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F Viallet

Publications and source records attributed to F Viallet.

At least 37 records · Page 2Linked to original sources
PubMed1996

Impairment of posturo-kinetic co-ordination during initiation of forward oriented stepping movements in parkinsonian patients.

In order to differentiate between a specific impairment affecting gait initiation and a non-specific deficit in the postural adjustment which occurs prior to any forward oriented stepping movement, 3 forward oriented movements (FOMs), performed by a group of parkinsonian patients and a group of healthy age-matched subjects, were compared in the present study. These FOMs all consisted of initiating 1 step, but differed in their respective planning characteristics. The first consisted of initiating normal walking. The second consisted of initiating a single step, while the third was a visually guided task, consisting of placing the foot just behind a mark on the ground. In all 3 FOMs, the postural phase, i.e., the time elapsing between the initial shift of the center of pressure (CP) and the onset of the first step, was significantly longer in the patients than in the healthy subjects, whereas the duration of the subsequent movement phase, i.e., that of the first step, was within the same range in both groups. The horizontal reaction forces that led to a forward center of gravity (CG) acceleration during the postural phase were markedly reduced in the patients in all 3 FOMs, and the maximal velocity of the iliac crest marker, which corresponds approximately to that of the CG, decreased significantly in the patients. In addition, the length of the first step was significantly shorter in the patients than in the healthy subjects, in all 3 FOMs. The EMG pattern differed significantly between the patients and the healthy subjects; the amplitudes of the early tibialis anterior (TA) and vastus lateralis (VL) activations often decreased and were unilateral rather than bilateral. In addition, the gastrocnemius medialis (GM) burst associated with foot lift-off at the end of the postural phase was either absent or greatly reduced, thus suggesting that the co-ordination between the preparatory postural adjustment of the whole body and the actual stepping movement was impaired. The present results suggested that the lengthening of the postural phase is a common deficit in all FOM tasks in parkinsonian patients and is due to the impaired production of the requisite propulsive forces providing the forward acceleration of the CG. Consequently, a shortening of the first step length occurs. However, the step length is reduced less in the FOM tasks which provide some information about the goal of the first step (single step, visually guided step) than in a normal walking task, during which such information is missing. This suggests that although the stepping movement can be improved with the aid of any sensory cue about the end of the step in patients with Parkinson's disease, the postural phase will always be prolonged whichever FOM task they perform.

Aged↗
PubMed1996

[2 cases of frontal dementia with non-specific histological lesions: clinico-pathological and nosological discussion].

We report two cases of "frontal lobe dementia", patho-anatomically defined by non-specific as neuronal loss, gliosis and spongosis. The review of the literature permit to discuss the clinical picture of "fronto-temporal dementia" in regard to neuropathological basis. Further, the boundaries with Pick's disease, Kraepelin disease, subcortical gliosis and the "prions diseases" are considered. Without more precise nosological status, tacking in count the great variability of the clinical signs, we can concluded that, at present time, the term of frontal type dementia with "non-specific histological features", that underlines the neuropathological characteristics is the most appropriate to define this clinico-pathological entity.

Aged↗
PubMed1995

Magnetic resonance imaging evidence of decreased putamenal iron content in idiopathic Parkinson's disease.

OBJECTIVE: To determine the changes in basal ganglia iron content associated with various stages of idiopathic Parkinson's disease. DESIGN: Prospective magnetic resonance imaging study using a 2-T magnet. SETTING: Ambulatory care referral center. PATIENTS AND PARTICIPANTS: Forty-five patients suffering from levodopa-responsive Parkinson's disease and 45 age-matched controls. MAIN OUTCOME MEASURES: The T2 relaxation time calculated in various regions of the basal ganglia, the duration of Parkinson's disease, and the age of subjects. RESULTS: Patients with Parkinson's disease exhibited significantly decreased T2 relaxation time in the pars compacta of the substantia nigra compared with controls (P < .01), regardless of disease duration. Patients with a duration of illness above 10 years (n = 12) exhibited significantly increased T2 relaxation time in the anterior and posterior putamen (P < .005 and P < .01, respectively) and in the pallidum (P < .05) compared with age-matched controls. Putamental T2 relaxation time positively correlated with disease duration (P < .05). CONCLUSION: These results suggest that more complex brain iron changes than those previously reported are associated with idiopathic Parkinson's disease, including increased nigral iron content and decreased putamenal and pallidal iron concentration in patients with a duration of illness above 10 years.

Adult↗
PubMed1995

Planning and execution of pointing movements in cerebellar patients.

Twelve patients with cerebellar dysfunction including a limb ataxia and 12 age-matched controls performed pointing movements with an arm. In one condition, the task was a simple reaction time (RT) movement directed toward a spatially defined target. The other two conditions involved choice tasks in which the amplitude and direction of movement were varied. The variables recorded were: movement latency determined by measuring the RT, duration of movement and the terminal accuracy of pointing as reflected in the movement time (MT), pointing surfaces (PS), and systematic errors. RTs and MTs were found to be significantly longer in cerebellar patients than in controls. In both groups the choice RT increased significantly as compared to simple RT, but no significant difference between patients and controls was found for the mean increase of the choice RT as compared with the mean increase for simple RT. A strong correlation between MTs and PSs was found in the controls. The cerebellar patients showed no correlation between MTs and PSs. The results are discussed in relation to the ability in cerebellar patients to program and execute voluntary movements.

Adult↗
PubMed1995

Bilateral and side-related reaction time impairments in patients with unilateral cerebral lesions of a medial frontal region involving the supplementary motor area.

Human subjects (nine patients with unilateral brain lesions of a medial frontal region involving the supplementary motor area, SMA, and 10 controls) performed two reaction time (RT) tasks in response to the presentation of a luminous signal: an aimed movement towards a spatially defined target involving hand lifting and pointing with the index finger, and a no-aimed movement consisting of the hand lifting phase completed by the stabilization of the limb posture without any pointing. When compared with controls, the patients exhibited a bilateral RT increase which was more pronounced in the hand contralateral to the lesion. Moreover, comparison between the two tasks showed that this contralateral RT impairment was more marked in the no-aiming than in the aiming task. These results suggest that unilateral lesions of a medial frontal region involving the SMA cause two types of RT impairment in these motor tasks. The first may concern a supramotor function which acts bilaterally and initiates the motor programme of the limb movement as the first step of preparatory processes. The second component of this RT impairment would concern a supplementary motor function which consists of the feed forward control of the coupling between the hand lifting and the appropriate posture, just before the triggering of the limb movement. This interpretation leads to the hypothesis that the SMA region, and the medial motor system in general, may have a dual motor function.

Adult↗
PubMed1995

[Diagnosis of narcolepsy-cataplexy: importance of continuous recording in ambulatory EEG. Report of 20 cases].

Ambulatory EEG (A-EEG) allows longterm polygraphic recording over 24 hours or more and proves to be particularly useful in the diagnosis of narcolepsy-cataplexy (N/C). We performed A-EEG using the Medilog 9000-8 channel system over a total of 36 24-hour periods in 20 consecutive N/C patients and recorded an average of 3.5 daytime sleep episodes, of which 2.2 were with SOREMP, AND 21 evening SOREMP (58%). A MSLT was performed using A-EEG in 16 cases. Continuous A-EEG proved to be more informative than the MSLT, and may represent a valid alternative to the classic continuous polygraphic recordings performed in the sleep lab, that are more cumbersome and costly. Although a full-night polysomnographic recording is still necessary whenever other sleep disorders are suspected in association with N/C, A-EEG is a first-line, practical method for the confirmation of N/C, which remains a clinical diagnosis.

Adolescent↗
PubMed1995

Preparatory postural adjustments in parkinsonian patients with postural instability.

BACKGROUND: Postural instability is a common problem in patients with Parkinson's disease. This paper reports results of a study undertaken to investigate some of the possible mechanisms responsible for this instability. METHODS: Preparatory postural adjustments associated with a lateral leg raising task were studied in five parkinsonian patients and four age-matched controls. Recordings included ground reaction forces, kinematics, and surface EMG activity from multiple leg muscles. RESULTS: In normal subjects there was a well-defined sequence of events preceding the onset of leg elevation, beginning with a transfer of centre of foot pressure (CP), initially toward the moving leg and then back to the support side, followed by displacement of the trunk toward the support side. In the more severely affected parkinsonian patients, the amplitude of the initial displacement of CP was markedly reduced. The interval between the earliest force changes and the onset of leg elevation was prolonged and the relative timing of the kenematic adjustments during this interval was disrupted. In addition the alternating burst and periods of inhibition observed in the EMG recordings from the normal subjects were replaced by continuous tonic EMG activity. CONCLUSIONS: These observations suggest that abnormalities in programming preparatory postural adjustments may contribute to postural instability in some patients with advanced Parkinson's disease.

Aged↗
PubMed1995

[Parkinson disease and alkaptonuria: fortuitous association or striatonigral ochronosis?].

We report the case of a 64 year old woman treated for 10 years by DOPA for Parkinson's disease and displaying brown urine. Homogentisic acid was found in urine, establishing the diagnosis of alkaptonuria. Clinical and radiological studies demonstrated ochronosis and ochronotic arthropathy, blue pigmentation of ear cartilage and calcification of the intervertebral lumbar disc giving the classical "inverted spine". Interrelation between this metabolic abnormality and Parkinson's disease is discussed. The recent cloning and mapping of the human gene for alkaptonuria to chromosome 3q should bring some clarification among relationships between these two diseases.

Alkaptonuria↗
PubMed1994

[Quantitative approach of postural asynergia in cerebellar diseases].

In his original description of cerebellar asynergia, Babinski, in 1899, presented a patient with cerebellar dysfunction performing a backward upper trunk bending. When the patient tried to bend his head and trunk, his lower limbs stayed almost motionless, because the associated flexion of the knee and hip, usually observed in a normal subject, did not take place. To reassess the possibility that asynergia may actually be a symptom of cerebellar dysfunction, a combined kinematic and electromyographic (EMG) analysis of the upper-trunk bending was performed on 3 patients suffering from progressive cerebellar ataxia of late onset and showing a significant atrophy of the vermis on MRI examination. Compared with 3 age and sex-matched control subjects, a significant slowing down of the upper-trunk displacement and a marked reduction of the associated displacement of hip and knee was observed. EMG recordings of three pairs of antagonistic muscles at trunk level (rectus abdominis, erectores spinae), at thigh level (vastus lateralis, semi membranosus), and at leg level (tibialis anterior, gastrocnemius lateralis), showed that the reciprocal activation pattern characteristic of a normal fast movement was absent at the thigh level in the cerebellar patients. This lack of reciprocal activation of the thigh muscles during the upper-trunk bending might explain the reduction of the compensatory displacement of the hip and knee. It might also represent an essential feature of cerebellar dysfunction in provoking axial asynergia between the upper-trunk, which is the moving segment, and the leg, which is the supporting segment during equilibrium control and during whole body displacement.

Adult↗
PubMed1992

Coordination between posture and movement in a bimanual load lifting task: putative role of a medial frontal region including the supplementary motor area.

The aim of the present experimental series was to investigate the role of the medial frontal region including the supplementary motor area in the coordination between posture and movement in a bimanual load lifting task. The seated subject was instructed to maintain in a horizontal position one forearm (postural arm) which was loaded with a 1 kg weight. The unloading was performed either by the experimenter (imposed unloading) or by a voluntary movement of the other arm (voluntary unloading). In normal individuals, with the voluntary unloading, the movement control was accompanied by an anticipatory adjustment of the postural forearm flexor activity, which resulted in the maintenance of the forearm position despite the unloading. The anticipatory postural adjustments were impaired in 4 out of 5 patients with unilateral lesion of the SMA region; the defect was observed mainly when the postural forearm was contralateral to the lesion. No change in the anticipatory postural adjustment was observed in one patient with complete callosal section. This finding indicates that the coordination between the posture and movement in this task is not organized through callosal fibers linking the cortices on both sides but rather at a subcortical level. The anticipatory postural adjustments were abolished in two patients with spastic hemiparesis when the postural forearm was the spastic arm. It is suggested that the SMA region contralateral to the postural forearm, together with other premotor or motor areas, may select the circuits responsible for the phasic postural adjustments which are necessary to ensure postural maintenance, whereas the motor cortex contralateral to the voluntary movement controls both the movement and, via collaterals, the preselected circuits responsible for the associated postural adjustments.

Adult↗
PubMed1990

Multiple sclerosis: cell-mediated immunity to human brain gangliosides.

Cell-mediated immunity (CMI) to myelin components has been implicated in Multiple Sclerosis (MS) pathogenesis: two targets were suggested, Myelin Basic Protein with controversial results and, more recently, gangliosides. In order to investigate their possible involvement, we have performed Leukocyte Migration inhibition (LMI) tests in the presence of human brain gangliosides. Thirty nine MS patients (twenty four being "definite", according to McDonald and Halliday's classification), twenty nine patients with Other Neurological Diseases (OND), thirty six patients with Inflammatory diseases (ID) and forty healthy controls were tested. MS patients were divided into two groups, depending on the clinical stage of the disease. The mean migration inhibition percentage of the MS-attack group was found to be significantly different from the four others (p less than 0.01) (24.4 +/- 16.2 versus 10.9 +/- 8.5 in MS without attack, 4.4 +/- 12.9 in OND, 3.9 +/- 13.9 in ID and 11.1 +/- 12.1 in healthy subjects). LMI to gangliosides is therefore significantly increased during the attack stage in MS. These results support the notion of a Delayed Type Hypersensitivity to these glycolipids during the active stage of the disease.

Adult↗
PubMed1989

Experimental bradykinesia in the monkey: speed control impairments after lesion of the substantia nigra.

Unilateral lesions of the substantia nigra were performed on baboons which had been previously trained to perform a visual pointing movement. The resulting motor impairment consisted of an increase in movement duration. This bradykinesia shows as a regular decrease in velocity. A possible change in mode of motor control caused by lesion of the SN is discussed. Partial exclusion of SN might bring about a shift from the feedforward to a feedback mode relaying more heavily on visual cues.

Acceleration↗
PubMed1989

[The supplementary motor area is implicated in the coordination between posture and movement in man].

The aim of the present experimental series was to investigate the central organization of the coordination between posture and movement in a bimanual load lifting task. The seated subject was instructed to maintain horizontal one forearm (postural arm) which was loaded with a 1 kg weight. The unloading was performed either by the experimenter (imposed unloading) or by a voluntary movement of the other arm (bimanual unloading). With the bimanual unloading, the movement control was accompanied by an anticipatory adjustment of the postural forearm flexors activity, which resulted in the maintenance of the forearm position despite the unloading. No change in the anticipatory postural adjustment was observed in one patient with complete callosal section. It was reduced in 5 patients with lesion of the SMA region, but only when the postural forearm was contralateral to the lesion. It is suggested that the SMA region contralateral to the postural forearm may select the circuits responsible for the phasic postural adjustments which are necessary to ensure postural maintenance, whereas the motor cortex contralateral to the voluntary movement controls both the movement and, via collaterals, the preselected circuits responsible for the associated postural adjustment.

Adult↗
PubMed1988

Long-term follow-up after stereotaxic basal ganglia surgery in parkinsonism. A neuroanatomical study of a case showing unusual postural disorders.

A 60-year-old man who had Parkinson's disease for 25 years became unable to maintain the upright position of the trunk while standing or walking. Because of a loss of postural fixation, his trunk sank forward until his back was horizontal. Fifteen years before, a bifocal implantation of radioactive yttrium-90 had been performed by a stereotaxic procedure at the level of the globus pallidus (GP) and the ventrolateral thalamus, respectively on the right side. A second operation, 2 years later, had been made by electrocoagulation in the left ventrolateral thalamus. Postmortem examination showed the following features (a) neuronal cell loss in the pigmented nuclei of the brainstem with intracellular Lewy bodies and gliosis. These data corresponded with the usual pathology of idiopathic Parkinson's disease; (b) surgical lesions resulting from the previous stereotaxic operations in the right GP and the ventrolateral thalamus on both sides and (c) neuronal cell loss without gliosis in the right GP that was evident in regions spared by the surgical lesion. Moreover, these degenerative changes were particularly seen in the left GP, which was surgically unlesioned. The ansa lenticularis was demyelinated on both sides. These data might be consistent with a retrograde degenerative process affecting the pallidothalamic projections. Beside the role of the neuronal cell loss affecting the pars compacta of the substantia nigra (SN) in akinesia, the role of the lesions affecting the G.P. in the genesis of postural disorders is suggested.

Follow-Up Studies↗
PubMed1987

[The anterior pituitary endocrine function in Parkinson's disease].

Dopamine exerts an inhibitory or stimulant action on some of the hormones produced by the anterior pituitary gland. The dopamine content of the hypothalamus is considerably reduced in patients with Parkinson's disease. We have tested the anterior pituitary endocrine function in such patients to evaluate the repercussions on this function of the dopaminergic deficiency: the secretion of pituitary stimulins was found to be unaltered both at baseline level and after pharmacological stimulation.

Aged↗