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Biomedical subjects

B Lechevalier

Publications and source records attributed to B Lechevalier.

At least 19 recordsLinked to original sources
PubMed1996

Agraphia in Alzheimer's disease: an independent lexical impairment.

This study was conducted to delineate the pattern of the writing impairments in 12 patients with Alzheimer type dementia. The patients performed writing tasks involving regular and irregular words and nonwords given by dictation as well as a decision test composed of printed words and pictures requiring phonologic, lexical, and semantic processing. Writing from dictation demonstrated a predominant, but nonisolated, lexical deficit. In order to better evaluate this lexical disorder, the correlation between the dictation writing scores and the decision task scores was analyzed. No significant correlation was found among scores for irregular words, phonologically plausible errors, and scores of the lexical or semantic decision tasks, but there was a significant correlation among scores for the nonwords, nonphonological spelling errors, and scores of the phonologic decision task using printed words. These results would suggest that the "lexical" deficit in agraphia, i.e., difficulty in retrieval or loss of the spelling representations of words, is independent of the lexical or semantic capacities involved in other modalities.

Aged↗
PubMed1996

Memory disorders in Alzheimer's disease and the organization of human memory.

The Squire and Zola-Morgan parallel organization model of the memory and the Tulving hierarchical model were developed mainly through the study of amnesic patients. The predictions of these two models are different, the first being more open to double dissociations and less restrictive than the second. Alzheimer's Disease is characterized by a differential impairment of the memory systems and by an interindividual variability which may take the form of dissociations between preserved and disturbed abilities in some patients. The objective of this study was to use the memory dysfunctions of patients with AD to test the validity of the two models. Analysis of the group data provided an average profile of memory disturbance consistent both with much of the data given in AD literature and with the two models. Using a multiple single-case strategy, we demonstrated several simple dissociations which are for the greater part compatible with the two models. Two of the dissociations underline the limits of the Tulving model, which otherwise accounts for a lot of results. The study supports the relevance of AD for the understanding of the cognitive architecture of the human memory.

Aged↗
PubMed1996

[Akinetic mutism with right hemiplegia caused by infarction in the territory of the left anterior cerebral artery].

A 65 years old woman with chronic high blood pressure and diabetes mellitus presented with a mutism akinetic of sudden onset and a right total hemiplegia with a Babinski sign secondary to a left anterior cerebral artery infarction. She had had six months earlier a transient gait disturbance. At that time, the CT scan showed lacunar infarcts of the head of both caudate nuclei. Neuropathological examination revealed that the left infarction of the anterior cerebral artery involved the superior frontal gyrus, the supplementary motor area, the cingulate gyrus and the corpus callosum. There were also multiple lacunes of the head of both caudate nuclei, anterior limb of the internal capsules, white matter, basal ganglia and thalami. The mutism akinetic was thought to be the result of a bilateral disruption of a functional loop including on each side, the supplementary motor area, the cingulate gyrus, the subcallosal tract and the head of the caudate nucleus. On the right side, the lesion of the caudate nucleus could have interrupted this loop normally involved in the induction of voluntary movements and in the communication with the external surroundings.

Aged↗
PubMed1995

[Celiac disease in adults revealed by sensory-motor neuropathy].

Central or peripheral nervous system complications are occasionally observed in adult patients with celiac disease. Several mechanisms have been proposed including vitamin deficiency, vascular inflammation and a direct effect of gluten intolerance. Typical nerve fiber damage due to demyelinization has been suggested. We observed a 65-year old woman with a right peroneal nerve palsy superimposed on a diffuse peripheral neuropathy who was found to have folic acid deficiency which in turn led to the diagnosis of adult celiac disease. Electrophysiological and histological studies demonstrated a predominantly demyelinating peripheral neuropathy which responded first to parenteral folic acid supplementation and second to a gluten-free diet. The mechanisms of peripheral nerve damage in adult celiac disease are briefly discussed and the possible role of folic acid deficiency is emphasized.

Aged↗
PubMed1995

[Diagnosis of vascular dementia].

Vascular dementia is most often the result of multiple lesions affecting deep brain structures and the white matter. Diagnosis sometimes appears much simpler than it really is. Indeed, it is difficult to evaluate the impairment of higher brain functions and even to affirm dementia. Although the definition of dementia is simple theoretically, in clinical practice it is sometimes particularly difficult to assess when neurological impairments cause a socio-professional handicap. Two pitfalls should be avoided. First, a patient with signs of mental deficiency and a vascular lesion of brain vessels so easily identified by CT scan or MRI does not necessarily have vascular dementia. Secondly and inversely, dementia could be missed in a patient with a physical handicap whose defective mental functions go unnoticed both by his family and physician. Unlike Alzheimer's disease where neuropsychological problems predominate because these patients retain good physical autonomy for a long time, patients with vascular dementia are not explored routinely for neuropsychological disorders which may be hidden by more obvious neurological symptoms. Such disorders, especially gait disorders, are however the key to diagnosis. Mixed dementia is a third pitfall. This concept is based on histological findings and should not be used as a "catch-all" category. During the patient's lifetime diagnosis is probably impossible; current clinical scales do not take it into consideration.

Dementia, Vascular↗
PubMed1995

Cytoplasmic body myopathy: familial cases with accumulation of desmin and dystrophin. An immunohistochemical, immunoelectron microscopic and biochemical study.

Muscle biopsy samples from five patients with cytoplasmic body myopathy (CBM) were investigated by immunohistochemical (antibodies to desmin, actin, dystrophin, spectrin, alpha actinin and utrophin), immunoelectron microscopic (antibodies to desmin, actin and dystrophin) and biochemical (desmin, dystrophin, actin and utrophin western blots) methods. Using immunofluorescence it was shown that the centers of cytoplasmic bodies (CB) were stained by anti-actin, anti-utrophin and three different anti-dystrophin antibodies. The peripheries were labeled by the anti-desmin antibody. Moreover, fibers containing CB showed a markedly increased staining of their entire sarcoplasm with the anti-desmin antibody. Using immunoelectron microscopy it was shown that anti-dystrophin antibodies selectively stained the external limit of the central granular region. Anti-desmin antibody labeled the filamentous halo, and anti-actin antibody stained the central core and the radiating filaments. Biochemical studies showed storage of desmin and dystrophin, both of normal molecular weight. Our results suggest that CBM should be considered along with a wider group of intermediate filament pathologies that include desmin-storage myopathies.

Antibodies↗
PubMed1995

PET imaging of neocortical monoaminergic terminals in Parkinson's disease.

Post-mortem neurochemical studies in Parkinson's disease (PD) have shown that, in addition to the typical nigro-striatal dopamine denervation, there exists a concomitant neocortical monoamine fibre deafferentation (of variable severity) whose role in motor, and especially in associated cognitive and affective impairment, remains elusive. We have extensively examined whether PET imaging with 11C-S-Nomifensine (11C-NMF), a radioligand of the dopamine and norepinephrine presynaptic reuptake sites which has been used so far to investigate the striatum, could provide a method for assessing in vivo the neocortical monoamine terminal loss in PD; previously, this has been a little addressed and controversial issue. To this end, we prospectively selected a highly homogeneous sample of nine non-demented, non-depressed idiopathic PD patients with mild to marked side-to-side asymmetry in motor impairment. In addition to recovering the previously-reported correlations with putaminal 11C-NMF specific uptake asymmetries, the clinical motor asymmetries also significantly correlated in the clinically expected direction to neocortical (especially frontal) 11C-NMF asymmetries, suggesting the monoamine neocortical denervation might play a direct role in motor impairment in PD. These results demonstrate that it is possible to assess in vivo the neocortical monoamine terminal loss, and to elucidate its potential role in the complex cognitive and affective impairment, in both PD and atypical degenerative parkinsonism.

Aged↗
PubMed1995

Topographic EEG activations during timbre and pitch discrimination tasks using musical sounds.

Successive auditory stimulation sequences were presented binaurally to 18 young normal volunteers. Five conditions were investigated: two reference tasks, assumed to involve passive listening to couples of musical sounds, and three discrimination tasks, one dealing with pitch, and two with timbre (either with or without the attack). A symmetrical montage of 16 EEG channels was recorded for each subject across the different conditions. Two quantitative parameters of EEG activity were compared among the different sequences within five distinct frequency bands. As compared to a rest (no stimulation) condition, both passive listening conditions led to changes in primary auditory cortex areas. Both discrimination tasks for pitch and timbre led to right hemisphere EEG changes, organized in two poles: an anterior one and a posterior one. After discussing the electrophysiological aspects of this work, these results are interpreted in terms of a network including the right temporal neocortex and the right frontal lobe to maintain the acoustical information in an auditory working memory necessary to carry out the discrimination task.

Adolescent↗
PubMed1995

Healthy aging, memory subsystems and regional cerebral oxygen consumption.

The present study was designed to search for concomitant age-related changes in memory subsystems, defined according to current structural theories, and resting oxygen consumption in selected brain regions. We have investigated a sample of subjects between 20 and 68 years of age and strictly screened for their good health. We applied in the same subjects a battery of neuropsychological tests selected to investigate several memory subsystems, and high-resolution positron imaging with stereotaxic localization to study a purposely limited number of cerebral structures, selected on a priori hypotheses to match the different memory subsystems. Our results showed significant age-related changes in performance on some tests, consistent with the literature, including an increase in semantic memory and a decrease in both working memory (central executive system) and verbal episodic and explicit memory. There was also an age-related linear decrease in global brain oxygen consumption which regionally reached statistical significance for the neocortical areas and the left thalamus. There was a limited number of significant, age-independent correlations between the raw psychometric test scores and resting regional oxidative metabolism. Consistent with our present understanding of the functional anatomy of memory, the Associate Learning scores (verbal episodic and explicit memory) were positively correlated with left hippocampal and thalamic metabolism. The positive relationships found between right hippocampal metabolism and performance in the Associate Learning and the Brown-Peterson tests were less expected but would be consistent with findings from recent PET activation studies. The results from this investigation are discussed in the light of current knowledge concerning the neuropsychology and the neurobiology of both aging and memory.

Adult↗
PubMed1995

[Myositis ossificans progressiva].

BACKGROUND: Myositis ossificans progressiva is a rare progressive disease of connective tissue with a poor prognosis. CASE REPORT: A 16 year-old girl suffered from lameness of her right leg associated with inguinal swelling. Progressive aggravation of pain with extension of swelling to the posterior part of her thigh required an X-ray examination which showed hip dysplasia and calcifications around the hip. Angiography was normal; a diagnosis of hematoma was suggested by scannography and bone scintigraphy, but biopsy showed features of nodular fasciitis. The association of progressive ectopic ossification to malformation of the big toe led to diagnosis of myositis ossificans progressiva. CONCLUSIONS: Congenital malformations, most commonly of big toes and thumbs, are important for distinguishing myositis ossificans progressiva from other diseases of muscle.

Adolescent↗
PubMed1995

Disorders of auditory identification in dementia of the Alzheimer type.

Fifteen patients with probable DAT and 18 matched controls were given tests that required the identification of verbal (phonemes and words) and non verbal (sounds and melodies) stimuli. In all tests, DAT patients made significantly more errors than controls. Errors predominated in non verbal tests in both groups. DAT patients (and, to a lesser degree, control subjects) made almost exclusively acoustic errors in word-identification, while errors in the identification of sounds and melodies could be either semantic or acoustic. Some categories of errors were observed predominantly in DAT patients. These results suggest that, in addition to their cognitive impairment, DAT patients have a specific deficiency of central auditory perception.

Aged↗
PubMed1995

A PET study of the functional neuroanatomy of writing impairment in Alzheimer's disease. The role of the left supramarginal and left angular gyri.

A dissociation in the central processes of spelling, with preferentially lexical over phonological impairment, frequently affects patients with early Alzheimer's disease. The aim of this work was to test whether dissociations in the language domain in Alzheimer's disease can be exploited with PET to assess the neural basis of cognition. To this end, we studied the functional neuroanatomy of writing impairment in Alzheimer's disease by means of PET measurements of the local cerebral glucose utilization and neuropsychological tests specially designed to assess the phonological and lexical components of writing. We analysed the performance in written spelling of irregular words and non-words of 11 right-handed patients with mild-to-moderate Alzheimer's disease. For each patient, we calculated a residual phonological score and a residual lexical score, based on a cognitive interpretation of the errors according to the item category. In each of these 11 patients, using PET, we measured the resting-state utilization of glucose in the left supramarginal gyrus and the left angular gyrus, two cortical regions selected a priori because of their presumed role in the central processes for spelling, and identified on CT scans obtained according to stereotaxic references and coregistered with PET. To assess the relationships between the neuropsychological scores and the metabolic data, we used the 'ratio paradigm', the sensitivity of which has been previously documented in cognitive-metabolic correlative PET studies of Alzheimer's disease that were less focused than the present study in both cognitive and anatomical terms. We found a highly significant positive correlation between phonological score:lexical score neuropsychological ratios and corresponding supramarginal gyrus:angular gyrus metabolic ratios. These findings further support the role of these two left-sided temporo-parietal regions in the central processes of writing and show that the neuropsychological dissociations in early Alzheimer's diseases can be exploited to further our understanding of the functional neuroanatomy of cognitive operations. The role of focal, as compared with more diffuse, brain damage in the development of impaired written language of central origin in Alzheimer's disease is also discussed.

Aged↗
PubMed1995

[Vascular dementia: clinical and radiological characteristics in 26 cases].

Twenty six patients with vascular dementia were studied. Five of them only, were referred for a cognitive decline and all the others because of focal neurological symptoms or a stroke. Twelve patients had a previous history of stroke and 21 an history of high blood pressure. Twenty three patients had gait disturbances. CT scanner and MRI showed a large proportion (23 patients) of lacunar or small sub-cortical strokes. Leuko-araiosis was present in 21 patients and cortical stroke only in 6. Finally, the lack of information concerning the onset and the course of the cognitive decline in 12 patients explain the difficulties to fulfill the criteria in some diagnostic evaluation scores particularly those of the DSM III R.

Aged↗
PubMed1994

[Multimodal or multisensorial agnosia?].

A 75 year-old right handed woman had persistent right homonymous hemianopia and alexia without agraphia caused by a haemorrhagic stroke of the left occipito-temporal region. Six months later she suffered sudden onset visual and auditory agnosia, following a second haematoma, contralateral to the first one, in the right occipito-temporal region including the lingual and fusiform gyri. None of the disorders concerned semantic representation, so that an asemantic agnosia was excluded. Her performance in naming and recognition tests, in both visual and auditory modalities, demonstrated a wide range of responses and errors. The pattern of visual symptoms suggested "associative visual agnosia narrow sense" (Farah, 1990); auditory agnosia concerned only the non verbal stimuli. These findings were discussed in terms of anatomical mechanisms subserving perceptual, semantical, visuo and auditory-verbal representation. In this case, visual and auditory, agnosia appears to be independent.

Aged↗
PubMed1993

[Extrapulmonary and disseminated pneumocystosis in HIV infection].

Three cases of extrapulmonary disseminated Pneumocystis carinii infection are reported. All 3 patients had HIV infection with less than 50 CD4 lymphocytes per cubic millimeter and were having aerosols of pentamidine as prophylactic treatment of pneumocystosis. P. carinii may invade numerous organs and in particular the liver, spleen and bone marrow. Extrapulmonary lesions, often pan-symptomatic, are to be feared in deeply immunodepressed patients receiving prophylactic aerosols of pentamidine. Infection of the choroid can be detected by systematic ophthalmoscopy. An early diagnosis raises hopes of a good, if temporary, response to treatment.

AIDS-Related Opportunistic Infections↗