Associations of dual-task walking costs with cognition in Parkinson's disease.

BACKGROUND: Gait and cognition are closely associated in Parkinson's disease (PD), with specific cognitive domains being associated with different motor symptoms. By identifying gait parameters affected by cognition, clinicians can develop targeted interventions that address cognitive impairment, improve gait, and reduce the risk of injury in PD patients. RESEARCH QUESTION: What gait parameters are affected by cognition in PD patients during dual-task walking, and how are these parameters related to cognitive function as measured by the Montreal Cognitive Assessment (MoCA)? METHODS: 36 patients with available gait data and cognitive assessments were enrolled. Gait data of usual and dual-task walking sessions were recorded using lightweight wireless wearable sensors attached to trunk, lower, and upper extremities. Dual-task costs were calculated from usual and dual-task measures. Statistical analysis included non-parametric tests, Wilcoxon signed-rank test, Spearman's correlation, and stepwise linear regression models. RESULTS: Walking speed, cadence, asymmetry in arm swing (ASA), between arms' amplitude symmetry (BAS), average stride time, and jerk of the acceleration movement of the legs were found to be affected during the dual-task walking session (P<0.05). Spearman's correlation showed significant correlations between MoCA scores and ASA (ρ=-0.469, P=0.036) and BAS (ρ=-0.448, P=0.036) costs. Stepwise linear regression models found that MoCA scores were significant predictors of BAS and ASA costs (P<0.05). SIGNIFICANCE: This study found a significant association between global cognitive ability and several gait parameters costs under cognitive load caused by dual-task walking in PD patients. The study identified the gait parameters that were affected by cognitive load and found that MoCA scores were significant predictors of those gait parameters. Identifying gait parameters affected by cognition can lead to more targeted interventions for improving gait and reducing injury risk in PD patients.

Validation of the Gait Outcomes Assessment List questionnaire and caregiver priorities for individuals with cerebral palsy.

AIM: To expand upon previous validation of the Gait Outcomes Assessment List (GOAL) questionnaire in individuals with cerebral palsy (CP), to rank items by importance, and to summarize written-in (free text) goals. METHOD: For this cross-sectional study, the parent-version 5.0 of the GOAL was completed by 310 consecutive caregivers of 310 individuals aged 3 to 25 years with CP (189 males, 121 females; mean [SD] age: 10y [4y 2mo]; Gross Motor Function Classification System [GMFCS] levels I-IV) concurrent with a gait analysis. Distribution properties and validity were quantified using questionnaires, kinematics, and oxygen consumption. Items classified as at least 'difficult' to perform and 'very important' to improve were considered caregiver priorities and rank ordered. Free text goals were categorized. Results were summarized for everyone and by GMFCS level. RESULTS: Most scores were normally distributed. Validity was acceptable, with concurrent greater than construct validity. Among all 310 caregivers, fatigue was the highest priority, followed by gait pattern and appearance items. The rank of priorities varied by GMFCS level. Common free text goals included toileting independently as well as improved fine motor and ball sport skills. INTERPRETATION: The GOAL is a valid tool that can help prioritize goals across GMFCS levels I to IV. Identifying the top goals may improve shared decision-making and prioritize research for this sample.

The Functional Independence of Patients With Stroke Sequelae: How Important Is the Speed, Oxygen Consumption, and Energy Cost of Walking?

OBJECTIVE: To evaluate the association between self-selected walking speed (Sfree), oxygen consumption at Sfree (Vo2free), the oxygen cost of walking (Cw) at Sfree, and mobility independence and independence for activities of daily living in individuals poststroke. DESIGN: Cross-sectional study. SETTING: Hospital. PARTICIPANTS: Individuals with stroke who were able to walk without human assistance were included. We included 90 individuals (N=90; mean age, 63.5±14.0y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Cw was captured during walking from measurements of Sfree and Vo2free. We assessed mobility independence based on the modified Functional Ambulation Classification (mFAC) and independence in activities of daily living by the Barthel Index (BI). Multiple linear regression analyses were performed to evaluate the independence of Cw, Vo2free, and Sfree from the determination of BI and mFAC among the various characteristics of the population (age, stroke delay, body mass index, motor function, spasticity). RESULTS: We reported Cw=0.36 mL/kg/m (interquartile range [IQR]=0.28 mL/kg/m), Sfree=0.60±0.32 m/s, Vo2free=11.2 mL/kg/min (IQR=1.8 mL/kg/min). The multiple linear regression analyses showed that Cw and Sfree were independently associated with the BI (P<.01) and the mFAC (P<.01) scores. Vo2free was not found to be an explanatory variable of functional independence (P>.05). CONCLUSIONS: Cw was independently associated with functional independence. This association appears to be primarily determined by Sfree and not Vo2free, underscoring the importance of evaluating and acting on Sfree to improve the functional independence of individuals with stroke.

Validity of quantitative assessment of posterior pelvic tilt and contralateral vaulting in hemiplegia using 3D treadmill gait analysis.

BACKGROUND: Assessing abnormal gait patterns could indicate compensatory movements, which could be an index for recovery and a process of motor learning. To quantify the degree of posterior pelvic tilt, contralateral vaulting is necessary. OBJECTIVES: This study aimed to develop and evaluate the validity of quantitative indices for posterior pelvic tilt and contralateral vaulting in hemiplegic patients. METHODS: Forty-six healthy control subjects and 112 hemiplegic patients participated in this study. Of the 112 patients, 50 were selected into each abnormal gait pattern group, with some overlap. Three experienced physical therapists observed their walking and graded the severity of the two abnormalities in five levels. An index to quantify each of the two abnormal gait patterns was calculated from the three-dimensional treadmill gait analysis. The index values of patients were compared with those of healthy subjects and with the results of observational gait assessment done by three physical therapists with expertise in gait analysis. RESULTS: The index values were significantly higher in hemiplegic patients than in healthy subjects (28.0% and 44.7% for the posterior pelvic tilt in healthy subjects and patients, respectively and 0.9 and 4.7 for the contralateral vaulting, respectively). A strong correlation was observed between the index value and the median observational rating for two abnormal gait patterns (r = -0.68 and -0.72). CONCLUSIONS: The proposed indices for posterior pelvic tilt and contralateral vaulting are useful for clinical gait analysis, and thus encouraging a more detailed analysis of hemiplegic gait using a motion analysis system.

Asymmetry and Variability Should Be Included in the Assessment of Gait Function in Poststroke Hemiplegia With Independent Ambulation During Early Rehabilitation.

OBJECTIVE: To extract independent features from spatiotemporal data of poststroke gait. DESIGN: Retrospective observational study. SETTING: Motion analysis laboratory in the rehabilitation department of a university hospital. PARTICIPANTS: Convenience sample from inpatients in subacute recovery stage post stroke. Of 98 patients post stroke who underwent gait assessment, 69 patients post stroke were included in the data analysis (N=69). They could walk more than 10 m without personal assist or assistive devices. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Spatiotemporal parameters during level walking and their asymmetry and variability were obtained by insole foot pressure measurement system. RESULTS: Of independent components extracted by principal component analysis, 3 independent components explained 81.9% of total variance of spatiotemporal poststroke gait data. The first component has associations with walking speed and proportion of double support phase, and it explains 46.6% of total variance. The second component has association with temporal asymmetry, and it explains 21.1% of total variance. The third component has association with temporal variability, and it explains 14.2% of total variance. Principal component scores did not show significant differences between stroke types and among stroke lesions. CONCLUSIONS: Temporal asymmetry and variability should be included in the assessment of poststroke gait during early rehabilitation. They are independent of each other and provide characteristics of poststroke gait that are independent to the walking speed. They are helpful for rehabilitation planning and developing treatment strategy in poststroke gait rehabilitation.

Validity and sensitivity of instrumented postural and gait assessment using low-cost devices in Parkinson's disease.

BACKGROUND: Accurate assessment of balance and gait is necessary to monitor the clinical progress of Parkinson's disease (PD). Conventional clinical scales can be biased and have limited accuracy. Novel interactive devices are potentially useful to detect subtle posture or gait-related impairments. METHODS: Posturographic and single and dual-task gait assessments were performed to 54 individuals with PD and 43 healthy controls with the Wii Balance Board and the Kinect v2 and the, respectively. Individuals with PD were also assessed with the Tinetti Performance Oriented Mobility Assessment, the Functional Gait Assessment and the 10-m Walking Test. The influence of demographic and clinical variables on the performance in the instrumented posturographic and gait tests, the sensitivity of these tests to the clinical condition and phenotypes, and their convergent validity with clinical scales were investigated. RESULTS: Individuals with PD in H&Y I and I.5 stages showed similar performance to controls. The greatest differences in posture and gait were found between subjects in H&Y II.5 and H&Y I-I.5 stage, as well as controls. Dual-tasking enhanced the differences among all groups in gait parameters. Akinetic/rigid phenotype showed worse postural control and gait than other phenotypes. High significant correlations were found between the limits of stability and most of gait parameters with the clinical scales. CONCLUSIONS: Low-cost devices showed potential to objectively quantify posture and gait in established PD (H&Y ≥ II). Dual-tasking gait evaluation was more sensitive to detect differences among PD stages and compared to controls than free gait. Gait and posture were more impaired in akinetic/rigid PD.

Self-selected step length asymmetry is not explained by energy cost minimization in individuals with chronic stroke.

BACKGROUND: Asymmetric gait post-stroke is associated with decreased mobility, yet individuals with chronic stroke often self-select an asymmetric gait despite being capable of walking more symmetrically. The purpose of this study was to test whether self-selected asymmetry could be explained by energy cost minimization. We hypothesized that short-term deviations from self-selected asymmetry would result in increased metabolic energy consumption, despite being associated with long-term rehabilitation benefits. Other studies have found no difference in metabolic rate across different levels of enforced asymmetry among individuals with chronic stroke, but used methods that left some uncertainty to be resolved. METHODS: In this study, ten individuals with chronic stroke walked on a treadmill at participant-specific speeds while voluntarily altering step length asymmetry. We included only participants with clinically relevant self-selected asymmetry who were able to significantly alter asymmetry using visual biofeedback. Conditions included targeting zero asymmetry, self-selected asymmetry, and double the self-selected asymmetry. Participants were trained with the biofeedback system in one session, and data were collected in three subsequent sessions with repeated measures. Self-selected asymmetry was consistent across sessions. A similar protocol was conducted among unimpaired participants. RESULTS: Participants with chronic stroke substantially altered step length asymmetry using biofeedback, but this did not affect metabolic rate (ANOVA, p = 0.68). In unimpaired participants, self-selected step length asymmetry was close to zero and corresponded to the lowest metabolic energy cost (ANOVA, p = 6e-4). While the symmetry of unimpaired gait may be the result of energy cost minimization, self-selected step length asymmetry in individuals with chronic stroke cannot be explained by a similar least-effort drive. CONCLUSIONS: Interventions that encourage changes in step length asymmetry by manipulating metabolic energy consumption may be effective because these therapies would not have to overcome a metabolic penalty for altering asymmetry.

A comparison of three balance-assessment scales for patients after stroke with various levels of balance disorder.

It is often difficult for the clinician to choose the most appropriate balance-assessment measure. We wanted to facilitate this decision based on the stroke patient's functional abilities. The aim of our study was to compare three established scales [Berg Balance Scale (BBS), mini-BESTest (MBT) and Functional Gait Assessment (FGA)] in terms of responsiveness, floor and ceiling effects at different levels of ambulation as defined by the Functional Ambulation Classification (FAC). The 18-month prospective study included 88 patients after cerebral stroke, who were able to walk independently or with assistance of one person (FAC 2-6). BBS showed the highest relative gain in the FAC 2-3 group (17% of maximum scale score); in the other two groups (FAC 4-5 and FAC 6), MBT showed the highest relative gain (16 and 13%, respectively), followed by FGA (11 and 10%, respectively). Among the patients with initial FAC 2-3, a floor effect occurred with FGA, while a ceiling effect occurred with BBS among patients with initial FAC 6. Gain in FGA correlated slightly more with improvement detected by MBT (r = 0.60) than with BBS (r = 0.50). We can conclude that BBS seems to be suitable for stroke patients with initial FAC 2-5, whereas MBT and FGA for those with FAC 4-6.

Clinical assessment, management, and rehabilitation of walking impairment in MS: an expert review.

INTRODUCTION: One of the most common and life-altering consequences of Multiple Sclerosis (MS) is walking impairment. The distance, speed, and Gait pattern functions are components of the International Classification of Functioning, Disability, and Health (ICF) and are also predictors of dependency in terms of daily living activities in patients with MS (pwMS). AREAS COVERED: This article provides an overview of walking impairment in pwMS, with focus on the assessment of gait and the rehabilitation approaches. EXPERT OPINION: The authors recommend that pwMS undergo gait assessment integrating the ICF perspective using validated clinical outcome measures that cover spatiotemporal gait parameters. Moreover, assessment of walking speed with short walking capacity tests such as the timed 25-foot walk (T25FW) or the 10-m walk test (10 MWT) and tests for walking distance with middle distance tests such as the 2-min walk test (2MWT) and the 6-min walk test (6MWT). This review further highlights strategies that may restore walking function including pharmacological symptomatic treatment and non-pharmacological rehabilitation approaches such as exercise and task-specific training providing an appraisal of mobility targeted therapies to be considered when planning multidisciplinary comprehensive-care of pwMS. Finally, new and novel strategies such as motor imagery and rhythmic auditory stimulation have been developed to improve walking speed and distance in pwMS.

Kinematic gait asymmetry assessment using joint angle data in patients with chronic stroke-A normalized cross-correlation approach.

BACKGROUND: Gait asymmetry is an important characteristic often studied in stroke patients. Several methods have been used to define gait asymmetry using joint angles. However, these methods may require normative data from healthy individuals as reference points. This study used normalized cross-correlation (CCnorm) to define kinematic gait asymmetry in individuals after stroke and investigated the usefulness of this assessment. RESEARCH QUESTION: Is the analysis of kinematic gait asymmetry based on joint angle data using CCnorm useful for gait assessment in patients with chronic stroke? METHODS: The study involved 12 patients with chronic stroke. A motion analysis system was used to record gait speed, hip joint angles, knee joint angles, ankle joint angles, stance time, and swing time. The CCnorm was calculated using the flexion-extension joint angles of hip, knee, and ankle in the sagittal plane to assess the degree of kinematic gait asymmetry. The symmetry ratio (SR) was calculated using stance and swing times to assess the degree of temporal gait asymmetry. Clinical outcomes were measured using the Fugl-Meyer Assessment for the lower extremity (FMA-LE), Berg Balance Scale (BBS), and Functional Independence Measure (FIM). RESULTS: Hip CCnorm was correlated with SRswing (r=-0.612, p < 0.05). Knee CCnorm was correlated with SRstance (r = 0.807, p < 0.01), SRswing (r=-0.752, p < 0.05), gait speed (r = 0.654, p < 0.05), BBS (r = 0.717, p < 0.01), and FIM (r = 0.735, p < 0.01). SIGNIFICANCE: Hip and knee joint CCnorm appear to be useful tools for the assessment of gait asymmetry in stroke patients. In addition, kinematic gait asymmetry of the knee joint could reflect physical function, balance, and activities of daily living. These findings underline the importance of using kinematic gait asymmetry assessment in chronic stroke patients.

Ankle foot orthoses in cerebral palsy: Effects of ankle stiffness on trunk kinematics, gait stability and energy cost of walking.

In children with cerebral palsy (CP), rigid ventral shell ankle-foot orthoses (vAFOs) are often prescribed to reduce excessive knee flexion in stance and lower the energy cost of walking (ECW). However, how vAFOs affect ECW is a complex issue, as vAFOs may have an impact on lower limb biomechanics, upper body movements, and balance. Besides, the vAFO's biomechanical effect have been shown to be dependent on its stiffness around the ankle joint. We examined whether vAFO stiffness influences trunk movements and gait stability in CP, and whether there is a relationship between these factors and ECW. Fifteen children with spastic CP were prescribed vAFOs. Stiffness was varied into a rigid, stiff and flexible configuration. At baseline (shoes-only) and for each vAFO stiffness configuration, 3D-gait analyses and ECW-tests were performed. From the gait analyses, we derived trunk tilt, lateroflexion, and rotation range of motion (RoM) and the mediolateral and anteroposterior Margins of Stability (MoS) and their variability as measures of gait stability. With the ECW-test we determined the netEC. We found that wearing vAFOs significantly increased trunk lateroflexion (Wald χ2 = 33.7, p < 0.001), rotation RoM (Wald χ2 = 20.5, p < 0.001) and mediolateral gait instability (Wald χ2 = 10.4, p = 0.016). The extent of these effects partly depended on the stiffness of the vAFO. Significant relations between trunk movements, gait stability and ECW were found r = 0.57-0.81, p < 0.05), which indicates that trunk movements and gait stability should be taken into account when prescribing vAFOs to improve gait in children with CP walking with excessive knee flexion.

Reliability and Validity of the Functional Gait Assessment in Incomplete Spinal Cord Injury.

BACKGROUND: There are limited psychometrically sound measures to assess higher level balance in individuals with incomplete spinal cord injury (iSCI). OBJECTIVES: To evaluate interrater and intrarater reliability and convergent validity of the Functional Gait Assessment (FGA) in individuals with iSCI. METHODS: Twelve participants (11 male, 1 female) 32 to 73 years old with chronic motor iSCI, American Spinal Injury Association Impairment Scale C (n = 2) or D (n = 10), were included. Participants completed five outcome measures during a single test session including lower extremity motor scores from the International Standards for the Neurological Classification of Spinal Cord Injury, FGA, 10-Meter Walk Test (10MWT), Walking Index for Spinal Cord Injury (WISCI-II), and the Spinal Cord Injury Functional Ambulation Profile (SCI-FAP). RESULTS: Inter- and intrarater reliability for the FGA were excellent. Interrater reliability was excellent with intraclass correlation coefficient (ICC) scores greater than 0.92 (p < .001). Interrater reliability against an expert was also excellent for all raters, with an ICC greater than or equal to 0.92 (p < .01). Intrarater reliability was excellent with an ICC score of greater than 0.91 (p < .002) for all raters. Validity of the FGA with 10MWT was -0.90 (p = .000), FGA with WISCI-II was 0.74 (p = .006), and FGA with SCI-FAP was -0.83 (p = .001). CONCLUSION: The FGA is a reliable and valid outcome measure to use when assessing gait and balance in individuals with motor iSCI. The FGA provides clinicians with a single tool to utilize across a variety of neurologic diagnoses.

Vision-Based Assessment of Gait Features Associated With Falls in People With Dementia.

BACKGROUND: Gait impairments contribute to falls in people with dementia. In this study, we used a vision-based system to record episodes of walking over a 2-week period as participants moved naturally around their environment, and from these calculated spatiotemporal, stability, symmetry, and acceleration gait features. The aim of this study was to determine whether features of gait extracted from a vision-based system are associated with falls, and which of these features are most strongly associated with falling. METHODS: Fifty-two people with dementia admitted to a specialized dementia unit participated in this study. Thirty different features describing baseline gait were extracted from Kinect recordings of natural gait over a 2-week period. Baseline clinical and demographic measures were collected, and falls were tracked throughout the participants' admission. RESULTS: A total of 1,744 gait episodes were recorded (mean 33.5 ± 23.0 per participant) over a 2-week baseline period. There were a total of 78 falls during the study period (range 0-10). In single variable analyses, the estimated lateral margin of stability, step width, and step time variability were significantly associated with the number of falls during admission. In a multivariate model controlling for clinical and demographic variables, the estimated lateral margin of stability (p = .01) was remained associated with number of falls. CONCLUSIONS: Information about gait can be extracted from vision-based recordings of natural walking. In particular, the lateral margin of stability, a measure of lateral gait stability, is an important marker of short-term falls risk.

Quantitative gait assessment in children with 16p11.2 syndrome.

BACKGROUND: Neurodevelopmental disorders such as 16p11.2 syndrome are frequently associated with motor impairments including locomotion. The lack of precise measures of gait, combined with the challenges inherent in studying children with neurodevelopmental disorders, hinders quantitative motor assessments. Gait and balance are quantifiable measures that may help to refine the motor phenotype in 16p11.2. The characterization of motor profile is useful to study the trajectories of locomotion performance of children with genetic variants and may provide insights into neural pathway dysfunction based on genotype/phenotype model. METHODS: Thirty-six children (21 probands with 16p11.2 deletion and duplication mutation and 15 unaffected siblings), with a mean age of 8.5 years (range 3.2-15.4) and 55% male, were enrolled. Of the probands, 23% (n = 6) had a confirmed diagnosis of autism spectrum disorder (ASD) and were all male. Gait assessments included 6-min walk test (6MWT), 10-m walk/run test (10MWR), timed-up-and-go test (TUG), and spatio-temporal measurements of preferred- and fast-paced walking. The Pediatric Evaluation of Disability Inventory-Computer Adaptive Tests (PEDI-CAT), a caregiver-reported functional assessment, was administered. Measures of balance were calculated using percent time in double support and base of support. Analyses of the six children with ASD were described separately. RESULTS: Thirty-six participants completed the protocol. Compared with sibling controls, probands had significantly lower scores on the 6MWT (p = 0.04), 10MWR (p = 0.01), and TUG (p = 0.005). Group differences were also identified in base of support (p = 0.003). Probands had significantly lower PEDI-CAT scores in all domains including the mobility scale (p < 0.001). Using age-matched subsamples, the ASD and non-ASD genetic variant groups had larger base of support compared to the controls. In the fast-paced condition, all participants increased their velocity, and there was a corresponding decrease in percent time in double support compared to the preferred-pace condition in all participants. Only the ASD group presented with upper limb arm/hand stereotypies. CONCLUSIONS: Children with 16p11.2, with and without ASD, present with balance impairment during locomotion activities. Probands performed worse on functional assessments, and quantitative measures revealed differences in base of support. These results highlight the importance of using precise measures to differentiate motor dysfunction in children with neurodevelopmental disorders.

A wearable gait analysis protocol to support the choice of the appropriate ankle-foot orthosis: A comparative assessment in children with Cerebral Palsy.

BACKGROUND: Cerebral Palsy is, nowadays, the most common cause of pediatric disabilities, particularly debilitating for daily living activities. While the adoption of ankle-foot orthoses is very well established as gait treatment, the choice of the most appropriate orthotic configuration is not strongly supported by scientific evidence. The aim of this study was to develop an instrumented assessment protocol based on wearable gait analysis to support clinicians in ankle-foot orthoses configuration selection. METHODS: Ten children with spastic diplegic Cerebral Palsy were assessed (7 males, aged 4 to 11 years; all functionally classified as Gross Motor Function Classification System I or II, with clinical indication of conservative treatment through use of ankle-foot orthoses). They performed a 10Meter Walk Test in three conditions: barefoot and wearing alternatively a polypropylene hinged and solid ankle-foot orthosis accommodated in the same off-the-shelf shoe model, after 20 days of daily use of each configuration. An instrumented assessment protocol based on body-mounted magneto-inertial sensors was devised to derive spatio-temporal, gait stability and symmetry biomechanical parameters within an observational pre and post cross over design. FINDINGS: The analysis at the individual level quantitatively revealed how different patients benefited differently from the two orthoses. No general indications were obtained in favour of or against a specific configuration for the sample as a whole. INTERPRETATION: The proposed instrumented protocol represents a quantitative and useful tool to support the clinical selection of an appropriate orthotic treatment and, potentially, in evaluating its effectiveness.

Gait analysis with the Kinect v2: normative study with healthy individuals and comprehensive study of its sensitivity, validity, and reliability in individuals with stroke.

BACKGROUND: Gait is usually assessed by clinical tests, which may have poor accuracy and be biased, or instrumented systems, which potentially solve these limitations at the cost of being time-consuming and expensive. The different versions of the Microsoft Kinect have enabled human motion tracking without using wearable sensors at a low-cost and with acceptable reliability. This study aims: First, to determine the sensitivity of an open-access Kinect v2-based gait analysis system to motor disability and aging; Second, to determine its concurrent validity with standardized clinical tests in individuals with stroke; Third, to quantify its inter and intra-rater reliability, standard error of measurement, minimal detectable change; And, finally, to investigate its ability to identify fall risk after stroke. METHODS: The most widely used spatiotemporal and kinematic gait parameters of 82 individuals post-stroke and 355 healthy subjects were estimated with the Kinect v2-based system. In addition, participants with stroke were assessed with the Dynamic Gait Index, the 1-min Walking Test, and the 10-m Walking Test. RESULTS: The system successfully characterized the performance of both groups. Significant concurrent validity with correlations of variable strength was detected between all clinical tests and gait measures. Excellent inter and intra-rater reliability was evidenced for almost all measures. Minimal detectable change was variable, with poorer results for kinematic parameters. Almost all gait parameters proved to identify fall risk. CONCLUSIONS: Results suggest that although its limited sensitivity to kinematic parameters, the Kinect v2-based gait analysis could be used as a low-cost alternative to laboratory-grade systems to complement gait assessment in clinical settings.

Kin-FOG: Automatic Simulated Freezing of Gait (FOG) Assessment System for Parkinson's Disease.

Parkinson's disease (PD) is one of the leading neurological disorders in the world with an increasing incidence rate for the elderly. Freezing of Gait (FOG) is one of the most incapacitating symptoms for PD especially in the later stages of the disease. FOG is a short absence or reduction of ability to walk for PD patients which can cause fall, reduction in patients' quality of life, and even death. Existing FOG assessments by doctors are based on a patient's diaries and experts' manual video analysis which give subjective, inaccurate, and unreliable results. In the present research, an automatic FOG assessment system is designed for PD patients to provide objective information to neurologists about the FOG condition and the symptom's characteristics. The proposed FOG assessment system uses an RGB-D sensor based on Microsoft Kinect V2 for capturing data for 5 healthy subjects who are trained to imitate the FOG phenomenon. The proposed FOG assessment system is called "Kin-FOG". The analysis of foot joint trajectory of the motion captured by Kinect is used to find the FOG episodes. The evaluation of Kin-FOG is performed by two types of experiments, including: (1) simple walking (SW); and (2) walking with turning (WWT). Since the standing mode has features similar to a FOG episode, our Kin-FOG system proposes a method to distinguish between the FOG and standing episodes. Therefore, two general groups of experiments are conducted with standing state (WST) and without standing state (WOST). The gradient displacement of the angle between the foot and the ground is used as the feature for discriminating between FOG and standing modes. These experiments are conducted with different numbers of FOGs for getting reliable and general results. The Kin-FOG system reports the number of FOGs, their lengths, and the time slots when they occur. Experimental results demonstrate Kin-FOG has around 90% accuracy rate for FOG prediction in both experiments for different tasks (SW, WWT). The proposed Kin-FOG system can be used as a remote application at a patient's home or a rehabilitation clinic for sending a neurologist the required FOG information. The reliability and generality of the proposed system will be evaluated for bigger data sets of actual PD subjects.

Gaussian Process Trajectory Learning and Synthesis of Individualized Gait Motions.

This paper proposes a Gaussian process-based method for trajectory learning and generation of individualized gait motions at arbitrary user-designated walking speeds, intended to be used in generating reference motions for robotic gait rehabilitation systems. We utilize a nonlinear dimension reduction technique based on Gaussian process dynamical models (GPDMs), in which the internal dynamics is modeled as a second-order Markov process evolving in a lower-dimensional latent space. After the GPDM parameters are identified with training data obtained from gait motions of healthy subjects walking at different speeds, our method then employs Gaussian process regression (GPR) to predict the initial two states of the latent space dynamics from any arbitrary desired walking speed and the anthropometric parameters of the test subject. Motions are then generated by directly mapping the latent space dynamics to joint trajectories. Experimental studies involving more than 100 subjects indicate that our method generates gait patterns with 30% less mean square prediction errors compared to recent state-of-the-art methods, while also allowing for arbitrary user-specified walking speeds.

Single and dual tandem gait assessment post concussion: What performance time is clinically relevant across adult ages and what can influence results?

AIM: The three-metre tandem gait test (TG) is used to assess postural control during locomotion following sports concussion. However, values used to determine a pass/fail result are currently based on young athletic populations. Times for test completion may be influenced by several intrinsic or extrinsic factors. The aim of this study was to collate healthy individual single, dual task as well as dual task cost - motor TG times for a non-elite athlete population, across several age groups, and to investigate several potential influencing factors. METHODS: Healthy individuals aged 18-55+, who had never experienced a concussion completed single and dual task TG following the SCAT5 protocol. A separate group (n = 20, age, foot length and body mass index matched) performed the tests with alternate instructions. RESULTS: Mean best TG time for all participants were: single task 21.03 (±5.26s), dual task 29.59 (±9.84s) and DTC-motor 8.57 (±7.5s:41.7%). Age and foot length but not specificity of verbal instructions were related to TG times. Significantly slower single and dual task times were identified for the 55 + age group when compared to the three youngest groups (p < 0.01). No difference was seen for DTC-motor time or % between age groups (p > 0.05). CONCLUSION: Healthy individual data collected exceeded previously reported average times. Faster times were evident in younger participants and those with longer foot length. Results from this study can be used as a reliable guideline to inform clinical decisions around the pass/fail result of TGT across age ranges in non-elite athlete populations post-concussion.

Development of the clinical assessment scale in autoimmune encephalitis.

OBJECTIVE: There is no scale for rating the severity of autoimmune encephalitis (AE). In this study, we aimed to develop a novel scale for rating severity in patients with diverse AE syndromes and to verify the reliability and validity of the developed scale. METHODS: The key items were generated by a panel of experts and selected according to content validity ratios. The developed scale was initially applied to 50 patients with AE (development cohort) to evaluate its acceptability, reproducibility, internal consistency, and construct validity. Then, the scale was applied to another independent cohort (validation cohort, n = 38). RESULTS: A new scale consisting of 9 items (seizure, memory dysfunction, psychiatric symptoms, consciousness, language problems, dyskinesia/dystonia, gait instability and ataxia, brainstem dysfunction, and weakness) was developed. Each item was assigned a value of up to 3 points. The total score could therefore range from 0 to 27. We named the scale the Clinical Assessment Scale in Autoimmune Encephalitis (CASE). The new scale showed excellent interobserver (intraclass correlation coefficient [ICC] = 0.97) and intraobserver (ICC = 0.96) reliability for total scores, was highly correlated with modified Rankin scale (r = 0.86, p < 0.001), and had acceptable internal consistency (Cronbach α = 0.88). Additionally, in the validation cohort, the scale showed high interobserver reliability (ICC = 0.99) and internal consistency (Cronbach α = 0.92). INTERPRETATION: CASE is a novel clinical scale for AE with a high level of clinimetric properties. It would be suitable for application in clinical practice and might help overcome the limitations of current outcome scales for AE. ANN NEUROL 2019;85:352-358.