Insufficient Balance Recovery Following Unannounced External Perturbations in Persons With Stroke

Abstract

Background. Persons with stroke (PwS) are at increased risk of falls, especially toward the paretic side, increasing the probability of a hip fracture. The ability to recover from unexpected loss of balance is a critical factor in fall prevention. Objectives. We aimed to compare reactive balance capacity and step kinematics between PwS and healthy controls. Methods. Thirty subacute PwS and 15 healthy controls were exposed to forward, backward, right, and left unannounced surface translations in 6 increasing intensities while standing. Single step threshold, multiple step threshold, and fall threshold (ie, perturbation intensity leading to a fall into harness system) were recorded as well as reactive step initiation time, step length, and step velocity. Results. Twenty-five PwS fell into harness system during the experiment while healthy controls did not fall. Fourteen out of 31 falls occurred in response to surface translations toward the nonparetic side, that is, falling toward the paretic side. Compared with healthy controls, PwS demonstrated significantly lower fall threshold and multiple step threshold in response to forward, backward, and lateral surface translations. Impairments were more pronounced in response to forward surface translation and toward the nonparetic side (ie, loss of balance toward the paretic side). A trend toward significant shorter step length in response to lateral surface translations was found in PwS compared with healthy controls. Conclusions. Findings highlight the importance of assessing reactive balance capacity in response to perturbations in different directions and intensities in addition to the routine assessment in PwS.

The kinematics and strategies of recovery steps during lateral losses of balance in standing at different perturbation magnitudes in older adults with varying history of falls

“…1 ). Lower single-step and multiple-step thresholds were found earlier in older adults compared with young’s [ 22 ] and in stroke patients compared with age matched healthy controls [ 28 ]. A recovery step at a lower perturbation magnitude in OFs may suggest a lower balance recovery function, i.e., less ability to control the CoM motion over the BoS, or may be due to a past single fall event which resulted in a greater fear of falling (FES-I) that does not actually represent true balance abilities.…”

The Stepping Threshold Test for Reactive Balance: Validation of Two Observer-Based Evaluation Strategies to Assess Stepping Behavior in Fall-Prone Older Adults

“…The single-step and multiple stepping thresholds were determined. The assessment tool developed, hereafter referred to as the Stepping Threshold Test (STT), proved to be inter-observer reliable in both populations and convergent validity for individuals after stroke (Handelzalts et al, 2019b). However, data on the validity of the STT in healthy older adults are not yet available.…”

“…For this reason, we developed a new strategy to evaluate the step and stepping behavior of the STT, which we called the 'direction-sensitive evaluation' (DSE). As opposed to counting every step is taken (Handelzalts et al, 2019b;Batcir et al, 2020;Crenshaw et al, 2020), which we called the 'all-stepcount evaluation' (ACE), our approach considers two important characteristics in the step and stepping behavior. First, our approach leads to a direction-specific consideration since steps counted only in the opposite direction to the surface translation.…”

“…Our first aim was to test the convergent validity of the STT in fall-prone older adults with respect to fall risk. For this purpose, we used an established method and investigated associations between widely used clinical measures of balance and fall risk (Handelzalts et al, 2019b) and the STT sum score (convergent validity). We expected to find moderate correlations with the Brief Balance Evaluations Systems Test (BriefBEST, global balance), moderate correlation with the TUG (proactive balance), low to moderate correlations with the 8-level balance scale (8LBS, static balance), and low to moderate correlations with the Short Falls Efficacy Scale-International (Short FES-I, fear of falling).…”

“…We expected to find moderate correlations with the Brief Balance Evaluations Systems Test (BriefBEST, global balance), moderate correlation with the TUG (proactive balance), low to moderate correlations with the 8-level balance scale (8LBS, static balance), and low to moderate correlations with the Short Falls Efficacy Scale-International (Short FES-I, fear of falling). This expectation is based on the results of Handelzalts et al (2019b), Crenshaw et al (2018), and a meta-analysis by Kiss et al (2018) who found associations between reactive balance and other balance domains. Our second aim was to explore the association between the STT and the experience of at least one fall in the past 12 months.…”