RESUMEN
OBJECTIVES: The technique of additional visual feedback has been shown to significantly decrease the center of pressure (CP) displacements of a standing subject. Body-weight asymmetry is known to increase postural instability due to difficulties in coordinating the reaction forces exerted under each foot and is often a cardinal feature of various neurological and traumatic diseases. To examine the possible interactions between additional visual feedback and body-weight asymmetry effects, healthy adults were recruited in a protocol with and without additional visual feedback, with different levels of body-weight asymmetry. METHODS: CP displacements under each foot were recorded and used to compute the resultant CP displacements (CPRes) and to estimate vertically projected center of gravity (CGv) and CPRes-CGv displacements. Overall, six conditions were randomly proposed combining two factors: asymmetry with three BW percentage distributions (50/50, 35/65 and 20/80; left/right leg) and feedback (with or without additional VFB). RESULTS: The additional visual feedback technique principally reduces CGv displacements, whereas asymmetry increases CPRes-CGv displacements along the mediolateral axis. Some effects on plantar CP displacements were also observed, but only under the unloaded foot. Interestingly, no interaction between additional visual feedback and body-weight asymmetry was reported. DISCUSSION: These results suggest that the various postural effects that ensue from manipulating additional visual feedback parameters, shown previously in healthy subjects in various studies, could also apply independently of the level of asymmetry. CONCLUSION: Visual feedback effects could be observed in patients presenting weight-bearing asymmetries.
Asunto(s)
Retroalimentación Sensorial , Equilibrio Postural , Postura , Adulto , Peso Corporal , Femenino , Humanos , Masculino , Persona de Mediana Edad , Soporte de PesoRESUMEN
In 1995, David Winter concluded that postural analysis of upright stance was often restricted to studying the trajectory of the center of pressure (CoP). However, postural control means regulation of the center of mass (CoM) with respect to CoP. As CoM is only accessible by using a biomechanical model of the human body, the present article proposes to determine which models are actually used in postural analysis, twenty years after Winter's observation. To do so, a selection of 252 representative articles dealing with upright posture and published during the four last years has been checked. It appears that the CoP model largely remains the most common one (accounting for nearly two thirds of the selection). Other models, CoP/CoM and segmental models (with one, two or more segments) are much less used. The choice of the model does not appear to be guided by the population studied. Conversely, while some confusion remains between postural control and the associated concepts of stability or strategy, this choice is better justified for real methodological concerns when dealing with such high-level parameters. Finally, the computation of the CoM continues to be a limitation in achieving a more complete postural analysis. This unfortunately implies that the model is chosen for technological reasons in many cases (choice being a euphemism here). Some effort still has to be made so that bioengineering developments allow us to go beyond this limit.
Asunto(s)
Modelos Biológicos , Equilibrio Postural , Postura , Fenómenos Biomecánicos , HumanosRESUMEN
Gait and balance disorders are often major causes of handicap in patients with cerebellar ataxia. Although it was thought that postural and balance disorders in cerebellar ataxia were not treatable, recent studies have demonstrated the beneficial effects of rehabilitation programs. This article is the first systematic review on the treatment of postural disorders in cerebellar ataxia. Nineteen articles were selected, of which three were randomized, controlled trials. Various aetiologies of cerebellar ataxia were studied: five studies assessed patients with multiple sclerosis, four assessed patients with degenerative ataxia, two assessed stroke patients and eight assessed patients with various aetiologies. Accurate assessment of postural disorders in cerebellar ataxia is very important in both clinical trials and clinical practice. The Scale for the Assessment and Rating of Ataxia (SARA) is a simple, validated measurement tool, for which 18 of the 40 points are related to postural disorders. This scale is useful for monitoring ataxic patients with postural disorders. There is now moderate level evidence that rehabilitation is efficient to improve postural capacities of patients with cerebellar ataxia - particularly in patients with degenerative ataxia or multiple sclerosis. Intensive rehabilitation programs with balance and coordination exercises are necessary. Although techniques such as virtual reality, biofeedback, treadmill exercises with supported bodyweight and torso weighting appear to be of value, their specific efficacy has to be further investigated. Drugs have only been studied in degenerative ataxia, and the level of evidence is low. There is now a need for large, randomized, controlled trials testing rehabilitation programs suited to postural and gait disorders of patients with cerebellar ataxia.
Asunto(s)
Ataxia Cerebelosa/rehabilitación , Terapia por Ejercicio , Equilibrio Postural , Trastornos de la Sensación/rehabilitación , Ataxia Cerebelosa/complicaciones , Humanos , Trastornos de la Sensación/etiologíaRESUMEN
AIM OF THE STUDY: The objective of this preliminary study was to evaluate the effectiveness, in terms of fall reduction, of an in-home strategy that we have developed for elderly fallers. We also aimed at finding links between the expected changes in the data obtained in static posturography and in clinical balance tests through our program. PATIENTS AND METHODS: Twelve elderly patients living at home who were diagnosed as fallers (5 males and 7 females; 77.9±4.1 years) participated in the study. Our multimodal intervention lasted 6 months. Before this period, and one year later, an evaluation was conducted using cognitive (MMSE), clinical balance tests (i.e. Berg Balance Scale, Balance One leg, Timed Up and Go, and Functional Reach tests) and static posturography (where the area of body sway, velocity and medio-lateral and antero-posterior amplitudes were recorded twice, first with eyes open and then with eyes closed). RESULTS: Among the 12 patients who were diagnosed as fallers, eight became non-fallers. When comparing data obtained after the intervention with those obtained beforehand, we found significant changes in all of the clinical balance tests and in the posturographic-derived variables indicating improvements in the balance control in our group of subjects. We also found significant correlations between the changes in the Berg Balance Scale scores and the changes in the area of body sway data, in antero-posterior amplitude both with eyes open and with eyes closed, and also in the medio-lateral amplitude in the eyes closed condition. CONCLUSIONS: We prospectively demonstrated the relevance of our anti-falling intervention at home and of the use of posturography for clinical follow-up.