Assessment of dynamic balancing responses following perturbations during slow walking in relation to clinical outcome measures for high-functioning post-stroke subjects

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background</jats:bold>: Generating appropriate balancing reactions in response to unexpected loss of balance during walking is important to prevent falls. The purpose of this study was to assess dynamic balancing responses following pushes to the pelvis in groups of post-stroke and healthy subjects. <jats:bold>Methods</jats:bold>: Forty-one post-stroke subjects and forty-three healthy subjects participated in the study. Dynamic balancing responses to perturbations triggered at heel strike of the left or right leg, directed in the forward, backward, inward and outward directions during slow treadmill walking were assessed. Responses of the healthy group provided reference values used to classify responses of the post-stroke group into two subgroups; one within the reference responses (“inside” subgroup) and the other that falls out (“outside” subgroup). A battery of selected clinical outcome measures (6-Minute Walk Test, 10-Meter Walk Test, Timed-Up-and-Go test, Four Square Step Test, Functional Gait Assessment, Functional Independence Measure and One-legged stance test) was additionally assessed in the post-stroke group. <jats:bold>Results</jats:bold>: The “inside” subgroup of post-stroke subjects was able to appropriately modulate centre-of-pressure and ground-reaction-force both under the impaired and non-impaired leg in response to perturbations. The “outside” subgroup of post-stroke subjects showed limited modulation of centre-of-pressure and ground-reaction-force under the impaired leg; instead stepping strategy was used in which the non-impaired leg was placed such as to make a longer step (forward perturbation), to make a shorter step (backward perturbation) or to make a cross-step (outward perturbation). Consequently, peak centre-of-mass displacements following perturbations were significantly higher in the “outside” subgroup compared to the “inside” subgroup. Responses in both subgroups following inward perturbations did not differ. Majority of clinical outcome measures moderately correlated with the peak centre-of-mass displacements for forward perturbations and exhibited weak correlations for other perturbation directions.<jats:bold>Conclusions</jats:bold>: Substantial number of post-stroke subjects, that were considered to be independent walkers, have reduced capabilities to execute appropriate balancing responses following perturbations commencing on the hemiparetic leg and may thus benefit from perturbation-based training. Timed-Up-and-Go and Functional Independence Measure tests may provide an indication on the abilities of each subject to counteract unexpected loss of balance. However, a reliable assessment should be done through perturbation-based measures.</jats:p>

Toward improving the specificity of perturbation-based training through assessment of dynamic balancing responses: a series of N-of-1 studies in subacute stroke

“…The study was approved by the institutional Ethics Committee and the participants signed written informed consent. Reactive balancing responses of 43 healthy participants were used as control normative [4].…”

“…GRF, COP, center-of-mass (COM) and gait cycle timing were obtained from the instrumented treadmill and pelvic link. BART is fully described in [4,17,20]. Figure 1 represents training session workflow, which consisted of three 10-min subsessions: (1) gait symmetry training, (2) active virtual environment training and (3) perturbation balance training.…”

“…Neurological disorders reduce abilities to maintain dynamic balance during walking [1–4]. This is frequently a cause of falls following an unexpected event such as slip, trip or bump [5,6].…”

“…An efficient balancing response following a perturbing push in slow-walking comes primarily as an ‘in-stance’ response requiring appropriate modulation of center-of-pressure (COP) and ground-reaction-force (GRF) under the leg in-stance [14]. A significant portion of poststroke subjects rely on ‘stepping’ responses following unexpected pushes [4,15] and are unable to execute ‘in-stance’ response. Thus, the observed functional improvement in balancing abilities in poststroke subjects following PBT-based training is due to the development of compensatory mechanisms largely coming from the modified activity of the unimpaired limb in terms of more efficient stepping response, which is known to be the primary balancing mechanism at higher walking speeds [15].…”

To Observe the Dynamic Balance Problem in Deaf Children`s Via Four Square Step Test

“…Misconceptions persist in mainstream society about the capabilities of Deaf individuals, often underestimating their potential and contributions. Efforts by NGOs around the world have sought to rectify this by supporting educational and technological access for the Deaf and hard of hearing in underserved regions, enhancing their integration and providing them with platforms to express their aspirations and experiences (17,18).…”