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Biomedical subjects

A Léger

Publications and source records attributed to A Léger.

18 recordsLinked to original sources
PubMed2002

Neural substrates of spoken language rehabilitation in an aphasic patient: an fMRI study.

Little is known about the neural counterparts of speech therapy in aphasic patients. An fMRI experiment was performed before and after a specific and intensive speech output therapy in RC, a patient with long-lasting speech output deficit following a left-sided ischemic lesion. Overt picture naming and picture/word rhyming were used as activation tasks in RC and 6 control subjects. The naming task concerned the output lexicon deficit to be rehabilitated while rhyming referred to preserved levels of processing and was used to control for repetition effect. The speech therapy program improved naming performance. By comparison to the pattern observed before therapy, the naming task after therapy induced a pattern of activation close to that observed in control subjects, involving left-sided language areas surrounding the lesion. Speech therapy effect was associated with activations in Broca's area and the left supra-marginal gyrus, which might reflect a therapy-induced phonological compensatory strategy for naming.

Adult↗
PubMed2000

[(99m)Tc]-sestamibi parathyroid scintigraphy in chronic haemodialysis patients: static and dynamic explorations.

BACKGROUND: The place of parathyroid gland imaging by [(99m)Tc](technetium)-sestamibi scintigraphy in uraemic patients with secondary hyperparathyroidism remains a matter of debate. The purpose of the present study was (i) to assess its value with respect to plasma intact parathyroid hormone (iPTH) levels and to surgical parathyroidectomy (PTx), and (ii) to explore the possibility of suppressing parathyroid [(99m)Tc]-sestamibi uptake by calcitriol. METHODS: In a first cross-sectional, static study 52 chronic haemodialysis (HD) patients with plasma iPTH levels between 14 and 2791 pg/ml (normal, 10-65 pg/ml) had a [(99m)Tc]-sestamibi scan, and 21 of them underwent surgical PTx. In a second longitudinal, dynamic study 14 chronic HD patients with advanced secondary hyperparathyroidism received short-term calcitriol treatment in an attempt to suppress [(99m)Tc]-sestamibi imaging of parathyroid glands. Calcitriol was given intravenously for 2 weeks, 2 microg after each haemodialysis session. Scintigraphy was carried out before and at the end of this inhibition test. RESULTS: [(99m)Tc]-Sestamibi scan led to imaging of one or more (maximum three) parathyroid glands in most, but not all, HD patients with plasma iPTH values >600 pg/ml. Based on surgical findings, overall sensitivity of [(99m)Tc]-sestamibi scan in correctly locating parathyroid glands was only 50%, whereas specificity was 100%. In contrast, its sensitivity was 100% in locating single glands in the subgroup of five patients with recurrent hyperparathyroidism. The calcitriol inhibition test showed suppression of [(99m)Tc]-sestamibi uptake by at least one parathyroid gland in eight patients (57%), with complete suppression in five of them (36%). Basal plasma iPTH or decrease of plasma iPTH in response to calcitriol was not predictive of suppressible [(99m)Tc]-sestamibi uptake in the individual case, although mean iPTH was markedly higher in patients with non-suppressible parathyroid glands. CONCLUSION: Because of its relatively low sensitivity the [(99m)Tc]-sestamibi scan is of limited help in the exploration of uraemic patients with severe secondary hyperparathyroidism before a first surgical PTx. However, it is very useful in locating the remaining parathyroid gland(s) in case of reoperation. The novel calcitriol inhibition test of [(99m)Tc]-sestamibi uptake could help to better distinguish parathyroid glands with non-suppressible, autonomous activity from glands whose activity might be amenable to long-term suppression.

Calcitriol↗
PubMed1999

[Imaging of thyroid nodules].

Ultrasonography and scintigraphy are the first line diagnostic imaging modalities for the evaluation of thyroid nodules. Scintigraphy provides functional informations, mainly detection of hot nodules. US provides accurate morphologic evaluation and it may sometimes suggest malignancy. US is the modality of choice for follow-up of non resected nodules and is very useful for guidance during biopsy. CT and MRI are mainly used for preoperative evaluation of thyroid nodules.

Biopsy, Needle↗
PubMed1990

[Hemodynamic, coagulation and glycoregulation changes induced by brain death].

Brain death results in various changes in circulation haemostasis, acid-base balance and glycoregulation. This study was carried out between February 1988 and December 1988 in 91 patients with brain death. Age range was between 6 and 58 years. The cause of brain death was brain trauma (71%) and vascular malformations (26%). In all patients a cardio-vascular collapse occurred at the moment of brain death, requiring an intravascular loading (466.3 +/- 240.3 ml.h-1) with crystalloids and albumin. Dopamine was used in 70% of cases at the dose of 3 micrograms.kg.min-1 to improve kidney and splanchnic perfusion. No alterations of acid-base balance were observed in these patients who admitted for organ donation in a short delay (17.1 +/- 6 h). Haemostasis was modified in all patients but the alterations occurred before the brain death and were related to brain injury. Further investigations are required for a better understanding of glycoregulation changes as they could influence pancreatic transplant survival. Hormonal changes have also to be more extensively studied for possible physiopathologic causes of the variations. A better understanding of these alterations will be of benefit for management of patients in brain death and potential organ donors.

Adolescent↗
PubMed1988

[Changes in intracranial pressure in severe head injured patients in hemodialysis].

Two cases of acute post-traumatic renal failure in severely head injured patients are reported. An increase in intracranial pressure (ICP) was shown up by continuous monitoring during haemodialysis: it was more important during conventional haemodialysis than during continuous arteriovenous haemofiltration. Although this effect is well known experimentally, few cases of continuous ICP pressure monitoring have been reported in head injury patients undergoing haemodialysis. The increase in ICP is explained in the dog as a result of blood-brain differences in urea concentration and osmolality leading to an increase in cerebral spinal fluid volume and cerebral tissue swelling. If dialysis is necessary in these patients, it should be carried out early and progressively, the patient's ICP being monitored continuously.

Acute Kidney Injury↗
PubMed1986

[ORL selection of French astronauts].

Strict criteria were used, under the control of the Centre National d'Etudes Spatiales (CNES) to select seven French spationautes for future participation in human cargo space flights to take place between 1987-1991 within the framework of the scientific missions of the USA and USSR. Data and results of the clinical O.R.L. examinations and vestibular tests conducted during medical operations of this selection procedure are presented.

Adult↗
PubMed1980

Influence of otolithic stimulation by horizontal linear acceleration on optokinetic nystagmus and visual motion perception.

Several studies in the past have demonstrated the existence of an Otolith-Ocular Reflex (OOR) in man, although much less sensitive than canal ocular reflex. The present paper 1 confirms these previous results. Nystagmic eye movements (L-nystagmus) appear in the seated subject during horizontal acceleration along the interaural axis in the dark for an acceleration level (1 m/s2) about ten times the perception threshold with a sensitivity of about 0.035 rad/m. When sinusoidal linear acceleration is combined with optokinetic stimulation, the recorded nystagmus slow phase velocity exhibits strong periodic modulation related to subject motion. This marked effect of linear acceleration on the optokinetic nystagmus (OKN) appears at a level (0.1 m/s2) close to the acceleration perception threshold and has a 4-fold higher sensitivity than L-nystagmus. Modulation of OKN can reach a peak-to-peak amplitude as great as 20 degrees/s for a given optokinetic field size it increases with the velocity of the optokinetic stimulus, i.e. with the slow phase eye velocity. In parallel with changes in OKN slow phase velocity, linear acceleration induces a motion related decrease in the perceived velocity of the visual scene and modifications in self-motion perception. The results are interpreted in terms of a mathematical model of visual-vestibular interaction. They show that sensory interaction processes can magnify the contribution given to the control of eye movements by the otolithic system and provide a way of exploring its function at low levels of acceleration.

Acceleration↗
PubMed1979

Otolithic-acoustic interaction in the control of eye movement.

In order to examine otolithic contribution to eye movements ten subjects were asked to track either a moving acoustic target or a stationary target during subject linear motion on a cart. The relative displacement between the subject and the target was the same in the two situations. Recordings of eye movements during subject lateral acceleration in the dark without any task, or with the task of tracking an imagined stationary target were made as a control. The frequencies ranged between 0.15 and 0.3 Hz and peak acceleration between 0.55 and 1.2 m/s2. No lateral eye movements (L-nystagmus) were recorded in the dark. Only saccadic eye movements were recorded during the tracking of a moving acoustic target. Slow eye movements interspersed by saccades were observed when the moving subject tracked an imagined or an acoustic stationary target. Contribution of the slow phase to tracking was more important in the presence of an acoustic target than in the presence of imagined target. The results are interpreted in terms of an otolithic contribution to the central reconstruction of the acoustic target velocity, or in terms of an adaptive control of the otolithic-ocular reflex gain. A conceptual model accounting for these interpretations is proposed.

Acoustic Maculae↗
PubMedDate not supplied

[Fetal hypothyroidism: a complication of amniofetography. Apropos of 3 cases].

The authors present three cases of fetal hypothyroidism following amniofetography, after they have reviewed the technique and complications of this procedure. (For outlining the fetus by injecting radio-opaque iodides into the amniotic sac). These are cases of hypothyroidism in the fetus caused by overdosage with iodides. The fetal thyroid is blocked by the large quantity of iodine which is necessary for amniofetography. The indications then for amniofetography should be reviewed. The only valid indication that remains is for the diagnosis of neurological malformations and especially spina bifida. Whenever amniofetography has been carried out the newborn should be assessed for thyroid function routinely.

Adult↗