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Dannenbaum E.,Feil and Oberfeld Research Center | Chilingaryan G.,Feil and Oberfeld Research Center | Fung J.,Feil and Oberfeld Research Center | Fung J.,McGill University
Journal of Vestibular Research: Equilibrium and Orientation | Year: 2011

A common symptom for people with vestibulopathy is dizziness induced by dynamic visual input, known as visual vertigo (VV). The goal of this study is to present a novel method to assess VV, using a nine-item analog scale. The subjects rated the intensity of their dizziness on each item of the Visual Vertigo Analogue Scale (VVAS), which represented a daily situation typically inducing VV. The questionnaire was completed by participants with vestibulopathy (n=102) and by subjects receiving out-patient orthopaedic physiotherapy (n=102). The dizziness handicap inventory (DHI) was also completed by the vestibulopathic group. The Cronbach's Alpha index indicated the VVAS is internally consistent and reliable (Cronbach's Alpha=0.94). The study also found that the VVAS severity scores from vestibular and a non-vestibular population were significantly different (Wilcoxon-Mann Whitney test p < 0.0001). Spearman correlation analysis conducted between DHI and VVAS scores for the clients with vestibulopathy showed positive moderate correlations between the VVAS score and the total DHI score (r=0.67, p< 0.0001). This study showed that the VVAS scale may be useful in providing a quantitative evaluation scale of visual vertigo. © 2011 - IOS Press and the authors. All rights reserved.

Popov A.G.,Feil and Oberfeld Research Center | Lamontagne A.,Feil and Oberfeld Research Center | Lamontagne A.,McGill University
2011 International Conference on Virtual Rehabilitation, ICVR 2011 | Year: 2011

The ability of healthy young individuals to accurately steer toward a virtual target while experiencing different foci of expansion (FOE) and target positions was examined with the use of a virtual reality task. Ten participants steered toward the virtual target with the use of mouse displacements while sitting or while changing their body orientation during over-ground walking. Net virtual errors showed that participants were able to accurately align themselves with the target despite having confounding visual information regarding FOE location and heading direction. Participants performed better in the mouse-driven task than the walking task. This may be attributed to the nature of the tasks that employ different degrees of freedom. Altogether, results support the use of this virtual reality-based paradigm to further investigate the contribution of altered visual self-motion processing and gait-related impairments on steering abilities in stroke and in the elderly. © 2011 IEEE.

Aravind G.,McGill University | Aravind G.,Feil and Oberfeld Research Center | Lamontagne A.,McGill University | Lamontagne A.,Feil and Oberfeld Research Center
Journal of NeuroEngineering and Rehabilitation | Year: 2014

Background: For safe ambulation in the community, detection and avoidance of static and moving obstacles is necessary. Such abilities may be compromised by the presence of visuospatial neglect (VSN), especially when the obstacles are present in the neglected, i.e. contralesional field. Methods. Twelve participants with VSN were tested in a virtual environment (VE) for their ability to a) detect moving obstacles (perceptuo-motor task) using a joystick with their non-paretic hand, and b) avoid collision (locomotor task) with moving obstacles while walking in the VE. The responses of the participants to obstacles approaching on the contralesional side and from head-on were compared to those during ipsilesional approaches. Results: Up to 67 percent of participants (8 out of 12) collided with either contralesional or head-on obstacles or both. Delay in detection (perceptuo-motor task) and execution of avoidance strategies, and smaller distances from obstacles (locomotor task) were observed for colliders compared to non-colliders. Participants' performance on the locomotor task was not explained by clinical measures of VSN but slower walkers displayed fewer collisions. Conclusion: Persons with VSN are at the risk of colliding with dynamic obstacles approaching from the contralesional side and from head-on. Locomotor-specific assessments of navigational abilities are needed to appreciate the recovery achieved or challenges faced by persons with VSN. © 2014 Aravind and Lamontagne; licensee BioMed Central Ltd.

Aravind G.,McGill University | Aravind G.,Feil and Oberfeld Research Center | Lamontagne A.,McGill University | Lamontagne A.,Feil and Oberfeld Research Center
2013 International Conference on Virtual Rehabilitation, ICVR 2013 | Year: 2013

Persons with visuospatial neglect are at risk of colliding with objects while walking due to their inattention to the contralesional space. Twelve participants were assessed on their ability to avoid moving obstacles while walking. Collisions were observed for head-on and contralesionally approaching obstacles, but not for ipsilesional ones. Participants showed delayed responses and maintained smaller distances from contralesional obstacles compared to other approaches. Collisions with head-on vs. contralesional obstacles appeared to depend on walking speed. It is suggested that persons with visuospatial neglect are at risk of colliding with moving obstacles due to contribution of both perceptual and locomotor factors. © 2013 IEEE.

Krasovsky T.,McGill University | Krasovsky T.,Feil and Oberfeld Research Center | Banina M.C.,McGill University | Banina M.C.,Feil and Oberfeld Research Center | And 9 more authors.
Journal of Neurophysiology | Year: 2012

Most falls in older adults occur when walking, specifically following a trip. This study investigated the short- and longer term responses of young (n = 24, 27.6 ± 4.5 yr) and older adults (n = 18, 69.1 ± 4.2 yr) to a trip during gait at comfortable speed and the role of interlimb coordination in recovery from tripping. Subjects walked on a self-paced treadmill when forward movement of their dominant leg was unexpectedly arrested for 250 ms. Recovery of center of mass (COM) movements and of double-support duration following perturbation was determined. In addition, the disruption and recovery of interlimb coordination of the arms and legs was evaluated. Although young and older subjects used similar lower limb strategies in response to the trip, older adults had less stable COM movement patterns before perturbation, had longer transient destabilization (>25%) after perturbation, required more gait cycles to recover double-support duration (older, 3.48 ± 0.7 cycles; young, 2.88 ± 0.4 cycles), and had larger phase shifts that persisted after perturbation (older, -83° to -90°; young, -39° to -42°). Older adults also had larger disruptions to interlimb coordination of the arms and legs. The timing of the initial disruption in coordination was correlated with the disturbance in gait stability only in young adults. In older adults, greater initial COM instability was related to greater longer term arm incoordination. These results suggest a relationship between interlimb coordination and gait stability, which may be associated with fall risk in older adults. Reduced coordination and gait stability suggest a need for stability-related functional training even in high-functioning older adults. © 2012 the American Physiological Society.

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