The application of multilevel modelling to account for the influence of walking speed in gait analysis

Neurological scoring and gait kinematics to assess functional outcome in an ovine model of ischaemic stroke

Background

Assessment of functional impairment following ischaemic stroke is essential to determine outcome and efficacy of intervention in both clinical patients and pre-clinical models. Although paradigms are well described for rodents, comparable methods for large animals, such as sheep, remain limited. This study aimed to develop methods to assess function in an ovine model of ischaemic stroke using composite neurological scoring and gait kinematics from motion capture.

Methods

Merino sheep (n = 26) were anaesthetised and subjected to 2 hours middle cerebral artery occlusion. Animals underwent functional assessment at baseline (8-, 5-, and 1-day pre-stroke), and 3 days post-stroke. Neurological scoring was carried out to determine changes in neurological status. Ten infrared cameras measured the trajectories of 42 retro-reflective markers for calculation of gait kinematics. Magnetic resonance imaging (MRI) was performed at 3 days post-stroke to determine infarct volume. Intraclass Correlation Coefficients (ICC's) were used to assess the repeatability of neurological scoring and gait kinematics across baseline trials. The average of all baselines was used to compare changes in neurological scoring and kinematics at 3 days post-stroke. A principal component analysis (PCA) was performed to determine the relationship between neurological score, gait kinematics, and infarct volume post-stroke.

Results

Neurological scoring was moderately repeatable across baseline trials (ICC > 0.50) and detected marked impairment post-stroke (p < 0.05). Baseline gait measures showed moderate to good repeatability for the majority of assessed variables (ICC > 0.50). Following stroke, kinematic measures indicative of stroke deficit were detected including an increase in stance and stride duration (p < 0.05). MRI demonstrated infarction involving the cortex and/or thalamus (median 2.7 cm³, IQR 1.4 to 11.9). PCA produced two components, although association between variables was inconclusive.

Conclusion

This study developed repeatable methods to assess function in sheep using composite scoring and gait kinematics, allowing for the evaluation of deficit 3 days post-stroke. Despite utility of each method independently, there was poor association observed between gait kinematics, composite scoring, and infarct volume on PCA. This suggests that each of these measures has discreet utility for the assessment of stroke deficit, and that multimodal approaches are necessary to comprehensively characterise functional impairment.

Computerized Dual-Task Testing of Gait Visuomotor and Cognitive Functions in Parkinson's Disease: Test-Retest Reliability and Validity

BACKGROUND

Mobility and cognitive impairments in Parkinson's disease (PD) often coexist and are prognostic of adverse health events. Consequently, assessment and training that simultaneously address both gait function and cognition are important to consider in rehabilitation and promotion of healthy aging. For this purpose, a computer game-based rehabilitation treadmill platform (GRP) was developed for dual-task (DT) assessment and training.

OBJECTIVE

The first objective was to establish the test-retest reliability of the GRP assessment protocol for DT gait, visuomotor and executive cognitive function in PD patients. The second objective was to examine the effect of task condition [single task (ST) vs. DT] and disease severity (stage 2 vs. stage 3) on gait, visuomotor and cognitive function.

METHODS

Thirty individuals aged 55 to 70 years, diagnosed with PD; 15 each at Hoehn and Yahr scale stage 2 (PD-2) and 3 (PD-3) performed a series of computerized visuomotor and cognitive game tasks while sitting (ST) and during treadmill walking (DT). A treadmill instrumented with a pressure mat was used to record center of foot pressure and compute the average and coefficient of variation (COV) of step time, step length, and drift during 1-min, speed-controlled intervals. Visuomotor and cognitive game performance measures were quantified using custom software. Testing was conducted on two occasions, 1 week apart.

RESULTS

With few exceptions, the assessment protocol showed moderate to high intraclass correlation coefficient (ICC) values under both ST and DT conditions for the spatio-temporal gait measures (average and COV), as well as the visuomotor tracking and cognitive game performance measures. A significant decline in gait, visuomotor, and cognitive game performance measures was observed during DT compared to ST conditions, and in the PD-3 compared to PD-2 groups.

CONCLUSION

The high to moderate ICC values along with the lack of systematic errors in the measures indicate that this tool has the ability to repeatedly record reliable DT interference (DTI) effects over time. The use of interactive digital media provides a flexible method to produce and evaluate DTI for a wide range of executive cognitive activities. This also proves to be a sensitive tool for tracking disease progression.

CLINICAL TRIAL REGISTRATION

www.ClinicalTrials.gov, identifier NCT03232996.

Changes in Metabolic Activity and Gait Function by Dual-Task Cognitive Game-Based Treadmill System in Parkinson's Disease: Protocol of a Randomized Controlled Trial

Balance and gait impairments, and consequently, mobility restrictions and falls are common in Parkinson’s disease (PD). Various cognitive deficits are also common in PD and are associated with increased fall risk. These mobility and cognitive deficits are limiting factors in a person’s health, ability to perform activities of daily living, and overall quality of life. Community ambulation involves many dual-task (DT) conditions that require processing of several cognitive tasks while managing or reacting to sudden or unexpected balance challenges. DT training programs that can simultaneously target balance, gait, visuomotor, and cognitive functions are important to consider in rehabilitation and promotion of healthy active lives. In the proposed multi-center, randomized controlled trial (RCT), novel behavioral positron emission tomography (PET) brain imaging methods are used to evaluate the molecular basis and neural underpinnings of: (a) the decline of mobility function in PD, specifically, balance, gait, visuomotor, and cognitive function, and (b) the effects of an engaging, game-based DT treadmill walking program on mobility and cognitive functions. Both the interactive cognitive game tasks and treadmill walking require continuous visual attention, and share spatial processing functions, notably to minimize any balance disturbance or gait deviation/stumble. The ability to “walk and talk” normally includes activation of specific regions of the prefrontal cortex (PFC) and the basal ganglia (site of degeneration in PD). The PET imaging analysis and comparison with healthy age-matched controls will allow us to identify areas of abnormal, reduced activity levels, as well as areas of excessive activity (increased attentional resources) during DT-walking. We will then be able to identify areas of brain plasticity associated with improvements in mobility functions (balance, gait, and cognition) after intervention. We expect the gait-cognitive training effect to involve re-organization of PFC activity among other, yet to be identified brain regions. The DT mobility-training platform and behavioral PET brain imaging methods are directly applicable to other diseases that affect gait and cognition, e.g., cognitive vascular impairment, Alzheimer’s disease, as well as in aging.

Spatiotemporal gait analysis of older persons in clinical practice and research : Which parameters are relevant?

For older persons walking is a basic activity of daily life which characterizes the person's functional mobility. Therefore, the improvement of walking performance is a major clinical outcome during geriatric rehabilitation. Furthermore, walking performance is relevant for several geriatric research issues. Quantitative gait analysis can describe walking performance in detail. Besides gait speed, various qualitative parameters related to different aspects of walking performance, such as symmetry, regularity, coordination, dynamic balance and foot movement during the swing phase, can serve as outcome parameters in geriatric research and in clinical practice. Clinicians and researchers have to decide which parameters are appropriate to be used as relevant outcome parameters in the investigated person or group of persons.

A mixed linear modelling characterisation of gender and speed related changes in spatiotemporal and kinematic characteristics of gait across a wide speed range in healthy adults

In exploring the relationship between the kinematics of gait and speed of progression individual variation in patterns and gender differences have not always been adequately taken into account. In the current study mixed linear modelling was used to isolate changes with speed from those associated with individual variation and gender. Three-dimensional motion analysis of 20 participants (10M/10F, 25.7 ± 5.1 years) walking at a wide range of speeds (normalised speeds 0.10-0.55 ∼0.41-2.26 m/s) was recorded (775 walks). Spatiotemporal (speed, cadence, step length, percentage of single and double support) and kinematic characteristics (pelvis through ankle) were determined. Significant between participant differences were highlighted in both intercept and slope of relationships. In addition females exhibiting different peak pelvic tilt and obliquity, hip flexion and internal rotation and ankle dorsiflexion compared to males. Spatiotemporal parameters exhibited non-linear relationships with normalised speed (R²> 0.5). Kinematic features exhibited significant relationships with normalised speed, varying from linear to cubic, from very weak to strong in fit (0.010 > R²> 0.672). Mixed linear modelling highlighted gender dependent, speed related changes in addition to inter-individual variation. Gender and speed are both important determinants of gait patterns, however, individual variations remain.

Spatiotemporal and kinematic characteristics of gait initiation across a wide speed range

BACKGROUND

Gait initiation can be performed at a range of speeds. Those with disability tend to use a slower speed compared to those without disability. In assessing the spatiotemporal and kinematic characteristics of gait initiation it is therefore important to consider the effects of speed on outcomes.

RESEARCH QUESTION

What is the effect of speed of performance on spatiotemporal and kinematic characteristics of gait initiation?

METHODS

Spatiotemporal and kinematic characteristics were measured across a wide range of speeds from very slow to very fast (normalised initiating leg (swing or SW limb) step speed 0.1-0.5) for 20 health adults (10 men/10 women, 22-44 years) using three-dimensional motion analysis of the first two steps of gait.

RESULTS

Mixed linear modelling of 295 walking trials indicated differences between individuals, sexes and strong non-linear relationships between normalised initiating leg step speed and cadence and step lengths (R² > 0.5). Particular characteristics of joint kinematics (maxima and minima for both initiating (SW) and contralateral limb (stance or ST limb)) demonstrated significant non-linear (squared, cubic and power law) changes with speed. Moderate to strong relationships were identified for sagittal plane pelvis, hip and knee kinematics as well as hip adduction (0.3 < R² < 0.7).

SIGNIFICANCE

Gait initiation spatiotemporal and kinematic characteristics were quantified across the maximum range of speeds achievable, providing comprehensive characterisation of changes with speed. Significant, non-linear changes with speed were identified, suggesting different strategies are employed to modify speed at low and high speeds. The highlighted changes with speed illustrate the importance of taking speed into account when comparing outcomes between healthy adults and those with pathology.

Measuring physical capacity and performance in older people

We highlight the important differences between the concepts of capacity and performance and highlight the development of measures and their application in common conditions encountered in health care practice with older people. A number of expert consensus projects have concluded that mobility, balance, muscle strength and dexterity are core domains for capacity measurement in older people. Instruments with evidence of adequate psychometric properties for the evaluation of capacity in response to intervention programmes include the Short Physical Performance Battery, hand grip strength, mini-BEST and 9-hole pegboard test. Measures that can track individual change and convey information that can be used to inform clinical decision-making, individual prognosis or prediction of events require greater precision. However, few such measures are available. Performance measurement usually focuses on basic or instrumental (advanced) Activities of Daily Living performed by people in their usual environments. Finally, we discuss the limitations of physical performance and capacity measures and future developments that may enhance the use of these measures in health and clinical care.

The interacting effects of treadmill walking and different types of visuospatial cognitive task: Discriminating dual task and age effects

OBJECTIVE

The objective of this study is to examine the influence that visuospatial cognitive tasks have on gait function during DT treadmill walking, and as a function of age. Conversely, to examine the influence that walking has on executive functions involving visuospatial processing.

METHODS

Twenty-five young (26±6.1years) and 25 older adults (76±3.9) performed different types of computerized visuomotor (VM) tracking and visuospatial cognitive tasks (VCG) while standing and treadmill walking. Spatiotemporal gait variables, average values and co-efficient of variation (COV) were obtained from 40 consecutive steps during single- and dual-task walk trials. Performance-based measures of the VM and VCG task were obtained during standing and walking.

RESULTS

VM dual-task walking had a significant effect on gait measures in the young age group (YG), but no DT effect was observed in the old age group (OG). Visuomotor tracking performance, however, was significantly reduced in the OG as compared to the YG when tested in both standing and walking. The opposite was true for VCG; a significant DT effect on gait performance was observed in the OG, but no DT effect was observed in the YG. Success rate of the VCG task decreased during walking, but only for OG.

CONCLUSION

Controlling gait speed and objective evaluation of the visuospatial cognitive tasks helps to determine the level of engagement in the DT tasks. This is important in order to determine the strategies used during the DT test protocols, i.e. cross-domain interference.

A translational approach to capture gait signatures of neurological disorders in mice and humans

A method for capturing gait signatures in neurological conditions that allows comparison of human gait with animal models would be of great value in translational research. However, the velocity dependence of gait parameters and differences between quadruped and biped gait have made this comparison challenging. Here we present an approach that accounts for changes in velocity during walking and allows for translation across species. In mice, we represented spatial and temporal gait parameters as a function of velocity and established regression models that reproducibly capture the signatures of these relationships during walking. In experimental parkinsonism models, regression curves representing these relationships shifted from baseline, implicating changes in gait signatures, but with marked differences between models. Gait parameters in healthy human subjects followed similar strict velocity dependent relationships which were altered in Parkinson’s patients in ways that resemble some but not all mouse models. This novel approach is suitable to quantify qualitative walking abnormalities related to CNS circuit dysfunction across species, identify appropriate animal models, and it provides important translational opportunities.

Computerized Dual-Task Testing of Gait and Visuospatial Cognitive Functions; Test-Retest Reliability and Validity

The common occurrence of age decline in mobility and cognition does cause a decrease in the level of physical activity and an increased falls risk. Consequently, dual -task (DT) assessment that simultaneously addresses both mobility skills and cognitive functions are important because, continued difficulties and fall injuries will have a sizable impact in this population. The first objective of the present study was to assess test-retest reliability of a computerized DT treadmill walking protocol and concurrent outcome measures of gait and visuospatial executive function in a group of healthy older adults. Secondly, discriminative validity was evaluated by examining the effect of DT conditions (single task vs. dual-task) on; (a) spatiotemporal gait measures (average and coefficient of variation) and (b) visuomotor and visuospatial executive performance measures. Twenty-five community-dwelling individuals median age 65 (range 61-67) were recruited from a Fitness Facility. Participants performed a computerized visuomotor tracking task and a visuospatial executive game task in standing and while treadmill walking. Testing was conducted on two occasions, 1 week apart. Moderate to high test-retest reliability (ICC values of 0.65-0.88) were observed for spatiotemporal gait variables. No significant differences between the group means were observed between test periods in any gait variable. Moderate test-retest reliability (ICC values of 0.6-0.65) was observed for measures of visuomotor and visuospatial executive performance during treadmill walking. Significant DT effects were observed for both spatiotemporal gait variables and visuospatial executive performance measures. This study demonstrates the reliability and reproducibility of the computer-based assessment tool for dual task treadmill walking. The high to moderate ICC values and the lack of systematic errors in the measures indicate that this tool has the ability to repeatedly record reliable data from community-dwelling older adults. The present computerized dual-task protocols broaden the types of standardized visuomotor and visuospatial executive activities for use with DT treadmill walking that has previously been reported.

The Immediate Effects of Different Types of Ankle Support Introduced 6 Weeks After Surgical Internal Fixation for Ankle Fracture on Gait and Pain: A Randomized Crossover Trial

STUDY DESIGN

Randomized 3-treatment, 3-period crossover trial.

BACKGROUND

There is variation in clinical practice regarding the type of ankle support used to aid recovery after ankle fracture internal fixation surgery.

OBJECTIVE

To determine the immediate effects of different ankle supports commonly issued to patients 6 weeks after surgery.

METHODS

Participants were 18 adults, 6 weeks after internal fixation for transsyndesmotic/infrasyndesmotic fracture, in a major trauma center in the UK. Interventions were a stirrup brace and walker boot compared with Tubigrip. Outcomes were (1) step-length and single-limb support time asymmetry (percentage comparing injured and uninjured limbs), (2) step width, (3) gait velocity, and (4) pain during walking (visual analog scale, 0-100).

RESULTS

Participants (mean ± SD age, 47 ± 14 years) included 8 women and 10 men, 6 weeks after surgical internal fixation for ankle fracture. Single-limb support time asymmetry reduced by 3% (95% confidence interval [CI]: 0%, 6%; P = .02) in the stirrup brace and by 5% (95% CI: 2%, 7%; P = .001) in the walker boot compared with Tubigrip. Step width was 1.2 cm (95% CI: 0.6, 1.7; P<.001) wider in the walker boot than in Tubigrip. Self-reported pain was lower in the walker boot (5/100) and in the stirrup brace (13/100) compared to the Tubigrip (18/100, P = .03). No significant differences were found in the effects of the supports on step-length asymmetry between the walker boot or stirrup brace and Tubigrip.

CONCLUSION

At 6 weeks after surgical internal fixation for ankle fracture, pain and single-limb support time asymmetry over a short distance and for a short-term walk were immediately reduced with the use of a walker boot use and, to a lesser extent, a stirrup-brace compared to Tubigrip. Step width also widened in a walker boot, which may confer some additional gait stability. These results apply to immediate effects, so studies with longer-term follow-up are now indicated. The trial was registered at http://www.isrctn.com/ (ISRCTN84536917). Level of Evidence Therapy, level 2b.