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Biomedical subjects

M Rousseaux

Publications and source records attributed to M Rousseaux.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Analysis and course of cognitive deficits after rupture of aneurysms of the anterior communicating artery].

The aim of this study is to investigate general intellectual and memory performances at the secondary (3 weeks to 4.5 months) and late (10 to 16 months) stages following rupture of anterior communicating artery aneurysms (AACA). Twenty one patients presenting with selective lesion within frontal, or cingulate, callosal, caudate, basal forebrain areas were evaluated. At the secondary stage, the analysis of the general intellectual capacities revealed a drop of performance, prominent on performance IQ, which was more severe than the learning deficit. Specific cognitive evaluations revealed increase of the execution time, but performance was relatively preserved: in the Stroop test, focused attention disorder was moderate: the modified Wisconsin Card Sorting test was correctly performed in most cases; significant deficits of verbal short-term memory, long-term verbal and visuo-spatial learning, and access to semantic memory were observed. At the late stage, general intellectual performance improved, but did not reached the estimated prelesional level in most cases; specific cognitive disorders had most often disappeared. Most performances were best explained by the severity of lesions in the left cingulate cortex and corpus callosum area. These results show that the cognitive profile of AACA patients is different from classical descriptions of the "amnesic syndrome", and is also different at the secondary and late stages; this evolution has to be taken into account in studies describing cognitive deficits of such patients, or comparing them with others presenting with "annesic syndrome".

Adult↗
PubMed1996

[Dystonia and tremor in bilateral lesion of the posterior mesencephalon and the vermis].

The aim of this study is to report the association of diffuse dystonia and tremor in a bilateral and extended lesion of the posterior mesencephalon. After surgery on a meningioma of the upper part of the fourth ventricle, this patient presented with facial dystonia, predominating on orbicularis muscles and peribuccal area, and limb dystonia, with tonic extension of fingers and first toes. The tremor was associated with a rhythmic and most often alternate agonist-antagonist muscular activation, whose frequency varied from 3 to 7 Hz. These disorders were increased by the standing position, voluntary movement, somatosensory stimulations, stress or emotion. Pyramidal and somatosensory tracts were spared. Therapeutic trials showed that both the dystonia and tremor were improved by subcutaneous injection of apomorphine, the dystonia by trihexyphenidyle, and the tremor by carbamazepine and propranolol, but not by levodopa and benserazide. The cerebral blood flow study using HMPAO showed a relatively important activity on the cerebellum, which could play a role in the onset of these disorders.

Adult↗
PubMed1995

Cerebral blood flow in lateral medullary infarcts.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate the diaschisis phenomenon in patients presenting with lateral medullary infarct (Wallenberg's syndrome). METHODS: We examined all patients admitted between 1991 and 1993. The localization of lesions was evaluated by MRI. Single-photon emission computed tomographic technique was used to assess cerebral blood flow by two methods (133Xe and hexamethylpropyleneamine oxime) on five slices of brain tissue. Flow values were calculated in 11 regions of interest in each cerebral hemisphere and in the cerebellum and were compared with those obtained in 20 control subjects. RESULTS: Three patients had selective lateral medullary infarct: Relative reduction of flow (133Xe) and of tracer uptake (HMPAO) were observed in one patient in the ipsilateral cerebellum and contralateral hemisphere; in two patients, hemispheric flow values were relatively low, without significant asymmetry. Two patients also presented with cerebellar infarct: Flow drop was severe in the ipsilateral cerebellum, and contralateral reduction in the brain hemisphere was observed in both cases. CONCLUSIONS: Lateral medullary infarct can be associated with ipsilateral reduction of flow in the cerebellum, but this phenomenon is inconstant. Severe flow drop suggests infarction in the territory of the posterior inferior cerebellar artery. Contralateral hemispheric flow reduction can also be observed. These phenomena of cerebellar and crossed hemispheric diaschisis are probably related to lesions of tracts from the olivary and reticular nuclei.

Adult↗
PubMed1995

[Deficit of verbal recall caused by left dorso-lateral thalamic infarction].

A case of amnesia with preferential disorder of verbal recall, associated to a limited infarct of the left superior, external and anterior thalamus, is reported. This lesion involved the anterior and middle dorso-lateral nuclei and the centrolateral nucleus, sparing most of the structures classically incriminated in diencephalic amnesia. At the initial stage, the patient presented discrete language impairment and severe deficit of semantic processing, which later recovered. At the late stage, the anterograde and retrograde amnesia principally concerned the recall of verbal information used in daily life, verbal learning using short-term and long-term recall, questionnaires evaluating retrograde memory and requiring the evocation of proper names. Verbal priming was also affected. Verbal recognition was preserved. Evocation of the most recent events of the personal life was also impaired. Confrontation of this case with others previously reported suggests that various thalamic amnesias may be described, associated to different cognitive deficits, in relation with the preferential situation of lesions.

Amnesia↗
PubMed1994

Reliability of reaction time measurements in brain-damaged patients.

The higher sensitivity of chronometric analysis leads to an increase of their use in the evaluation of brain-damaged patients. However, patients have usually higher reaction time (RT) variability, suggesting a possible decrease in the reliability of RT measurement. This reliability has never been evaluated in patients. This study assessed the reliability of RT estimates in 2 populations of brain-damaged patients and controls, using the Kendall coefficient of concordance W. Concordance coefficients were computed for simple detection and choice tests. W values were good and significant. This study suggests that RT measured in simple detection and choice tasks represent a reliable measurement and supports the idea that the higher sensitivity associated with the use of chronometric analysis is not obtained at the cost of a lower reliability. Moreover, these results provide information for the elaboration of RT tests.

Adult↗
PubMed1994

Vigilance and effects of fatigability, practice and motivation on simple reaction time tests in patients with lesion of the frontal lobe.

Despite the wide use of RT tests in brain-damaged patients assessment, effects of the level of vigilance, fatigability, practice and motivation on RT have been poorly investigated. We assessed vigilance and effects of fatigability, practice and motivation on brain-damaged patients suffering from lesion of the prefrontal cortex prominent in basofrontal areas and controls using simple RT tests. Our study showed fatigability and practice effects which did not affect RT differences between groups, whereas motivation effect was not significant. Finally, patients did not suffer from a deficit of vigilance. These results suggest that the attentional disorders demonstrated in the same patient group were related neither to a higher sensitivity to fatigability nor to an insufficient practice.

Adolescent↗
PubMed1994

Visual hallucinations with written words in a case of left parietotemporal lesion.

A 15 year old ambidextrous patient presented with left temporoparietal lesions after head trauma. Seizures associated with visual hallucinations of written words arose six months later. Electroencephalography showed spike and wave complexes with phase opposition over the left parietal area. On MRI a post-traumatic porencephalic lesion was seen in area 7 and the superior part of area 39 of Brodmann; on T2 sequences, it was surrounded by a hyperecho predominating in the inferior part of the parietal lobe and extending in the posteroexternal temporal cortex. This first description of hallucinations of written words raises the possibility of the presence, in the temporoparietal cortex, of specific representations ("lexicon") of corresponding information.

Adolescent↗
PubMed1994

Neuropsychological changes related to unilateral lenticulostriate infarcts.

According to previous studies, focal capsulostriatal lesions may produce aphasia, hemineglect, gestural apraxia, frontal lobe dysfunction, and memory impairment. A few reports of capsulostriate infarcts secondary to involvement of lenticulostriate arteries have confirmed that aphasia and hemineglect may occur whereas gestural apraxia, anosognosia and frontal-lobe symptoms are rare. Most studies used CT scan assessment and did not exclude possible associated lesions. Neuropsychological changes in 11 patients with lenticulostriate infarcts diagnosed by CT scan were prospectively investigated. MRI in five of the 11 patients showed an associated cortical lesion not seen on CT scan. Patients with pure lenticulostriate infarcts on MRI may exhibit aphasia of mild severity whereas Broca's aphasia, hemineglect, gestural apraxia, and anosognosia were only seen in the subgroup with associated cortical lesions. Aphasia in patients with pure lenticulostriate infarcts was characterised by prominent expressive and lexicosemantic task impairments. The results strongly suggest that cortical involvement is critical to the extent and severity of neuropsychological changes in patients with lenticulostriate infarcts.

Adolescent↗
PubMed1994

Cerebral blood flow in frontal lesions of aneurysms of the anterior communicating artery.

BACKGROUND AND PURPOSE: The aim of this study was to investigate local and remote regional cerebral blood flow in patients with prefrontal lesions resulting from rupture (and operation) of aneurysms of the anterior communicating artery. METHODS: The localization and severity of the lesions were evaluated by magnetic resonance imaging on T2 sequences. Blood flow measurements were performed in 21 patients at least 3 weeks after surgery using single-photon emission computed tomography. Flow values were calculated in 10 regions of interest in each cerebral hemisphere and compared with those of 21 control subjects matched for age. RESULTS: A drop in regional cerebral blood flow, predominating on the right side, was observed in the frontal areas. Flow values were not reduced in the thalamus and striatum but were significantly elevated in the posterior cortical areas and cerebellum. This latter phenomenon was significantly correlated with the severity of frontal lesions on magnetic resonance imaging. CONCLUSIONS: Blood flow drop in frontal areas was correlated with the cerebral lesions, which predominated in the anterior prefrontal lobe, on the side of the surgical flap; most of these prefrontal lesions were likely due to the surgical procedure and not to classic arterial spasm. Elevated perfusion in the temporo-parieto-occipital cortex and cerebellum might be due to the release of a physiological inhibition exerted by the prefrontal cortex.

Adolescent↗
PubMed1994

Regional cerebral blood flow imaging: a quantitative comparison of 99mTc-bicisate with 133Xe using single photon emission computed tomography.

The aim of this study was to compare 99mTc-bicisate with 133Xe inhalation in regional CBF (rCBF) imaging. Five healthy volunteers and five patients were imaged with both techniques. Regional standardized values (SVs) of 99mTc-bicisate, uptake indexes (UIs), and asymmetry indexes (AIs) were compared quantitatively with, respectively, rCBF, flow indexes (FIs), and AIs. Areas with highest rCBF (sylvian and thalamic areas) appeared to be underestimated with 99mTc-bicisate, but significant correlations were found between SV and rCBF (n = 140, r = 0.468, p < 0.01) and for the 10 subjects between UI and FI and between AIs (p < 0.0001). There are therefore distinct regional differences in the cerebral distinction of 99mTc-bicisate and CBF, particularly in the thalamus and the temporal cortex. It is probable but not yet proved that an underestimation of high flow rates occurs with bicisate.

Adolescent↗
PubMed1993

Early and delayed distribution of N-isopropyl-[123I]-p-iodoamphetamine in haemorrhagic and ischaemic brain.

Single photon emission computed tomography (SPECT) was used to study redistribution of N-isopropyl-[123I]-p-iodoamphetamine (IAMP) in 10 patients with intracerebral haemorrhage and 7 with ischaemic stroke. Delayed/early IAMP uptake ratios (D/E) were calculated for four different cerebral zones: haematoma or infarct, perilesional, normal and crossed cerebellar diaschisis areas. Delayed uptake was observed in all areas, but there were no significant differences between the haematoma and infarct results nor between the lesional and perilesional results. Delayed redistribution of IAMP therefore did not seem to be associated with neuronal metabolic activity.

Adult↗
PubMed1993

Carboxyl terminus structural requirements for glycosyl-phosphatidylinositol anchor addition to cell surface proteins.

Glycosyl phosphatidylinositol (GPI)-anchored proteins contain in their COOH-terminal region a peptide segment that is thought to direct glycolipid addition. This signal has been shown to require a pair of small amino acids positioned 10-12 residues upstream of an hydrophobic C-terminal domain. We analysed the contribution of the region separating the anchor acceptor site and the C-terminal hydrophobic segment by introducing amino acid deletions and substitutions in the spacer element of the GPI-anchored Thy-1 glycoprotein. Deletions of 7 amino acids in this region, as well as the introduction of 2 charged residues, prevented the glycolipid addition to Thy-1, suggesting that the length and the primary sequence of the spacer domain are important determinants in the signal directing GPI anchor transfer onto a newly synthesized polypeptide. Furthermore, we tested these rules by creating a truncated form of the normally transmembranous Herpes simplex virus I glycoprotein D (gDI) and demonstrating that when its C-terminal region displays all the features of a GPI-anchored protein, it is able to direct glycolipid addition onto another cell surface molecule.

Amino Acid Sequence↗
PubMed1993

[Transient severe orthostatic hypotension and hematoma of the pontine tegmentum].

A 57-year old patient presented with a posterior pontine hematoma and severe postural hypotension. The lesions were localized in the pontine tegmentum. They were bilateral and involved the area of the nucleus reticularis pontis caudalis, left medial lemniscus and roots of several cranial nerves, especially the VIth. The patient had lasting postural hypotension, with reduction of the physiological tachycardia. Investigation of heart rate regulation during manoeuvres however revealed that the accelerating reaction partially persisted, especially with Valsalva manoeuvre. Heart rate recording for 24 hours showed that the physiological nocturnal slowing down reaction had disappeared. In the following months, progressive but limited recovery of blood pressure regulation and accelerating reactions was observed.

Blood Pressure↗
PubMed1993

[Bulbar hematoma of the olivary area. An analysis of the autonomic syndrome].

The consequences of an anterolateral medullary hematoma in a 50 year old patient are reported. The lesions principally involved the inferior olive nuclei, the lateral reticular nucleus, and, partially, the nucleus ambiguus. Long-lasting postural control deficit and hypotonia were observed, associated with alpha motoneurons hyperexcitability. Analysis of the heart rate regulation showed a severe reduction of the normal accelerating reactions and a relative preservation of slowing down reactions that suggested a deficit of the ortho-sympathetic control. Unilateral palsy of the tongue and pharynx was also observed without sensory or sensorial deficit. The long term course was favourable.

Autonomic Nervous System Diseases↗
PubMed1992

Membrane mu poly(A) signal and 3' flanking sequences function as a transcription terminator for immunoglobulin-encoding genes.

Developmentally regulated mechanisms involving alternative RNA splicing and/or polyadenylation, as well as transcription termination, are implicated in controlling the levels of secreted mu (mu s), membrane mu (mu m) and delta immunoglobulin (Ig) heavy chain mRNAs during B cell differentiation (mu gene encodes the mu heavy chain). Using expression vectors constructed with genomic DNA segments composed of the mu m polyadenylation signal region, we analyzed poly(A) site utilization and termination of transcription in stably transfected myeloma cells and in murine fibroblast L cells. We found that the gene segment containing the mu m poly(A) signals, along with 536 bp of downstream flanking sequence, acted as a transcription terminator in both myeloma cells and L cell fibroblasts. Neither a 141-bp DNA fragment (which directed efficient polyadenylation at the mu m site), nor the 536-bp flanking nucleotide sequence alone, were sufficient to obtain a similar regulation. This shows that the mu m poly(A) region plays a central role in controlling developmentally regulated transcription termination by blocking downstream delta gene expression. Because this gene segment exhibited the same RNA processing and termination activities in fibroblasts, it appears that these processes are not tissue-specific.

Alternative Splicing↗
PubMed1992

Frontal lobe dysfunction in unilateral lenticulostriate infarcts. Prominent role of cortical lesions.

Most studies on frontal lobe dysfunction (FLD) in patients with striatal lesions did not consider possible associated cortical lesions not seen on computed tomographic scans. To determine the possible role of such cortical lesions, we assessed FLD in 10 patients with unilateral lenticulostriate infarct on computed tomographic scans. Magnetic resonance imaging revealed an associated cortical infarct not seen on computed tomographic scans in four patients. Using a battery of neuropsychological tests sensitive to FLD, we found that (1) the crossed tapping test was the only FLD test significantly disturbed in patients with pure unilateral lenticulostriate infarcts, (2) FLD was only present in patients with associated cortical infarct, and (3) caudate lesions only account for the number of echopraxic errors in the crossed tapping test. We conclude that unilateral isolated lenticulostriate infarcts might not lead to FLD, even though they may disturb the development of strategies involved in motor procedural learning.

Adolescent↗
PubMed1992

Crossed hemispheric diaschisis in unilateral cerebellar lesions.

BACKGROUND AND PURPOSE: We studied 12 patients with unilateral cerebellar hemorrhage to look at its effect on regional cerebral blood flow. METHODS: We used single-photon emission computed tomography by continuous inhalation of xenon-133. The blood flow was quantified in the cerebellum and in nine areas of interest on the slice passing through the basal ganglia. RESULTS: The comparison of the blood flow values of the patients and control subjects showed a significant reduction in the contralateral hemisphere of the patients, predominantly in the frontal region and in the lenticular nucleus of the contralateral hemisphere but also in the anterointernal frontal area of the ipsilateral hemisphere. The analysis of the asymmetry indexes revealed in the same way significant differences between patients and control subjects in the frontal cortex and in the lenticular nucleus. CONCLUSIONS: These results provided concordant evidence suggesting a blood flow reduction in the contralateral hemisphere. This phenomenon of "crossed hemispheric diaschisis" is probably related to the interruption of cerebellocortical tracts.

Adult↗