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M Rousseaux

Publications and source records attributed to M Rousseaux.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Neuropsychological correlates of cerebral blood flow anomalies and MRI lesions after rupture of anterior communicating artery aneurysms].

The aim of this study was to investigate relations between neuropsychological disorders resulting from rupture of aneurysms of the anterior communicating artery, regional cerebral blood flow anomalies and brain lesions revealed on MRI. Blood flow was analyzed in 22 consecutive patients at least 3 weeks after surgery using single photon emission computed tomography. Flow values were calculated in 10 regions of interest on each side of the brain. Attention, motor control, executive functions, short-term and long-term learning (verbal, visuo-spatial), categorical evocation, general intellectual performances were investigated. Flow drop was observed over frontal areas, which predominated on the right side. The correlation analyses showed that

Aged↗
PubMed1999

Attentional resources in major depression.

Depression appears to interfere more with effortful processes than with automatic processes. This study aimed to examine attentional resources allocation by means of RT on effortful detection tasks. Ten depressed inpatients during illness and at recovery and ten healthy control subjects were given simple and choice reaction time tasks. Two types of effort demanding conditions were assessed (1) the combination of two concurrent tasks and (2) tasks involving decision making. Depressed patients improved from single to dual tasks whereas recovered and control worsened. Depressed patients showed a significant time and accuracy impairment when decision processes were involved. The decision making impairment co-occurred with a deficit in the orientation of the attention. The decline with decision making was not worsened when the choice task combined with a concurrent task and was reversible with recovery. This pattern of results exhibits differential sensitivity between two effortful tasks. Depressives may be able to mobilize resources to complete effortful tasks as far as decision processing is not required.

Adult↗
PubMed1999

Control functions of the frontal lobes. Modularity of the central-supervisory system?

Lesions of the prefrontal cortex result in a wide variety of neuropsychological disorders. Despite recent advances, the executive processes and their functional architecture remain poorly specified. This study assessed control processes operating in novel, conflicting and combined tasks in patients with lesion of the prefrontal or posterior cortices. Experiments used two-choice reaction time tests with similar perceptuo-motor and decision processes. It mainly showed (1) impaired short term memory in posterior patients, and (2) impairment of response inhibition and tasks combination in some frontal patients. Selective deficits with double dissociations were evidenced on novel, conflicting and combined tasks. This study provides additional evidence for the prominent role of the frontal lobes in control processes. The demonstration of selective deficits of specific control processes suggests that executive functions depend on multiple separable control processes, and that their operations can be specified in cognitive terms.

Adult↗
PubMed1999

Analysis of the perception of and reactivity to pain and heat in patients with wallenberg syndrome and severe spinothalamic tract dysfunction.

BACKGROUND: The aim of the study was to assess the consequences of severe spinothalamic tract lesions resulting from lateral medullary infarct and to show that a specific pain perception can be elicited by strong thermal stimulation. CASE DESCRIPTIONS: Both patients examined presented with severe thermoalgic dissociation of the limbs contralateral to the lesion, with normal discriminative somatosensory perception and motor strength. They reported pain perception when touching very warm (>50 degrees C to 60 degrees C) objects and a brisk, occasionally uncontrolled withdrawal reaction of the arm and hand under the same conditions, without any perception of the heat nature of the stimulus. Warm stimulation, <45 degrees C, elicited no thermal perception or discrimination. Pain perception could be elicited in both patients by increasing the temperature, with a reproducible threshold of 47 degrees C to 49 degrees C. Pain always occurred after a prolonged delay of 8 to 10 seconds in response to threshold heat, and was described as deep and osseous, and clearly different from that perceived on the nonaffected side. The delay was much shorter when the temperature was increased by 4 degrees C to 5 degrees C. Cold stimulation elicited similar pain perception in one patient. Analysis of subjective perception of laser stimulation showed a much higher pain threshold on the affected hand. There were no laser-evoked potentials on this side, which suggested major spinothalamic injury. Assessment of the RIII noxious reflex revealed persistent response withdrawal reactions, with an increased threshold on the affected side, and partial consciousness of the noxious nature of the stimulus. CONCLUSIONS: To our knowledge, this is the first description of the appearance of pain perception of high temperatures in patients with severe spinothalamic injury who are suffering from a complete loss of temperature perception. This implies that noxious thermal stimulation can still be perceived via extra spinothalamic pathways (which are slow and multisynaptic), such as the spinoreticulothalamic tract. Patients with Wallenberg syndrome should be informed and made aware of their residual perception of and reactions to noxious stimulation.

Central Nervous System Diseases↗
PubMed1999

Validation of a standardized assessment of postural control in stroke patients: the Postural Assessment Scale for Stroke Patients (PASS).

BACKGROUND AND PURPOSE: Few clinical tools available for assessment of postural abilities are specifically designed for stroke patients. Most have major floor or ceiling effects, and their metrological properties are not always completely known. METHODS: The Postural Assessment Scale for Stroke patients (PASS), adapted from the BL Motor Assessment, was elaborated in concordance with 3 main ideas: (1) the ability to maintain a given posture and to ensure equilibrium in changing position both must be assessed; (2) the scale should be applicable for all patients, even those with very poor postural performance; and (3) it should contain items with increasing difficulty. This new scale has been validated in 70 patients tested on the 30th and 90th days after stroke onset. RESULTS: Normative data obtained in 30 age-matched healthy subjects are presented. The PASS meets the following requirements: (1) good construct validity: high correlation with concomitant Functional Independence Measure (FIM) scores (r=0.73, P=10(-6)), with lower-limb motricity scores (r=0.78, P<10(-6)), and with an instrumental measure of postural stabilization (r=0.48, P<10(-2)); (2) excellent predictive validity: high correlation between PASS scores on the 30th day and FIM scores on the 90th day (r=0.75, P<10(-6)); (3) high internal consistency (Cronbach alpha-coefficient=0.95); and (4) high interrater and test-retest reliabilities (average kappa=0.88 and 0.72). CONCLUSIONS: Our results confirm that the PASS is one of the most valid and reliable clinical assessments of postural control in stroke patients during the first 3 months after stroke.

Cerebrovascular Disorders↗
PubMed1999

Remote regional cerebral blood flow consequences of focused infarcts of the medulla, pons and cerebellum.

UNLABELLED: The aim of this study was to evaluate regional and remote diaschisis of inferior brain stem or cerebellar infarcts in 25 patients presenting with relatively limited lesions. Patients presented with medullary, pontine or cerebellar infarction. METHODS: Lesions were evaluated on MRI (0.5 T). Regional cerebral blood flow (rCBF) was assessed by means of SPECT, after injection of 9rmTc-hexamethyl propyleneamine oxime (HMPAO) and, when possible, inhalation of 133Xe in the same session. For each method, asymmetry indices (Als), comparing contralateral to ipsilateral rCBF values, were calculated in four areas of each cerebral hemisphere and in the cerebellum and later compared with values obtained in healthy subjects (P = 0.05). RESULTS: Higher rCBF values were observed in the contralateral cerebellum in 2 of 7 patients with selective lateral medullary lesions, and cerebellar Als were significantly increased. When a cerebellar infarct was associated with a lateral medullary lesion, the cerebellar and contralateral hemispheric asymmetries were more severe. Unilateral paramedian pontine infarcts had more frequent consequences on the cerebellum (2 of 3 cases), with rCBF or tracer uptake being reduced in the ipsilateral or the contralateral lobe. Inverse cerebral hemispheric asymmetry could then be observed. Bilateral pontine lesions were difficult to evaluate. Using 99mTc-HMPAO, discrete cerebellar asymmetry was observed in 3 of 6 cases. Pure cerebellar infarcts in the posterior inferior cerebellar artery territory were always associated with a severe ipsilateral flow drop in the cerebellum, and contralateral hemispheric diaschisis was frequent (3 of 4 patients), predominating in the frontotemporal cortex and subcortical structures. This was also more obvious using 99mTC-HMPAO than 133Xe. Variance analysis showed that hemispheric diaschisis was more severe in mixed brain stem and cerebellar infarcts than in pure cerebellar or brain stem lesions. Furthermore, cerebellar and hemispheric AI values were not correlated with measurements of clinical deficits, disability or handicap. CONCLUSION: Unilateral and limited inferior brain stem lesions can have ipsi- or contralateral consequences on the cerebellum and cerebral hemispheres rCBF. These remote effects are related to lesions of the main pathways joining these structures, resulting in deactivation and, in some cases, overactivation. Contrary to what has been suggested, consequences on cerebral hemispheres are more severe in mixed cerebellar and brain stem infarcts than in pure cerebellar lesions.

Adult↗
PubMed1999

[Postural balance following stroke: towards a disadvantage of the right brain-damaged hemisphere].

In the light of studies published in the last ten years, we have suspected a differential influence of the sides of hemispheric cerebral lesions on posture and balance. A study was aimed at verifying this hypothesis, the method of which being original because many possible confounding factors such as age, sex as well as topography and size of the brain lesion have been taken into account in the statistical analysis. Inclusion criteria were: right-handed patients, first stroke, no previous disease which might have affected balance. Their postural abilities (ranging from 0 to 36) were assessed 90 +/- 3 days after stroke onset on a clinical scale. This clinical assessment was used here because it could be easily performed in all patients, irrespective of the severity of their impairment. Lesion locations were determined using the Atlas by Talairach and Tournoux and the number of cerebral areas altered gave an estimation of the lesion size. The first fifty patients consecutively admitted to rehabilitation and responding to the inclusion criteria were thus examined (25 with a right and 25 with a left hemispheric lesion; 14 women and 36 men; mean age 57.2 = yrs). The main result was lower postural performances in right brain-damaged patients than in left brain damaged patients (21.5 vs 29.4; p = 0.01). Postural abilities were also inversely related to age (r = -0.28; p = 0.04), lesion size (r = -0.41; p = 0.003) and were lower in women than in men (22.1 vs 28.8; p = 0.02). This study therefore confirms the existence of a right hemispheric dominance for postural control. The existence of inverse correlation between postural abilities and the number of omitted targets in cancellation task on one hand (r = -0.63, p < 0.001), the ipsilesional bias in line bissection on the other hand (r = -0.36; p = 0.01), argued for a relationship between the main result of this study and the well known cerebral organization of spatial information processing, based on a right hemisphere dominance for spatial attention and/or representation. The 'postural neglect' concept is discussed.

Aged↗
PubMed1998

Divided attention in major depression.

Depressive illness has been reported to interfere with effortful processing, which requires conscious attention. The aim of this study was to evaluate divided attention in depressed patients, as a function of the degree of difficulty of the task performed. Tasks designed to measure unimodal and bimodal reaction times were presented to 10 patients with major depression and 10 normal control subjects. Performance was evaluated both before treatment when the patients were depressed and after treatment when they had recovered. Unlike the unimodal trials, the bimodal reaction time tasks were designed to evaluate decision-making under conditions in which attention was divided between two perceptual channels. Reaction times were measured under two different conditions in order to assess the extent of the response delay induced by divided attention, modality shifting, and decision processing. During simple response tasks, the depressed patients displayed significantly greater lengthening of reaction times when their attention was divided between two perceptual channels. This cross-modal delay effect occurred both for stimuli of the same modality and when shifting between modalities. The cross-modal delay effect was evident only for the choice tests in both the depressed and the recovered patients, but only the recovered patients were as accurate as the control subjects. These results suggest that the need for decision processing in depressed patients results in a failure to allocate the mental resources required to complete interchannel shifting, when attention is divided between two perceptual channels. These data are consistent with the hypothesis that attentional regulation is impaired in major depression.

Adult↗
PubMed1998

[Residual deficit of verbal recall after a left internal cerebral vein infarct].

A case of unilateral infarct in the territory of the left internal cerebral vein, severely disturbing cognitive processes, and more especially recall in verbal memory, is reported. This 22-year-old patient survived a left thalamic and striato-capsular infarct related to a straight sinus and left internal cerebral vein thrombosis. Motor and functional recovery was fair, despite late dystonia. At the secondary phase post-stroke, cognitive disorders were severe, including increased short-term forgetting and episodic (anterograde and retrograde) and semantic amnesia. One year later, a residual deficit of verbal recall was observed, which participated in the anterograde and retrograde amnesia. Recognition was well preserved. This case showed that: (1) internal cerebral vein thrombosis can have severe consequences on cognition and memory, and that late prognosis is not as fair as has been previously reported in selected patients, and (2) left diencephalic structures are specifically associated with recollection of verbal information from long-term memory.

Adult↗
PubMed1998

[Learning disorders after ruptured aneurysms of the anterior communicating artery].

The aim of this study was to reevaluate short term and long term memory disorders after anterior communicating artery rupture, then to more specifically assess the importance and the role of forgetting, proactive and retroactive interferences, impaired memory for temporal order, attention disorders and dysexecutive syndrome, and finally MRI-defined brain lesions. Twenty one patients presenting with selective anterior brain injury, were assessed at the secondary and late post stroke phases. The short term memory analysis showed the digit span was reduced at the secondary stage, but that mean performances were preserved in the Peterson and Sternberg paradigms. Verbal and visuospatial learning in long term memory showed a severe deficit in free recall, chiefly serial, and associative recall. Recognition was mildly impaired at the secondary phase, and later normalized. A definite and lasting increase of proactive and retroactive interferences and an impairment in discriminating the temporal order of word presentations were observed. Amnesic impairment was relatively well correlated with forgetting, severity of interferences and temporal order amnesia, so as with disorders of attention and executive functions (Wisconsin Card Sorting Test). However, intrusions in free recall and false recognitions were not clearly related with the dysexecutive syndrome. The severity of amnesia was associated with lesions of the left anterior cingulate cortex, and of the corpus callosum. These results suggest that these patients mainly had a deficit in information retrieval, mostly compromising long term memory, but also to a lesser degree short term memory. Forgetting, interferences and the dysexecutive syndrome probably play an important role in the decline of mnemonic performance, but do not clearly explain intrusions in recall and errors in recognition.

Aged↗
PubMed1997

Novel decision making in patients with prefrontal or posterior brain damage.

Patients with lesions of the frontal lobes experience greater difficulties in performing nonroutine tasks, but their ability to cope with novel situations has not been studied. We assessed novel and previously practiced decisions in normal subjects and patients with frontal or posterior brain damage using a unimanual two-choice response time test. Patients with frontal damage had a dramatic impairment on novel decision, whereas practiced decision was normal. Relative Judgment Theory analysis suggested that the basic disorder concerns the ability to create internal referents that are determined from instructions and are subsequently required to associate the current stimulus with the appropriate response. The results of the study suggest that the prefrontal cortex is critical for novel decision making and that it operates mainly at the stage of creation of internal referents that associate some subsequent event with the selection of appropriate processing. This basic disorder may underlie some behavioral changes such as apathy and difficulty on tests that are sensitive to frontal damage.

Adult↗
PubMed1997

[Retrograde memory after rupture of aneurysms of the anterior communicating artery].

The aim of this study was to investigate deficits of retrograde memory, semantic, autobiographical, and for famous events, associated with prefrontal, cingulate and subcortical lesions resulting from anterior communicating artery rupture. Analyses were performed during the secondary phase post-stroke in 16 patients, and performances were compared to those of an equivalent number of matched control subjects. Semantic investigations revealed a significant deficit in each task using evocation, more especially categorical and literal evocations, and the verbal subtests of the WAIS-R: vocabulary, information, comprehension, and similarities. Furthermore, the capacity to categories was preserved. The Crovitz paradigm, which evaluated the autobiographical memory showed a severe deficit in the evocation of events associated with a precise context in place and moreover in time, with a clear tendency to produce semantic responses, but without significant increase in confabulations. The questionnaire on famous events (1936-1985) did not document deficit in recognition and recall. Furthermore, the patients disorder was more severe in learning new information. Memory disorders were best explained by the severity of lesions in the medio-basal frontal and cingulate cortices, but also by the subcortical injury. Significant correlations were observed between the retrograde memory performance and "frontal" tasks, more especially the WCST; however, similar relations were also documented between learning new information and "frontal" performance. These data suggest that retrograde amnesia results from a selective impairment in accessing old memory representations, and that cognitive processes more specifically altered have tight relations with the capacity to organize the search and to shift.

Adult↗
PubMed1996

Divided and focused attention in patients with lesion of the prefrontal cortex.

Despite the common claim of attention disorders in patients with frontal lobe lesion, attention has been poorly investigated and its contribution to behavioral changes has not been studied. The aim of this study was to assess divided (Experiment I) and focused attention (Experiment II) in patients with prefrontal damage. The study used simple detection tests measuring reaction times (RT) to successive stimuli of one modality and of randomly varying modalities (divided attention) and Go No-Go tests (focused attention). Experiment I showed that RT difference between patients and controls increased when stimuli modality was uncertain, a result we attributed to a deficit of divided attention. Experiment II showed that patients remained sensitive to irrelevant stimuli, demonstrating their inability to focus attention. The prominent behavioral change in patients consisted of increased distractibility which was correlated with divided and focused attention deficits. Finally, the presence on magnetic resonance imaging of a left lesion in the superior part of the prefrontal cortex and in the head of the caudate nucleus was the best predictor of attention disorders. In conclusion, this study shows that patients with a prefrontal lesion suffer from divided and focused attention deficits that correspond to behavioral changes.

Adult↗
PubMed1996

Binary choice in patients with prefrontal or posterior brain damage. A relative judgement theory analysis.

Binary choice task has been poorly evaluated in patients with focal brain damage. We assessed the decision process in normal subjects and patients with frontal or posterior brain damage using a unimanual two-choice response time (CRT) paradigm. The decision was manipulated by varying the response probability and parameters were analysed with the relative judgement theory. The results suggest that the binary decision process is spared in patients with focal lesions and that their longer CRT is mainly related to slowing the perceptual or motor stages. The prominent role of the left hemisphere in binary choice received support.

Adult↗
PubMed1996

Non-spatial attention disorders in patients with frontal or posterior brain damage.

The few studies that have looked at attention in patients with brain damage suggest a prominent role for the frontal lobe in nonspatial attentional control. However, the studies usually focus on one variety of attention and do not address the nature of the alteration of attention. In addition, the behavioural consequences of nonspatial attentional deficit remain unknown. The aim of this study was to evaluate the role of focal brain damage on divided and focused attention and the relationship between attention disorders and behavioural changes. The study group consisted of patients with lesions of the prefrontal and posterior cortices and control subjects. The assessment of attention used reaction time tests that evaluated the ability to divide attention between two sources (detection tests) and to focus attention on one source (Go/No-Go Tests). The response retardation of the 'frontal' group became more pronounced as the number of sources to be monitored increased, suggesting the presence of a deficit of divided attention. Focused attention deficit was demonstrated in the 'frontal' group by the more frequent responses to irrelevant stimuli on Go/No-Go Tests. Both focused and divided attention deficits were prominent when the lesion included the left dorsolateral prefrontal cortex and the caudate nucleus. Selective deficit of divided or focused attention was shown in a few patients. Finally, the clinically assessed distractibility was related to disorders of divided and focused attention. This study provides additional evidence for the prominent role of the frontal lobe in nonspatial attention regulation and shows that it also operates in elementary perceptuomotor processes. The relationship between distractibility and attention indexes supports the idea that attention disorders may have a functional counterpart that is clinically assessable. The demonstration of selective deficit of divided or focused attention suggests that nonspatial attention depends upon different mechanisms and that it is not an undifferentiated general purpose mechanism. Further studies addressing the nature of the interactions between attentional mechanisms and other cognitive processes are required.

Adult↗
PubMed1996

Disorders of smell, taste, and food intake in a patient with a dorsomedial thalamic infarct.

BACKGROUND: We report that a lasting deficit in the hedonic character of olfactory and gustatory perception can be observed in bilateral dorsomedial and intralaminar thalamic lesions. CASE DESCRIPTION: A 68-year-old patient abruptly presented with vigilance disorders associated with a reduction of olfactory and gustatory perceptions. A severe drop in appetite for foods and a weight loss of 10 kg were observed, which were partially reversed with time. Two years later, the main persisting disorder was a change in the quality of perceptions: odors and taste were perceived either in a neutral way, their pleasant character having disappeared, or as unpleasant. However, identification was preserved. MRI showed that lesions principally involved the dorsomedial thalamic nuclei and the adjacent part of the intralaminar nuclei. CONCLUSIONS: This case suggests that the dorsomedial thalamus may play a role in the hedonic perception of food, thus affecting short-term regulation of food intake, and may possibly have a role in the long-term control of body weight.

Aged↗
PubMed1996

Late contralateral hyperhidrosis in lateral medullary infarcts.

BACKGROUND AND PURPOSE: This study describes unilateral increases of sweating reactions observed in the months after contralateral medullary infarct; evaluation of sympathetic cutaneous response may help to explain sweating disorders. SUMMARY OF REPORT: After the discovery of the clinical phenomenon in one case, patients admitted between 1990 and 1993 were systematically evaluated clinically and electrophysiologically. In a group of five patients presenting with lateral or dorsal medullary lesions, two exhibited an increase of contralateral sweating reactions that appeared 6 to 8 months after stroke, were elicited by effort and exposure to heat and stress, and were more severe over the forehead, face, and upper trunk. In one case, this was clinically associated with an absence of sweating on the side of the lesion. During the late phase after stroke, in three patients presenting with lateral medullary lesions, electrophysiological evaluation revealed significant asymmetry of the sympathetic skin response, which was higher on the side contralateral to the lesion than on the ipsilateral side. In one patient, no response could be elicited by stimulations applied on the side of the lesion. CONCLUSIONS: Contralateral hyperhidrosis can be observed in the late phase after lateral medullary infarct and is likely due to lesion of the sympathetic pathway passing through the lateral medulla, which inhibits sudomotor neurons. Evaluation of sympathetic skin response may help to explain such clinical disorders.

Adult↗