Human-Human Hand Interactions Aid Balance During Walking by Haptic Communication

Principles from human-human physical interaction may be necessary to design more intuitive and seamless robotic devices to aid human movement. Previous studies have shown that light touch can aid balance and that haptic communication can improve performance of physical tasks, but the effects of touch between two humans on walking balance has not been previously characterized. This study examines physical interaction between two persons when one person aids another in performing a beam-walking task. 12 pairs of healthy young adults held a force sensor with one hand while one person walked on a narrow balance beam (2 cm wide x 3.7 m long) and the other person walked overground by their side. We compare balance performance during partnered vs. solo beam-walking to examine the effects of haptic interaction, and we compare hand interaction mechanics during partnered beam-walking vs. overground walking to examine how the interaction aided balance. While holding the hand of a partner, participants were able to walk further on the beam without falling, reduce lateral sway, and decrease angular momentum in the frontal plane. We measured small hand force magnitudes (mean of 2.2 N laterally and 3.4 N vertically) that created opposing torque components about the beam axis and calculated the interaction torque, the overlapping opposing torque that does not contribute to motion of the beam-walker’s body. We found higher interaction torque magnitudes during partnered beam-walking vs. partnered overground walking, and correlation between interaction torque magnitude and reductions in lateral sway. To gain insight into feasible controller designs to emulate human-human physical interactions for aiding walking balance, we modeled the relationship between each torque component and motion of the beam-walker’s body as a mass-spring-damper system. Our model results show opposite types of mechanical elements (active vs. passive) for the two torque components. Our results demonstrate that hand interactions aid balance during partnered beam-walking by creating opposing torques that primarily serve haptic communication, and our model of the torques suggest control parameters for implementing human-human balance aid in human-robot interactions.

Two-Week Rehabilitation with Auditory Biofeedback Prosthesis Reduces Whole Body Angular Momentum Range during Walking in Stroke Patients with Hemiplegia: A Randomized Controlled Trial

Walking rehabilitation is challenging in stroke patients with sensory impairments. In this study, we examined the two-week effect of an auditory biofeedback prosthesis, Auditory Foot (AF), on the change in the frontal whole body angular momentum (WBAM) range, before and after a two-week walking rehabilitation. We conducted a pilot randomized controlled trial (RCT). We employed statistical Bayesian modeling to understand the mechanism of the rehabilitation effect and predict the expected effect in new patients. The best-performing model indicated that the frontal WBAM range was reduced in the AF group by 12.9–28.7%. This suggests that the use of kinesthetic biofeedback in gait rehabilitation contributes to the suppression of frontal WBAM, resulting in an improved walking balance function in stroke patients.

939Longitudinal trends of work productivity in a representative sample of Australians living with multiple sclerosis

Background studies have documented increased employment rates and MS-related work productivity loss in people living with multiple sclerosis (PwMS). Little is known about the longitudinal trends of work productivity of PwMS. Objectives To describe the longitudinal patterns of work productivity of PwMS, and examine the factors associated with longitudinal change of work productivity of PwMS. Methods Study participants were from the Australian MS Longitudinal Study (AMSLS) followed from 2015 to 2018 (n = 2724) who were employed. We described the longitudinal patterns of work productivity and determined the correlates of the changes in work productivity of PwMS. We used linear mixed effect modelling to analyse the data. Results From our mixed effect model analysis, feelings of depression, walking difficulties, and spasticity problems were independently associated with -1.45 (-1.95 to -0.95), -1.35 (-1.98 to -0.72) and -1.04 (-1.63 to -0.45) per annum change in work productivity respectively. Annual changes in MS symptom clusters: difficulties with walking, balance and spasticity; anxiety and depression; and fatigue and cognitive symptoms were independently associated with -2.53 (-3.53 to -1.52), -1.51 (-2.27 to -0.74), -0.86 (-1.67 to -0.06) percent annual change in work productivity of PwMS respectively. Conclusion Symptoms cluster like ‘difficulties with walking, balance and spasticity’, ‘feelings of anxiety and depression’, and ‘fatigue and cognitive symptoms’ impact significantly on work productivity. Key messages MS related annual work productivity loss is marginal but is strongly driven by annual changes in walking difficulties, feelings of depression and spasticity problems

Similar sensorimotor transformations control balance during standing and walking

Standing and walking balance control in humans relies on the transformation of sensory information to motor commands that drive muscles. Here, we evaluated whether sensorimotor transformations underlying walking balance control can be described by task-level center of mass kinematics feedback similar to standing balance control. We found that delayed linear feedback of center of mass position and velocity, but not delayed linear feedback from ankle angles and angular velocities, can explain reactive ankle muscle activity and joint moments in response to perturbations of walking across protocols (discrete and continuous platform translations and discrete pelvis pushes). Feedback gains were modulated during the gait cycle and decreased with walking speed. Our results thus suggest that similar task-level variables, i.e. center of mass position and velocity, are controlled across standing and walking but that feedback gains are modulated during gait to accommodate changes in body configuration during the gait cycle and in stability with walking speed. These findings have important implications for modelling the neuromechanics of human balance control and for biomimetic control of wearable robotic devices. The feedback mechanisms we identified can be used to extend the current neuromechanical models that lack balance control mechanisms for the ankle joint. When using these models in the control of wearable robotic devices, we believe that this will facilitate shared control of balance between the user and the robotic device.

Enriched gardens improve cognition and independence of nursing home residents with dementia: a pilot controlled trial

Background Dementia is a major issue worldwide, and considerable efforts were made to design therapeutic mediation tools and evaluate their benefits on the health of patients. Methods Design: Multi-center cluster-controlled pilot trial. Settings and participants: Four nursing homes that offered separated access to one conventional sensory garden (CSG) and one enriched garden (EG). The participants were residents with dementia, independent for walking and with no severe dementia or behavioural troubles. Eligible residents were divided into three groups according to the proximity of their room: close to the CSG or EG gardens for the first two groups and further from the gardens for the third (control) group. Interventions: We asked staff members to frequently invite residents to visit the EG or the CSG depending on their group allocation. No invitation to gardens was made to the control group. We installed 12 enrichment modules in the EG that stimulated cognitive, independence and walking/balance functions. Measures: Cognitive function (MMSE), independence for activities of daily living (ADL) and risk of falls (unipodal stance and timed up and go – (TUG)) were assessed at baseline and after 6 months. Results The 120 participants were 81·0 ± 3·5 years old and comprised of 83 women. Their MMSE score was 17·5 ± 2·9. Patients’ characteristics were not significantly different between the three groups. Among the participants invited to visit the EG group, 6-month changes in MMSE showed improvement compared to other groups (+ 0·93 ± 0·65 vs −0·25 ± 0·71 and −0·24 ± 0·73 in the EG vs CSG and control groups, respectively, P < 0·0001). Changes in ADL, TUG and unipodal stance were significantly improved in the group visiting the EG as compared to other groups, which indicates better functioning. Conclusions EGs offer a new approach to therapeutic mediation for residents of nursing homes with dementia.

Unusual side effects of levetiracetam

We present a 75-year-old man who was admitted to our hospital due to 4 months of general deterioration, gait disturbance and cognition impairment which appeared very close to the start of levetiracetam (LEV) as a new antiepileptic drug. Brain CT shows central and less peripheral atrophy of brain, and diagnosis of normal pressure hydrocephalus was raised; however, removal of 30 cc of cerebrospinal fluid (CSF) by lumbar puncture in order to amend walking did not lead to gait improvement. After excluding metabolic, vascular, infection, inflammatory and other reasons explaining his status. Thinking that may be any correlation between LEV added in the last months and his clinical condition, we stopped LEV. Several days after that, there is marked improvement in his general sensation, alertness and cognitive status and there is marked improvement in walking balance to the point of being able to walk without the use of walker or cane or help from other person. Certain cognitive impairment and gait difficulties are not known as side effects of LEV treatment.