Elizabeth L. Inness

Relationship between asymmetry of quiet standing balance control and walking post-stroke

Spatial and temporal gait asymmetry is common after stroke. Such asymmetric gait is inefficient, can contribute to instability and may lead to musculoskeletal injury. However, understanding of the determinants of such gait asymmetry remains incomplete. The current study is focused on revealing if there is a link between asymmetry during the control of standing balance and asymmetry during walking. This study involved review of data from 94 individuals with stroke referred to a gait and balance clinic. Participants completed three tests: (1) walking at their usual pace; (2) quiet standing; and (3) standing with maximal loading of the paretic side. A pressure sensitive mat recorded placement and timing of each footfall during walking. Standing tests were completed on two force plates to evaluate symmetry of weight bearing and contribution of each limb to balance control. Multiple regression was conducted to determine the relationships between symmetry during standing and swing time, stance time, and step length symmetry during walking. Symmetry of antero-posterior balance control and weight bearing were related to swing time and step length symmetry during walking. Weight-bearing symmetry, weight-bearing capacity, and symmetry of antero-posterior balance control were related to stance time symmetry. These associations were independent of underlying lower limb impairment. The results support the hypothesis that impaired ability of the paretic limb to control balance may contribute to gait asymmetry post-stroke. Such work suggests that rehabilitation strategies that increase the contribution of the paretic limb to standing balance control may increase symmetry of walking post-stroke.

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.

Immediate Effects of Cane Use on Gait Symmetry in Individuals with Subacute Stroke

PURPOSE In stroke rehabilitation, there is a lack of consensus regarding the effects of cane use on gait symmetry. This study aimed to evaluate the immediate effects on gait symmetry of ambulating with a standard cane and a quad cane among individuals with subacute stroke. METHOD A within-subject experimental design was used to evaluate symmetry in in-patients with subacute stroke during ambulation on a pressure-sensitive walkway for three task conditions: with no cane, with standard single-point cane, and with quad cane. RESULTS Fourteen patients were classified as symmetric (n = 5) or asymmetric (n = 9) based on their gait symmetry while walking without an aid. Overall, use of a standard cane during ambulation significantly improved symmetry in asymmetric patients (p = 0.028). In contrast, the use of a quad cane did not improve symmetry (p = 0.36). There was no effect on symmetry in symmetric patients with use of either a standard cane (p = 0.88) or a quad cane (p = 0.32). CONCLUSIONS These results indicate that the immediate effect of a standard cane is to improve symmetry in patients with subacute stroke who have asymmetric gait. Future studies are required to determine the long-term effects of canes on gait symmetry in this population.

Is Impaired Control of Reactive Stepping Related to Falls During Inpatient Stroke Rehabilitation

Background. Individuals with stroke fall more often than age-matched controls. Although many focus on the multifactorial nature of falls, the fundamental problem is likely the ability for an individual to generate reactions to recover from a loss of balance. Stepping reactions to recover balance are particularly important to balance recovery, and individuals with stroke have difficulty executing these responses to prevent a fall following a loss of balance. Objective. The purpose of this study is to determine if characteristics of balance recovery steps are related to falls during inpatient stroke rehabilitation. Methods. We conducted a retrospective review of individuals with stroke attending inpatient rehabilitation (n = 136). Details of falls experienced during inpatient rehabilitation were obtained from incident reports, nursing notes, and patient interviews. Stepping reactions were evoked using a “release-from-lean” postural perturbation. Poisson regression was used to determine characteristics of stepping reactions that were related to increased fall frequency relative to length of stay. Results. In all, 20 individuals experienced 29 falls during inpatient rehabilitation. The characteristics of stepping reactions significantly related to increased fall rates were increased frequency of external assistance to prevent a fall to the floor, increased frequency of no-step responses, increased frequency of step responses with inadequate foot clearance, and delayed time to initiate stepping responses. Conclusions. Impaired control of balance recovery steps is related to increased fall rates during inpatient stroke rehabilitation. This study informs the specific features of stepping reactions that can be targeted with physiotherapy intervention during inpatient rehabilitation to improve dynamic stability control and potentially prevent falls.

Clinical Correlates of Between-Limb Synchronization of Standing Balance Control and Falls During Inpatient Stroke Rehabilitation

Background. Stroke-related sensorimotor impairment potentially contributes to impaired balance. Balance measures that reveal underlying limb-specific control problems, such as a measure of the synchronization of both lower limbs to maintain standing balance, may be uniquely informative about poststroke balance control. Objective. This study aimed to determine the relationships between clinical measures of sensorimotor control, functional balance, and fall risk and between-limb synchronization of balance control. Methods. The authors conducted a retrospective chart review of 100 individuals with stroke admitted to inpatient rehabilitation. Force plate–based measures were obtained while standing on 2 force plates, including postural sway (root mean square of anteroposterior and mediolateral center of pressure [COP]), stance load asymmetry (percentage of body weight borne on the less-loaded limb), and between-limb synchronization (cross-correlation of the COP recordings under each foot). Clinical measures obtained were motor impairment (Chedoke-McMaster Stroke Assessment), plantar cutaneous sensation, functional balance (Berg Balance Scale), and falls experienced in rehabilitation. Results. Synchronization was significantly related to motor impairment and prospective falls, even when controlling for other force plate–based measures of standing balance control (ie, postural sway and stance load symmetry). Conclusions. Between-limb COP synchronization for standing balance appears to be a uniquely important index of balance control, independent of postural sway and load symmetry during stance.

Determinants of Limb Preference for Initiating Compensatory Stepping Poststroke

OBJECTIVE To investigate the determinants of limb preference for initiating compensatory stepping poststroke. DESIGN Retrospective chart review. SETTING Inpatient rehabilitation. PARTICIPANTS Convenience sample of individuals admitted to inpatient rehabilitation with poststroke hemiparesis. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Compensatory stepping responses were evoked using a lean-and-release postural perturbation. The limb used to initiate compensatory stepping was determined. The relationships between stepping with the paretic limb and premorbid limb dominance, weight bearing on the paretic limb in quiet standing, ability to bear weight on the paretic limb, preperturbation weight bearing on the paretic limb, and lower-limb motor recovery scores were determined. RESULTS The majority (59.1%) of responses were steps initiated with the nonparetic limb. Increased lower-limb motor recovery scores and preperturbation weight bearing on the nonparetic limb were significantly related to increased frequency of stepping with the paretic limb. When the preferred limb was physically blocked, an inappropriate response was initiated in 21% of trials (ie, nonstep responses or an attempt to step with the blocked limb). CONCLUSIONS This study reveals the challenges that individuals with poststroke hemiparesis face when executing compensatory stepping responses to prevent a fall after a postural perturbation. The inability or challenges to executing a compensatory step with the paretic limb may increase the risk for falls poststroke.

Longitudinal changes in poststroke spatiotemporal gait asymmetry over inpatient rehabilitation.

Background. Little information exists about longitudinal changes in spatiotemporal gait asymmetry during rehabilitation, despite it being a common goal. Objectives. To describe longitudinal changes in spatiotemporal gait asymmetry over rehabilitation and examine relationships with changes in other poststroke impairments. Methods. Retrospective chart reviews were conducted for 71 stroke rehabilitation inpatients. Admission and discharge measures of spatiotemporal symmetry, velocity, motor impairment, mobility and balance were extracted and change scores were calculated. Relationships between changes in spatiotemporal symmetry and other change scores were investigated with Spearman correlations. Individuals were divided into four groups (worse, no change-symmetric, no change-asymmetric, improved) based on (1) symmetry/asymmetry at admission and (2) symmetry change scores >minimal detectable change. Differences in change scores between groups were investigated with analyses of covariance using the admission value as a covariate. Results. At admission, 59% and 49% of individuals were asymmetric in swing time and step length, respectively. Of these individuals, 21% and 14% improved swing symmetry or step symmetry, respectively. In contrast, 30% improved gait velocity, 62% improved functional balance and 73% improved functional mobility. Associations between change in swing symmetry and change in paretic limb weight bearing in standing and change in step symmetry and change in velocity were significant. There were no significant differences in change scores between the symmetry groups. Conclusions. The majority of asymmetric stroke patients did not improve spatiotemporal asymmetry during rehabilitation despite the fact that velocity, balance and functional mobility improved. Future work should investigate other factors associated with improved spatiotemporal symmetry and interventions to specifically improve it.

Clinical balance assessment: perceptions of commonly-used standardized measures and current practices among physiotherapists in Ontario, Canada

BackgroundBalance impairment is common in multiple clinical populations, and comprehensive assessment is important for identifying impairments, planning individualized treatment programs, and evaluating change over time. However, little information is available regarding whether clinicians who treat balance are satisfied with existing assessment tools. In 2010 we conducted a cross-sectional survey of balance assessment practices among physiotherapists in Ontario, Canada, and reported on the use of standardized balance measures (Sibley et al. 2011 Physical Therapy; 91: 1583-91). The purpose of this study was to analyse additional survey data and i) evaluate satisfaction with current balance assessment practices and standardized measures among physiotherapists who treat adult or geriatric populations with balance impairment, and ii) identify factors associated with satisfaction.MethodsThe questionnaire was distributed to 1000 practicing physiotherapists. This analysis focuses on questions in which respondents were asked to rate their general perceptions about balance assessment, the perceived utility of individual standardized balance measures, whether they wanted to improve balance assessment practices, and why. Data were summarized with descriptive statistics and utility of individual measures was compared across clinical practice areas (orthopaedic, neurological, geriatric or general rehabilitation).ResultsThe questionnaire was completed by 369 respondents, of which 43.4% of respondents agreed that existing standardized measures of balance meet their needs. In ratings of individual measures, the Single Leg Stance test and Berg Balance Scale were perceived as useful for clinical decision-making and evaluating change over time by over 70% of respondents, and the Timed Up-and-Go test was perceived as useful for decision-making by 56.9% of respondents and useful for evaluating change over time by 62.9% of respondents, but there were significant differences across practice groups. Seventy-nine percent of respondents wanted to improve their assessments, identifying individual, environmental and measure-specific barriers. The most common barriers were lack of time and knowledge.ConclusionsThis study offers new information on issues affecting the evaluation of balance in clinical settings from a broad sample of physiotherapists. Continued work to address barriers by specific practice area will be critical for the success of any intervention attempting to implement optimal balance assessment practices in the clinical setting.

Use of Accelerometer-Based Feedback of Walking Activity for Appraising Progress With Walking-Related Goals in Inpatient Stroke Rehabilitation A Randomized Controlled Trial

Background. Regaining independent ambulation is important to those with stroke. Increased walking practice during “down time” in rehabilitation could improve walking function for individuals with stroke. Objective. To determine the effect of providing physiotherapists with accelerometer-based feedback on patient activity and walking-related goals during inpatient stroke rehabilitation. Methods. Participants with stroke wore accelerometers around both ankles every weekday during inpatient rehabilitation. Participants were randomly assigned to receive daily feedback about walking activity via their physiotherapists (n = 29) or to receive no feedback (n = 28). Changes in measures of daily walking (walking time, number of steps, average cadence, longest bout duration, and number of “long” walking bouts) and changes in gait control and function assessed in-laboratory were compared between groups. Results. There was no significant increase in walking time, number of steps, longest bout duration, or number of long walking bouts for the feedback group compared with the control group (P values > .20). However, individuals who received feedback significantly increased cadence of daily walking more than the control group (P = .013). From the in-laboratory gait assessment, individuals who received feedback had a greater increase in walking speed and decrease in step time variability than the control group (P values < .030). Conclusion. Feedback did not increase the amount of walking completed by individuals with stroke. However, there was a significant increase in cadence, indicating that intensity of daily walking was greater for those who received feedback than the control group. Additionally, more intense daily walking activity appeared to translate to greater improvements in walking speed.

Measuring Balance and Mobility after Traumatic Brain Injury: Validation of the Community Balance and Mobility Scale (CB&M)

PURPOSE To further investigate the construct validity of the Community Balance and Mobility Scale (CB&M), developed for ambulatory individuals with traumatic brain injury (TBI). METHODS A convenience sample of 35 patients with TBI (13 in-patients, 22 outpatients) was recruited. Analyses included a comparison of CB&M and Berg Balance Scale (BBS) admission and change scores and associations between the CB&M and measures of postural sway, gait, and dynamic stability; the Community Integration Questionnaire (CIQ); and the Activities-specific Balance Confidence (ABC) Scale. RESULTS Mean admission scores on the BBS and the CB&M were 53.6/56 (SD=4.3) and 57.8/96 (SD=23.3) respectively. Significant correlations were demonstrated between the CB&M and spatiotemporal measures of gait, including walking velocity, step length, step width, and step time; measures of dynamic stability, including variability in step length and step time; and the ABC (p<0.05). Significant correlations between the CB&M and CIQ were revealed with a larger data set (n=47 outpatients) combined from previous phases of research. CONCLUSIONS In patients with TBI, the CB&M is less susceptible to a ceiling effect than the BBS. The construct validity of the CB&M was supported, demonstrating associations with laboratory measures of dynamic stability, measures of community integration, and balance confidence.