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Biomedical subjects

M Poncet

Publications and source records attributed to M Poncet.

At least 73 records · Page 4Linked to original sources
PubMed1993

MRI exploration of the intrapetrous facial nerve.

We report our experience of intrapetrous facial nerve evaluation in 33 patients examined by three-dimensional MRI (3D-FT) with intravenous gadolinium injection. The examinations were performed by a 1 Tesla magnet, using Flash and Turbo-Flash sequences which enabled us to obtain contiguous millimetric sections and to make reconstructions in all planes. Among these 33 patients, 31 had facial palsy and 2 a facial nerve lesion without clinical signs and discovered by chance. Facial palsy had started rather abruptly in 26 cases. It was either idiopathic (n = 20) or caused by herpes zoster (n = 1), injuries (n = 2), metastasis (n = 1) and tumour (n = 1); it was concomitant with a granuloma in 1 case. Five patients seen or explored late had congenital cholesteatoma (n = 2), facial nerve neurinoma (n = 2) or persistent idiopathic facial palsy (n = 1). There was no contrast enhancement in "chronic" non tumoral facial palsy. All tumours (neurinoma, neurofibroma, metastasis) were contrast-enhanced, as were the 2 cases of traumatic palsy and the case with granuloma of the labyrinth. In acute idiopathic facial palsy (n = 20), contrast enhancement was demonstrated in 11 patients; among these, recovery was complete at 2 months in 1 case and incomplete in 9 cases; 1 patient was lost sight of. In the 9 patients without contrast enhancement, recovery was complete in 7; 2 patients were lost sight of. This study shows that minute lesions of the facial nerve can be detected with millimetric MRI T1-weighted sequences and contrast enhancement. It also suggests that contrast enhancement has some prognostic value in patients with acute idiopathic facial palsy.

Acute Disease↗
PubMed1992

Perception of optical flow in cortical blindness: a case report.

Motion perception was studied in a subject with bilateral lesion of the visual cortex, involving severe damage to cortical areas V1 and V4, but with no apparent damage to visual associative areas situated in occipito-parietal and lateral occipito-temporal (presumably V5) zones. He was able to perceive optical flow motions simulating motion in depth in "blind" parts of his visual field, provided that the stimulus-onset was temporally dissociated from its motion. Moreover, he was able to discriminate between different velocities and directions of motion. The results suggest that perimetrically "blind" parts of the visual field in this patient have true capacities to process visual motion. They are discussed in reference to the subject's ability to move freely in his environment and in reference to the role of extrastriate visual pathways in visual motion processing.

Acceleration↗
PubMed1992

[Interhemispheric transfer in multiple sclerosis. Morphofunctional correlations].

Signs of cerebral disconnection, especially left ear suppression to dichotically presented verbal stimuli, have been reported in multiple sclerosis patients and found to be correlated to morphological atrophy of the corpus callosum on magnetic resonance imaging. To reinvestigate this issue, 26 patients satisfying criteria for definite multiple sclerosis were proposed 3 tasks aimed at evaluating interhemispheric function: a dichotic listening task, a motor finger-tapping task and a sensory transfer task. Performance at these tasks suggested impaired callosal function in MS patients, compared to normal controls. Callosal morphology was assessed on midsagittal MRI sections using a digitalised method of partition of the callosal area into 6 subregions and automatized surface measurements. Results of correlations between task performance and callosal areas showed a significant correlation between total callosal atrophy and severity of interhemispheric impairment on each functional task. Moreover, impaired motor transfer was specifically related to atrophy of the anterior callosal regions. These results suggest that MS patients may constitute a suitable population to studying interhemispheric transfer of information through the callosal commissure and that this approach may be useful in the clinical management of MS patients.

Adolescent↗
PubMed1992

[Ambulatory autonomy and visual motion perception in a case of almost total cortical blindness].

A 37-year-old man experienced cortical blindness following a bilateral stroke in the territory of the posterior cerebral arteries. Four years later, the measurement of visual field defects (Goldmann perimeter) showed persistence of bilateral blindness with a 2-degree preservation of macular vision and a perifoveal sparing between 10 to 30 degrees of eccentricity in the left inferior quadrant. Despite this visual impairment, the subject was able to perform visually-guided locomotion. Moreover he consciously perceived visual motion in the blind parts of his visual field. CT and MRI showed a lesion involving most of the striated cortex. The visual cortex located in the internal occipito-parital regions was relatively spared. The contribution of this structure to extra-striated vision of motion is discussed.

Adult↗
PubMed1991

[The frontiers of aphasia].

Brain lesions located outside the language area may be associated with non-aphasic disorders of language. The difficulties encountered by these patients concern one or several of the following levels: incitement to communicate, initiation and maintenance of verbal activity, internal organization and adequation of the discourse to the context, mastery of the lexico-semantic code. In every case, the elementary aspects of language are untouched, but verbal communication is severely perturbed.

Aphasia↗
PubMed1991

Processing and statistical analysis of laser Doppler data applied to the assessment of systemic anti-inflammatory drugs.

Continuous laser Doppler measurements of methyl nicotinate-induced skin inflammation have been used to evaluate the activities of three oral non-steroidal anti-inflammatory drugs, indomethacin 50 mg (Indocid), tiaprofenic acid 100 mg (Surgam) and sodium acetylsalicylate 1 g (Catalgine). They were compared in a single-blind, randomized, intra-individual comparison (N = 16) versus placebo (lactose). One hour after each drug was ingested, four concentrations of methyl nicotinate were applied to the subject's forearms. Simultaneous skin blood flow (SBF) measurements were then carried out on the four tested zones, by use of four calibrated laser Doppler flowmeters. Computerized processing of recorded SBF levels provided data related to flow amplitude, kinetics and magnitude (area under the curve) of the reactions. A detailed statistical analysis was performed to establish the selectivity of this type of test and the following points were demonstrated: adjustment of SBF data to baseline did not improve precision, data had to be log-transformed before analysis, and magnitude data gave the best product discrimination. Under the conditions of this study, i.e. one hour after oral administration and for the indicated doses, the tested products could be classified, in terms of anti-inflammatory activity, as follows: Lactose less than Indomethacin 50 mg = Tiaprofenic acid 100 mg less than Sodium acetylsalicylate 1 g.

Adult↗
PubMed1991

The role of sensorimotor experience in object recognition. A case of multimodal agnosia.

Object recognition was studied in a 19-yr-old male patient who presented severe multimodal amnesia and agnosia without significant intellectual, linguistic or perceptual deficits. Bilateral temporal lobe lesions involved medial, polar and anterior infero-temporal structures. Although visual recognition was impaired to various extents for all categories of objects, preservation of certain capacities were demonstrated. In particular, the patient was able to determine specifically how to manipulate certain objects, in spite of his incapacity to define their function or their context of utilization. It is argued that object recognition involves different processing modes such that when direct access to representations of an object is impaired, sensorimotor information activated via alternative cortical and subcortical pathways may provide a limited mechanism for recognition.

Adult↗
PubMed1991

Quantification of skin-colour changes induced by topical corticosteroid preparations using the Minolta Chroma Meter.

The Minolta tri-stimulus colorimeter CR-200 was used to quantify the blanching effect of topical corticosteroids in a non-occluded vasoconstriction test. To investigate the influence of time on variations in colorimetric parameters, an initial series of measurements was performed on Day 1 on six predetermined sites on the ventral surface of the forearm of six healthy volunteers every 2 h over a 12-h period. The colorimetric values were shown to be site related but hourly variations occurred with similar profiles for all the sites. On Day 2, four topical corticosteroid creams, representative of their potency groups, as well as a base were applied in a randomized double-blind manner on five of the predetermined sites. Visual gradings and colorimetric measurements were carried out every 2 h over the following 12-h diurnal period and were continued on Day 3. The colorimetric parameters L* (luminance) and a* (colour hue ranging from green(-) to red(+] gave a rank order correlated to corticosteroid potency that showed superior discrimination compared to simple visual grading. In this study, L* was more discriminative parameter than a*. The Minolta Chroma Meter CR-200 appears to be a simple and accurate device for objectively measuring the blanching effects of topical corticosteroids.

Administration, Topical↗
PubMed1991

Magnetic resonance imaging in gangliogliomas and gangliocytomas of the nervous system.

Gangliogliomas and gangliocytomas are rare and benign neuronal tumors which affect young subjects. This study concerns 3 cases of ganglioglioma and 3 cases of gangliocytoma explored by CT and MRI and confirmed by pathological examination. The most typical CT image was that of an often calcified contrast-enhanced cystic tumor. At MRI, each tumor emitted a low-intensity signal on T1-weighted sequences and a high-intensity signal on T2-weighted sequences. Contrast enhancement after gadolinium injection was frequent. Neuroradiology is not specific, and these tumors are usually diagnosed at pathology. However, the diagnosis may be considered in young patients with a history of old, drug-resistant partial epilepsy and having a contrast-enhanced, calcified cystic lesion in the temporal lobe or the cerebellum.

Adolescent↗
PubMed1991

[Changes in personality and hypertension. The "athymhormic" syndrome].

In 3 hypertensive patients, aged 57 to 66, profound behavioral and personality changes occurred rather abruptly, characterized by total loss of spontaneous activity and initiative, apathetic behavior, passivity, lack of drive and motivation, loss of interest for any of previous occupations and hobbies, and total flatness of affect. Neurological examination was normal or only showed mild extra-pyramidal signs. Neuropsychological evaluation was only remarkable for mild intellectual impairment suggestive of frontal lobe dysfunction. None of the 3 patients fulfilled criteria for dementia or severe depression. This neurobehavioral syndrome has been coined "athymhormic syndrome" (Habib & Poncet, 1988), a term emphasizing the specific defect in drive ("horme") and affect ("thumos"). Electrical and clinical heart examination was unremarkable. Blood pressure was always found within normal limits during hospitalization, including 24-hour monitoring in one case. However, all patients were known as hypertensive in the past, with repeated bouts of high blood pressure (up to 270 mmHg systolic in one case). X-ray CT-scan was usually normal or showed non-specific white matter changes (so-called "leukoaraiosis"). In all 3 cases, a brain MRI scan showed multiple small infarcts mainly involving deep subcortical structures (caudate nuclei and/or adjacent periventricular white matter) of both hemispheres, consistent with the definition of lacunes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

From covert to overt recognition of faces in a prosopagnosic patient.

Prosopagnosia is an inability to recognize known persons as a result of a failure to access relevant memories through the inspection of their faces. The nature of this disturbance, and the fate of memories related to faces, were investigated in a long-standing prosopagnosic woman (P.V.). An examination of P.V.'s perceptual capacities indicated no major impairment at matching faces, including different views of the same faces, and multidimensional scaling analysis showed that she could achieve configurational representations of faces as do normal subjects. In spite of her inability to evoke memories of known persons from their faces, P.V. displayed clear evidence that she could use pertinent memories related to these faces in tasks that did not explicitly call for their evocation. This covert recognition of faces was observed in perceptual learning and cued-recognized faces, attempts were made at surmounting the blocked activation of pertinent memories. Some of these attempts were successful in inducing P.V. into experiencing a sense of familiarity with the faces and identifying them, and this was the first occurrence of overt face recognition by P.V. since the onset of her illness. These findings provide clarification of the nature of the prosopagnosic disturbance and new information about the processes by which faces are recognized. They suggest that (1) prosopagnosia may result from a breakdown at different levels of face-recognition processes, (2) prosopagnosia may occur in spite of normal configurational encoding of facial representations, (3) covert recognition of overtly unrecognized faces requires the integrity of perceptual processes, and (4) failure of overt face recognition reflects a disturbance in the normal interactions between pertinent memories and facial representations which thus remain meaningless.

Agnosia↗
PubMed1990

Objective assessment of topical corticosteroids and non-steroidal anti-inflammatory drugs in methyl-nicotinate-induced skin inflammation.

The aim of this study was to compare the activities of the two main classes of topical anti-inflammatory drugs in methyl-nicotinate-induced skin inflammation, using a new methodology based on laser-Doppler velocimetry. Six topical non-steroidal anti-inflammatory drugs (NSAIDs) (bufexamac, diclofenac, ibuprofen, indomethacin, phenylbutazone and niflumic acid) and three topical corticosteroids (clobetasol propionate, hydrocortisone and hydrocortisone butyrate) were tested. Drugs were commercially available (except indomethacin) and were applied under occlusion for 4 h to the forearms of 16 healthy male volunteers. Thirty minutes after excess drug removal, skin inflammation was induced by a 1-min application of methyl nicotinate (3 mM). This was repeated 44 h later. Each methyl-nicotinate application was followed by continuous skin blood flow recordings over 1 h. Overall, NSAIDs proved more effective than corticosteroids in inhibiting methyl-nicotinate-induced increases in skin blood flow. Diclofenac and indomethacin showed a potent prolonged inhibitory effect. Different types of activity were observed in the corticosteroid group: (a) At 30 min, hydrocortisone and hydrocortisone butyrate moderately inhibited methyl-nicotinate reactions whereas clobetasol propionate produced no detectable effects; (b) at 44 h, clobetasol propionate produced a significant inhibition whereas hydrocortisone butyrate and hydrocortisone exhibited either weak or no inhibitory action at all. These pharmacodynamic discrepancies between the corticosteroids tested could be related to differences in drug affinity to cutaneous receptors and in vasoconstrictive potency.

Adult↗
PubMed1990

Objective assessment of topical anti-inflammatory drug activity on experimentally induced nickel contact dermatitis: comparison between visual scoring, colorimetry, laser Doppler velocimetry and transepidermal water loss.

Four topical anti-inflammatory drugs were investigated for their effect on allergic contact dermatitis. Nickel dermatitis was chosen for its high incidence in European healthy volunteers. Experimental lesions were treated twice daily with two steroids, two non-steroidal anti-inflammatory drugs and a blank base for 4.5 days without occlusion. The influence of treatments was assessed by daily visual grading and one site was left untreated for comparison over the same period. To quantify drug activities objectively, skin colour (colorimetry), skin blood flow (laser Doppler velocimetry) and transepidermal water loss (evaporimetry) were measured before drugs were first applied, then 6 hr after the last application. As expected, only Dermoval cream significantly improved the spontaneous clinical evolution in comparison with the other creams (Hydrocortisone Aster à 1%. Parfenac, indomethacin 2.5% and Skinbase) and the untreated site. Colorimetric parameter a* (redness) and L* (luminance) showed more differences between treatments than the other criteria and a close relationship was obtained between these two parameters and skin blood flow, all three being highly correlated to visual grading. Transepidermal water loss appeared less related to clinical improvement but this parameter could prove helpful for detecting compounds which could be irritant to diseased skin.

Administration, Topical↗
PubMed1990

[Callosal disconnection syndrome caused by left hemisphere infarction].

A 49-year old right-handed taxi-driver experienced right upper limb weakness and global aphasia following internal carotid artery occlusion. Five months later, aphasia and hemiparesis had resolved but he complained of difficulties in his daily activities, termed "inner conflict". Specific testings disclosed typical features of a callosal syndrome: left unilateral ideomotor apraxia, left hand agraphia, left tactile dysnomia, right hand constructional difficulties, and left ear extinction on dichotic listening. Naming and recognition of tachistoscopically presented images or words was similar to that of classical split-brain studies. MRI showed a left-hemisphere periventricular increased signal involving the callosal outflow of the whole posterior half of the corpus callosum and partially destroying the splenium. Fibers from the anterior half of the body and the genu were spared. According to clinical and MRI findings in this case and other documented cases of callosal syndrome, localization of callosal transfer of various hemisphere functions is discussed. The relevance of callosal symptoms to the diagnosis of watershed infarcts is emphasized.

Agraphia↗
PubMed1989

[Subcortical dementia syndrome: semiology and physiopathology].

Among the dementia syndromes--that is, disorders of memory associated with a global alteration of cognitive functions sufficient to affect the subject's normal social behaviour--the current trend is to individualize a particular syndrome due to a primary dysfunction of the subcortical structures. The main characteristics of this syndrome are a slowing down of cognitive processes (bradyphrenia), a preferential disturbance of the fundamental processes (memory, motivation, attention, etc.) and a relative preservation of specific functions (speech, praxis, gnosis). Such a syndrome has been described not only in some cases of degeneration of the basal ganglia, but also in other brain diseases, notably vascular diseases, and in severe depressive states. Various recent clinical or fundamental studies have shed some light on the neuronal and neurochemical substrate of the syndrome, thus providing proof of the reality of the subcortical dementia concept which contributes to a better understanding of the relationship between brain and mental functions.

Aged↗