Comparaison de l’effet de vibrations cervicales et de vibrations du muscle gluteus medius sur l’équilibre postural statique de sujets sains

National audienceIntroduction : Comparer l’effet et le post-effet de vibrations des muscles du cou (NMV) et de vibrations du gluteus medius (GMV) sur l’équilibre debout statique chez le sujet sain. Méthode Treize sujets sains d’âge moyen 23 ans, droitiers, sont testés debout yeux fermés sur plate-forme de force pendant la vibration (durée 5 min), à l’arrêt et 5 minutes après, au cours de 2 sessions successives NMV gauche ou GMV droite selon un ordre randomisé. Le critère principal était la variation du déplacement moyen du centre de Pression (CoP) sur l’axe médiolatéral. Résultats Les GMV provoquent un déplacement du CoP vers le côté gauche chez 70 % des sujets (9 répondeurs) (moyenne ± SD = 5,2 ± 4,8 mm) (p = 0,003). Immédiatement après, l’effet reste présent (moyenne ± SD = 4,7 ± 4 mm) (p = 0,001) et après 5 minutes, les sujets retrouvent leur position antérieure (moyenne ± SD = 1,25 ± 6,8) (p = 0,33). Pour la NMV, seulement 5 sujets avaient un déplacement vers le côté gauche, qui semblait se maintenir. La variation du CoP n’était pas significative pendant (p = 1), immédiatement après (p = 0,72) et après 5 minutes (p = 0,89). Discussion–conclusion Les GMV provoquent un déplacement chez 70 % des sujets en moyenne d’un peu plus de 5 mm. L’effet des NMV est plus variable d’un sujet à l’autre. Ceci pourrait être expliqué par une action sensorimotrice périphérique majoritaire de la vibration du muscle GM alors que la NMV mettrait en jeu des circuits plus haut situés au niveau de la représentation du corps dans l’espac

CO35-004-e Effect of neck muscles and gluteus medius vibrations on standing balance in healthy subjects

International audienceIntroduction Muscle vibration can be used to improve the center of pressure (CoP) shift. Several muscle sites have been used for various diseases without that we know their respective interest. Objective To compare the effects and post-effects of neck muscle vibrations (NMV) and gluteus medius vibrations (GMV) on balance in healthy subjects Methods Thirteen healthy subjects, mean: 23 years, right handed were tested on posturography, closed eyes, in standing position. They received successively left NMV and right GMV in a randomized order. The variation of the deviation of CoP on the médiolatéral plane was evaluated under vibration stimulation (5 min), at the end of the vibration and 5 minutes after. Results GMV induce a CoP movement to left side (9 responders) (mean: 5.21 mm; SD: 4.79; P = 0.003). At the end of the vibration, the effect remained significant (mean: 4.73, SD: 4.02; P = 0.001) and after 5 minutes, the subjects restored their initial balance (mean: 1.25, SD: 6.82; P = 0.33). For NMV, a movement toward left side was observed only in 5 subjects but this deviation seemed to be maintained at 5 min. The CoP deviation was not significant during (P = 1), immediately after (P = 0.72), and after 5 minutes of NMV (P = 0.89). Discussion GMV cause a lateral shift in 70% of the subjects of nearly 5 mm. The effect of NMV was lower and less constant (only 5 responders) but sustainable. This could be explained by a sensorimotor peripheral action for GMV while NMV would involve high level body representation in spac

Relation entre les perturbations de la représentation égocentrique et l’équilibre après un AVC

National audienceIntroduction L’asymétrie posturale retrouvée en position debout après un AVC est bien connue. Elle est due en partie à un déficit sensorimoteur mais semblerait aussi liée à un trouble de la représentation du corps dans l’espace, dont la perturbation de la perception de l’axe égocentrique. L’objectif de cette recherche est de déterminer si l’asymétrie posturale des patients cérébrolésés évalués en position debout par la Plateforme (PF) et en position assise par l’échelle Scale Contraversive Pushing (SCP) est corrélée à une mauvaise appréhension du référentiel égocentrique, évalué par le test de l’Axe longitudinal (LBA) et le test Droit devant (DD). Matériels et méthodes Trente-deux patients et 31 sujets sains volontaires ont participé à l’étude. La relation entre l’axe égocentrique et l’asymétrie posturale a été testée par un test de corrélation partielle avec la force musculaire et la sensibilité comme covariables. Résultats Les résultats montrent un lien significatif entre le SCP et le test DD (r = 0,49, p = 0,01) chez les patients ne tenant pas debout mais pas de lien significatif entre le SCP et le test LBA (r = −0,31, p = 0,14) ; ainsi qu’un lien significatif entre la PF et le test LBA (r = 0,42, p = 0,03) dans le sous-groupe de patients tenant debout mais pas entre la PF et le test DD (r = −0,12, p = 0,51). Discussion–conclusion Ces tests LBA et DD pourraient être utilisés en clinique dans l’évaluation des facteurs de trouble de l’équilibre du patient et permettre de proposer une rééducation ciblé

Effect of sensorial stimulations on postural disturbances related to spatial cognition disorders after stroke

Bonan M2SInternational audienceBalance disorders related to disturbances in perception of spatial reference systems are common especially after right hemispheric stroke. Mental misrepresentation of bodily orientation in space is then often superimposed upon other factors affecting imbalance such as motor and sensory impairments. Traditional rehabilitation for balance recovery has not been specifically designed to improve balance disorders related to spatial cognition. The traditional approach, consisting of stimulating the conscious perception of body orientation in space, is demanding and laborious. The approach based on sensorial stimulation is completely different. The relevance of this method lies in the fact that, firstly it is specifically active in the cognitive component of balance disorders; and secondly, it can passively be applied with minimal patient participation, which is of particular importance for this patient group characterized by disorders of attention and concentration. These techniques, such as proprioceptive, visual or vestibular stimulation, have been found to correct spatial neglect but also postural bias. Clinical and data from functional neuro-imaging suggest a direct central action on cortical structures involved in the elaboration of spatial representation. These are promising techniques for the rehabilitation of postural disturbances related to spatial cognition disorders but are as yet at the stage of preliminary result

Effects of vibration on the bearing asymmetry walking in chronic stroke patients

International audienceIntroduction The asymmetry of support when walking, common after a stroke, is a known risk factor for falls. The objective of this study is to assess effects of muscle vibrations on various sites on correcting this asymmetry. Methods Twenty-one patients (61 ± 13 years) with hemiplegia (10 right, 11 left) chronic vascular (mean time post stroke 48 ± 44months) received vibratory stimulation transcutaneous 70 Hz at the posterior cervical lesion contralateral muscles (NMV), the gluteus medius lesion side (GMV) and the biceps contralateral lesion (sham). An analysis of the percentage of one-foot support measured by GAITRite was performed before, during, and 2 and 10 minutes after each stimulation. Results Before stimulation, supporting asymmetry is noted with a percentage of the push side hemiplegic averaged 31.5% (±6.0%, min = 20%, max = 37%). Under GMV we find that this increases to 35.0% (±5.9%, min = 28.8%, max = 41.2%) against 31.1% (±7.5%, min = 20%, max = 42%) in NMV and 32.0% (±6.9%, min = 28.6%, max = 39.4%) in the sham. 2 minutes, the effect persists for GMV stimulation with 35.5% (±9.0%, min = 35%, max = 42.4%) 4% improvement then disappears in 10 minutes. The results are more significant in left hemiplegia with 7% improvement for GMV (P < 0.005). There is a more moderate effect on the NMV with a post effect at 2 min (32.6%) and 10 min (32.2%). Discussion–conclusion Vibratory stimulations therefore seem to improve support asymmetric walking hemiplegic patients. Different kinetic effect is observed between the cervical stimulation and gluteus medius. These results seem to reflect a different pathophysiology between the gluteus medius and cervical postural muscles. These could act through a central mechanism of spatial cognition while the hip muscles have a more immediate effect proprioceptive device. These analyses were complemented by a 3D gait analysis in an attempt to better understand the mechanisms of adaptation. This is the first study concerned with the effectiveness of vibratory stimulation on dynamic balanc

Imaging Artificial Membranes Using High-Speed Atomic Force Microscopy

International audienceSupported lipid bilayers represent a very attractive way to mimic biological membranes, especially to investigate molecular mechanisms associated with the lateral segregation of membrane components. Observation of these model membranes with high-speed atomic force microscopy (HS-AFM) allows the capture of both topography and dynamics of membrane components, with a spatial resolution in the nanometer range and image capture time of less than 1 s. In this context, we have developed new protocols adapted for HS-AFM to form supported lipid bilayers on small mica disks using the vesicle fusion or Langmuir-Blodgett methods. In this chapter we describe in detail the protocols to fabricate supported artificial bilayers as well as the main guidelines for HS-AFM imaging of such samples