Search PubMed⌕ Search

Biomedical subjects

M Poncet

Publications and source records attributed to M Poncet.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Current imaging of vasculo-neural conflicts in the cerebellopontine angle].

UNLABELLED: To demonstrate the high sensitivity of high definition MRI and particularly "Constructive Interference in Steay State" (Ciss) imaging sequence, in depicting neurovascular conflicts in the CP angle cistern, cisternographic imaging and high definition T1 weighed (Turbo flash), contrast enhanced imaging were used to investigate hemifacial spasm (72 patients) and tinnitus with abnormal BER (5 patients). The study was complemented with Angio MR in 25 patients. The results were compared with findings in a control group of 200 patients, and with the surgical observations in 57 operated cases. In hemifacial spasm, the morphology of the neurovascular conflict was determined, as well as the site of compression (lateral medullary fossa 38 cases; nerve 9; both 15 cases), and the vessel involved (VA 25 cases; PICA 16 cases; AICA 10 cases; VA and PICA 8 cases; VA and AICA 3 cases; lateral medullary vein 1 case). In tinnitus (5 cases), the AICA was involved in every case in the IAM. Among 57 operated cases, only one false negative was observed. In the asymptomatic control group, a nerovascular conflict was observed in 3, 5% of the cases only. CONCLUSION: CISS imaging is the single most efficient technique, but the combined used of the 3 types of imaging brings the highest diagnostic efficiency, for identifying a neurovascular conflict in the CPA cistern.

Adult↗
PubMed1995

[Prodromic fit of laughter and prerolandic tumor].

We report a case of "fou rire prodromique" heralding a right hemispheric glioblastoma involving the prerolandic cortex. The clinicoanatomical correlations of this phenomenon are discussed.

Brain Neoplasms↗
PubMed1995

In vivo MR study of brain maturation in normal fetuses.

PURPOSE: To illustrate normal maturation of the fetal brain, including the migrational layer, gray matter, early myelination of internal capsules, optic radiations, and corona radiata. METHODS: Seventy-seven fetal brains, ranging from 21 to 38 weeks of gestational age, were examined with MR in vivo; 33 were considered normal. MR examinations were performed as T1-weighted sequences in the axial, sagittal, and coronal planes. The neuropathologic examination (four cases) and clinical and/or neuroradiologic examinations confirmed the antenatal data. RESULTS: From 21 to 25 weeks, the cerebral ventricles are large, corresponding to the relative fetal hydrocephalus. A slight high signal intensity can be observed in the basal ganglia as early as 21 weeks. In the cerebral hemispheres, a multilayered pattern that can be observed from 23 to 28 weeks includes the cortical ribbon, the germinal matrix, and an intermediate layer corresponding to the migrating glial cells. These findings are probably related to areas of increased cellularity. A high signal intensity can be seen within the dorsal part of the brain stem as early as 23 weeks, within the posterior limb of the internal capsules at 31 weeks, and within the central area of the cerebral hemispheres at 35 weeks. Those patterns are probably caused by the evolving process of myelination. CONCLUSIONS: MR allows depiction of signal changes corresponding either to an increase in cellularity or to the evolving processes of myelination, depending on the stage of the pregnancy.

Brain↗
PubMed1995

[Fahr's disease and mitochondrial myopathy].

The case of a 41 years old man presenting with mitochondrial myopathy associated with calcification of the basal ganglia (Fahr's disease) neurosensorial and endocrine-deficits is reported. These different symptoms could share a common physiopathological process.

Adult↗
PubMed1994

3D-FT MRI of the facial nerve.

Contrast-enhanced 3D-FT MRI of the intrapetrous facial nerve was obtained in 38 patients with facial nerve disease, using a 1.0 T magnet and fast gradient-echo acquisition sequences. Contiguous millimetric sections were obtained, which could be reformatted in any desired plane. Acutely ill patients, were examined within the first 2 months, included: 24 with Bell's palsy and 6 with other acute disorders (Herpes zoster, trauma, neuroma, meningeal metastasis, middle ear granuloma). Six patients investigated more than a year after the onset of symptoms included 3 with congenital cholesteatoma, 2 with neuromas and one with a chronic Bell's palsy. The lesion was found incidentally in two cases (a suspected neurofibroma and a presumed drop metastasis from an astrocytoma). Patients with tumours had nodular, focally-enhancing lesions, except for the leptomeningeal metastasis in which the enhancement was linear. Linear, diffuse contrast enhancement of the facial nerve was found in trauma, and in the patient with a middle ear granuloma. Of the 24 patients with an acute Bell's palsy 15 exhibited linear contrast enhancement of the facial nerve. Three of these were lost to follow-up, but correlation of clinical outcome and contrast enhancement showed that only 4 of the 11 patients who made a complete recovery and all 10 patients with incomplete recovery demonstrated enhancement. Possible explanations for these findings are suggested by pathological data from the literature. 3D-FT imaging of the facial nerve thus yields direct information about the of the nerve condition and defines the morphological abnormalities. It can also demonstrate contrast enhancement which seems to have some prognostic value in acute idiopathic Bell's palsy.

Adolescent↗
PubMed1994

3D-FT thin sections MRI of prolactin-secreting pituitary microadenomas.

We studied 76 patients with endocrinological features of prolactin-secreting microadenoma by MRI, using three dimensional (3D) gradient echo acquisition (FLASH) sequences. MRI revealed a focal signal abnormality in the pituitary in all 37 patients who had not previously taken bromocriptine. However, focal abnormality was shown in only half the patients had been on dopamine agonist therapy; the MRI findings in these 39 patients were not affected by the duration and dosage bromocriptine, nor by the time elapsed since its discontinuation. The microadenoma gave spontaneous high signal on the unenhanced T1-weighted images in 8 cases; it was not seen on unenhanced images in 25 cases. It appeared as low signal within the enhancing gland in 51 cases but enhanced in 7 cases. The 3D technique gives thin (1 mm) slices and therefore facilitates detection of small focal abnormalities in the pituitary gland (2 x 2 mm). In the 19 previously treated patients in whom MRI did not demonstrate a focal abnormality, it showed localised atrophy of the gland in 3, a large, round gland with homogeneous signal in 1, and a heterogeneous appearance in 11; it was normal in 4 cases.

Adolescent↗
PubMed1994

Temporary forced laughter after unilateral strokes.

Forced laughter generally occurs in bilateral or diffuse lesions of the brain and is generally associated with pathologic crying. We report the cases of 3 patients in whom temporary forced laughter occurred after unilateral supratentorial infarction demonstrated by CT scan or MRI. In all cases, the lesion was exclusively subcortical and involved the striatocapsular region. For all patients the laughter occurred during the recovery phase of motor deficit and was 'pure' without associated weeping or other clinical features of pseudobulbar palsy. In all cases, the laughter attacks had become much less frequent or had totally disappeared 1 or 2 months after the stroke. According to a 'motor' hypothesis, a unilateral striatocapsular lesion may lead to temporary deregulation of the expression mechanisms.

Adult↗
PubMed1994

Chronic topical application of all-trans-retinoic acid in man does not affect corneocyte surface area.

The potential therapeutic activity of topically applied novel analogues of retinoic acid is currently measured in many different animal models. In most cases, the technique used is invasive and biopsy specimens are required. Furthermore, efficacy in these models is not a guarantee of success in treatment of humans. Therefore, predictive human pharmacology tests are required in order to quantify a retinoid effect on human skin before conducting large clinical trials. The aim of this study was to determine whether changes in corneocyte surface area could be used as a predictive measure for the efficacy of topical retinoids in man. Topical applications of all-trans retinoic acid gel (Aberel), salicylic acid gel and the gel vehicle were made once daily for 4 weeks to skin of the lumbar region of healthy human volunteers. Corneocytes were recovered from these three treated zones as well as from one zone of untreated skin, and their surface areas were measured by image analysis using a MOP-Videoplan. The results showed that at no point during the 4 weeks of daily application to healthy human skin was there a statistically significant difference in the surface area of corneocytes recovered from Aberel, salicylic acid-, vehicle-treated or untreated sites. No specific effect of retinoic acid could be detected. However, although no between-treatment differences were found, significant cyclical changes in the mean surface areas with respect to baseline were observed.

Administration, Topical↗
PubMed1994

[Percutaneous venoplasty for the implantation of a dual-chamber cardiac pacemaker].

During reoperation for pacemaker implantation, venous catheterisation of the homolateral subclavian vein encountered obstruction at the brachiocephalic vein. Balloon angioplasty of the severe brachiocephalic stenosis was performed via the femoral vein. After repeat subclavian venous catheterisation two new pacing wires could be introduced without difficulty followed by active fixation in the atrium and passive fixation in the ventricular apex. The initial ventricular pacing wire was isolated and respected. The femoral vein approach gave simple and direct access to the site of dilatation at a distance to the operative field which was shielded from an infectious risk. The technique and results of percutaneous venous recanalisation have not been extensively analysed during reoperation for cardiac pacing. In chronic cardiac pacing, the success of homolateral operation despite venous occlusion or stenosis, ensures preservation of the venous capital.

Aged↗
PubMed1994

[Post-traumatic interhemispheric disconnection syndrome].

A left-handed man presented with a partial hemispheric disconnection syndrome of traumatic origin composed by a left hand unilateral agraphia, a left hand tactile anomia, a left visual field anomia, a left visual field alexia and a partial left ear extinction for verbal material. MRI of the brain showed lesion involving the trunk of the corpus callosum.

Adult↗
PubMed1993

[Progressive encephalopathy in antiphospholipid antibody syndrome].

The most frequent neurological complications of antiphospholipid antibodies syndrome (APS) are cerebral infarctions. In cases with recurrent strokes this syndrome may be associated with multi infarct dementia. We report the case of a 40-year old man presenting as "primary" APS with multiple cerebral infarctions. This patient had insidiously and progressively developed a cognitive impairment predominant in memory. The progressive encephalopathy associated with APS is very different from multi infarct dementia and could be caused either by a vascular mechanism (vascular occlusion with fibrin thrombi or disseminated vasculitis) or by an immunological mechanism.

Adult↗
PubMed1993

Functional and magnetic resonance imaging correlates of callosal involvement in multiple sclerosis.

To investigate functional and anatomical features of callosal involvement in multiple sclerosis (MS), performances of 90 patients with definite MS and 25 matched normal control subjects were compared on three tasks exploring interhemispheric transfer of auditory, sensory, and motor information: a verbal dichotic listening task, a crossed tactile finger localization task, and an alternate finger tapping task. Each patient also underwent a magnetic resonance imaging (MRI) scan (1) to appreciate the extent of white-matter changes by a semiquantitative evaluation of hemispheric brain MRI hyperintensities and (2) to measure the degree of total and regional callosal atrophy using an automatized method of partition of the midsagittal callosal area. Interhemispheric transfer and/or integration was impaired in patients with MS for all modalities explored and proportional to both degree of callosal atrophy and diffusion of white-matter lesions. Moreover, in good agreement with data obtained from partial commissurotomy studies, performance on each functional task was predominantly associated with atrophy of one part of the callosum, namely left-ear dichotic suppression with the posterior callosal region, alternate finger tapping with the anterior region, and cross-localization with midanterior and posterior regions. Finally, a subgroup of patients without MRI white-matter hyperintensities also showed significant impairment of callosal function and relative atrophy of the callosum. These findings suggest the potential clinical value of callosal involvement in MS and the usefulness of MS as a model of interhemispheric disconnection.

Adolescent↗
PubMed1993

Unilateral neglect in route description.

Route description was investigated in two patients suffering from left unilateral neglect. Both had evident difficulty with left turns. This finding suggests that the topological correspondence between represented environment and representational mechanisms in the brain is not confined to frozen (picture-like) perspectives.

Aged↗
PubMed1993

The vellus hair follicle in acne: hair growth and sebum excretion.

In this study we investigated the activity of the vellus hair follicle in acne. Hair growth and sebum excretion in vellus hair follicles were measured on the forehead and back of men, and on the forehead, cheek, and back of women with acne. Hair growth was assessed by computerized image analysis (phototrichogram), and sebum excretion by computer analysis using Sebutape. In patients with acne, marked differences were revealed when results were compared with recent data from healthy persons. In particular, the mean growth rate of vellus hairs was higher, whereas the percentage of anagen hairs was lower, and the duration of the anagen phase shorter in patients with acne than in healthy individuals. Hair growth and sebum excretion depended significantly (P < 0.01) on the anatomical site (forehead 414 hairs/cm2, 0.053 mm/day, 34%; back 93 hairs/cm2, 0.16 mm/day, 21%). In addition, analysis of hair growth revealed significantly higher values in females than in males for (i) percentage of anagen hairs (P > 0.01), (ii) for vellus hair length (P < 0.05), and (iii) for the duration of the anagen phase (P < 0.01). The present study demonstrates that the activity of the vellus hair follicle is influenced by acne, and vice versa, and therefore its role in the aetiopathogenesis of acne should be reconsidered.

Acne Vulgaris↗
PubMed1993

Circadian variations in the number of actively secreting sebaceous follicles and androgen circadian rhythms.

Sebum excretion has been shown to demonstrate a circadian rhythm using a gravimetric method (cigarette paper). With the newly introduced method of Sebutape, we confirmed this periodicity and showed that the elevation in sebum excretion is correlated with an increase in the number of secreting follicles. We found, furthermore, that the number of secreting follicles on the forehead showed a distinct and statistically significant circadian rhythmicity, in contrast to those of the chest, which remained almost constant. The quantification in plasma levels of cortisol, melatonin, delta-4-androstenedione, dehydroepiandrosterone sulphate, and free testosterone showed no correlation with sebum excretion at either site. These observations suggest that local factors are involved in control of sebum secretion.

Adult↗
PubMed1993

[Aging and cerebral representation of language].

Some characteristics of acquired aphasias during adulthood--frequency, severity, type of aphasia--would change with aging. In particular, Wernicke's aphasia patients are repeatedly reported to be older than Broca's. Several hypotheses are proposed to account for these age-related changes. One of the explanations puts forward hypothetical changes in the neural substrate with aging. A second hypothesis refers to the involvement of cognitive and behavioral changes occurring in elderly. A third one claims that changes in functional distribution of language in brain (between hemispheres and within left hemisphere) may occur with aging.

Aged↗