Reduced sway during dual task balance performance among people with stroke at 6 and 12 months after discharge from hospital

Quiet standing postural control variables in subacute stroke: associations with gait and balance, falls prediction and responsiveness

PURPOSE

To examine the construct validity, predictive validity and responsiveness of standing centre of pressure variables in subacute stroke.

MATERIALS AND METHODS

Seventy-nine ambulatory individuals were assessed before inpatient rehabilitation discharge and three months later. Measures were: gait speed (6-metre walk), dynamic balance (step test), and quiet standing (Wii Balance Board). Centre of pressure speed, amplitude, standard deviation, root mean square, wavelet decomposition, and detrended fluctuation analysis were examined. Falls data were collected over a 12-month period post-discharge.

RESULTS

Moderate strength correlations (r = -0.505 to -0.548) with gait speed and step test scores were shown for 3/26 centre of pressure variables (mediolateral speed, low and moderate frequency wavelet). Twenty-two participants fell and the prediction was significant for gait speed and step test (IQR-odds ratio (OR) = 4.00 & 3.21) and 3/26 centre of pressure variables (mediolateral low-frequency wavelet: IQR-OR = 2.71; mediolateral detrended fluctuation analysis: IQR-OR = 3.06; anteroposterior detrended fluctuation analysis: IQR-OR = 2.71). Significant changes over time occurred for gait speed and step test scores and 20/26 centre of pressure variables.

CONCLUSIONS

Standing centre of pressure variables have limited validity to reflect dynamic balance and falls risk after stroke. Frequency and complexity measures warrant further exploration.Implications for rehabilitationOur findings indicate that quiet standing centre of pressure variables have limited validity to reflect dynamic balance tasks and predict falls after stroke.The mediolateral and higher frequency variables may be more strongly recommended than the commonly used total centre of pressure speed measure.Measures of signal frequency and complexity may provide insight into postural control mechanisms and how these change over time following stroke.

Apathy exacerbates postural control impairments in stroke survivors: The potential effects of cognitive dual-task for improving postural control

Apathy is a stressor and debilitating common condition for both stroke survivors and their caregivers. However, its effects on the postural control of these patients have not yet been investigated. Improved postural stability through withdrawing attention from postural control by concurrent cognitive task (i.e. dual-task condition) has been reported previously, but the effect of apathy, as a confounding factor, remains unknown. This study aimed to examine the effects of apathy and dual-task condition on postural control of chronic stroke survivors from biomechanical and neurophysiological perspectives. Twenty non-apathetic stroke survivors, 20 apathetic stroke survivors, and 20 sex-, age-, weight-, and height-matched healthy subjects were assessed using different postural sway measures and electromyography activity of ankle and hip muscles while quietly standing on rigid and foam surfaces under single-task, easy dual-task, and difficult dual-task conditions. The results showed postural instability and neuromuscular stiffening of stroke survivors, particularly apathetic stroke survivors, compared with healthy controls as evidenced by significantly greater postural sway measures and increased co-contraction of ankle muscles as well as hip muscles. Notably, concurrently performing a cognitive task significantly reduced postural instability and neuromuscular stiffening in chronic stroke survivors even in those with apathy. In conclusion, apathy exacerbates postural control impairments in chronic stroke survivors promoting an inefficient conscious mode of postural control. It is recommended that distracting the attention away from postural control by performing a concurrent cognitive task can be considered an effective strategy while designing interventions for improving postural control in apathetic stroke survivors.

Obstacle Avoidance and Dual-Tasking During Reaching While Standing in Patients With Mild Chronic Stroke

Background. Poststroke individuals use their paretic arms less often than expected in daily life situations, even when motor recovery is scored highly in clinical tests. Real-world environments are often unpredictable and require the ability to multitask and make decisions about rapid and accurate arm movement adjustments. Objective. To identify whether and to what extent cognitive-motor deficits in well-recovered individuals with stroke affect the ability to rapidly adapt reaching movements in changing cognitive and environmental conditions. Methods. Thirteen individuals with mild stroke and 11 healthy controls performed an obstacle avoidance task in a virtual environment while standing. Subjects reached for a virtual juice bottle with their hemiparetic arm as quickly as possible under single- and dual-task conditions. In the single-task condition, a sliding glass door partially obstructed the reaching path of the paretic arm. A successful trial was counted when the subject touched the bottle without the hand colliding with the door. In the dual-task condition, subjects repeated the same task while performing an auditory-verbal working memory task. Results. Individuals with stroke had significantly lower success rates than controls in avoiding the moving door in single-task (stroke: 51.8 ± 21.2%, control: 70.6 ± 12.7%; P = .018) and dual-task conditions (stroke: 40.0 ± 27.6%, control: 65.3 ± 20.0%; P = .015). Endpoint speed was lower in stroke subjects for successful trials in both conditions. Obstacle avoidance deficits were exacerbated by increased cognitive demands in both groups. Individuals reporting greater confidence using their hemiparetic arm had higher success rates. Conclusion. Clinically well-recovered individuals with stroke may have persistent deficits performing a complex reaching task.

Overload of anxiety on postural control impairments in chronic stroke survivors: The role of external focus and cognitive task on the automaticity of postural control

Background

Despite the high prevalence of anxiety among chronic stroke survivors and evidence of its negative effects on postural control in healthy subjects, it is unclear whether anxiety also affects postural control in these patients. Recent evidence of improved postural control of healthy subjects by distracting the attention using an external focus (EF) or cognitive task, raises the question of whether similar benefits would be observed in stroke survivors. Thus, the current study aimed to investigate the effects of anxiety and distracting the attention on postural control of chronic stroke survivors in terms of both postural sway measures and neuromuscular regulation.

Methods

Postural sway measures and ankle muscle activity of chronic stroke survivors with the high and low level of anxiety (HA-stroke (n = 17), and LA-stroke (n = 17), respectively) and age-, sex-, height-, and weight-matched healthy subjects (n = 17) were assessed while standing on rigid and foam surfaces under following conditions: baseline, internal focus (IF), EF, simple and hard cognitive tasks (SC and HC, respectively).

Results

Stroke survivors, particularly HA-stroke participants, showed greater postural sway measures (i.e. postural instability) and enhanced co-contraction of ankle muscles (i.e. stiffening of the neuromuscular system) compared with healthy subjects. As opposed to baseline and IF conditions, postural instability and neuromuscular stiffening significantly reduced in EF condition and decreased more in cognitive task conditions, particularly HC condition.

Conclusions

The results suggest that anxiety enhances stroke-induced postural instability promoting improper neuromuscular control of posture with stiffening strategy, which can be alleviated by EF and cognitive tasks.

Effects of smart phone use on lower limb joint angle and dynamic balance during gait

BACKGROUND

Cognitive tasks influence gait by reducing balancing abilities. Diverse studies to date have examined dual-tasking and gait.

OBJECTIVE

This study aimed to determine the influences of smart phone use while walking on lower limb joint angle and dynamic balancing ability.

METHODS

Thirty healthy subjects were voluntarily recruited from the university population. All subjects were required to perform the tasks under three conditions: not using a smart phone, having a conversation by phone, and playing a smart phone game. Lower limb joint angle and dynamic balance ability related to smart phone use during gait were measured. Motion analysis was used to measure lower limb joint angle changes during gait, while balance measuring equipment was used to measure the dynamic balancing ability.

RESULTS

In the stability limit test to measure the changes in dynamic balancing abilities, significant differences were found among the different smart phone use conditions.

CONCLUSIONS

Smart phone use during movements that are required for balance requires special attention, and this study provides important basic data for follow-up studies.

Standing Balance Strategies and Dual-Task Interference Are Differentially Modulated Across Various Sensory Contexts and Cognitive Tests in Individuals With Chronic Stroke

BACKGROUND AND PURPOSE

Mental tracking and verbal fluency tests have been linked to poor mobility and falls; however, no studies have examined the influence of imposing these tests on standing balance post-stroke. The purpose of this study was to investigate standing balance and cognitive performance across sensory conditions and cognitive tests post-stroke.

METHODS

Ninety-two participants with chronic stroke stood on dual-force platforms while performing various sensory conditions (eyes open/fixed surface, eyes closed/fixed surface, eyes open/sway-referenced surface, and eyes closed/sway-referenced surface) and cognitive tests (no cognitive test, serial subtractions, and verbal fluency). Equilibrium scores were computed based on the anterior-posterior sway angle. The number of correct verbal responses was recorded.

RESULTS

Performing serial subtractions during eyes closed/sway-referenced surface revealed the highest equilibrium score (64.0 ± 13.5), followed by the same sensory condition with added verbal fluency test (59.6 ± 15.1), followed by the single-task condition with no cognitive test (52.6 ± 20.9). The number of correct serial subtractions between seated (7.7 ± 3.7) and standing (7.2 ± 3.5) conditions was similar. A trend for more correct verbal fluency responses emerged when seated (8.1 ± 2.9) than the eyes open/sway-referenced surface condition (7.5 ± 2.8). Greater correct verbal fluency responses emerged when seated (8.6 ± 3.1) than the eyes closed/sway-referenced surface condition (7.8 ± 2.7).

DISCUSSION AND CONCLUSIONS

Standing balance enhancement (higher equilibrium score/better balance) depends on the neuropsychological process targeted and the sensory input available post-stroke. Cognitive dual-task interference emerged for the verbal fluency test during the most attention demanding sensory condition. Cognitive tests that enhance standing balance should be considered in assessments and interventions to evaluate and improve dual-tasking post-stroke.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A321).

Concussed athletes walk slower than non-concussed athletes during cognitive-motor dual-task assessments but not during single-task assessments 2 months after sports concussion: a systematic review and meta-analysis using individual participant data

Objectives

To determine whether individuals who sustained a sports concussion would exhibit persistent impairments in gait and quiet standing compared to non-injured controls during a dual-task assessment .

Design

Systematic review and meta-analysis using individual participant data (IPD).

Data sources

The search strategy was applied across seven electronic bibliographic and grey literature databases: MEDLINE, EMBASE, CINAHL, SportDISCUS, PsycINFO, PsycARTICLES and Web of Science, from database inception until June 2017.

Eligibility criteria for study selection

Studies were included if; individuals with a sports concussion and non-injured controls were included as participants; a steady-state walking or static postural balance task was used as the primary motor task; dual-task performance was assessed with the addition of a secondary cognitive task; spatiotemporal, kinematic or kinetic outcome variables were reported, and; included studies comprised an observational study design with case–control matching.

Data extraction and synthesis

Our review is reported in line with the Preferred Reporting Items for Systematic review and Meta-Analyses-IPD Statement. We implemented the Risk of Bias Assessment tool for Non-randomised Studies to undertake an outcome-level risk of bias assessment using a domain-based tool. Study-level data were synthesised in one of three tiers depending on the availability and quality of data: (1) homogeneous IPD; (2) heterogeneous IPD and (3) aggregate data for inclusion in a descriptive synthesis. IPD were aggregated using a ‘one-stage’, random-effects model.

Results

26 studies were included. IPD were available for 20 included studies. Consistently high and unclear risk of bias was identified for selection, detection, attrition, and reporting biases across studies. Individuals with a recent sports concussion walked with slower average walking speed (χ2=51.7; df=4; p<0.001; mean difference=0.06 m/s; 95% CI: 0.004 to 0.11) and greater frontal plane centre of mass displacement (χ2=10.3; df=4; p=0.036; mean difference −0.0039 m; 95% CI: −0.0075 to −0.0004) than controls when evaluated using a dual-task assessment up to 2 months following concussion.

Summary/conclusions

Our IPD evidence synthesis identifies that, when evaluated using a dual-task assessment, individuals who had incurred a sports concussion exhibited impairments in gait that persisted beyond reported standard clinical recovery timelines of 7–10 days. Dual-task assessment (with motion capture) may be a useful clinical assessment to evaluate recovery after sports concussion.

Protocol pre-registration

This systematic review was prospectively registered in PROSPERO CRD42017064861.

Cognitive-motor interference in post-stroke individuals and healthy adults under different cognitive load and task prioritization conditions

[Purpose] We aimed to compare the effects of cognitive load and task prioritization on dual task strategies in patients with stroke and healthy adults in order to clarify the characteristics of cognitive-motor interference. [Participants and Methods] In total, 26 patients with stroke and 26 age-matched healthy adults (controls) performed the Timed Up and Go Test while performing a serial subtraction task from random numbers between 90 and 100. Dual task was measured under four conditions in which two difficulty levels of "3 subtraction" and "7 subtraction" were multiplied by two prioritizing tasks that involved "paying equal attention to both walking and subtraction tasks" (no priority) and "paying attention while mainly focusing on subtraction tasks" (cognitive priority). [Results] Increasing cognitive load and prioritizing cognitive tasks affected motor performance in terms of the amount of time and number of steps required to complete the Timed Up and Go Test in both the patients and controls. However, cognitive load and task prioritization did not affect cognitive performance. [Conclusion] When cognitive load increases and instructions are given to prioritize increases in cognitive load, patients with stroke use the "posture first" strategy to stabilize their gait as effectively as healthy adults do.

Dynamic balance and instrumented gait variables are independent predictors of falls following stroke

BACKGROUND

Falls are common following stroke and are frequently related to deficits in balance and mobility. This study aimed to investigate the predictive strength of gait and balance variables for evaluating post-stroke falls risk over 12 months following rehabilitation discharge.

METHODS

A prospective cohort study was undertaken in inpatient rehabilitation centres based in Australia and Singapore. A consecutive sample of 81 individuals (mean age 63 years; median 24 days post stroke) were assessed within one week prior to discharge. In addition to comfortable gait speed over six metres (6mWT), a depth-sensing camera (Kinect) was used to obtain fast-paced gait speed, stride length, cadence, step width, step length asymmetry, gait speed variability, and mediolateral and vertical pelvic displacement. Balance variables were the step test, timed up and go (TUG), dual-task TUG, and Wii Balance Board-derived centre of pressure velocity during static standing. Falls data were collected using monthly calendars.

RESULTS

Over 12 months, 28% of individuals fell at least once. The faller group had increased TUG time and reduced stride length, gait speed variability, mediolateral and vertical pelvic displacement, and step test scores (P < 0.001-0.048). Significant predictors, when adjusted for country, prior falls and assistance (i.e., physical assistance and/or gait aid use) were stride length, step length asymmetry, mediolateral pelvic displacement, step test and TUG scores (P < 0.040; IQR-odds ratio(OR) = 1.37-7.85). With comfortable gait speed as an additional covariate, to determine the additive benefit over standard clinical assessment, only mediolateral pelvic displacement, TUG and step test scores remained significant (P = 0.001-0.018; IQR-OR = 5.28-10.29).

CONCLUSIONS

Reduced displacement of the pelvis in the mediolateral direction during walking was the strongest predictor of post-stroke falls compared with other gait variables. Dynamic balance measures, such as the TUG and step test, may better predict falls than gait speed or static balance measures.

Effects of visual cue and cognitive motor tasks on standing postural control following a chronic stroke

[Purpose] The objective of the study was to examine the effects of visual cue and cognitive motor tasks on quiet standing posture center of pressure (COP) and the weight loads to the paretic and non-paretic legs in chronic stroke patients. [Subjects and Methods] Twenty chronic stroke patients were included in the study. COP total distance, sway velocity, and the weight loads to the paretic and non-paretic legs of the participants were measured while they performed a visual cue task, cognitive motor task, and dual task. The parameters were compared using a repeated three-way analysis of variance. [Results] When the visual cue was provided, the COP total distance and sway velocity were significantly reduced compared with when no visual cue was given. When the cognitive motor task was performed, the COP total distance and sway velocity decreased significantly compared to when the task was not performed. [Conclusion] These findings suggest that visual cue and cognitive motor tasks could be used as parts of a rehabilitative training program to improve the control of standing in chronic stroke patients. In addition, visual cues can be used as an intervention to train the paretic leg of stroke patients.

Manual tracking impairs postural stability in older adults

Introduction

Older adults show increased postural sway and a greater risk of falls when completing activities with high cognitive demands. While dual-task approaches have clarified an association between cognitive processes and postural control, it is unclear how manual ability, which is also required for the successful completion of cognitively demanding tasks (such as putting a key into a lock), affects this relationship.

Method

Kinematic technology was used to explore the relationship between postural sway and manual control in healthy younger and older adults. Participants ( n = 82) remained standing to complete a visual-motor tracking task on a tablet computer. Root mean square tracking error measured manual performance, and a balance board measured deviations in centre of pressure as a marker of postural sway.

Results

Older adults displayed poorer manual accuracy and increased postural sway across all testing conditions.

Conclusions

Cognitive capacity can interact with multiple task demands, and in turn affect postural sway in older adults. Improving our understanding of factors that influence postural control will assist falls-prevention efforts and inform clinical practice.

Cognitive-Motor Interference on Upper Extremity Motor Performance in a Robot-Assisted Planar Reaching Task Among Patients With Stroke

OBJECTIVE

To explore motor performance on 2 different cognitive tasks during robotic rehabilitation in which motor performance was longitudinally assessed.

DESIGN

Prospective study.

SETTING

Rehabilitation hospital.

PARTICIPANTS

Patients (N=22) with chronic stroke and upper extremity impairment.

INTERVENTION

A total of 640 repetitions of robot-assisted planar reaching, 5 times a week for 4 weeks.

MAIN OUTCOME MEASURES

Longitudinal robotic evaluations regarding motor performance included smoothness, mean velocity, path error, and reach error by the type of cognitive task. Dual-task effects (DTEs) of motor performance were computed to analyze the effect of the cognitive task on dual-task interference.

RESULTS

Cognitive task type influenced smoothness (P=.006), the DTEs of smoothness (P=.002), and the DTEs of reach error (P=.052). Robotic rehabilitation improved smoothness (P=.007) and reach error (P=.078), while stroke severity affected smoothness (P=.01), reach error (P<.001), and path error (P=.01). Robotic rehabilitation or severity did not affect the DTEs of motor performance.

CONCLUSIONS

The results provide evidence for the effect of cognitive-motor interference on upper extremity performance among participants with stroke using a robotic-guided rehabilitation system.

Timing of reactive stepping among individuals with sub-acute stroke: effects of 'single-task' and 'dual-task' conditions

Performance decrements in balance tasks are often observed when a secondary cognitive task is performed simultaneously. This study aimed to determine whether increased cognitive load resulted in altered reactive stepping in individuals with sub-acute stroke, compared to a reactive stepping trial with no secondary task. The secondary purpose was to determine whether differences existed between the first usual-response trial, subsequent usual-response trials, and the dual-task condition. Individuals with sub-acute stroke were exposed to external perturbations to elicit reactive steps. Perturbations were performed under a usual-response (single-task) and dual-task condition. Measures of step timing and number of steps were based on force plate and video data, respectively; these measures were compared between the usual-response and dual-task trials, and between the first usual-response trial, later usual-response trials (trials 2-5) and a dual-task trial. A longer time of unloading onset and greater number of steps were identified for the first usual-response trial compared to later usual-response trials. No significant differences were identified between usual-response and dual-task trials. Although improvements were observed from the first to subsequent usual-response lean-and-release trials, performance then tended to decrease with the introduction of the dual-task condition. These findings suggest that when introduced after usual-response trials, the dual-task trial may represent the first trial of a new condition, which may be beneficial in reducing the potential for adaptation that may occur after multiple repetitions of a reactive stepping task. Therefore, these findings may lend support to the introduction of a new condition (i.e. a dual-task trial) in addition to usual-response trials when assessing reactive balance in individuals with stroke.

Effect of aquatic dual-task training on balance and gait in stroke patients

[Purpose] The purpose of this study was to determine the effect of aquatic dual-task training on balance and gait in stroke patients. [Subjects and Methods] Twenty stroke patients were divided into the experimental (n=10) and control (n=10) groups. Both groups underwent neurodevelopmental treatment. The experimental group additionally underwent aquatic dual-task training for 30 minutes a day, 5 days a week, for 6 weeks. Balance was measured using the Berg balance scale, Five Times Sit-to Stand Test, and Functional Reach Test. Gait was measured using the 10-Meter Walk Test, Timed Up and Go Test, and Functional Gait Assessment. [Results] For intragroup comparison, the experimental group showed a significant change after the experiment in all balance and gait assessment tests. For intergroup comparison, the experimental group showed relatively more significant change after the experiment in all balance and gait assessment tests. [Conclusion] Our results showed that aquatic dual-task training has a positive effect on balance and gait in stroke patients.

Examining interference of different cognitive tasks on voluntary balance control in aging and stroke

This study compared the effect of semantic and working memory tasks when each was concurrently performed with a voluntary balance task to evaluate the differences in the resulting cognitive-motor interference (CMI) between healthy aging and aging with stroke. Older stroke survivors (n = 10), older healthy (n = 10) and young adults (n = 10) performed the limits of stability, balance test under single task (ST) and dual task (DT) with two different cognitive tasks, word list generation (WLG) and counting backwards (CB). Cognitive ability was evaluated by recording the number of words and digits counted while sitting (ST) and during balance tasks (DT). The balance and cognitive costs were computed using [(ST-DT)/ST] × 100 for all the variables. Across groups, the balance cost was significantly higher for the older stroke survivors group in the CB condition than older healthy (p < 0.05) and young adult groups (p < 0.05) but was similar between these two groups for the WLG task. Similarly, the cognitive cost was significantly higher in older stroke survivors than in older healthy (p < 0.05) and young adults (p < 0.01) for both the cognitive tasks. The working memory task resulted in greater CMI than the semantic one, and this difference seemed to be most apparent in older stroke survivors. Young adults showed the least CMI, with a similar performance on the two memory tasks. On the other hand, healthy aging and stroke impact both semantic and working memory. Stroke-related cognitive deficits may further significantly decrease working memory function.

Neurofeedback training improves the dual-task performance ability in stroke patients

Owing to the reduced capacity for information processing following a stroke, patients commonly present with difficulties in performing activities of daily living that combine two or more tasks. To address this problem, in the present study, we investigated the effects of neurofeedback training on the abilities of stroke patients to perform dual motor tasks. We randomly assigned 20 patients who had sustained a stroke within the preceding 6 months to either a pseudo-neurofeedback (n = 10) or neurofeedback (n = 10) group. Both groups participated in a general exercise intervention for 8 weeks, three times a week for 30 min per session, under the same conditions. An electrode was secured to the scalp over the region of the central lobe (Cz), in compliance with the International 10-20 System. The electrode was inactive for the pseudo-training group. Participants in the neurofeedback training group received the 30-min neurofeedback training per session for reinforcing the sensorimotor rhythm. Electroencephalographic activity of the two groups was compared. In addition, selected parameters of gait (velocity, cadence [step/min], stance phase [%], and foot pressure) were analyzed using a 10-m walk test, attention-demanding task, walk task and quantified by the SmartStep system. The neurofeedback group showed significantly improved the regulation of the sensorimotor rhythm (p < 0.001) and ability to execute dual tasks (p < 0.01). Significant improvements on selected gait parameters (velocity and cadence; p < 0.05) were also observed. We thus propose that the neurofeedback training is effective to improve the dual-task performance in stroke patients.

The effect of dual-task training on balance and cognition in patients with subacute post-stroke

Objective

To investigate the effect of dual-task training on the recovery of balance ability and cognitive function in patients with subacute stroke.

Methods

Twenty patients (12 males and eight females; average age, 59.70 years) with subacute stroke were enrolled in this study. All participants were randomly assigned to one of two groups, the dual-task group (n=10) or the control group (n=10). The dual task was simultaneous balance and cognitive training using the BioRescue. All patients were evaluated with posturographic parameters and the Berg Balance Scale for balance ability, a computerized neuropsychological test and the Korean version of the Mini-Mental State Examination for cognitive function, the Fugl-Meyer Assessment for motor function, and the Korean-Modified Barthel Index for activities of daily living (ADL) function before and after 4 weeks of rehabilitation.

Results

The dual-task group showed significant improvements in the pressure of the weight distribution index (WDI), surface area, and length of the stability index during the eyes-open condition; surface area of the limit of stability (LOS) on the hemiparetic and intact sides, and the auditory continuous performance test and backward visual span test after rehabilitation. Although no significant difference was observed for the changes in balance ability or cognitive, motor, and ADL functions between the groups, changes in the WDI pressure during the eyes-open condition and in the area ratio of LOS (hemiparetic/intact) showed a tendency to improve in the dual-task group.

Conclusion

Our findings suggest that dual-task training could be as effective as conventional balance training for improving balance and cognition in subacute post-stroke patients.

Instrumented static and dynamic balance assessment after stroke using Wii Balance Boards: reliability and association with clinical tests

Background and Objectives

The Wii Balance Board (WBB) is a globally accessible device that shows promise as a clinically useful balance assessment tool. Although the WBB has been found to be comparable to a laboratory-grade force platform for obtaining centre of pressure data, it has not been comprehensively studied in clinical populations. The aim of this study was to investigate the measurement properties of tests utilising the WBB in people after stroke.

Methods

Thirty individuals who were more than three months post-stroke and able to stand unsupported were recruited from a single outpatient rehabilitation facility. Participants performed standardised assessments incorporating the WBB and customised software (static stance with eyes open and closed, static weight-bearing asymmetry, dynamic mediolateral weight shifting and dynamic sit-to-stand) in addition to commonly employed clinical tests (10 Metre Walk Test, Timed Up and Go, Step Test and Functional Reach) on two testing occasions one week apart. Test-retest reliability and construct validity of the WBB tests were investigated.

Results

All WBB-based outcomes were found to be highly reliable between testing occasions (ICC  = 0.82 to 0.98). Correlations were poor to moderate between WBB variables and clinical tests, with the strongest associations observed between task-related activities, such as WBB mediolateral weight shifting and the Step Test.

Conclusions

The WBB, used with customised software, is a reliable and potentially useful tool for the assessment of balance and weight-bearing asymmetry following stroke. Future research is recommended to further investigate validity and responsiveness.

Effect of the cognitive-motor dual-task using auditory cue on balance of surviviors with chronic stroke: a pilot study

Objective:

To investigate the effect of a cognitive-motor dual-task using auditory cues on the balance of patients with chronic stroke.

Design:

Randomized controlled trial.

Setting:

Inpatient rehabilitation center.

Subjects:

Thirty-seven individuals with chronic stroke.

Interventions:

The participants were randomly allocated to the dual-task group ( n=19) and the single-task group ( n=18). The dual-task group performed a cognitive-motor dual-task in which they carried a circular ring from side to side according to a random auditory cue during treadmill walking. The single-task group walked on a treadmill only. All subjects completed 15 min per session, three times per week, for four weeks with conventional rehabilitation five times per week over the four weeks.

Main measures:

Before and after intervention, both static and dynamic balance were measured with a force platform and using the Timed Up and Go (TUG) test.

Results:

The dual-task group showed significant improvement in all variables compared to the single-task group, except for anteroposterior (AP) sway velocity with eyes open and TUG at follow-up: mediolateral (ML) sway velocity with eye open (dual-task group vs. single-task group: 2.11 mm/s vs. 0.38 mm/s), ML sway velocity with eye close (2.91 mm/s vs. 1.35 mm/s), AP sway velocity with eye close (4.84 mm/s vs. 3.12 mm/s). After intervention, all variables showed significant improvement in the dual-task group compared to baseline.

Conclusion:

The study results suggest that the performance of a cognitive-motor dual-task using auditory cues may influence balance improvements in chronic stroke patients.

Postural perturbations induced by a moving virtual environment are reduced in persons with brain injury when gripping a mobile object

BACKGROUND AND PURPOSE

Gripping a mobile (unfixed) object increases standing postural stability in healthy individuals. We tested whether the same strategy is effective for stabilizing upright posture perturbed by a moving environment (virtual perturbation) in participants with traumatic brain injury (TBI).

METHODS

Fifteen participants with mild-to-moderate postural deficits after TBI and a comparison group of 15 age-matched healthy subjects participated in the study. Participants stood for 1 minute in front of a large screen with a projected three-dimensional image of a boat; for 30 seconds the boat remained stationary (no visual stimulation condition), and for 30 seconds the boat rocked on the water at a speed of 15°/s (visual stimulation condition). The visual stimulation was applied in pseudorandom order (during either the first or second half of the 1-minute trial). To analyze postural stability, the displacement and velocity of the center of mass in the sagittal and frontal planes were compared between groups and across 4 experimental conditions, including standing with/without visual stimulation and with/without gripping a 300-g object (short wooden stick) in the dominant hand.

RESULTS

Participants with TBI showed greater instability under all experimental conditions. The visual stimulation significantly increased postural oscillations in the sagittal plane by 35% to 63% across groups. Gripping a stick significantly reduced the stimulation-induced instability in the sagittal plane by 19% to 29%, although not to the level of the no-stimulation condition in either group.

CONCLUSION

The stabilizing effect of gripping an external object in participants with TBI was confirmed. A possibility of using this effect as a balance aid strategy requires further investigation.

Effect of dual tasking on intentional vs. reactive balance control in people with hemiparetic stroke

To examine the effect of a cognitive task on intentional vs. reactive balance control in people with hemiparetic stroke (PwHS). Community-dwelling PwHS ( n = 10) and healthy, age-similar controls performed two tests, which included the Limits of Stability Test (intentional control) and the Motor Control Test (reactive control), under single-task (ST) and dual-task (DT) conditions (addition of a cognitive task). Cognitive ability was measured on a word list generation task by recording the number of words enumerated in sitting (ST; for cognition) and during the balance tasks. The difference in response time between the ST and DT, defined as the “balance cost” was obtained [(ST − DT)/ST × 100] and compared between tests and across groups. The “cognitive cost” was similarly defined and compared. For both groups, the response time under DT condition was significantly greater for intentional than the reactive balance control task, leading to a higher balance cost for this task ( P < 0.05). However, the cognitive cost was significantly greater for the intentional than the reactive balance control task for only the PwHS. DT significantly affected intentional than reactive balance control for PwHS. The significant decrease in both balance and cognitive performance under DT compared with ST conditions during intentional balance control suggests sharing of attentional resources between semantic memory and intentional balance control. Decreased performance on the cognitive task only during the reactive balance test indicates possible central nervous system's prioritization of reactive balance control over cognition.

Dual-tasking postural control in patients with right brain damage

The control of dual-tasking effects is a daily challenge in stroke neurorehabilitation. It maybe one of the reasons why there is poor functional prognosis after a stroke in the right hemisphere, which plays a dominant role in posture control. The purpose of this study was to explore cognitive motor interference in right brain-lesioned and healthy subjects maintaining a standing position while performing three different tasks: a control task, a simple attentional task and a complex attentional task. We measured the sway area of the subjects on a force platform, including the center of pressure and its displacements. Results showed that stroke patients presented a reduced postural sway compared to healthy subjects, who were able to maintain their posture while performing a concomitant attentional task in the same dual-tasking conditions. Moreover, in both groups, the postural sway decreased with the increase in attentional load from cognitive tasks. We also noticed that the stability of stroke patients in dual-tasking conditions increased together with the weight-bearing rightward deviation, especially when the attentional load of the cognitive tasks and lower limb motor impairments were high. These results suggest that stroke patients and healthy subjects adopt a similar postural regulation pattern aimed at maintaining stability in dual-tasking conditions involving a static standing position and different attention-related cognitive tasks. Our results indicate that attention processes might facilitate static postural control.

Cognitive-motor interference during functional mobility after stroke: state of the science and implications for future research

Cognitive-motor interference (CMI) is evident when simultaneous performance of a cognitive task and a motor task results in deterioration in performance in one or both of the tasks, relative to performance of each task separately. The purpose of this review is to present a framework for categorizing patterns of CMI and to examine the specific patterns of CMI evident in published studies comparing single-task and dual-task performance of cognitive and motor tasks during gait and balance activities after stroke. We also examine the literature for associations between patterns of CMI and a history of falls, as well as evidence for the effects of rehabilitation on CMI after stroke. Overall, this review suggests that during gait activities with an added cognitive task, people with stroke are likely to demonstrate significant decrements in motor performance only (cognitive-related motor interference), or decrements in both motor and cognitive performance (mutual interference). In contrast, patterns of CMI were variable among studies examining balance activities. Comparing people poststroke with and without a history of falls, patterns and magnitude of CMI were similar for fallers and nonfallers. Longitudinal studies suggest that conventional rehabilitation has minimal effects on CMI during gait or balance activities. However, early-phase pilot studies suggest that dual-task interventions may reduce CMI during gait performance in community-dwelling stroke survivors. It is our hope that this innovative and critical examination of the existing literature will highlight the limitations in current experimental designs and inform improvements in the design and reporting of dual-task studies in stroke.

O ambiente virtual como interface na reabilitação pós-AVE: relato de caso

INTRODUÇÃO: O acidente vascular encefálico (AVE) é um quadro neurológico agudo de repercussões amplas, que exige de suas vítimas programas de reabilitação desafiadores na promoção da função. Nesse contexto, a Realidade Virtual (RV) é uma ferramenta de interface na reabilitação que pode gerar altos índices de motivação do paciente e permitir adaptação da terapia ao seu nível de função. OBJETIVO: Verificar o efeito da RV por meio de videogame sobre o controle postural de um indivíduo pós-AVE. MATERIAIS E MÉTODOS: Um indivíduo pós-AVE com um ano de lesão foi submetido a um protocolo de reabilitação física com videogame numa frequência de três vezes por semana por um período de 12 semanas. Anteriormente e após o programa foi realizada dinamometria por plataforma de força para análise de variáveis relacionadas ao centro de pressão (COP). RESULTADOS: Na reavaliação, observou-se que a amplitude de deslocamento médio-lateral (x) aumentou 67% na condição de olhos abertos (OA) e fechados (OF); amplitude anteroposterior (y) aumentou 25 e 44% em OA e OF, respectivamente; área aumentou 109 e 141% em OA e OF; velocidade diminuiu 26 e 0,27% em OA e OF. CONCLUSÃO: A RV como interface na reabilitação possivelmente ampliou a exploração da base de suporte para manutenção da estabilidade, constituindo recurso adicional no tratamento desses indivíduos.

Upper-limb motor control in patients after stroke: attentional demands and the potential beneficial effects of arm support

The goal of this study was to investigate the attentional load of using the upper limb in moderately and mildly affected patients after stroke, with and without arm support. Ten patients with stroke (4 mild and 6 moderate paresis) and ten healthy, gender- and age-matched control subjects performed a dual-task experiment that consisted of a circle drawing task and an auditive Stroop task. Complexity of the motor task was manipulated by supporting the arm against gravity. Individual motor (area×speed) and cognitive (accuracy/reaction time) scores during the dual-task conditions were converted into percentage scores relative to the respective single-task scores and then combined in a single measure of net dual-task performance. Without arm support, only moderately affected patients showed significantly greater side differences in dual-task performance to the detriment of the affected upper limb. With arm support, no side differences were found for any of the three groups. Thus, the hypothesis that patients with moderate upper-limb paresis suffer from a lack of automaticity of motor control was substantiated by the dual-task condition. Furthermore, supporting the arm reduced the attentional load of using the affected side.

People with stroke who fail an obstacle crossing task have a higher incidence of falls and utilize different gait patterns compared with people who pass the task

BACKGROUND

Obstacle crossing is impaired in people following stroke. It is not known whether people with stroke who fail an obstacle crossing task have more falls or whether the gait adjustments used to cross an obstacle differ from those used by people who pass the task.

OBJECTIVE

The purposes of this study were (1) to identify whether a group of people with stroke who failed an obstacle crossing task had a greater incidence of falling and (2) to determine whether people who fail an obstacle crossing task utilize different gait adjustments.

DESIGN

This was a prospective, observational study.

METHODS

Thirty-two participants with a recent stroke were recruited. Participants walked at self-selected speed and stepped over a 4-cm-high obstacle. Performance was rated as pass or fail, and spatiotemporal, center of mass (COM), and center of pressure (COP) data were collected. Prospective falls data were recorded for 20 participants over a 6-month period.

RESULTS

The incidence of fallers was significantly higher (incidence rate=0.833) in the group that failed the obstacle crossing task than in the group that passed the task (incidence rate=0.143). The group that failed the task had a slower walking speed and greater normalized separation between the trail heel (unaffected support limb) and COM as the affected lead toe cleared the obstacle. This group exhibited greater normalized times from affected lead toe clearance to landing, unaffected trail toe clearance to landing, and affected trail toe-off to toe clearance.

LIMITATIONS

The sample size was small, and falls data were available for only 20 participants.

CONCLUSIONS

Obstacle crossing is an important task to consider in people following stroke and may be useful in identifying those at risk of falls.

Performance of a cognitive, but not visual, secondary task interacts with alcohol-induced balance impairment in novice and experienced motorcycle riders

The appropriateness of applying drink driving legislation to motorcycle riding has been questioned as there may be fundamental differences in the effects of alcohol on driving and motorcycling. It has been suggested that alcohol may redirect riders' focus from higher-order cognitive skills such as cornering, judgement and hazard perception, to more physical skills such as maintaining balance. To test this hypothesis, the effects of low doses of alcohol on balance ability were investigated in a laboratory setting. The static balance of twenty experienced and twenty novice riders was measured while they performed either no secondary task, a visual (search) task, or a cognitive (arithmetic) task following the administration of alcohol (0%, 0.02%, and 0.05% BAC). Subjective ratings of intoxication and balance impairment increased in a dose-dependent manner in both novice and experienced motorcycle riders, while a BAC of 0.05%, but not 0.02%, was associated with impairments in static balance ability. This balance impairment was exacerbated when riders performed a cognitive, but not a visual, secondary task. Likewise, 0.05% BAC was associated with impairments in novice and experienced riders' performance of a cognitive, but not a visual, secondary task, suggesting that interactive processes underlie balance and cognitive task performance. There were no observed differences between novice vs. experienced riders on static balance and secondary task performance, either alone or in combination. Implications for road safety and future 'drink riding' policy considerations are discussed.

Turning Ability in Stroke Survivors: A Review of Literature

The aim of this paper is to explore the research literature on the turning ability among stroke survivors. Stroke is one of the top five leading causes of death and disability in Malaysia. Stroke survivors reported a higher rate of fall incidences with turning while walking has been the major contributor in most of the incidences. The attentional task requires stroke survivors to have higher cognitive and attention function, and sound muscle coordination in order to perform multitask activities such as driving, walking and turning while talking, carrying an object (holding a plastic bag), navigating corners and overcoming obstacles within the base of support. Most of the previous studies have focused on the kinematic and gait parameters measurement of turning ability among stroke survivors. However, studies conducted on muscle activity using electromyography to evaluate the time pattern of muscle contraction during turning event is lacking. With regards to dual-task ability among stroke survivors, there is insufficient information or research into dual task (motor and cognitive) ability during turning. Further studies are needed to understand the effects of dual-task activity on muscle activity and gait parameters and how this impairment affects the turning ability. This needs to be addressed in order to prevent falls among stroke survivors.

The Diagnostic Accuracy of Static Posturography in Predicting Accidental Falls in People With Multiple Sclerosis

Background. Quantitative posturography has been reported as a reliable tool to measure balance in people with multiple sclerosis (MS). However, data on its diagnostic accuracy in predicting the occurrence of falls are lacking. Objective. To determine sensitivity, specificity, predictive values, and accuracy of posturography in detecting falls in MS subjects over a 3-month follow-up period. Methods. One hundred consecutive patients with MS were tested by the Berg Balance Scale (BBS) and by static posturography on a monoaxial platform. Participants recorded the occurrence of accidental falls for the next 3 months. Abnormal cutoff values for static standing balance measures were set at 2 standard deviations above the mean values obtained from 50 healthy controls (HC). The diagnostic accuracy of the BBS and static posturography was analyzed with respect to the prospectively collected data on the occurrence of falls. Results. Posturometric measures in participants with MS were significantly worse than in HC (all P values <.0001); however, only the center of pressure (COP) path with open eyes condition had substantial test–retest reliability. Static posturography was more sensitive (88% vs 37%) and accurate (75% vs 63%), but slightly less specific (67% vs 81%), than the BBS in predicting accidental falls. A logistic regression analysis revealed that the worse the COP path, the greater the risk for accidental falls (odds ratio = 1.08; P < .0001), even after adjusting for sex, age, disease duration, body mass index, MS subtype, Expanded Disability Status Scale, and BBS score. Conclusion. The COP path measurement in static position is a sensitive and accurate tool to identify people with MS who are at risk of accidental falls.

Effects of dual task balance training on dual task performance in elderly people: a randomized controlled trial

OBJECTIVE

To investigate the effects of dual task balance training in the elderly on standing postural control while performing a cognitive task.

DESIGN

A randomized two-group parallel controlled trial.

PARTICIPANTS

Forty-three subjects (all >65 years old) were enrolled in the study and were assigned randomly to either an experimental group (n = 21) or a control group (n = 22).

INTERVENTIONS

Subjects in the experimental group were given strength and balance training while performing cognitive tasks simultaneously. Subjects in the control group were given strength and balance training only. The training was administered twice a week for three months.

MEASUREMENTS

The Chair Stand Test, Functional Reach Test, Timed Up and Go Test and Trail Making Test were measured. The sway length of the centre of gravity was measured during standing while performing the Stroop task. The rate of Stroop task was also measured. All measurements were collected at baseline and after the training period.

RESULTS

There were no significant differences in Functional Reach Test, Timed Up and Go Test and sway length at baseline and after training between the two groups. However, the rate of Stroop task (P < 0.05) was significantly higher after training in the experimental group than in the control group.

CONCLUSIONS

These results suggest that dual task balance training in elderly people improves their dual task performance during standing postural control.

Interference between cognition, double-limb support, and swing during gait in community-dwelling individuals poststroke

BACKGROUND

Dual tasking can interfere with activity after stroke.

OBJECTIVE

The authors examined the interactions between 3 different cognitive tasks and the swing and double-limb support (DLS) components of the gait cycle in community-dwelling individuals poststroke.

METHODS

Acquisition of cognitive and gait data were synchronized to study the cognitive-motor interference effects during the different phases of the gait cycle. Participants performed 3 different cognitive tasks in isolation and in combination with walking as well as a single walking task. Tasks were performed continuously for 3 minutes, generating 131 +/- 39 gait cycles per person for analysis for each walking trial. Data were analyzed for 8 participants 7.6 +/- 4.2 months poststroke.

RESULTS

A significant increase was found in the proportion of the gait cycle spent in DLS in dual-task walking because of an increased duration of the DLS phase associated with paretic weight acceptance. There was a significant dual-task effect on nonparetic swing duration: participants reduced the amount of time in paretic single-limb stance in the 3 dual-task conditions. Temporal asymmetry of gait did not increase significantly under dual-task conditions. Reaction times were not affected by whether the stimuli were present during the swing or DLS phase of the gait cycle.

CONCLUSIONS

The findings from this pilot study provide evidence that cognitive-motor interference during gait may be influenced by the phase of the gait cycle, especially DLS involving paretic weight acceptance, which may affect community ambulators with hemiparetic stroke.