Between-limb synchronization for control of standing balance in individuals with stroke

Background

During standing, forces and moments exerted at the feet serve to maintain stability in the face of constant centre-of-mass movement. These actions are temporally synchronized in healthy individuals. Stroke is typically a unilateral injury resulting in increased sensori-motor impairment in the contra-lesional compared with the ipsi-lesional lower-limb, which could lead to reduced between-limb synchronization for control of standing balance. The purpose of this study is to investigate between-limb synchronization of standing balance control in individuals with stroke; a potentially important index of control of upright stability.

Methods

Twenty healthy controls and 33 individuals with unilateral stroke were assessed. Stability was assessed during a 30-second quiet standing trial by measuring data from two force plates (one per foot). Limb-specific centre of pressure was calculated. Between-limb synchronization was defined as the coefficient of the correlation between the left and right foot for both the antero-posterior and medio-lateral centre of pressure time series. Synchronization, weight-bearing symmetry, and root mean square of the total centre of pressure excursion were compared between controls and stroke participants.

Findings

Stroke participants swayed more, were more asymmetric, and had less between-limb synchronization than healthy controls. Among individuals with stroke, reduced between-limb synchronization was related to increased postural sway in the medio-lateral direction and increased weight-bearing asymmetry.

Interpretation

Individuals with stroke have reduced temporal synchronization of centre of pressure fluctuations under the feet when controlling quiet standing. The clinical significance of reduced synchronization remains to be determined, although it appears linked to increased medio-lateral sway and weight-bearing asymmetry.     

Transcranial direct current stimulation in the recovery of postural control after stroke: a pilot study

Abstract

Purpose: This pilot study aimed to evaluate the effectiveness of multiple sessions of transcranial Direct Current Stimulation (tDCS) during 4 weeks on balance and gait parameters after stroke. Method: Thirty-one stroke patients were included in this randomised, double-blind, sham-controlled crossover study. The Tinetti test was used to assess functional balance and gait after stroke. Secondary measures, Rivermead Motor Assessment (RMA) and Trunk Impairment Scale (TIS), were registered to asses both motricity and trunk performance. All tests were administered at baseline, after 4 and 8 weeks. Patients were randomly divided into two groups. Both groups received both sixteen 20-min sessions of tDCS and sixteen 20-min sessions of Sham stimulation. Application method between groups was changed after 4 weeks. A general linear repeated measures model was used to analyse the results of our study. Results: Results revealed an effect on the total score of the Tinetti test (p?=?0.049). No significant results were obtained for the RMA (p?=?0.166) and the TIS (p?=?0.479). Conclusions: This pilot study indicates that 16 tDCS-sessions could have a beneficial effect on balance and gait in stroke patients measured with the Tinetti test. However, further research is needed to elucidate these findings.

• Implications for Rehabilitation

• Sixteen sessions of tDCS is beneficial in the recovery of postural control in stroke patients.

• tDCS has to be applied as soon as possible to enhance beneficial effects.

     

Acute effect of core stability and sensory-motor exercises on postural control during sitting and standing positions in young adults

SummaryCore stability exercises and exercises that stimulate sensory-motor information are recommended for the prevention of injuries and the maintenance and rehabilitation of deficits related to postural control (PC). However, the comparison of results between core stability and sensory-motor exercises in the literature is limited to sitting and standing positions.ObjectiveTo determine the acute effect of core stability and sensory-motor exercises on PC during sitting and standing in young adults.MethodsA total of 39 participants, with a mean age of 23 years, were randomly divided into three groups (1) Core stability exercises; (2) Sensory-motor exercises; (3) Control. Each group performed a sequence of five specific exercises of core stability and sensory-motor exercises (except controls). PC was evaluated before and after exercise in the seated and the one-legged stance conditions using a force platform.ResultsNo significant difference was found for any variables of postural oscillation (P > 0.05) among the three groups studied. The magnitude of the effect of interventions in general was a small to moderate effect (d = 0.02/-0.48).ConclusionThe findings show that acute intervention with core stability and sensory-motor exercises did not produce any significant effects (reduction of postural oscillation) on PC during sitting and standing positions in young adults.     

Rehabilitation of postural stability in ataxic/hemiplegic patients after stroke

Purpose.?This study assesses the postural stability and the effect of balance training using a force platform visual biofeedback among outpatients with postural disturbances following stroke.

Method.?A tilting multiaxial force platform was used to assess bilateral postural stability in 38 outpatients (mean age 69.50?±?8.57 years) with hemiplegia and/or ataxia after stroke. Stability indexes were obtained. Afterwards, a subgroup of 12 patients with the poorest overall stability index (OASI) started a balance training programme in the force platform. Postural control training consisted of a 30-min training session once a week for a 15-week period. The test was then repeated.

Results.?In the 38 outpatients sample, the mean OASI was 4.7?±?2.0 and 42.1% of the patients used their hands for support. In the 12 outpatients group, the initial OASI was 5.8?±?2.3 and half of the patients used their hands for support. The final OASI was 3.3?±?1.0 (p?=?0.005) and only two of the patients used their hands for support (p?=?0.046).

Conclusion.?Our results suggest that a training programme using force platform visual biofeedback improves objective measures of bilateral postural stability in patients with hemiplegia and/or ataxia after stroke.     

Effect of dynamic tape on postural sway in individuals with chronic ankle instability

ObjectiveTo examine the effects of dynamic tape on balance control in subjects with chronic ankle instability (CAI).MethodsThis two group experimental pre- and post-treatment design included 18 individuals with CAI and 18 controls. The single-limb stance test with eyes open and closed, standing on a force plate (Accusway Plus; AMTI) for 30 s, was conducted before, 10 min (T1) and 24 h (T24) after a dynamic tape application over the gastrocnemius muscle. Outcome measurements were: mean sway velocity, sway area (circular area), and standard deviation of the body center of pressure path length in both mediolateral and anteroposterior directions. Individuals with poor (unable to perform a single leg test for at least 30 s, eyes closed) vs. good postural stability, were also compared.ResultsIn both groups, a repeated analysis of variance demonstrated a significant time main effect on sway velocity (F = 14.95; p < 0.001) and path length (F = 14.95; p < 0.001) during eyes closed. Post-hoc analysis revealed a significant decrease in T1 values compared to baseline. When comparing individuals with poor vs good stability amongst the CAI group, a statistically significant interaction was observed between group, time on sway velocity and path length (F = 3.92; p < 0.05) during eyes closed. In the poor postural group, most T1 values were significantly lower than baseline.ConclusionsDynamic tape when applied to posterior calf muscles, enhanced balance control with no difference between CAI individuals and controls. The contribution of the tape was greater in those with poor postural stability.     

Effect of sacroiliac manipulation on postural sway in quiet standing: a randomized controlled trial

Background

Sacroiliac joint manipulation can alter joint and muscle control mechanisms through local and remote effects. Postural balance is controlled by supraspinal (rambling) and spinal–peripheral (trembling) mechanisms. A manipulation may interfere with postural control in quiet standing.

Postural balance during quiet standing in patients with total hip arthroplasty and surface replacement arthroplasty

BACKGROUND: Primary total hip arthroplasty leads to better functional capacities but a general weakness of abductor muscles often persists. A larger head component may improve the postural balance in the medial-lateral direction. The aims of this study are (1) to compare postural stability in patients after total hip and surface replacement arthroplasties and (2) to evaluate the effect of the biomechanical reconstruction on postural stability. METHODS: Six months post-surgery, three groups of ten subjects (total hip and surface replacement arthroplasties and control) performed quiet standing tasks in both dual and one leg stance and a hip abductor muscles strength test. The root-mean-square amplitude of centre of pressure and centre of mass displacement in the anterior-posterior and medial-lateral directions were calculated for dual stance task. FINDINGS: Statistical analyses showed greater centre of pressure and centre of mass displacement amplitude in the medial-lateral direction during the dual stance for the total hip arthroplasty compared to the surface replacement and control subjects (P<0.05). All control subjects completed the one leg stance compared to nine in the surface replacement and five in the total hip arthroplasty group. No statistical difference was found between the groups in the hip abductor muscles strength. INTERPRETATION: The better anatomical preservation, absence of femoral stem and the larger bearing component could account for the return to better postural stability in surface replacement patients in comparison to total hip patients. Further studies are needed to determine the impact of each of these factors on the postural balance.     

The effect of Kinesio Taping on postural control in subjects with non-specific chronic low back pain

Purpose

The aim of this study was to investigate the possible alterations in postural control during upright standing in subjects with non-specific chronic low back pain and the effect of Kinesio taping on the postural control.

三种量表评定脑卒中急性期患者姿势控制能力的分析研究

目的探讨3种量表在评定脑卒中急性期患者姿势控制能力方面的应用情况。方法对45例脑卒中急性期患者分别采用脑卒中患者姿势评定量表（PASS）、Fugl—Meyer平衡量表（FM—B）及Berg平衡量表（BBS）对其姿势控制能力进行评定。所有病例均评定3次，评定时间分别为脑卒中起病后1周内、起病第3周时及出院前。选用Spearman统计法分析3种量表间的相关性；并同时计算3种量表的地板效应及天花板效应。结果PASS与FM—B及BBS间均具有高度相关性（r=0.867—0．957，P〈0．01）；在本研究各次评定中，PASS无明显的地板效应和天花板效应，而FM-B和BBS在第1次评定时均存在明显的地板效应（FM—B为26．6％．BBS为26．6％）。结论PASS与FM—B及BBS均能客观反映脑卒中急性期患者的姿势控制能力，而且PASS还能对脑卒中患者的卧位姿势控制能力进行评定，故在评定脑卒中急性期患者姿势控制能力方面，PASS优于FM—B和BBS。     

Validity of the postural control and balance for stroke test

Background and Purpose. To determine the construct and predictive validity and sensitivity of the sub‐scale items for postural changes, sitting balance and standing balance of the Postural Control and Balance for Stroke (PCBS) test over a 90‐day follow‐up. Method. In the initial phase of stroke the PCBS test scores were compared with values obtained for the Barthel Index (BI) and the four neuropsychological domains most widely studied in the literature: memory; language; visuo‐spatial functions; and visual inattention. The ability of the PCBS test at an early stage to predict functional status, as measured by the BI, and tendency to falls at 90 days after stroke was studied. The sensitivity of the PCBS test in evaluating postural control was studied by comparing the changes between the initial and 90 days' measures, and by examining the ability of the test to discriminate between healthy people and stroke patients. Forty stroke patients (aged 51–89 years), measured 7 and 90 days post‐stroke, and 35 healthy control subjects (aged 50–90 years) participated in the study. Results. Moderate correlations were found between the initial PCBS test and the BI (Spearman's r = 0.56–0.79) and a negative correlation between the sum variables for visual inattention and postural changes (Spearman's r = ?0.39) and sitting balance (Spearman's r = ?0.55). The score for postural changes predicted functional capacity (p < 0.002) and standing balance predicted falls at the three‐month follow‐up (p < 0.007). The PCBS test proved to be sensitive to change: the median change in the PCBS test scores during the three‐month follow‐up was 6.06. The control subjects mostly obtained maximum scores, indicating that the PCBS test was able to discriminate between healthy individuals and those with stroke. Conclusions. The results confirm that the PCBS test has good construct validity, good ability to predict functional capacity and safe moving, and it is sensitive to changes in balance control after stroke. Copyright © 2007 John Wiley & Sons, Ltd.     

脑卒中偏瘫侧负重率与步行时间的关系

目的探讨脑卒中偏瘫患者的患侧负重率与步行时间的关系。方法选择 5 8例脑卒中偏瘫患者 ,分为 3组 :院外独立步行组 2 0例 ,院内监视下步行组 19例 ,训练室内步行组 19例 ,测定 3组患者患侧负重率和最大患侧负重率以及 10m距离的步行时间。结果 3组在安静负重率、最大负重率、10m步行时间存在非常显著性差异 (P <0 0 1) ,安静负重率和 10m步行时间呈负相关 (r =-0 60 4,P <0 0 1) ,努力负重率和 10m步行时间呈负相关 (r =-0 72 3 ,P <0 0 1) ,安静负重率和努力负重率呈正相关 (r= 0 72 5 ,P <0 0 1)。结论脑卒中偏瘫患者的患侧负重率的增加与步行时间的缩短有很大关系     

Adaptation process for standing postural control in individuals with hemiparesis

Purpose.?To study the adaptation process for standing postural control in patients with hemiparesis after stroke.

Methods.?The changes of a standing posture developed in nine hemiparetic patients who had never maintained an upright stance alone (aged 48–62 years; 6–19 days after stroke) was evaluated by recording ground reaction forces and surface electromyographic (EMG) from lower limbs. A 60-s standing trial without any instruction about body alignment was repeated five times, and the experience-related changes of centre of pressure (COP) and integrated EMG data were estimated.

Results.?In the early standing trials, patients balanced themselves by managing the average COP position around the midline of both feet, accompanied by increased muscular activity of the non-paretic leg. COP displacement gradually decreased in the later standing trials (P < 0.05). Postural adaptations were achieved by shifting the centre of body sway to the side of the non-paretic foot (P < 0.05) while reducing biceps femoris muscular activity (P < 0.01) in the non-paretic leg.

Conclusions.?This study revealed that weight-bearing asymmetry might contribute to improving increased body sway and muscular over-activity of the non-paretic leg. When planning rehabilitative treatment for hemiparetic patients, we should consider that weight-bearing asymmetry may be a result of systematic postural control.     

Effect of finding-oriented manual therapy techniques on muscle activity and postural control in patients with chronic ankle instability - A randomized controlled feasibility study

IntroductionPrevious studies have analyzed the effects of manual therapy techniques (MTT) in patients with chronic ankle instability (CAI). Clinicians treat patients according the finding-oriented MTT approach. This approach is seldom pursued in research. The purpose of this study was to evaluate the feasibility and efficacy of finding-oriented MTT applications in patients with CAI.MethodIn this randomized controlled, blinded assessor crossover feasibility trial, participants were randomized to receive nine finding-oriented MTT treatments or no treatment during a three-week period, followed by a six-day washout period after which participants were crossed-over. Criteria under evaluation were adherence and attrition rates, safety (adverse events (AEs)) and acceptability and preliminary effects of finding-oriented MTT on muscular activity (measured by surface Electromyography (sEMG)) and on dynamic balance (measured by time to stabilization (TTS) and the modified Star Excursion Balance Test (modified STBT)).ResultsSeven women and two men (mean age: 26 ± 6.1 years) with CAI enrolled in this feasibility study. Success criteria showed a high adherence (90%) and low attrition rate (10%). All data could be used for analysis. AEs such as tingling in the foot during a short time frame were reported after four finding-oriented MTT interventions. Preliminary effect sizes showed divergence and few statistically significant results for sEMG.ConclusionThe participants were adherent to the finding-oriented MTT intervention. The acceptability of data recording and data analysis was good. In addition, the study protocol should be adapted by adding a 10-min warm up period, a participant familiarization to TTS and modified STBT, and test repetitions.     

Augmented reality-based postural control training improves gait function in patients with stroke: Randomized controlled trial

The purpose of this study was to determine the effects of augmented reality (AR)-based postural control training on balance and gait function in stroke patients. Twenty-one stroke patients were assigned to either an experimental group (n = 10) or a control group (n = 11). Patients in both groups received a general physical therapy program for a duration of 30 minutes per session, 5 days per week, for a period of 4 weeks. Participants in the experimental group received additional AR-based postural control training for 30 minutes per day, 3 days per week, for a period of 4 weeks. Patients were assessed with the timed up-and-go test, Berg Balance Scale test, and spatiotemporal parameters using the GAITRite system. Results of repeated-measures analysis of covariance showed a significant main effect of time on timed up-and-go test, Berg Balance Scale, velocity, cadence, step length and stride length of paretic and nonparetic sides. In addition, walking velocity, step length, and stride length on both the paretic and nonparetic sides showed a significant group × time interaction effect. The results of this study provide evidence in support of incorporating an AR environment into postural control training for improving gait of stroke patients.     

The effect of a concomitant stroop task during sit-to-stand tasks on postural control

[Purpose] This study aimed to explain the effect of a dual-task technology that utilizes motor and/or cognitive skills on the performance of major tasks, postural control, and gait consistency. [Participants and Methods] Eighteen healthy adults were divided into two groups: the single-word dual-task group and the control group (study 1). We enrolled 32 healthy adults to perform four-word Stroop (study 2) and sit-to-stand tasks simultaneously to determine the attentional demand for postural control and locomotion. [Results] The dynamic condition of postural control differed significantly between the single-task and single-word dual-task groups in Study 1. In Study 2, postural control in the four-word dual-task condition improved under both static and dynamic conditions. On comparing the results of studies 1 and 2, we found that during a four-word dual-task, healthy participants experienced a more significant decrease in postural sway than that experienced during the single-word dual-task. [Conclusion] Dual task of Stroop task with sit-to-stand could improve a postural control.     

The effect of post-stroke lower-limb spasticity on the control of standing balance: Inter-limb spatial and temporal synchronisation of centres of pressure

Background

Challenges in stability control are common post-stroke. Although lower-limb spasticity is a common sensorimotor consequence post-stroke, its potential to further complicate stability control among stroke-survivors remains largely unknown. Advancing such understanding can help inform strategies to reduce fall risk and increase independence among these individuals. The purpose of this study was to characterise the extent of limb-specific dyscontrol among individuals with spasticity.

Methods

A retrospective analysis of 131 patients assessed for spasticity was performed. Patients selected for inclusion were categorised into two groups, with (n = 19) or without (n = 63) unilateral lower-limb spasticity. Two force platforms were used to determine the individual-limb and net centres of pressure in both anteroposterior and mediolateral directions during 30 s of quiet standing. Limb-specific dyscontrol was assessed by calculating weight-bearing symmetry ratios, cross-correlation coefficients at zero phase-shift (temporal synchrony) and ratios of individual-limb root-mean-square displacements (spatial symmetry). Total body postural control was assessed by examining the root-mean-square of the net centre of pressure displacement.

Findings

The group with spasticity bore less weight on the affected limb and exhibited reduced temporal synchrony of centre of pressure displacements. There were no differences in inter-limb root-mean-square centre of pressure ratios or in the root-mean-square of the net centre of pressure displacement.

Interpretation

Individuals with lower-limb spasticity may have additional challenges with stability control, specifically linked to the ability to modify the location of the centre of pressure beneath the affected limb, in a time-sensitive manner so as to contribute beneficially to the control of whole body stability.     

动态姿态平衡仪训练对脑卒中偏瘫患者平衡功能的影响

目的:探讨使用动态姿态平衡仪对脑卒中后偏瘫患者进行平衡功能训练的效果。方法:选取20例符合入选标准的脑卒中患者,随机分为治疗组(n=10)和对照组(n=10)。对照组进行传统的平衡功能训练,30min/d;治疗组根据动态姿态平衡仪评估结果采用内置的训练方案进行平衡功能训练,20min/d。两组训练时间均为5d/周,共2周。在治疗前和治疗2周后分别采用动态姿态平衡仪中的感觉整合能力试验(SOT)、Berg平衡量表(BBS)及"起立—行走"计时测试(TUGT)进行定性、定量的评估。结果:两组受试对象的SOT指数、BBS和TUGT得分在治疗前后均有明显差异,但治疗组的改善程度明显大于对照组(P<0.05);治疗组中SOT测试的闭眼、平台沿矢状面旋转(ECSS)、平台与视窗沿矢状面旋转(SVSS)程序下,治疗后的平衡指数与运动策略较对照组均有显著的改善(P<0.05)。结论:利用动态姿态平衡仪对脑卒中后偏瘫患者进行平衡功能训练比传统训练方法能更有效地改善患者的平衡功能。     

Analysis of postural control synergies during quiet standing in healthy children and children with cerebral palsy

OBJECTIVE: To estimate the contribution of body transverse rotation using weighted differential center of pressure signals during quiet standing in healthy children and in children with cerebral palsy. DESIGN: Body sway was indirectly measured through center of pressure data, which was calculated using dual force platforms. BACKGROUND: Assessment of postural control synergies using center of pressure data provides a unique method for center of mass data analysis in characterizing complex balance sway. METHODS: Using dual force platforms, linear expressions for the coordinates of right and left center of pressure signals were developed to identify and characterize balance control synergies during quiet standing. Subjects were also tested during eyes open and eyes closed trials to determine the significance of visual input on these control synergies. RESULTS: The limb protraction/retraction control was found to be dominant during medial-lateral sway, whereas the estimated body transverse rotation contribution was found to be more significant than the previously reported measures of anterior-posterior balance. These findings were consistent in healthy children and in children with cerebral palsy during both eyes open and eyes closed trials. CONCLUSION: The weighted differential center of pressure signals show that the estimated body transverse rotation contribution is significant in healthy children and critical for postural stability in children with cerebral palsy. RELEVANCE: This study identifies the significance of body transverse rotation control contribution in upright posture. Children with cerebral palsy with relatively poor ankle control demonstrate the importance of body transverse rotation for postural stability.