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Biomedical subjects

J D Guieu

Publications and source records attributed to J D Guieu.

At least 19 recordsLinked to original sources
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↗
PubMed1995

Event-related desynchronization (ERD) patterns during memory processes: effects of aging and task difficulty.

Event-related desynchronization (ERD) was studied in 10 young (mean age = 19.1) and 10 older (mean age = 62.8) subjects during two recognition tasks: verbal and visuo-spatial. The difficulty of these tasks varied according to the difficulty to distinguish between targets and distractors. EEGs recorded from 29 electrodes were used to compute ERDs from 14 source derivations in 125 msec intervals. Thereafter, they were displayed as spatio-temporal maps. The results show that desynchronization was more widespread in the visuo-spatial compared to the verbal task. This was observed in the two age groups, although it was more pronounced in the young subjects. The effect of task complexity was also influenced by the kind of material to be remembered: more differences between the two levels of difficulty were observed during the verbal task. The results revealed significant influences of the task and time variables on the ERD patterns. A distinct time course of the desynchronization phenomenon was observed to be related to the kind of recognition task. Age and task complexity interacted with the other variables.

Adolescent↗
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↗
PubMed1994

Event-related desynchronization (ERD) patterns during verbal memory tasks: effect of age.

Event-related desynchronization (ERD) was studied in 10 young (mean age = 19.1) and 10 older (mean age = 62.8) subjects during a verbal recognition task. The attention load of the task varied according to the difficulty of discriminating between targets and distractors. EEG recorded from 29 electrodes was used to compute ERD from 14 source derivations in 125 ms intervals. Thereafter, it was displayed as spatiotemporal maps. The results show that attention influences the characteristics of EEG desynchronization. In young subjects, ERD is more pronounced and more widespread when the attentional load is high. In the elderly, differences between the two attention conditions are less marked. ANOVA reveals main effects of attention and time. The significant 'attention x time x age group' interaction confirms the presence of different brain activation patterns in the two age groups in relation to attention load.

Adolescent↗
PubMed1994

[Surgical treatment of snoring and sleep apnea syndromes. Results apropos of 59 cases].

From 1991 to 1993, 59 patients underwent surgical cure for snoring. Polysomnography was performed 47 times when history taking and clinical signs revealed diurnal and nocturnal manifestations. Sleep apnea was confirmed in 20 patients with a mean apnea-hypnea index of 34.1. Treatment was based on surgery of the velum palatinum in 59% of the cases, the palatine tonsils in 39% and the basilingual tonsils in 1 patient. Snoring disappeared in 24 patients (40%) and improved for 75% satisfaction in 22 patients (37%).

Adult↗
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

P300 component of the event-related potentials (ERP) during an attention task: effects of age, stimulus modality and event probability.

The effects of age, stimulus modality and event probability on event-related potentials (ERP) were studied in 12 young and 12 elderly healthy subjects. The ERP were recorded from 15 electrodes referred to linked ears. Results showed that both amplitude and latency of the P300 component are affected by aging. Study of the latency of the earlier ERP components in the two age groups revealed that the P300 delay was not imputable to a delay of the earlier components. P300 amplitude and latency were also affected by event probability and stimulus modality: infrequent stimulus involved higher and later P300, but this effect was more pronounced in the young than in the old group; higher and later P300 were also recorded during the visual task compared to the auditory. Topographical repartition of the brain wave revealed a predominance of the central sites (Fz, Cz, Pz). The findings are discussed in relation to the sensitivity of the ERP assessment procedures in age related modifications of information processing.

Acoustic Stimulation↗
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↗
PubMed1993

[Topographical study of event-related desynchronization: value in the psychophysiologic approach to cognitive processes].

The interest of the event-related desynchronization study has already been evidenced, for example in the study of the cerebral activation modifications consecutive to cognitive processes. We observed here the evolution of this index during a recognition task where the material to memorize varied. Ten young subjects had to learn and then recognize a list of words or forms. The desynchronization of the alpha rhythm consecutive to each stimulus was recorded at 14 localizations on the scalp. We observed that the time evolution of the event-related desynchronization was different in each task. In the visual task, the phenomenon began sooner and was longer lasting. As long as the cortical area were concerned, any dominance nor interhemispheric difference were observed. During the visuospatial recognition task, the event-related desynchronization was however more widespread.

Adolescent↗
PubMed1993

Chronic thalamic stimulation improves tremor and levodopa induced dyskinesias in Parkinson's disease.

Chronic thalamic stimulation was performed in 10 Parkinsonian patients with disabling tremor and poor response to drug therapy. During the stereotactic procedure, an electrode was introduced in the ventralis intermediate nucleus of the thalamus. Test stimulation was performed during the intra-operative procedure and a few days after surgery using an external stimulator. When tremor was obviously reduced by thalamic stimulation, an internal stimulator was implanted under the clavicle. Tremor was initially suppressed in all cases and reappeared whenever stimulation was stopped. Patients were followed for 22 to 34 months. Tremor was controlled in eight cases but reappeared after three months in two cases. Levodopa induced dyskinesias were observed before electrode implantation in 5 cases. They consisted of peak-dose choreic or ballistic dyskinesias in 4 cases and biphasic dystonic dyskinesias in 3 cases. Peak-dose dyskinesias were greatly improved or suppressed in all cases. Biphasic dyskinesias were improved in 2 cases. Thalamic stimulation was well tolerated. Mild dystonic hand posture related to the deep brain stimulation was observed in one case. No neuropsychological side-effects were noted. Thalamic stimulation could prove to be an adequate treatment for resistant tremor and levodopa induced dyskinesias.

Aged↗
PubMed1992

Motor evoked potentials to magnetic stimulation: technical considerations and normative data from 50 subjects.

Magnetic stimulation of the brain and cervical and lumbar spinal roots was performed on 50 healthy volunteers. Compound muscle action potentials (CMAPs) were recorded from biceps brachii, abductor digiti minimi (ADM), rectus femoris and tibialis anterior (TA). We assessed central conduction times by subtraction of peripheral from central latencies and compared results using either spinal root stimulation or the F-wave method. Side-to-side differences of total conduction time, peripheral conduction time and central conduction time (CCT) were measured and the effect of clockwise vs counterclockwise stimulations on latencies and sizes of CMAPs is emphasized. Amplitudes and areas of CMAPs were expressed as a percentage of the peripheral M response for ADM and TA. There was a positive correlation between CCT to the lumbosacral region and height, but not between the cervical region and height. No correlation was observed between genders and central conduction times, amplitudes or areas of CMAPs.

Action Potentials↗
PubMed1992

Control of tremor and involuntary movement disorders by chronic stereotactic stimulation of the ventral intermediate thalamic nucleus.

The authors report on the long-term results of chronic stereotactic stimulation of the ventralis intermedius thalamic nucleus performed in 14 cases of disabling and intractable tremor. There were 10 patients with parkinsonian tremor and four with essential tremor. Three of the 10 parkinsonian patients had previously undergone contralateral thalamotomy. Tremor was assessed by clinical evaluation, surface electromyography, accelerometer, and videotape recordings before and after stimulation. The deep-brain electrode was implanted in the ventralis intermedius nucleus according to stereotactic procedure and connected to a subcutaneous pulse generator after a stimulation test period. Tremor suppression or reduction was obtained in all cases with high-frequency (130 Hz) stimulation. Marked functional improvement was maintained in 11 patients with a mean follow-up interval of 17 months. Levodopa-induced dyskinesias observed in five parkinsonian patients prior to surgery were improved or suppressed in four cases by thalamic stimulation. Stimulation was continued during the day and stopped at night in eight cases. Six patients were stimulated night and day to avoid a rebound effect which appeared as soon as the pulse generator was stopped. The only side effects were hand tonic posture in one case and persistent paresthesia in another case. The mechanism of action of this attractive treatment may be a functional alteration of the thalamic discharging area. The authors conclude that this technique is a good alternative to thalamotomy, especially when the risks of high-frequency coagulation are severe in frail and older patients.

Adult↗
PubMed1991

[Chronic sciatalgia caused by sensitive deafferentiation following surgery for lumbar disk hernia: clinical and therapeutic aspects. Apropos of 110 patients].

Sensitive deafferentation is a well recognized entity which has changed the therapeutic approach of some kinds of chronic post operative sciatalgia. It mainly occurs related with a long story of radicular pain and the responsibility of so-called epidural fibrosis has to be discussed. The case records of 110 consecutive patients with deafferentation sciatalgia were reviewed and the clinical data precised: chronic and lasting burning pain with acute nightly paroxysms and sensitive alterations at objective examination. Neuroradiological explorations eliminated the possibility of recurrent disc herniation and neurophysiological tests assessed the chronic radicular suffering and the degree of lemniscal degeneration. After medical treatment (analgesic drugs with central tropism), a strict clinical assessment of pain intensity allowed optimal choice of the technique of neurostimulation: transcutaneous electrical stimulation (51 patients) and/or spinal cord stimulation (59 patients). The efficacy of transcutaneous stimulation (40 excellent and good results) was most often related to its continuous utilisation with a short post-effect. Its side-effects and the frequency of multiradicular involvement lead to spinal cord stimulation. With a mean follow-up period of 37 months, the pain relief was considered as excellent in 51.5%, good in 38% and poor in 8.5% of the patients. One patient had a negative test and was not definitively implanted. Another case failed to respond to stimulation. The clinical and technical complication of the method are reported.

Adult↗
PubMed1991

[Right unilateral auditory agnosia following left lenticular hemorrhage].

A 33-year old patient who had had left lenticular hemorrhage presented with an inability to understand with the right ear oral language and, in a less dramatic way, nonverbal sounds. This unilateral auditory agnosia was first associated with a right motor underutilization and right motor, sensitive, visual and auditive extinctions. Speech discrimination scores were 100% with the left ear and 15% with the right ear, even less in dichotic conditions. Tonal audiogram, as well as early and late components of the auditory evoked potentials were normal. Cerebral regional perfusion and metabolism were impaired over the left parietotemporal area. There was severe hypoactivation of the left hemisphere with right monaural verbal stimulations. Rehabilitation consisting of non-specific attention tasks and repetitions of words reaching only the right ear was undertaken 15 months after the stroke. The oral language comprehension improved, as did the left hemisphere activation, and the extinction phenomena disappeared, except for the auditory one. The unilaterality of the auditory agnosia could be due, in part, to a peculiar physiological processing in this patient, such as poor performance of his right ipsilateral auditory pathway which could be improved with practice. A striatal lesion could induce a spatial hemi-inattention as reflected by the multimodal extinction in this case. Besides, a lack of selective activation for verbal stimulation of the left hemisphere is suggested.

Adult↗
PubMed1991

[Hereditary parkinsonism-dystonia syndrome of juvenile onset with diurnal fluctuations].

Symptoms of fluctuating dystonia developed in 4 subjects of the same family during childhood or adolescence. In the 2 sisters, these symptoms were initially or subsequently associated with signs of parkinsonism, whereas in the 2 brothers they disappeared, spontaneously in at least 1 case, and signs of parkinsonism appeared later after a free interval. Anticholinergic agents and L-Dopa proved very effective against all extrapyramidal signs. These cases are similar to those gathered by Nygaard et al. in 1988 under the term "Dopa-responsive dystonia". Yet laboratory data seem to confirm that the common physiological mechanism is a disorder of tetrahydrobiopterin metabolism. Serum and urinary biopterin levels were lowered in our 4 cases but were normal in an unaffected sister. However, like the subjects affected this third sister showed a decrease of platelet serotonin which was taken as being a consequence of aromatic aminoacid hydroxylation defect due to tetrahydrobiopterin deficiency.

Adolescent↗