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Biomedical subjects

Luc Defebvre

Publications and source records attributed to Luc Defebvre.

15 recordsLinked to original sources
PubMed2006

New syndromic form of benign hereditary chorea is associated with a deletion of TITF-1 and PAX-9 contiguous genes.

Benign hereditary chorea is a rare autosomal dominant disorder presenting with a childhood-onset and slowly progressive chorea. The objective of this study was to describe the clinical and genetic features of 3 patients who developed childhood-onset chorea. Three affected patients from three generations of a family with benign hereditary chorea associated with a multisystemic disorder of the basal ganglia, thyroid, lungs, salivary glands, bowels, and teeth. The TITF-1 gene was screened by microsatellite analysis, gene sequencing, and fluorescence in situ hybridization. Genetic analysis revealed a novel 0.9-Mb deletion on chromosome 14, which includes the TITF-1 and PAX9 genes. We have identified a novel deletion responsible for a new syndrome of benign hereditary chorea, including symptoms of brain-thyroid-lung syndrome associated with bowels, salivary glands, and teeth disorders. Associated signs, sometimes of slight expression, remain of high interest for the clinical and genetic diagnosis of benign hereditary chorea.

Child↗
PubMed2005

Effect of age on anticipatory postural adjustments in unilateral arm movement.

Aging is frequently accompanied by a deterioration in postural control. Accordingly, the elderly adopt postural strategies in order to maintain balance. The purpose of this study was to compare anticipatory postural adjustments in (healthy) 10 young and 10 elderly subjects using electromyography (EMG) and biomechanical parameters. While standing on a force platform, subjects performed voluntary, arm-raising movements under five conditions: self-paced at three different velocities, self-paced with load and an externally triggered, both at maximal velocity. The force platform provided information on vertical torque (T(z)) and center of pressure anteroposterior displacements (COP). EMG activity was recorded from the biceps femoris, quadriceps, tibialis anterior and soleus muscles. Voluntary movements were associated with an early COP backward shift and an anticipatory T(z). At low velocity, elderly subjects did not show any impairment in stability. At maximal velocity, T(z) was delayed in all conditions in the elderly group, whereas COP latency was reduced only in the self-paced condition without load. Despite this decrease in anticipation, the movement was performed at the same velocity as in younger subjects. The elderly adopted various muscle strategies in order to perform the same movement with less stability. In the self-paced condition, elderly subjects used a hip strategy, whereas young subjects used an ankle strategy. In the triggered condition, the strategy corresponded to increased activation of certain thigh muscles, rather than a sequence modification. Hence, local muscle strategies were used to counteract the overall delay in postural preparation revealed by biomechanical parameters.

Adult↗
PubMed2005

Role of hypokinesia and bradykinesia in gait disturbances in Huntington's disease: a biomechanical study.

OBJECTIVE: To evaluate specific patterns of locomotion in Huntington's disease (HD) and notably the respective roles of hypokinesia (i. e. a decrease in the amplitude of movement) and bradykinesia (i. e. difficulty in executing a movement, slowness) in gait disturbance. METHODS: Kinematic, spatial (stride length, speed), temporal (cadence, speed, and stride time) and angular gait parameters (joint ankle range) were recorded in 15 early-stage HD patients by means of a video motion analysis system and then compared with 15 controls and 15 Parkinson's disease (PD) patients. Hypokinesia was studied in terms of both spatial (decrease in stride length) and angular gait parameters (decrease in joint ankle range), whereas hyperkinesia was characterized by an increase in joint ankle range. Bradykinesia (defined by a decrease in gait velocity) was also assessed in terms of temporal parameters (cadence, stride time). We studied the influence of clinical symptoms (motor dysfunction, chorea, overall disability and cognitive impairment) and the CAG repeat number on gait abnormalities. RESULTS: we observed a clear decrease in gait speed, a decrease in cadence and an increase in stride time (i. e. bradykinesia) for HD, with significant intra-individual variability. Cadence remained normal in PD. In HD, there was no evidence for a clear decrease in stride length, although the latter is a characteristic feature of hypokinetic gait (such as that observed in PD). Angle analysis revealed the coexistence of hyperkinesia and hypokinesia in HD, which thus participate in gait abnormalities. Gait speed in HD was correlated to the motor part of the UHDRS. CONCLUSION: Gait in HD is mainly characterized by a timing disorder: bradykinesia was present, with severe intra-individual variability in temporal gait parameters.

Adult↗
PubMed2005

Corticobasal degeneration and Parkinson's disease assessed by HmPaO SPECT: the utility of factorial discriminant analysis.

The diagnosis of corticobasal degeneration (CBD) is difficult despite the existence of some typical clinical features. Single photon emission computerized tomography (SPECT) in CBD presents an original pattern (with asymmetric hypoperfusion in pre- and retrorolandic regions) that could facilitate the differential diagnosis of CBD relative to the other degenerative parkinsonian syndromes. The objective of our study was to compare the regional cerebral blood flow measurements studied by SPECT in both CBD and Parkinson's disease (PD) using a multivariate procedure. Twenty-one patients with probable CBD and 20 patients with probable PD underwent brain (99m)Tc HmPaO SPECT. We used factorial discriminant analysis (FDA) to study the relative fixation of 26 regions of interest (ROIs) drawn on two transverse slices, together with the asymmetry indexes of 13 pairs of ROIs. FDA performed using the full set of parameters classified all the patients correctly. In order to classify the patients more easily, a predictive score using a selection of parameters was established. The most discriminating ROIs were the temporoinsular, temporoparietal, and frontal medial regions. We believe that this semiautomatic classification may be a precious tool for reinforcing the current clinical differential diagnosis of CBD and PD.

Aged↗
PubMed2005

Vertical torque allows recording of anticipatory postural adjustments associated with slow, arm-raising movements.

BACKGROUND: When performed in the upright position, voluntary arm-raising movements perturb balance. The maintenance of equilibrium requires postural adjustments, some of which can be anticipatory. It is usually suggested that the role of anticipatory postural adjustments is to stabilise the whole body centre of mass. During movements performed at low velocity (i.e. with a lower inertial perturbation), anticipatory postural adjustments have not systematically been detected by classical recording methods (mainly electromyography). The aim of this study was to use vertical torque to characterise anticipatory postural adjustments in slow movement and to determine the significance of this biomechanical parameter. METHODS: Twenty healthy subjects performed self-paced, right arm-raising movements at low and high velocities. Movements were recorded by an optoelectronic system enabling the synchronization of video, force plate and electromyographic data. The force platform provided information on vertical torque and centre of foot pressure anteroposterior displacement. Electromyography activity was recorded from the right anterior deltoid and the bilateral biceps femoris, tibialis anterior and soleus muscles. FINDINGS: Rapid, voluntary, unilateral movements were associated with an early centre of pressure backward shift, anticipatory vertical torque and electromyographic activities. In slow movements, only the anticipatory changes in vertical torque were consistently observed, with the same latency as in rapid movement. INTERPRETATION: The existence of vertical torque in slow movement (when stabilisation of the centre of mass is not necessary) shows that this parameter does not serve to minimise the centre of mass displacement but rather contributes to the generation of arm movement.

Adaptation, Physiological↗
PubMed2005

Abnormal cortical mechanisms in voluntary muscle relaxation in de novo parkinsonian patients.

This study aimed at elucidating how the cortical mechanism underlying the preparation and the postmovement phase of voluntary hand muscle relaxation is affected in Parkinson's disease. Event-related mu and beta (de)synchronization (ERD/S) related to voluntary muscle contraction and relaxation were recorded in 16 untreated, akineto-rigid, predominantly hemiparkinsonian patients. The results were compared with data from 10 age-matched, healthy subjects. In the muscle relaxation task, the subject held the wrist in an extended position and then let the hand drop by voluntarily relaxing wrist extensor contraction, i.e., without any overt, associated muscle contraction. In the muscle contraction task, subjects performed a self-initiated brief wrist extension. A same pattern of ERD/S was observed in control subjects and parkinsonian patients performing the motor tasks with their less affected limb. In contrast, related to voluntary relaxation performed with the more affected limb, a delayed mu and beta ERD and a disappearance of beta ERS were revealed. These results demonstrate that the pattern of cortical oscillatory activity in a relaxation task is abnormal in parkinsonian patients. The authors suggest that this may be due to anomalous activity in inhibitory motor cortical systems and impaired sensorimotor integration of afferent inputs from muscle and joint receptors.

Adult↗
PubMed2004

Cognitive and SPECT characteristics predict progression of Parkinson's disease in newly diagnosed patients.

OBJECTIVE: To identify features in cognitive functioning and regional cerebral blood flow (rCBF) in newly diagnosed Parkinson's disease (PD) patients and to determine whether these factors are able to predict the progression of the disease in general and the development of cognitive decline in particular. METHODS: 50 previously treatment-naive PD patients participated in the study. Cognitive assessment and SPECT were performed twice: at the time of diagnosis and then 3 years later. Six patients died or refused to continue. The Mattis dementia rating scale, the WAIS-R digit span test, a word list learning/recall test, a word fluency task and the Stroop word-colour test were used to assess cognitive function. rCBF was measured in 10 pairs of regions of interest. Principal component analysis of the data from the final examination was used to determine which variables allowed the formation of patient subgroups. Thereafter, factorial discriminant analysis (FDA) was performed in order to obtain a predictive model of these final classes. RESULTS: A stepwise procedure enabled the identification of 3 clusters (26, 16 and 2 patients). As the patients in the smallest cluster met the criteria for dementia at the final examination, they were discarded from further analyses. All the cognitive variables contributed to the constitution of the two other clusters. Age, educational level and all the rCBF parameters also contributed but to a lesser extent. Comparison of these groups showed reduced overall cognitive efficiency and an exacerbated subcorticofrontal syndrome in the 16-patient cluster. FDA showed that the best predictive model for the final classes was based on 7 variables: educational level, semantic and alternating word fluency, Stroop interference index and the right medial frontal, left parietal and left lenticular nucleus rCBF findings. CONCLUSION: Even though both cognitive and rCBF parameters help predict the progression of newly diagnosed PD patients and bearing in mind the limitations of the SPECT method used here, it appears that the contribution of cognitive assessment is greater than that of rCBF measurement.

Aged↗
PubMed2004

Deficits in decoding emotional facial expressions in Parkinson's disease.

INTRODUCTION: The basal ganglia have numerous connections not only with the motor cortex but also with the prefrontal and limbic cortical areas. Therefore, basal ganglia lesions can disturb motor function but also cognitive function and emotion processing. The aim of the present study was to assess the consequences of Parkinson's disease (PD) on ability to decode emotional facial expressions (EFEs)-a method commonly used to investigate non-verbal emotion processing. METHODS: Eighteen PD patients participated in the study, together with 18 healthy subjects strictly matched with respect to age, education and sex. The patients were early in the course of the disease and had not yet received any antiparkinsonian treatment. Decoding of EFEs was assessed using a standardized, quantitative task where the expressions were of moderate intensity, i.e. quite similar to those experienced in everyday life. A set of tests also assessed executive function. Visuospatial perception, depression and anxiety were measured. RESULTS: Early in the course of the disease, untreated PD patients were significantly impaired in decoding EFEs, as well as in executive function. The deficits were significantly interrelated, although neither was significantly related to severity of the motor symptoms. Visuospatial perception was not impaired, and the patients' impairment was related neither to their depression nor to their anxiety score. The PD patients' impairment in decoding EFEs was related to a systematic response bias. CONCLUSION: Early in the course of PD, non-verbal emotional information processing is disturbed. This suggests that in PD, nigrostriatal dopaminergic depletion leads not only to motor and cognitive disturbances but also to emotional information processing deficits. The observed correlation pattern does not enable adoption of a clear-cut position in the debate over totally or partially segregated functional organization of the basal ganglia circuits.

Aged↗
PubMed2003

Effects of subthalamic nucleus stimulation and levodopa treatment on gait abnormalities in Parkinson disease.

BACKGROUND: Stimulation of the subthalamic nucleus is proposed for the treatment of patients presenting with severe Parkinson disease. The effect on gait is not clearly established. OBJECTIVES: To evaluate objectively the influence of bilateral subthalamic nucleus stimulation on gait in Parkinson disease and to compare it with the effects of levodopa treatment. METHODS: Ten patients underwent bilateral subthalamic nucleus stimulation. The preoperative and postoperative (3 months after surgery) clinical gait disturbances, as well as spatial and temporal gait parameters, were analyzed in off and on-drug conditions. The gait analysis was performed using a video motion analysis system (optoelectronic VICON system; Oxford Metrics, Oxford, England). RESULTS: In the off condition, there was an improvement after surgery for the total motor score and the gait subscore. In the on-drug condition, there was an improvement in levodopa-induced dyskinesias and the motor score, whereas the gait subscore was unchanged. For the gait parameters measured by the video motion analysis system system, there was also an improvement in the off condition and to a lesser extent in the on-drug condition. CONCLUSIONS: Our method allowed exact quantification of the benefit of surgery on gait parameters. Compared with the levodopa treatment, the effect of stimulation on gait kinematic parameters seems to be qualitatively similar but quantitatively different with a lower benefit on gait velocity and stride length. Concerning the pathophysiology of gait troubles in Parkinson disease, the deficit in control of stride length would be the fundamental deficit. The study underlines the possible role of the subthalamic nucleus on the stride length regulation.

Antiparkinson Agents↗
PubMed2003

Executive function differences in multiple system atrophy and Parkinson's disease.

The aim of the present study was to assess executive function in patients with multiple system atrophy (MSA) and Parkinson's disease (PD) looking for specific differences and considering motor disability and disease duration. Performance of 11 MSA patients was compared to that of 12 healthy controls and two groups of 12 PD patients, one matched with respect to the severity of motor symptoms and the other with respect to disease duration. Compared to healthy controls, MSA and PD patients both presented executive dysfunction but, in MSA, the impairment was more severe and diffuse. This study suggests that despite the evidence of some differences in executive function in MSA and PD, the contribution of standard neuropsychological examination to the differential diagnosis of both syndromes remains still limited.

Adult↗
PubMed2002

[Anticipatory postural adjustments associated with arm flexion: interest of vertical torque].

OBJECTIVE: To find a biomechanical parameter able to characterize postural adjustments in different movement conditions. METHODS: The arm-raising movement performed during the upright human position imposes a vertical torque (Tz) that can be measured by a force plate-form. This torque was studied in ten healthy young subjects with opto electronic system Vicon 370. The subjects stood on a force platform, performed shoulder flexion of their right arm, to grasp a handle in front of them, in five conditions : self-paced at 3 different velocities (slow, medium, maximal), triggered by an auditory signal, loaded (1 kg attached to the wrist), all at maximal velocity. In a sixth condition, the arm was passively displaced by an experimenter. RESULTS: Tz displayed a negative phase (counter-clock wise body rotation) in all conditions. A positive phase occurred prior to the negative one, and preceded movement onset only if the movement was voluntary. In the triggered condition, the positive phase of Tz was delayed (- 60 ms) compared to the self-paced condition at maximal velocity (- 155 ms). However Tz onset latency was modified neither by load nor velocity. Tz amplitude increased with increasing velocity, load and in a reaction time condition. CONCLUSIONS: The vertical torque Tz, especially its positive phase gives useful informations about the latency, duration and intensity of the postural preparation related to a voluntary movement, according to the movement parameters. Tz is therefore able to characterise postural adjustments in all conditions, even with low movement velocity.

Adaptation, Physiological↗
PubMed2002

Relationship between oscillations in the basal ganglia and synchronization of cortical activity.

The functions of oscillations within the basal ganglia are poorly understood. We discuss in the present paper, the possible physiological or pathological roles of oscillatory activities within the basal ganglia, and their relationship to cortical oscillations. Three aspects are presented: 1. What do we know from animal studies? 2. What do we know from neurophysiological studies in parkinsonian patients? 3. What is the effect of L-dopa treatment and electrical stimulation within basal ganglia circuits on cortical oscillations? Animal studies suggest that neuronal oscillations are spontaneously generated within the basal ganglia system, especially from the GPE and the subthalamic nucleus (STN), but are mainly synchronized by cortical activity via the striatal inputs. Dopamine depletion results in a global increase of oscillations within the whole basal ganglia system, particularly in the GP-NST network. Oscillations within the basal ganglia may, in part, be related to tremor since they are enhanced, especially in the globus pallidus internus (GPI) and the STN, in human and animal dopaminergic depletion. However, they also play a role in the physiology of movement as revealed by coherence analysis between cortex, muscles and GPI/STN in parkinsonian patients undergoing deep brain stimulation. It is known that the basal ganglia may influence cortico-muscular oscillations such as the Piper rhythm and other rhythms in the beta band. In off-drug parkinsonian patients, low frequency oscillations (4-10 Hz) are favoured, presumably resulting in bradykinesia and low force. When medically (Ldopa) or surgically (deep brain stimulation) treated, these low frequency oscillations are replaced by high frequency (70 Hz) oscillations that are important for motor programs to be correctly executed. Studies of cortical reactivity related to planning of voluntary movement in parkinsonian patients provide evidence that it is possible to influence cortical reactivity through the basal ganglia system.

Animals↗
PubMedDate not supplied

Alpha-synuclein locus duplication as a cause of familial Parkinson's disease.

Genomic triplication of the alpha-synuclein gene (SNCA) has been reported to cause hereditary early-onset parkinsonism with dementia. These findings prompted us to screen for multiplication of the SNCA locus in nine families in whom parkinsonism segregates as an autosomal dominant trait. One kindred was identified with SNCA duplication by semiquantitative PCR and confirmed by fluorescent in-situ hybridisation analysis in peripheral leucocytes. By contrast with SNCA triplication families, the clinical phenotype of SNCA duplication closely resembles idiopathic Parkinson's disease, which has a late age-of-onset, progresses slowly, and in which neither cognitive decline nor dementia are prominent. These findings suggest a direct relation between SNCA gene dosage and disease progression.

Adult↗
PubMedDate not supplied

[Motor complications in dopa treatment of parkinson disease: clinical description and evaluation].

The aim of this study was to present the clinical characteristics of and the evaluation methods for the motor complications sometimes observed in the early stages of Parkinson's disease, differentiating motor fluctuations and levodopa-induced dyskinesias. The most common forms of motor fluctuations are the predictable end-of-dose deterioration (wearing off), the early-morning akinesia, and the on-off phenomenon. Non-motor fluctuations are often associated with different symptoms: dysautonomia, pain, psychic or cognitive signs during off periods and sometimes also during on periods. Levodopa-induced dyskinesias are classified according to their temporal profile after drug administration, namely peak-dose dyskinesias (mainly choreic movements), biphasic dyskinesias--onset and end-of-dose--(mainly dystonic and ballic movements), and finally off-period dyskinesias (dystonic movements). Clinical evaluation of motor complications must be performed precisely to establish the best therapeutic strategy.

Antiparkinson Agents↗