Metrics extracted from a single wearable sensor during sit-stand transitions relate to mobility impairment and fall risk in people with multiple sclerosis

BackgroundApproximately half of the 2.3 million people with multiple sclerosis (PwMS) will fall in any three-month period. Currently clinicians rely on self-report measures or simple functional assessments, administered at discrete time points, to assess fall risk. Wearable inertial sensors are a promising technology for increasing the sensitivity of clinical assessments to accurately predict fall risk, but current accelerometer-based approaches are limited.Research questionWill metrics derived from wearable accelerometers during a 30-second chair stand test (30CST) correlate with clinical measures of disease severity, balance confidence and fatigue in PwMS, and can these metrics be used to accurately discriminate fallers from non-fallers?MethodsThirty-eight PwMS (21 fallers) completed self-report outcome measures then performed the 30CST while triaxial acceleration data were collected from inertial sensors adhered to the thigh and chest. Accelerometer metrics were derived for the sit-to-stand and stand-to-sit transitions and relationships with clinical metrics were assessed. Finally, the metrics were used to develop a logistic regression model to classify fall status.ResultsAccelerometer-derived metrics were significantly associated with multiple clinical metrics that capture disease severity, balance confidence and fatigue. Performance of a logistic regression for classifying fall status was enhanced by including accelerometer features (accuracy 74%, AUC 0.78) compared to the standard of care (accuracy 68%, AUC 0.74) or patient reported outcomes (accuracy 71%, AUC 0.75).SignificanceAccelerometer derived metrics were associated with clinically relevant measures of disease severity, fatigue and balance confidence during a balance challenging task. Inertial sensors could feasibly be utilized to enhance the accuracy of functional assessments to identify fall risk in PwMS. Simplicity of these accelerometer-based metrics could facilitate deployment for community-based monitoring.     

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.     

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.     

Laplacian-Regularized Mean Apparent Propagator-MRI in Evaluating Corticospinal Tract Injury in Patients with Brain Glioma

ObjectiveTo evaluate the application of laplacian-regularized mean apparent propagator (MAPL)-MRI to brain glioma-induced corticospinal tract (CST) injury.Materials and MethodsThis study included 20 patients with glioma adjacent to the CST pathway who had undergone structural and diffusion MRI. The entire CSTs of the affected and healthy sides were reconstructed, and the peritumoral CSTs were manually segmented. The morphological characteristics of the CST (track number, average length, volume, displacement of the affected CST) were examined and the diffusion parameter values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), mean squared displacement (MSD), q-space inverse variance (QIV), return-to-origin probability (RTOP), return-to-axis probabilities (RTAP), and return-to-plane probabilities (RTPP) along the entire and peritumoral CSTs, were calculated. The entire and peritumoral CST characteristics of the affected and healthy sides as well as those relative CST characteristics of the patients with motor weakness and normal motor function were compared.ResultsThe track number, volume, MD, RD, MSD, QIV, RTAP, RTOP, and RTPP of the entire and peritumoral CSTs changed significantly for the affected side, whereas the AD and FA changed significantly only in the peritumoral CST (p < 0.05). In patients with motor weakness, the relative MSD of the entire CST, QIV of the entire and peritumoral CSTs, and the AD, MD, RD of the peritumoral CST were significantly higher, whereas the RTPP of the entire and peritumoral CSTs and the RTOP of the peritumoral CST were significantly lower than those in patients with normal motor function (p < 0.05 for all). In contrast, no significant changes were found in the CST morphological characteristics, FA, or RTAP (p > 0.05 for all).ConclusionMAPL-MRI is an effective approach for evaluating microstructural changes after CST injury. Its sensitivity may improve when using the peritumoral CST features.     

Gait parameters,functional performance and physical activity in active and inactive Juvenile Idiopathic Arthritis

BackgroundChildren with Juvenile Idiopathic Arthritis (JIA) may adopt different movement patterns and participate in physical activity during different states of disease.Research questionWhich specific features of gait and physical function performance differ among children with active or inactive JIA compared to healthy children?MethodsForty-three children participated (14.5 ± 4.2 yrs; 60 % female). 3D-motion analysis methods were coupled with force measures from an instrumented treadmill captured gait mechanical measures. The 30-second Chair Rise Test (repetitions) and stair ascent-descent tests were performed, and the 11-point Wong-Baker face scale assessed pain after each test.ResultsCompared to healthy controls children with active and inactive JIA had worse outcomes (12–21 % slower self-selected and fast walking speeds, 28–34 % slower stair navigation times, 28 % fewer chair rise repetitions in 30 s; all p < .05). Children with active JIA had 8–13 % slower gait speeds, 4 % fewer chair rise repetitions and 14–16 % slower stair navigation times. At faster walking speed, children with active JIA had less hip joint flexion/extension excursion in the sagittal plane during the gait cycle, produced higher leg stiffness, and demonstrated greater interlimb asymmetry in GRF vertical impulse during loading than healthy children (all p < .05). The Pedi-FABS subscore of “Duration: performing athletic activity for as long as you would like without stopping” was rated lower in children with active JIA compared to controls (p < .05).ConclusionGait speed, specific load-bearing functional tasks and leg stiffness features of gait may be informative ‘functional biomarkers’ for assessing JIA burden and tracking treatment efficacy. Additional prospective studies are needed to determine how these features change over time with pain change, and understand impact on quality of life and physical activity participation.     

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.     

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.     

Effect of calendar age on physical performance: A comparison of standard clinical measures with instrumented measures in middle-aged to older adults

BackgroundDecline in physical performance is highly prevalent during aging. Identification of sensitive markers of age-related changes in physical performance is important for early detection, development of therapeutic strategies and insight into underlying mechanisms. We studied the association of calendar age and familial longevity with standard clinical and instrumented measures of physical performance in a cohort of healthy middle-aged to older adults.MethodsCross-sectional analysis within the Leiden Longevity Study consisting of offspring of nonagenarian siblings and their partners (n = 300, mean age (SD) 65.3 (6.7) years). Standard clinical measures were 25-meter walking speed and total duration of the chair stand test (CST). Instrumented measures were determined using a body fixed sensor. Dependence of physical performance on calendar age and familial longevity (offspring versus partner status) was analyzed using linear and logistic regression, respectively, adjusted for gender and height.ResultsHigher calendar age was associated with slower walking speed and longer duration of the CST (standardized β (95% CI) −.024 (−.042; −.006) and .035 (.014;.056), respectively). Instrumented measures showed similar effect sizes with strongest associations for gait stability and symmetry in mediolateral direction and for the extension and flexion phase of sit-to-stand and stand-to-sit transfers, respectively. No differences were observed between offspring of nonagenarian siblings and their partners.ConclusionsStandard clinical and instrumented measures of physical performance are associated with similar effect size to age-related changes in physical performance observable from middle age. The potential added value of instrumented measures for understanding underlying mechanisms requires further attention.     

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.     

A randomized trial of traditional and golf-specific resistance training in amateur female golfers: Benefits beyond golf performance

ObjectiveCompare golf-specific resistance training (GSRT) with traditional resistance training (TRAD) with regard to golf performance and other outcome measures.DesignRandomized controlled study.SettingOutpatient gym.Participants45 female golfers were randomized into TRAD or GSRT, both of which targeted muscles active during the golf swing. Participants performed supervised training 3d^.wk⁻¹ for 10 weeks.Outcome MeasuresGolf performance, bone density, body composition, and physical performance tests.Results29 individuals (58.1 ± 2.1y; 15 TRAD, 14 GSRT) completed training. Completers were older (p = 0.048) and played golf more frequently than non-completers (p = 0.002), but were not otherwise different. Training decreased whole body fat mass (p = 0.013) and visceral fat mass (p = 0.033) across groups, but did not influence lean mass (p = 0.283) or bone mineral density (p = 0.205). Training increased driver speed (p = 0.001), driver distance (p = 0.020), and 7I distance (p < 0.001), but not 7I speed (p = 0.160), but no group or interaction effects were present. Training increased all physical performance tests (p ≤ 0.005) regardless of group, but the seated medicine ball throw was most related to baseline driver speed (r² = 0.384), and also most responsive to training (r² = 0.250).Conclusion10 weeks of supervised TRAD and GSRT provided similar improvements in body composition, golf performance, and physical performance in amateur female golfers.     

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.     

Cognitive-motor interference in multiple sclerosis: What happens when the gait speed is fixed?

During the last decade, numerous studies have confirmed a coupling between walking performance and cognition in people with multiple sclerosis (PwMS). Our aim was to provide new insights into a walking-cognitive dual-task (DT) in PwMS. We tested the DT phenomenon by controlling the walking speed using an instrumented treadmill. Thirty PwMS (20 women) with a mean age 40.1 (SD = 12.0) participated in the study. Twenty-one healthy subjects served as controls. Each subject completed a sequence of tests: a) Normal walking (ST) − the participant walked on the instrumented treadmill at a comfortable walking speed for 1 min; b) Cognitive evaluation (ST) − subjects performed two cognitive tests while seated; c) DT cognitive tests performed while walking on the treadmill at the identical speed performed during normal walking. Outcome measures were spatio-temporal parameters of gait (mean and variability), the Word List Generation Test (WLG) and the Serial-3 Subtraction Test. MS participants significantly decreased their cadence while increasing their stride length during the DT condition compared to the ST condition. Non-significant differences were observed for the WLG and Serial-3 Subtraction Cognitive Tests between the ST condition and the DT condition in both the MS and healthy groups. In terms of gait variability parameters, MS subjects demonstrated a 2 to 3-fold greater gait variability compared to the healthy controls. Non-significant differences in gait variability parameters were observed between the ST and DT conditions in both the MS and control groups. This study provides new insights into the DT phenomenon in the MS population.     

Torso kinematics during gait and trunk anthropometry in pregnant fallers and non-fallers

BackgroundPregnant women experience numerous physiological and biomechanical alterations which may be associated with their increased risk of experiencing a fall. Gait alterations in other populations who fall include increased step width and mediolateral trunk motion. It is not known if pregnant women who have fallen exhibit these alterations.Research questionOur purpose was to examine torso kinematics and step width during gait in pregnant fallers, pregnant non-fallers and non-pregnant controls. We also examined trunk anthropometry in the pregnant groups to determine if pregnant fallers have different trunk physiques than pregnant non-fallers.Methods3D kinematic data were collected on 14 pregnant fallers, 15 pregnant non-fallers and 40 non-pregnant controls. Pregnant women were in their second or third trimester of pregnancy. Frontal plane translations of C7 and L4, step width, stride length, walking velocity, and 3D thoracic and pelvic kinematics were determined. Anthropometric torso measurements were obtained on the pregnant women. A series of MANCOVAs was performed (covariate: walking velocity, α = 0.05) to compare the dependent variables between pregnant fallers, pregnant non-fallers, and controls. Tukey post-hoc analyses were performed when appropriate (α = 0.05). A MANOVA compared anthropometric variables between pregnant fallers and non-fallers (α = 0.05).ResultsPregnant non-fallers exhibited greater step width and frontal and transverse plane angles at heel contact and range of motion over the gait cycle when compared to the fallers. Trunk anthropometry did not differ between pregnant fallers and non-fallers.SignificancePregnancy-associated gait alterations differed between fallers and non-fallers. Greater step width of the pregnant non-fallers increased the base of support, thus increasing stability. Exercise participation may allow pregnant women to better adapt to their altered physiques and be more able to prevent a fall should a trip or slip occur.     

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.     

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.     

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.     

Construct validity of the walk ratio as a measure of gait control in people with multiple sclerosis without mobility aids

Ambulatory limitations are a key component of disability in people with multiple sclerosis (PwMS). Various tools are employed to assess walking performance in PwMS; however, no ideal measure has as yet been attained. In this situation, a walk ratio might be more advantageous compared with other gait measures. The walk ratio, a simple index for describing temporal and spatial co-ordination, denotes the relationship between step length and cadence during walking. Hence, the primary objective of this study was to determine the relationship between the walk ratio and measures of other theoretically related constructs. The walk ratio was studied using the GAITRite™ system (CIR Systems, Inc. Havertown, USA). The study group included 229 PwMS (143 women) and a mean disease duration of 5.8 (SD = 7.1) years. The walk ratio score of the total sample was 5.3 (SD = 0.8). Significant differences based on the expanded disability status scale (EDSS) scores (F = 11.616, P < 0.001) were observed between the neurological disability subgroups. Scores of the very mild (EDSS 0–2.0), mild (EDSS 2.5–4.0) and moderate (EDSS 4.5–5.5) groups were 5.5 (SD = 0.7), 5.2 (SD = 0.7), 4.9 (SD = 0.9), respectively. In terms of fall status, the MS fallers demonstrated a significant lower walk ratio compared to the MS non-fallers; 5.1 (SD = 0.8) vs. 5.5 (SD = 0.7); P < 0.001. Modest significant correlation scores were found between walk ratio and ambulation tests. Scores were slightly higher in the short walking tests, timed 25-foot walk and timed up and go tests (Pearson's rho = 0.369, 0.364) compared to the 6 and 2-min walk time tests (Pearson's rho = 0.344, 0.308). Collectively, the current study supports the construct validity of the walk ratio index in PwMS without mobility aids.     

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.     

Breast cancer detection: Comparison of digital mammography and digital breast tomosynthesis across non-dense and dense breasts

IntroductionBreast density is associated with an increase in breast cancer risk and limits early detection of the disease. This study assesses the diagnostic performance of mammogram readers in digital mammography (DM) and digital breast tomosynthesis (DBT).MethodsEleven breast readers with 1–39 years of experience reading mammograms and 0–4 years of experience reading DBT participated in the study. All readers independently interpreted 60 DM cases (40 normal/20 abnormal) and 35 DBT cases (20 normal/15 abnormal). Sensitivity, specificity, ROC AUC, and diagnostic confidence were calculated and compared between DM and DBT.ResultsDBT significantly improved diagnostic confidence in both dense breasts (p = 0.03) and non-dense breasts (p = 0.003) but not in other diagnostic performance metrics. Specificity was higher in DM for readers with >7 years' experience (p = 0.03) in reading mammography, non-radiologists (p = 0.04), readers who had completed a 3–6 months training fellowship in breast imaging (p = 0.04), and those with ≤2 years’ experience in reading DBT (p = 0.02), particularly in non-dense breasts.ConclusionDiagnostic confidence was higher in DBT when compared to DM. In contrast, other performance metrics appeared to be similar or better with DM and may be influenced by the lack of experience of the reader cohort in reading DBT.Implications for practiceThe benefits of DBT may not be entirely accrued until radiologists attain expertise in DBT interpretation. Specificity of DBT varied according to reader characteristics, and these characteristics may be useful for optimising pairing strategies in independent double reading of DBT as practiced in Australia to reduce false positive diagnostic errors.