Evaluation of unsupervised 30-second chair stand test performance assessed by wearable sensors to predict fall status in multiple sclerosis

BackgroundOne in two people with multiple sclerosis (PwMS) will fall in a three-month period. Predicting which patients will fall remains a challenge for clinicians. Standardized functional assessments provide insight into balance deficits and fall risk but their use has been limited to supervised visits.Research questionThe study aim was to characterize unsupervised 30-second chair stand test (30CST) performance using accelerometer-derived metrics and assess its ability to classify fall status in PwMS compared to supervised 30CST.MethodsThirty-seven PwMS (21 fallers) performed instrumented supervised and unsupervised 30CSTs with a single wearable sensor on the thigh. In unsupervised conditions, participants performed bi-hourly 30CSTs and rated their balance confidence and fatigue over 48-hours. ROC analysis was used to classify fall status for 30CST performance.ResultsNon-fallers (p = 0.02) but not fallers (p = 0.23) differed in their average unsupervised 30CST performance (repetitions) compared to their supervised performance. The unsupervised maximum number of 30CST repetitions performed optimized ROC classification AUC (0.79), accuracy (78.4%) and specificity (90.0%) for fall status with an optimal cutoff of 17 repetitions.SignificanceBrief durations of instrumented unsupervised monitoring as an adjunct to routine clinical assessments could improve the ability for predicting fall risk and fluctuations in functional mobility in PwMS.     

Evaluating the contribution of reactive balance to prediction of fall rates cross-sectionally and longitudinally in persons with multiple sclerosis

BackgroundFalls are common in persons with multiple sclerosis (PwMS). Reactive postural control—one’s response to a balance perturbation—is likely an aspect of fall risk; however, the relationship between reactive posture and falls is poorly understood in PwMS.ObjectiveWe evaluated tibialis anterior muscle onset latency (TA latency) after balance perturbations as a predictor of fall rates in PwMS, controlling for clinical, functional, sensory, psychological, and cognitive factors.MethodAt baseline of the 18-month cohort study, 122 participants with MS (EDSS = 2.23) were included. Assessments were conducted every 6 months.ResultsOf the original 122 participants at the baseline collection, data were available from 41, 39, and 34 people at the 6, 12, and 18 month follow-ups, respectively. Percent fallers at the four time points were 35.3%, 12.2%, 15.4%, and 20.5%. Cross-sectionally (i.e., at baseline), the Timed Up-and-Go, Falls Efficacy Scale – International (FES-I), and TA latency after perturbations were significant predictors of retrospective falls rates using negative binomial regression. Longitudinally, random-effects negative binomial regression found that trait-level FES-I, Stroop Color-Word, and TA latency were significant predictors for falls rates.ConclusionDelays in automatic postural responses seem to account uniquely for fall rates in PwMS—beyond clinical, balance, or mobility measures. These delays may contribute to the increased fall rate in PwMS. In addition to brief self-report instruments (FES-I) and cognitive assessments, muscle onset after balance perturbations may be a valuable tool for predicting falls in those with MS.     

Wearable inertial sensors to measure gait and posture characteristic differences in older adult fallers and non-fallers: A scoping review

BackgroundWearable inertial sensors have grown in popularity as a means of objectively assessing fall risk. This review aimed to identify gait and posture differences among older adult fallers and non-fallers which can be measured with the use of wearable inertial sensors. In addition to describing the number of sensors used to obtain measures, the concurrent anatomical locations, how these measures compare to current forms of clinical fall risk assessment tests and the setting of tests.MethodsFollowing the development of a rigorous search strategy, MEDLINE, Web of Science, Cochrane, EMBASE, PEDro, and CINAHL were systematically searched for studies involving the use of wearable inertial sensors, to determine gait and postural based differences among fallers or those at high fall risk compared with non-fallers and low fall risk adults aged 60 years and older.ResultsThirty five papers met the inclusion criteria. One hundred and forty nine gait and posture characteristic differences were identified using wearable inertial sensors. There were sensor derived measures which significantly and strongly correlated with traditional clinical tests. The use of a single wearable inertial sensor located at the lower posterior trunk, was most the most effective location and enough to ascertain multiple pertinent fall risk factors.ConclusionThis review identified the capabilities of identifying fall risk factors among older adults with the use of wearable inertial sensors. The lightweight portable nature makes inertial sensors an effective tool to be implemented into clinical fall risk assessment and continuous unsupervised home monitoring, in addition to, outdoor testing.     

The association between bladder dysfunction,balance and falls in women with multiple sclerosis: The specific contribution of fear of falling

BackgroundBladder dysfunction is the most common autonomic disturbance in people with MS (PwMS). Only a few studies have examined the relationship between bladder dysfunction and falls in PwMS. Bladder dysfunction has been deemed only a secondary outcome measure, and classified by a gross measure providing a limited perspective of this disturbing symptom. Furthermore, no study to date has focused on the relationship between bladder dysfunction and balance performance in PwMS.Research questionDetermine the relationship between bladder dysfunction with balance, falls and fear of falling in women with MS.MethodsThe study was observational, including 44 women with MS, mean age 46.3 (SD = 5.7), all with at least a mild bladder dysfunction. Outcome measures included the Urinary Incontinence Quality of Life Scale (I-QoL), Bladder Control Scale (BLCS), Timed Up and Go Test (TUG), Four Square Step Test (FSST), Falls Efficacy Scale International (FES-I), Falls status, and posturography.ResultsParticipants performed the TUG in 14.1 s (S.D. = 11.1), and the FSST in 20.5 s (S.D. = 22.4). A relatively large proportion (68.2 %) of women was classified as fallers. However, no differences were found between those classified as fallers (n = 30) or non-fallers (n = 14) in terms of the I-QoL and the BLCS, controlling for age, EDSS and number of vaginal deliveries. Significant correlations scores were found between the I-QoL, BLCS and FES-I (rho ∼0.47), while controlling for age, EDSS and number of vaginal deliveries. No associations were demonstrated between the bladder dysfunction outcome scores and either the TUG and/or FSST.SignificanceWomen afflicted with MS and suffering from bladder dysfunction tend to fall and present with more balance difficulties compared with disability-matched PwMS. Nevertheless, once bladder dysfunction is detected, the perceived severity of the condition is not associated with balance and prevalence of falling, but rather on fear of falling.     

Local dynamic stability during long-fatiguing walks in people with multiple sclerosis

BackgroundAltered balance/stability during walking is common in people with multiple sclerosis (PwMS). While dynamic gait stability has been related to falling and localized muscle fatigue, it has rarely been studied in MS. Specifically, the effects of walking-related fatigue on dynamic stability are unclear in PwMS. Research questions: 1) Are temporal changes in dynamic stability during long-walks different among PwMS and healthy controls (HC)? 2) Is there a relationship between stability and walking performance changes in PwMS?MethodsTwenty-five PwMS and ten HC participated in the six-minute walk test (6MWT) wearing six-wireless inertial sensors. Local dynamic stability (LDS) during gait was quantified by maximum-finite-time Lyapunov exponents (λS), where larger λS indicates less stable dynamics. Linear mixed models were fit to compare changes in LDS and walking performance over time among two groups. Additionally, the percent changes in λS and distance from minute 1 to 6 were recorded as Dynamic Stability Index (DSI6-1) and Distance-Walked Index (DWI6-1) respectively. Finally, Pearson correlation compared the association between DSI6-1 and DWI6-1.ResultsA significant group*time interaction was found for LDS. PwMS did not have different LDS than HC until minute-4 of walking, and differences persisted at minute-6. Further, PwMS walked significantly shorter distances and demonstrated a greater decline in walking performance (DWI6-1) during the 6MWT. Finally, DSI6-1 and DWI6-1 were significantly correlated in PwMS. Significance The dynamic stability differences among PwMS and HC were only apparent after 3-minutes of walking and ∼60% of PwMS became less stable over time, supporting the use of long walks in MS to capture stability changes during the motor task performance. A significant relationship between the decline in stability and poor walking performance over time during the 6MWT suggested a possible role of walking-related fatigue in the worsening of balance during long walks in PwMS.     

The association between gait variability with the energy cost of walking depends on the fall status in people with multiple sclerosis without mobility aids

BackgroundFalls, gait variability and increased energy cost of walking are common in people with multiple sclerosis (PwMS). However, no studies have as yet examined this triple association in PwMS or in other neurological populations.Research questionDoes a relationship exist between gait variability, falls and the energy cost of gait in PwMS?MethodsThis cross sectional study included 88 PwMS (50 women), mean age 39.8 (S.D = 13.0) and mean disease duration of 6.2 (SD = 8.2) years since diagnosis. Energy expenditure during walking was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Gait variability was measured by an electronic walkway (GAITRite™). Participants were divided into groups based on fall history (fallers and non-fallers). Differences between groups in terms of energy expenditure measures and gait variability metrics were determined by the analysis of variance test. The relationship between gait variability and energy cost of walking was examined by the Pearson's correlation coefficient test.ResultsThirty-three PwMS were classified as fallers and 55 as non-fallers. Non-significant differences between groups were observed in the energy expenditure measures, including cost of walking. Fallers demonstrated higher step length variability compared with non-fallers (4.58 (S.D. = 2.42 vs. 3.40 (S.D. = 1.40); p-value = 0.005). According to the Pearson's correlation coefficient analysis, a significant relationship was found between step length variability and energy cost of walking in the non-fallers group (Rho = 0.372, P-value = 0.006) and the total group (Rho = 0.296, p-value = 0.005), but not in those PwMS with a history of falls.SignificanceWe demonstrated a significant relationship between increased gait variability and energy expenditure while walking only in MS patients without a history of falls. This is important as there is evidence of the clinical relevance of increased gait variability, poor fitness level and high risk of falling in the MS population.     

Symmetry in vertical ground reaction force is not related to walking and balance difficulties in people with multiple sclerosis

Analysis of vertical ground reaction force (GRF) symmetry may benefit people with multiple sclerosis (PwMS) since it can detect important differences in gait mechanics which have not previously been discussed in the related literature. Therefore, the primary objective of the current study was to determine whether symmetry of the vertical GRF during gait is associated with validated gait and balance tests in PwMS. Additionally, we examined whether the symmetry of the vertical GRF differs between MS fallers, non-fallers and between neurological disability levels. Gait and balance data were collected from 402 PwMS (249 women) with a mean age of 42.1 (S.D = 14.1) years. Vertical GRF parameters were obtained using the Zebris FDM-T Treadmill (Zebris Medical GmbH, Germany). Clinical gait and balance tests included the 2 and 6-min Walk Test, Timed Up and Go Test, Timed 25 Foot Walk, Four Square Step Test, Multiple Sclerosis Walking Scale questionnaire, Modified Fatigue Impact Scale and the Falls Efficacy Scale International questionnaire. The vertical GRF symmetry index score of the total sample was 3.7 (SD = 3.1). In terms of fall status, non-significant differences were observed between the fallers and non-faller groups and between the neurological disability subgroups. Non-significant correlation scores were found between the vertical GRF symmetry index, all clinical walking and balance tests and self-reported questionnaires. We suggest clinicians, especially those involved in physical rehabilitation, accord low priority to this gait phenomenon in the MS population.     

U-turn speed is a valid and reliable smartphone-based measure of multiple sclerosis-related gait and balance impairment

BackgroundPeople living with multiple sclerosis (MS) experience impairments in gait and mobility, that are not fully captured with manually timed walking tests or rating scales administered during periodic clinical visits. We have developed a smartphone-based assessment of ambulation performance, the 5 U-Turn Test (5UTT), a quantitative self-administered test of U-turn ability while walking, for people with MS (PwMS).Research questionWhat is the test-retest reliability and concurrent validity of U-turn speed, an unsupervised self-assessment of gait and balance impairment, measured using a body-worn smartphone during the 5UTT?Methods76 PwMS and 25 healthy controls (HCs) participated in a cross-sectional non-randomised interventional feasibility study. The 5UTT was self-administered daily and the median U-turn speed, measured during a 14-day session, was compared against existing validated in-clinic measures of MS-related disability.ResultsU-turn speed, measured during a 14-day session from the 5UTT, demonstrated good-to-excellent test-retest reliability in PwMS alone and combined with HCs (intraclass correlation coefficient [ICC] = 0.87 [95 % CI: 0.80–0.92]) and moderate-to-excellent reliability in HCs alone (ICC = 0.88 [95 % CI: 0.69–0.96]). U-turn speed was significantly correlated with in-clinic measures of walking speed, physical fatigue, ambulation impairment, overall MS-related disability and patients’ self-perception of quality of life, at baseline, Week 12 and Week 24. The minimal detectable change of the U-turn speed from the 5UTT was low (19.42 %) in PwMS and indicates a good precision of this measurement tool when compared with conventional in-clinic measures of walking performance.SignificanceThe frequent self-assessment of turn speed, as an outcome measure from a smartphone-based U-turn test, may represent an ecologically valid digital solution to remotely and reliably monitor gait and balance impairment in a home environment during MS clinical trials and practice.     

Gait stability at early stages of multiple sclerosis using different data sources

BackgroundPeople at early stages of multiple sclerosis have subtle balance problems that may affect gait stability. However, differences in methods of determining stability such as sensor type and placements, may lead to different results and affect their interpretation when comparing to controls and other studies.QuestionsDo people with multiple sclerosis (PwMS) exhibit lower gait stability? Do location and type of data used to calculate stability metrics affect comparisons?Methods30 PwMS with no walking impairments as clinically measured and 15 healthy controls walked on a treadmill at 1.2 ms⁻¹ while 3D acceleration data was obtained from sacrum, shoulder and cervical markers and from an accelerometer placed at the sacrum. The local divergence exponent was calculated for the four data sources. An ANOVA with group (multiple sclerosis and control) and data source as main factors was used to determine the effect of disease, data source and their interaction on stability metrics.ResultsPwMS walked with significantly less stability according to all sensors (no interaction). A significant effect of data source on stability was also found, indicating that the local divergence exponent derived from sacrum accelerometer was lower than that derived from the other 3 sensor locations.SignificancePwMS with no evident gait impairments are less stable than healthy controls when walking on a treadmill. Although different data sources can be used to determine MS-related stability deterioration, a consensus about location and data source is needed. The local divergence exponent can be a useful measure of progression of gait instability at early stages of MS.     

Utility of an obstacle-crossing test to classify future fallers and non-fallers at hospital discharge after stroke: A pilot study

BackgroundExisting clinical assessments of balance and functional mobility have poor predictive accuracy for prospectively identifying post-stroke fallers, which may be due to a lack of ecological complexity that is typical of community-based fall incidents.Research questionDoes an obstacle-crossing test at hospital discharge predict fall status of ambulatory stroke survivors 3 months after discharge?MethodsAmbulatory stroke survivors being discharged home completed an obstacle-crossing test at hospital discharge. Falls were tracked prospectively for 3 months after discharge. Logistic regression examined the relationship between obstacle-crossing at discharge (pass/fail) and fall status (faller/non-faller) at 3 months post discharge.Results45 participants had discharge obstacle test and 3-month fall data. 21 (47 %) participants experienced at least one fall during follow-up, with 52 % of the falls occurring within the first month after discharge. Of the 21 fallers, 14 failed the obstacle-crossing test (67 % sensitivity). Among the 24 non-fallers, 20 passed the obstacle-crossing test (83 % specificity). The area under the receiver operating characteristic curve was 0.75 (95 % CI 0.60–0.90). Individuals who failed the obstacle-crossing test were 10.00 (95 % CI: 2.45–40.78) times more likely to fall in the first 3 months after discharge. The unadjusted logistic regression model correctly classified 76 % of the subjects. After adjusting for age, sex, days post stroke, and post-stroke disability, the odds ratio remained significant at 6.93 (95 % CI: 1.01–47.52) and correctly classified 79.5% of the participants.SignificanceThe obstacle-crossing test may be a useful discharge assessment to identify ambulatory stroke survivors being discharged home who are likely to fall in the first 3 months post discharge. Modifications to improve the obstacle-crossing test sensitivity should be explored further.     

Association of postural balance and falls in adult patients receiving haemodialysis: A prospective cohort study

BackgroundStatic postural balance performance is often impaired in people receiving haemodialysis (HD) for the treatment of stage-5 chronic kidney disease (CKD-5). However, the question as to whether lower postural balance is associated with adverse clinical outcomes such as falls has not been addressed yet.Research questionWe conducted a prospective cohort study to explore the association between static postural balance and falls in people receiving HD. We hypothesised that higher postural sway would be associated with increased odds of falling.MethodsSeventy-five prevalent CKD-5 patients receiving HD (age: 61.8 ± 13.4 years) from three Renal Units were enrolled in this prospective cohort study. At baseline, postural balance was assessed with a force platform in eyes open (EO) and eyes closed (EC) conditions. Centre of pressure (CoP) measures of range, velocity and area were taken for the analysis. Falls experienced by study participants were prospectively recorded during 12 months of follow-up. Secondary outcomes included timed-up and go, five-repetition sit-to-stand test and the Tinetti falls efficacy scale (FES).ResultsIn multivariable logistic regression analysis, higher CoP range in medial-lateral direction during EC was associated with increased odds of falling (OR: 1.04, 95 %CI: 1.00−1.07, p = 0.036). In ROC curve analysis, CoP velocity in EO exhibited the greatest prognostic accuracy (AUC: 0.69, 95 %CI: 0.55−0.82), however this was not statistically different from CoP measures of area and range. None of the postural balance measures exceeded the prognostic accuracy of the FES (AUC: 0.70, 95 %CI: 0.58−0.83, p = 0.005).SignificanceThis prospective cohort study showed that higher postural sway in medial-lateral direction was associated with increased odds of falling in people receiving HD. CoP measures of range, velocity and area displayed similar prognostic value in discriminating fallers from non-fallers. The overall utility of static posturography to detect future fall-risk may be limited in a clinical setting.     

Association between fall risk and assessments of single-task and dual-task walking among community-dwelling individuals with chronic stroke: A prospective cohort study

BackgroundFalling and fall-related injuries are common among community-dwelling individuals with chronic stroke. Falls often occur during dual-task walking scenarios. Accurate fall prediction is critical for formulating effective fall prevention strategies.Research questionsCan dual-task walking tests and corresponding single-task tests predict falls among individuals with chronic stroke? Are dual-task walking tests involving visuospatial cognition more effective in predicting falls than those involving other cognitive domains?MethodsNinety-three individuals with stroke (age: 62.4 ± 6.7 years; stroke duration: 5.6 ± 4.5 years) participated in this prospective cohort study. Two mobility tasks (level-ground walking and obstacle-crossing) were performed with and without two cognitive tasks (auditory clock test and auditory Stroop test). Demographic information and clinical measures of depression, motor function, walking speed and balance were collected. Monthly telephone interviews were conducted to collect data on fall incidence, related circumstances and injuries incurred during a 12-month follow-up period. Multivariate logistic regression analysis was performed to identify predictive factors associated with future risk of falls.ResultsThirty-six participants (39%) reported one or more falls during the follow-up period. The regression model including reaction time during the auditory clock task performance while negotiating obstacles correctly classified the fall status of 80% of the participants (72% future fallers and 84% non-fallers). Performance did not differ between fallers and non-fallers on any other measures tested.SignificanceDual-task assessment combining an auditory clock task with an obstacle-crossing task has potential clinical utility for identifying future fall risk among people with chronic stroke.     

Surrogates for rigidity and PIGD MDS-UPDRS subscores using wearable sensors

BackgroundTelemedicine has the advantage of expanding access to care for patients with Parkinson’s Disease (PD). However, rigidity and postural instability in PD are difficult to measure remotely, and are important measures of functional impairment and fall risk.Research questionCan measures from wearable sensors be used as future surrogates for the MDS-UPDRS rigidity and Postural Instability and Gait Difficulty (PIGD) subscores?MethodsThirty-one individuals with mild to moderate PD wore 3 inertial sensors at home for one week to measure quantity and quality of gait and turning in daily life. Separately, we performed a clinical assessment and balance characterization of postural sway with the same wearable sensors in the laboratory (On medication). We then first performed a traditional correlation analysis between clinical scores and objective measures of gait and balance followed by multivariable linear regression employing a best subset selection strategy.ResultsThe number of walking bouts and turns correlated significantly with the rigidity subscore, while the number of turns, foot pitch angle, and sway area while standing correlated significantly with the PIGD subscore (p < 0.05). The multivariable linear regression showed that rigidity subscore was best predicted by the number of walking bouts while the PIGD subscore was best predicted by a combination of number of walking bouts, gait speed, and postural sway.SignificanceThe correlation between objective sensor data and MDS-UPDRS rigidity and PIGD scores paves the way for future larger studies that evaluate use of objective sensor data to supplement remote MDS-UPDRS assessment.     

Brachytherapy outcome modeling in cervical cancer patients: A predictive machine learning study on patient-specific clinical,physical and dosimetric parameters

PurposeTo predict clinical response in locally advanced cervical cancer (LACC) patients by a combination of measures, including clinical and brachytherapy parameters and several machine learning (ML) approaches.MethodsBrachytherapy features such as insertion approaches, source metrics, dosimetric, and clinical measures were used for modeling. Four different ML approaches, including LASSO, Ridge, support vector machine (SVM), and Random Forest (RF), were applied to extracted measures for model development alone or in combination. Model performance was evaluated using the area under the curve (AUC) of receiver operating characteristics curve, sensitivity, specificity, and accuracy. Our results were compared with a reference model developed by simple logistic regression applied to three distinct clinical features identified by previous papers.ResultsOne hundred eleven LACC patients were included. Nine data sets were obtained based on the features, and 36 predictive models were built. In terms of AUC, the model developed using RF applied to dosimetric, physical, and total BT sessions features were found as the most predictive [AUC; 0.82 (0.95 confidence interval (CI); 0.79 –0.93), sensitivity; 0.79, specificity; 0.76, and accuracy; 0.77]. The AUC (0.95 CI), sensitivity, specificity, and accuracy for the reference model were found as 0.56 (0.52 ...0.68), 0.51, 0.51, and 0.48, respectively. Most RF models had significantly better performance than the reference model (Bonferroni corrected p-value < 0.0014).ConclusionBrachytherapy response can be predicted using dosimetric and physical parameters extracted from treatment parameters. Machine learning algorithms, including Random Forest, could play a critical role in such predictive modeling.     

Advanced characterization of static postural control dysfunction in persons with multiple sclerosis and associated neural mechanisms

BackgroundMultiple sclerosis (MS) is an autoimmune-based chronic inflammatory disease characterized by the neurodegeneration of the central nervous system and produces postural dysfunction. Quiet or static standing is a complex task carried out through afferent sensory inputs and efferent postural corrective outputs. Currently the mechanisms underlying these outputs remain largely unknown.Research questionAssess the relationship between multi-dimensional measures of postural control and microstructural integrity of the cortical sensorimotor pathway (CSP) in persons with MS (PwMS) and neurotypical adults.MethodsPostural control performance was assessed by both overall and directional time-to-boundary measures across four manipulated sensory stance conditions (eyes open/closed; stance firm/foam) in twenty-nine neurotypical and twenty-seven PwMS. These postural outcomes were evaluated with mixed-model repeated measures analysis of variance across group (MS and control) and stance condition. Postural performance was also correlated with magnetic resonance imaging diffusion tensor-derived measures of microstructural integrity of the CSP.ResultsPwMS displayed significantly (p = 0.026) worse anterior-posterior postural control compared to their neurotypical counterparts across sensory testing conditions and poorer CSP microstructural integrity in comparison to neurotypical adults (p = 0.008). Additionally, PwMS displayed a significant association (2D (rho = -0.384, p = 0.048), AP (rho = -0.355, p = 0.035), and ML (rho = -0.365, p = 0.030) between integrity of the CSP and postural control performance during proprioceptive-based balance, such that those with worse cortical structure had poorer balance control.SignificanceThis is the first study to establish connections between the microstructural integrity of the CSP and multi-dimensional postural control performance. Results indicate that a reduction in the CSP microstructural integrity is associated with poorer postural control in PwMS. These outcomes identify neural underpinnings of postural control dysfunction in PwMS and provide new avenues for evaluating the efficacy of postural rehabilitation strategies in PwMS that express proprioceptive-based postural deficits.     

The ability of the instrumented tandem walking tests to discriminate fully ambulatory people with MS from healthy adults

BackgroundPeople with multiple sclerosis (PwMS) experience walking and balance deficits at the initial phases of the disease, even when classified as only minimally disabled. Complex balance tasks, such as tandem walking, are probably more sensitive in detecting mild balance difficulties compared to the standard traditional tests in this population.Research questionThe aim was to investigate different types of 3-meter tandem walking tests in fully ambulatory PwMS.MethodsThis observational case-control study included 50 participants; 25 PwMS, 17 women and 8 men, aged 35.2 (S.D = 8.6) and 25 healthy subjects, 18 women and 7 men, aged 34.3 (S.D = 6.1). The 3-meter tandem walk tests were performed during a single session. Each subject completed a sequence of 3 consecutive tests under 3 different task conditions: normal tandem walking, backward tandem walking and cognitive tandem walking. Tandem walking tests were evaluated via three small, lightweight axial wearable accelerometers (APDM, Oregon, USA).ResultsThe mean EDSS for the MS group was 1.6 (S.D = 0.6) indicating minimal disability. PwMS walked slower and at a slower pace, with a prolonged double support and decreased swing phase compared to healthy subjects in normal and backward conditions. In contrast, during the cognitive task, non-significant differences were found in gait measures between the PwMS and the healthy controls. Significant differences were found between task conditions for all participants. All reduced their walking speed and walked at a slower pace in both the cognitive and backward conditions compared to the normal tandem walk condition. However, non-significant scores were found for the condition X group factor.SignificanceThe study provides new insights into the 3-meter tandem walk test. Findings should improve evaluation and training of dynamic balance in fully ambulatory PwMS.     

Is posturography able to identify fallers in patients with Parkinson's disease?

IntroductionParkinson’ disease (PD) is one of the most prevalent neurodegenerative diseases, and more than half of patients with PD experience falls. Research for clinically useful risk factors predicting falls has yielded inconsistent findings so far. Hence the aim of the study is to validate two different posturography techniques and one modified-timed up and go test (TUG) in discriminating fallers and non-fallers among PD patients.Methods32 patients diagnosed with idiopathic PD were assessed with: Dizziness handicap inventory, Activities-specific balance confidence scale, modified-TUG, sensorial organization test (SOT) and limits of stability (LOS) of computer dynamic posturography, results of free-field body sway analysis with Vertiguard device and number of falls.ResultsFallers had longer time to perform modified-TUG and required more steps. On average, fallers performed SOT and LOS significantly worse and Vertiguard device indicated a higher risk of falling. Based on the area under the curve of receiver operating characteristics analyses, the overall accuracy of directional control of LOS and steps in modified-TUG are close to 0.9 (high accuracy). Also assessment with Vertiguard device is more efficient in identifying fallers than the parameters of SOT.DiscussionOur results indicate that LOS, mobile posturography (Vertiguard), vestibular input of SOT and number of steps taken in modified-TUG are very useful to identify fallers in PD patients.     

Postural adjustments in anticipation of predictable perturbations allow elderly fallers to achieve a balance recovery performance equivalent to elderly non-fallers

BackgroundIn numerous laboratory-based perturbation experiments, differences in the balance recovery performance of elderly fallers and non-fallers are moderate or absent. This performance may be affected by the subjects adjusting their initial posture in anticipation of the perturbation.Research questions: Do elderly fallers and non-fallers adjust their posture in anticipation of externally-imposed perturbations in a laboratory setting? How does this impact their balance recovery performance?Methods21 elderly non-fallers, 18 age-matched elderly fallers and 11 young adults performed both a forward waist-pull perturbation task and a Choice Stepping Reaction Time (CSRT) task. Whole-body kinematics and ground reaction forces were recorded. For each group, we evaluated the balance recovery performance in the perturbation task, change in initial center of mass (CoM) position between the CSRT and the perturbation task, and the influence of initial CoM position on task performance.ResultsThe balance recovery performance of elderly fallers was equivalent to elderly non-fallers (p > 0.5 Kolmogorov-Smirnov test). All subject groups anticipated forward perturbations by shifting their CoM backward compared to the CSRT task (young: 2.1% of lower limb length, elderly non-fallers: 2.7%, elderly fallers: 2.2%, Hodges-Lehmann estimator, p < 0.001 Mann-Whitney U). This backward shift increases the probability of resisting the traction without taking a step.SignificanceThe ability to anticipate perturbations is preserved in elderly fallers and may explain their preserved balance recovery performance in laboratory-based perturbation tasks. Therefore, future fall risk prediction studies should carefully control for this postural strategy, by interleaving perturbations of different directions for example.     

Reliability and minimal detectable change of gait variables in community-dwelling and hospitalized older fallers

PurposeGait variables may constitute surrogate outcomes for fall risk. Their reliability in a specific population of older fallers has not been fully established, which limits their research and clinical applications. This study aimed to determine test–retest reliability and minimal detectable change (MDC) values for selected fall-related gait variables in older adults with a recent fall history.MethodsCommunity-dwelling (n = 30) and hospitalized (n = 30) fallers aged ≥ 65 years were assessed twice using an instrumented pressure-sensitive walkway, under single- and dual-task gait conditions. Intraclass correlation coefficient (ICC_(2,1)), standard error of measurement (SEM; SEM%) and MDC at 95% confidence level (MDC₉₅; MDC₉₅%), were used as reliability estimates.ResultsThe ICC_(2,1) for gait velocity was greater than 0.84 across all gait conditions and groups; SEM% and MDC₉₅% did not exceed 6.5% and 18.1%, respectively. Gait variability measures returned lower ICC_(2,1) (range 0.18–0.79), and markedly higher SEM% (16.3–31.9%) and MDC₉₅% (45.3–88.3%). Overall, hospitalized fallers exhibited larger SEM and MDC₉₅ values for variability measures compared to community-dwellers in all gait conditions, while larger values were found for all variables while dual-tasking compared to single-tasking in both groups.ConclusionsGait velocity was found to be highly reliable and likely to be sensitive to change over repeated sessions in community-dwelling and hospitalized older fallers, both under single- and dual-task conditions. Gait variability measures showed lower reliability, irrespective of gait condition or group, displaying consistently larger measurement error, particularly under dual-task conditions. Clinicians should consider MDC₉₅ values before using gait variability variables as evaluative outcome measures at patient level.