is deeply rooted in the powerful concept that during their random, diffusion-driven displacements molecules probe tissue structure at a microscopic scale well beyond the usual image resolution. As diffusion is truly a three-dimensional process, molecular mobility in tissues may be anisotropic, as in brain white matter. With diffusion tensor imaging (DTI), diffusion anisotropy effects can be fully extracted, characterized, and exploited, providing even more exquisite details on tissue microstructure. The most advanced application is certainly that of fiber tracking in the brain, which, in combination with functional MRI, might open a window on the important issue of connectivity. DTI has also been used to demonstrate subtle abnormalities in a variety of diseases (including stroke, multiple sclerosis, dyslexia, and schizophrenia) and is currently becoming part of many routine clinical protocols. The aim of this article is to review the concepts behind DTI and to present potential applications.

Brain Diseases↗
PubMed2001

Diffusion tensor imaging study of subcortical gray matter in cadasil.

BACKGROUND AND PURPOSE: In cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), water diffusion changes suggestive of microstructural tissue alterations have been recently reported in abnormal- and normal-appearing white matter as seen on T2-weighted images. In the subcortical gray matter, typical lacunar infarcts are repeatedly observed. Whether microstructural tissue changes are also present outside these lesions within the putamen or thalamus remains unknown. METHODS: We used diffusion tensor imaging, an MRI method highly sensitive to cerebral microstructure, in 20 CADASIL patients and 12 controls. Both the trace of the diffusion tensor [Tr(D)] and an anisotropic diffusion index (volume ratio) of diffusion were measured within the putamen and thalamus outside typical lacunar infarcts as detected on both T1- and T2-weighted images. RESULTS: A significant increase in Tr(D) and a decrease in anisotropy were observed in the putamen and thalamus in patients. The right/left indices of Tr(D) in the thalamus, but not in the putamen, were strongly correlated with the corresponding indices calculated in the white matter of the centrum semiovale. In addition, the diffusion increase in the thalamus was positively correlated with Tr(D) and with the load of small deep infarcts within the white matter and negatively correlated with the Mini-Mental State Examination score. CONCLUSIONS: Our results suggest that microstructural tissue alterations are present in the putamen and thalamus, outside the typical lacunar infarcts in CADASIL. In the thalamus, these microstructural changes appear constant and are even observed in asymptomatic subjects. Some of these thalamic changes appear to result from degeneration of thalamocortical pathways secondary to ischemic white matter damage. The importance of this degenerative phenomenon in the pathophysiology of CADASIL requires further investigation.

Analysis of Variance↗
PubMed2000

CACNA1A gene de novo mutation causing hemiplegic migraine, coma, and cerebellar atrophy.

Familial hemiplegic migraine is caused by CACNA1A missense mutations in 50% of families, including all families with cerebellar ataxia. A patient with healthy parents, who experienced prolonged attacks of migraine with hemiplegia, coma, and seizures, is reported. The patient also had mental retardation, permanent cerebellar ataxia with cerebellar atrophy, and right-sided brain atrophy. This patient carried a de novo Tyr 1385 Cys mutation in the CACNA1A gene and illustrates a novel phenotype associated with CACNA1A mutations.

Adult↗