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L Defebvre

Publications and source records attributed to L Defebvre.

At least 55 records · Page 3Linked to original sources
PubMed1998

Dystonia after striatopallidal and thalamic stroke: clinicoradiological correlations and pathophysiological mechanisms.

OBJECTIVE: To establish the pathophysiological mechanisms of striatopallidal and thalamic dystonia. METHODS: Five patients from among 26 who presented (between March 1987 and July 1996) with focal dystonia, segmental dystonia, or hemidystonia caused by a single localised vascular lesion, were selected. Patients with lesions with indefinite boundaries, and diffuse, or multiple, or large brain lesions were excluded. Three dimensional T1 weighted MRI (1.5 tesla) was performed to determine the topography of the lesions. The atlas of Hassler allowed the stereotactic localisation of the lesions to be specified exactly. RESULTS: Three patients had dystonic spasms associated with striatopallidal lesions and one with a thalamic and striatopallidal lesion. One other patient presented with a myoclonic dystonia related to a thalamic lesion. The striatopallidal lesions were located in the sensorimotor area with a somatotopical distribution. The pure thalamic lesion involved the centromedian nucleus, the sensory nuclei, and the pulvinar whereas the thalamic and striatopallidal lesion was located in the pallidonigral thalamic territory, which receives pallidonigral inputs. CONCLUSION: The striatopallidal dystonia might be the consequence of the interruption of the cortico-striato-pallido-thalamo-cortical loop induced by lesions located within the sensorimotor part of the striatopallidal complex. By contrast, it is suggested that thalamic dystonia might be caused by lesions located in the centro-median or the ventral intermediate nuclei, outside the pallidonigral territory, but leading also to a dysfunction of the cortico-striato-pallido-thalamo-cortical loop.

Adult↗
PubMed1997

Abnormal cortical activation during planning of voluntary movement in patients with epilepsy with focal motor seizures: event-related desynchronization study of electroencephalographic mu rhythm.

PURPOSE: The spatiotemporal distribution of EEG mu rhythm desynchronization was analyzed in patients with partial epilepsy to determine whether frequent focal motor seizures could induce a change of cortical activation during the planning of a voluntary movement. METHODS: The event-related desynchronization (ERD) of the mu rhythm was quantified during a self-paced voluntary movement of the thumb. The results were compared between two groups of patients with epilepsy: in one group (n = 12), the patients had frontal lobe epilepsy with frequent focal motor seizures (FMS); in the second group (n = 12), they had temporal lobe epilepsy (TLE) with complex partial seizures but no ictal movement disorder. The results were also compared with those of control subjects of same age (n = 10). RESULTS: In the control group, desynchronization of mu rhythm began over the contralateral central region 2,000 ms before the movement onset. In the FMS group, the desynchronization of mu rhythm was delayed, appearing only 500 ms before the movement onset, and the amplitude of ERD was increased over the frontocentral region. In the TLE group, the spatiotemporal pattern of ERD was the same as in normal subjects, but the amplitude of ERD was increased. CONCLUSIONS: These results indicate that there is a change of reactivity of mu rhythm in patients with partial epilepsy. The change in spatiotemporal pattern of ERD in patients with frequent focal motor seizures suggests that there is an abnormal cortical activation during the planning of a voluntary movement.

Adult↗
PubMed1997

Hereditary chin trembling or hereditary chin myoclonus?

Hereditary chin trembling is a rare autosomal dominant disease often considered as an "essential tremor variant". The clinical and neurophysiological data obtained in a new white family lead to the suggestion that this abnormal involuntary movement is a focal variant of hereditary essential myoclonus.

Adult↗
PubMed1996

Effect of thalamic stimulation on gait in Parkinson disease.

OBJECTIVE: To assess the influence of ventral intermediate thalamic nucleus stimulation on gait in idiopathic Parkinson disease. DESIGN: Clinical and physiological assessments were compared in patients with and without ventral intermediate thalamic nucleus stimulation. SETTING: The research clinic of a university department of gait analysis. PATIENTS: Seven patients with idiopathic Parkinson disease who had long-term monopolar stimulation of the ventral intermediate thalamic nucleus to control a large-amplitude tremor. MAIN OUTCOME MEASURES: Gait kinematic parameters were autonomically recorded using the Vicon optoelectric system for movement analysis. Measures of locomotor displacement (cadence, walking speed, stride and step times, single and double support times, and stride and step lengths) were computed successfully during 2 conditions: stimulation on and off. Traces of ankle joint position were also analyzed for the left and right lower limbs and for the affected and unaffected lower limbs. RESULTS: No difference in mean values was observed between the 2 conditions. CONCLUSION: This study seems to confirm that ventral intermediate thalamic nucleus stimulation, effective in reducing tremor, does not modify gait parameters in idiopathic Parkinson disease.

Ankle Joint↗
PubMed1996

Movement related desynchronisation pattern preceding voluntary movement in untreated Parkinson's disease.

OBJECTIVE: To study planning of movement in Parkinson's disease. METHODS: The spatiotemporal pattern of movement related desynchronisation (MRD) preceding a self paced voluntary wrist flexion was compared between two groups of 10 untreated right and left hemiparkinsonian patients receiving no treatment and 10 control subjects. The MRD was computed in the 9 to 11 Hz frequency band from 11 source derivations covering the frontocentral, central, and parietocentral areas, during two successive left and right experimental conditions. RESULTS: In the two patient groups the desynchronisation appeared over the primary sensorimotor area contralateral to the affected side with a shorter latency (750 ms before movement onset for the right hemiparkinsonian group and 875 ms for the left hemiparkinsonian group) than in the control group (1750 ms), only when the movements were performed with the akinetic hand. For the non-affected hand, the same latency as in the control group was noted (1750 ms). CONCLUSION: The delay of appearance of MRD in Parkinson's disease confirmed that the programming of movement is affected, thus partially explaining akinesia.

Aged↗
PubMed1996

Multiple calcified brain metastases revealing a lung carcinoma.

The case of a 50-year-old man with multiple calcified brain metastases revealing an undifferentiated lung carcinoma after a delay of two months, is reported. A slow and progressive clinical evolution was noted. Eight months after the brain lesion had been discovered, intramedullary and epidural spinal metastases appeared. However, the calcified brain metastases remained stable 11 months after the diagnosis. One month later the patient died after several episodes of generalized seizures.

Biopsy↗
PubMed1995

Regressive dystonia and cerebellar ataxia: two unusual symptoms in central pontine myelinolysis.

Two patients with central pontine myelinolysis who presented with dystonia are described. In one, it was associated with cerebellar ataxia which spontaneously improved. In the second, dystonia progressively disappeared 6 months later. In both cases magnetic resonance imaging (MRI) revealed characteristic pontine lesions. Extrapontine myelinolysis involving the putamen was also observed in one patient. Even when the basal ganglia seem to be spared on MRI, dystonia is probably due to their involvement by myelinolysis. Cerebellar ataxia may be related to peduncular or cerebellar lesions or both.

Adult↗
PubMed1995

Tomographic measurements of regional cerebral blood flow in progressive supranuclear palsy and Parkinson's disease.

Intellectual changes observed in progressive supranuclear palsy (PSP) are sometimes seen with lesser intensity in Parkinson's disease (PD). Cognitive impairment of PSP has been attributed to a frontal lobe dysfunction explaining the frontal cortex hypometabolism detected by PET. To establish whether this frontal hypometabolism is more pronounced in PSP than in PD, we compared frontal and temporo-parietal cerebral blood flow (CBF) indexes studied by SPECT using Tc99m HmPAO in 18 PSP, 18 PD and 8 control subjects. For each patient neuropsychological performances were also assessed. A significant left frontal hypoperfusion was observed in PSP (mean index value: 0.78 +/- 0.03, p < 0.01) and PD (0.78 +/- 0.04, p < 0.05) as compared to controls (0.84 +/- 0.03), whereas there was no difference between PSP and PD. No correlation was discovered between neuropsychological performances and frontal cortical index changes. This frontal uptake reduction of Tc99m HmPAO in PSP and PD could result from a disconnection phenomenon secondary to subcortical lesions. In both groups mean frontal indexes showed only a left frontal hypoperfusion suggesting that subcortical structures might be asymmetrically involved in early stages of the diseases. The lack of difference for indexe values between PSP and PD might be explained by the difference between the mean disease duration: 4.3 years for the PSP and 7.8 years for the PD. It might also suggest that frontal CBF reduction exists in the same proportions in PD and PSP, but at a later stage in the former case.

Aged↗
PubMed1994

Spatiotemporal study of Bereitschaftspotential and event-related desynchronization during voluntary movement in Parkinson's disease.

Bereitschaftspotential (BP) and Event-Related Desynchronization (ERD) were simultaneously recorded during a voluntary wrist flexion in 10 patients with Parkinson's disease (PD) treated with L-Dopa therapy and 10 control subjects. BP and ERD were analyzed 2 s before and 0.5 s after the movement, during two successive left and right experimental conditions. ERD (9-11 Hz) was computed from 11 source derivations (frontocentral, central, parietocentral). The BP was averaged from these 11 electrodes. For the BP, no spatiotemporal difference was found between the two groups. BP began bilaterally over the 3 groups of electrodes, 1250 ms before movement onset for the right flexion and 1500 ms for the left flexion. A contralateral predominance appeared 500 ms before movement onset over the central area. ERD began in the control group 1750 ms before movement over the contralateral central area, and then appeared bilaterally after its execution. In the PD group, the ERD appeared with a shorter latency than in the control group, 1250 ms (left flexion) and 1000 ms (right flexion) before movement onset; diffusion over the ipsilateral side was found 500 ms before movement onset. ERD also involved the frontocentral area and could be interpreted as a compensatory activity of the supplementary motor area. These findings suggest that with Parkinsonian and control subjects, ERD gives additional and maybe more information than the BP about changes of cortical activity during the motor preparation period. In the PD group the delay of ERD appearance seems to confirm that the programming of movement would be affected, thus explaining partially akinesia.

Aged↗
PubMed1993

Evaluation of event-related desynchronization (ERD) during a recognition task: effect of attention.

Event-related desynchronization (ERD) was studied in 10 subjects during a verbal recognition task. The attentional load of the task varied according to the difficulty to discriminate targets and distractors. The EEG recorded from 29 electrodes was used to compute ERD from 14 source derivations in 125 msec intervals and displayed as spatio-temporal maps. The results show that large brain areas of both hemispheres are significantly activated when the attentional load is high. This cerebral activation pattern is less pronounced when the load is low. ANOVA reveals main effects of attention and time and a significant interaction between attention and time.

Adolescent↗
PubMed1993

Effect of aging on the spatio-temporal pattern of event-related desynchronization during a voluntary movement.

Event-related desynchronization (ERD) of alpha components was studied in young and elderly subjects during planning of voluntary movement. ERD was quantified from 11 source derivations covering regions of the scalp corresponding to the supplementary motor area, the left and right primary sensorimotor areas, the vertex, and the medial posterior parietal cortex. Spatio-temporal display of ERD showed a very different pattern in elderly subjects, with mainly a spatial diffusion of ERD over the parietal and frontal regions. On the contrary, ERD in young subjects was limited to the central regions. ERD was also more lasting in elderly subjects. Changes of the ERD pattern in elderly subjects could indicate a change of cortical activation during voluntary movement. The data also confirm that ERD study is a useful electrophysiological exploration to observe the changes of cortical activation during cerebral aging.

Adult↗
PubMed1993

[Spatiotemporal study of event-related desynchronization during self-paced movement].

The desynchronization of Alpha band components during a self-paced movement of the thumb was studied in 7 subjects. The EEG was recorded from 23 electrodes located on the frontocentral, central, and parietocentral regions, referred to the right mastoïde, 4 s before and 2 s after movement onset. The data were then transformed to obtain 11 source derivations. The temporal evolution of the power of the signal within the Alpha band, every 250 ms, associated to the non parametric statistic test of Wilcoxon, authentifies the event-related desynchronization (ERD). The spatiotemporal analysis of ERD underlines on the central regions, two principal locations of ERD: one controlateral to the movement, starting more than 1 s before the movement; the other, ipsilateral, shorter, during the movement. However, no significance desynchronization was underlined on the vertex. The ANOVA used to analyse these results confirms the principal location of ERD on the central region, and seems to indicate a right lateralisation during the right or the left movement.

Adult↗